The libiberty library is a collection of subroutines used by various
GNU programs. It is available under the Library General Public
License; for more information, see GNU LESSER GENERAL PUBLIC LICENSE.
To date, libiberty is generally not installed on its own. It has evolved
over years but does not have its own version number nor release schedule.
Possibly the easiest way to use libiberty in your projects is to drop the
libiberty code into your project’s sources, and to build the library along
with your own sources; the library would then be linked in at the end. This
prevents any possible version mismatches with other copies of libiberty
elsewhere on the system.
Passing --enable-install-libiberty to the configure
script when building libiberty causes the header files and archive library
to be installed when make install is run. This option also takes
an (optional) argument to specify the installation location, in the same
manner as --prefix.
For your own projects, an approach which offers stability and flexibility
is to include libiberty with your code, but allow the end user to optionally
choose to use a previously-installed version instead. In this way the
user may choose (for example) to install libiberty as part of GCC, and use
that version for all software built with that compiler. (This approach
has proven useful with software using the GNU readline library.)
Making use of libiberty code usually requires that you include one or more
header files from the libiberty distribution. (They will be named as
necessary in the function descriptions.) At link time, you will need to
add -liberty to your link command invocation.
Functions contained in libiberty can be divided into three general categories.
Certain operating systems do not provide functions which have since
become standardized, or at least common. For example, the Single
Unix Specification Version 2 requires that the basename
function be provided, but an OS which predates that specification
might not have this function. This should not prevent well-written
code from running on such a system.
Similarly, some functions exist only among a particular “flavor”
or “family” of operating systems. As an example, the bzero
function is often not present on systems outside the BSD-derived
family of systems.
Many such functions are provided in libiberty. They are quickly
listed here with little description, as systems which lack them
become less and less common. Each function foo is implemented
in foo.c but not declared in any libiberty header file; more
comments and caveats for each function’s implementation are often
available in the source file. Generally, the function can simply
be declared as extern.
Some functions have extremely limited implementations on different
platforms. Other functions are tedious to use correctly; for example,
proper use of malloc calls for the return value to be checked and
appropriate action taken if memory has been exhausted. A group of
“replacement functions” is available in libiberty to address these issues
for some of the most commonly used subroutines.
All of these functions are declared in the libiberty.h header file. Many of the implementations will use preprocessor macros set by GNU Autoconf, if you decide to make use of that program. Some of these functions may call one another.
The functions beginning with the letter ‘x’ are wrappers around standard functions; the functions provided by the system environment are called and their results checked before the results are passed back to client code. If the standard functions fail, these wrappers will terminate the program. Thus, these versions can be used with impunity.
The existence and implementation of the atexit routine varies
amongst the flavors of Unix. libiberty provides an unvarying dependable
implementation via xatexit and xexit.
These are a set of routines to facilitate programming with the system
errno interface. The libiberty source file strerror.c
contains a good deal of documentation for these functions.
libiberty includes additional functionality above and beyond standard
functions, which has proven generically useful in GNU programs, such as
obstacks and regex. These functions are often copied from other
projects as they gain popularity, and are included here to provide a
central location from which to use, maintain, and distribute them.
An obstack is a pool of memory containing a stack of objects. You can create any number of separate obstacks, and then allocate objects in specified obstacks. Within each obstack, the last object allocated must always be the first one freed, but distinct obstacks are independent of each other.
Aside from this one constraint of order of freeing, obstacks are totally general: an obstack can contain any number of objects of any size. They are implemented with macros, so allocation is usually very fast as long as the objects are usually small. And the only space overhead per object is the padding needed to start each object on a suitable boundary.
The utilities for manipulating obstacks are declared in the header file obstack.h.
An obstack is represented by a data structure of type struct
obstack. This structure has a small fixed size; it records the status
of the obstack and how to find the space in which objects are allocated.
It does not contain any of the objects themselves. You should not try
to access the contents of the structure directly; use only the macros
described in this chapter.
You can declare variables of type struct obstack and use them as
obstacks, or you can allocate obstacks dynamically like any other kind
of object. Dynamic allocation of obstacks allows your program to have a
variable number of different stacks. (You can even allocate an
obstack structure in another obstack, but this is rarely useful.)
All the macros that work with obstacks require you to specify which
obstack to use. You do this with a pointer of type struct obstack
*. In the following, we often say “an obstack” when strictly
speaking the object at hand is such a pointer.
The objects in the obstack are packed into large blocks called
chunks. The struct obstack structure points to a chain of
the chunks currently in use.
The obstack library obtains a new chunk whenever you allocate an object
that won’t fit in the previous chunk. Since the obstack library manages
chunks automatically, you don’t need to pay much attention to them, but
you do need to supply a function which the obstack library should use to
get a chunk. Usually you supply a function which uses malloc
directly or indirectly. You must also supply a function to free a chunk.
These matters are described in the following section.
Each source file in which you plan to use obstacks must include the header file obstack.h, like this:
#include <obstack.h>
Also, if the source file uses the macro obstack_init, it must
declare or define two macros that will be called by the
obstack library. One, obstack_chunk_alloc, is used to allocate
the chunks of memory into which objects are packed. The other,
obstack_chunk_free, is used to return chunks when the objects in
them are freed. These macros should appear before any use of obstacks
in the source file.
Usually these are defined to use malloc via the intermediary
xmalloc (see Unconstrained Allocation in The GNU C Library Reference Manual). This is done with
the following pair of macro definitions:
#define obstack_chunk_alloc xmalloc #define obstack_chunk_free free
Though the memory you get using obstacks really comes from malloc,
using obstacks is faster because malloc is called less often, for
larger blocks of memory. See Obstack Chunks, for full details.
At run time, before the program can use a struct obstack object
as an obstack, it must initialize the obstack by calling
obstack_init or one of its variants, obstack_begin,
obstack_specify_allocation, or
obstack_specify_allocation_with_arg.
int obstack_init (struct obstack *obstack-ptr) ¶Initialize obstack obstack-ptr for allocation of objects. This
macro calls the obstack’s obstack_chunk_alloc function. If
allocation of memory fails, the function pointed to by
obstack_alloc_failed_handler is called. The obstack_init
macro always returns 1 (Compatibility notice: Former versions of
obstack returned 0 if allocation failed).
Here are two examples of how to allocate the space for an obstack and initialize it. First, an obstack that is a static variable:
static struct obstack myobstack; ... obstack_init (&myobstack);
Second, an obstack that is itself dynamically allocated:
struct obstack *myobstack_ptr = (struct obstack *) xmalloc (sizeof (struct obstack)); obstack_init (myobstack_ptr);
int obstack_begin (struct obstack *obstack-ptr, size_t chunk_size) ¶Like obstack_init, but specify chunks to be at least
chunk_size bytes in size.
int obstack_specify_allocation (struct obstack *obstack-ptr, size_t chunk_size, size_t alignment, void *(*chunkfun) (size_t), void (*freefun) (void *)) ¶Like obstack_init, specifying chunk size, chunk
alignment, and memory allocation functions. A chunk_size or
alignment of zero results in the default size or alignment
respectively being used.
int obstack_specify_allocation_with_arg (struct obstack *obstack-ptr, size_t chunk_size, size_t alignment, void *(*chunkfun) (void *, size_t), void (*freefun) (void *, void *), void *arg) ¶Like obstack_specify_allocation, but specifying memory
allocation functions that take an extra first argument, arg.
The value of this variable is a pointer to a function that
obstack uses when obstack_chunk_alloc fails to allocate
memory. The default action is to print a message and abort.
You should supply a function that either calls exit
(see Program Termination in The GNU C Library Reference Manual)
or longjmp and doesn’t return.
void my_obstack_alloc_failed (void) ... obstack_alloc_failed_handler = &my_obstack_alloc_failed;
The most direct way to allocate an object in an obstack is with
obstack_alloc, which is invoked almost like malloc.
void * obstack_alloc (struct obstack *obstack-ptr, size_t size) ¶This allocates an uninitialized block of size bytes in an obstack
and returns its address. Here obstack-ptr specifies which obstack
to allocate the block in; it is the address of the struct obstack
object which represents the obstack. Each obstack macro
requires you to specify an obstack-ptr as the first argument.
This macro calls the obstack’s obstack_chunk_alloc function if
it needs to allocate a new chunk of memory; it calls
obstack_alloc_failed_handler if allocation of memory by
obstack_chunk_alloc failed.
For example, here is a function that allocates a copy of a string str
in a specific obstack, which is in the variable string_obstack:
struct obstack string_obstack;
char *
copystring (char *string)
{
size_t len = strlen (string) + 1;
char *s = (char *) obstack_alloc (&string_obstack, len);
memcpy (s, string, len);
return s;
}
To allocate a block with specified contents, use the macro obstack_copy.
void * obstack_copy (struct obstack *obstack-ptr, void *address, size_t size) ¶This allocates a block and initializes it by copying size
bytes of data starting at address. It calls
obstack_alloc_failed_handler if allocation of memory by
obstack_chunk_alloc failed.
void * obstack_copy0 (struct obstack *obstack-ptr, void *address, size_t size) ¶Like obstack_copy, but appends an extra byte containing a null
character. This extra byte is not counted in the argument size.
The obstack_copy0 macro is convenient for copying a sequence
of characters into an obstack as a null-terminated string. Here is an
example of its use:
char *
obstack_savestring (char *addr, size_t size)
{
return obstack_copy0 (&myobstack, addr, size);
}
Contrast this with the previous example of savestring using
malloc (see Basic Allocation in The GNU C Library Reference Manual).
To free an object allocated in an obstack, use the macro
obstack_free. Since the obstack is a stack of objects, freeing
one object automatically frees all other objects allocated more recently
in the same obstack.
void obstack_free (struct obstack *obstack-ptr, void *object) ¶If object is a null pointer, everything allocated in the obstack is freed. Otherwise, object must be the address of an object allocated in the obstack. Then object is freed, along with everything allocated in obstack since object.
Note that if object is a null pointer, the result is an
uninitialized obstack. To free all memory in an obstack but leave it
valid for further allocation, call obstack_free with the address
of the first object allocated on the obstack:
obstack_free (obstack_ptr, first_object_allocated_ptr);
Recall that the objects in an obstack are grouped into chunks. When all the objects in a chunk become free, the obstack library automatically frees the chunk (see Preparing for Using Obstacks). Then other obstacks, or non-obstack allocation, can reuse the space of the chunk.
The interfaces for using obstacks are shown here as functions to specify the return type and argument types, but they are really defined as macros. This means that the arguments don’t actually have types, but they generally behave as if they have the types shown. You can call these macros like functions, but you cannot use them in any other way (for example, you cannot take their address).
Calling the macros requires a special precaution: namely, the first operand (the obstack pointer) may not contain any side effects, because it may be computed more than once. For example, if you write this:
obstack_alloc (get_obstack (), 4);
you will find that get_obstack may be called several times.
If you use *obstack_list_ptr++ as the obstack pointer argument,
you will get very strange results since the incrementation may occur
several times.
If you use the GNU C compiler, this precaution is not necessary, because various language extensions in GNU C permit defining the macros so as to compute each argument only once.
Note that arguments other than the first will only be evaluated once, even when not using GNU C.
obstack.h does declare a number of functions,
_obstack_begin, _obstack_begin_1,
_obstack_newchunk, _obstack_free, and
_obstack_memory_used. You should not call these directly.
Because memory in obstack chunks is used sequentially, it is possible to build up an object step by step, adding one or more bytes at a time to the end of the object. With this technique, you do not need to know how much data you will put in the object until you come to the end of it. We call this the technique of growing objects. The special macros for adding data to the growing object are described in this section.
You don’t need to do anything special when you start to grow an object.
Using one of the macros to add data to the object automatically
starts it. However, it is necessary to say explicitly when the object is
finished. This is done with obstack_finish.
The actual address of the object thus built up is not known until the object is finished. Until then, it always remains possible that you will add so much data that the object must be copied into a new chunk.
While the obstack is in use for a growing object, you cannot use it for ordinary allocation of another object. If you try to do so, the space already added to the growing object will become part of the other object.
void obstack_blank (struct obstack *obstack-ptr, size_t size) ¶The most basic macro for adding to a growing object is
obstack_blank, which adds space without initializing it.
void obstack_grow (struct obstack *obstack-ptr, void *data, size_t size) ¶To add a block of initialized space, use obstack_grow, which is
the growing-object analogue of obstack_copy. It adds size
bytes of data to the growing object, copying the contents from
data.
void obstack_grow0 (struct obstack *obstack-ptr, void *data, size_t size) ¶This is the growing-object analogue of obstack_copy0. It adds
size bytes copied from data, followed by an additional null
character.
void obstack_1grow (struct obstack *obstack-ptr, char c) ¶To add one character at a time, use obstack_1grow.
It adds a single byte containing c to the growing object.
void obstack_ptr_grow (struct obstack *obstack-ptr, void *data) ¶Adding the value of a pointer one can use
obstack_ptr_grow. It adds sizeof (void *) bytes
containing the value of data.
void obstack_int_grow (struct obstack *obstack-ptr, int data) ¶A single value of type int can be added by using
obstack_int_grow. It adds sizeof (int) bytes to
the growing object and initializes them with the value of data.
void * obstack_finish (struct obstack *obstack-ptr) ¶When you are finished growing the object, use
obstack_finish to close it off and return its final address.
Once you have finished the object, the obstack is available for ordinary allocation or for growing another object.
When you build an object by growing it, you will probably need to know
afterward how long it became. You need not keep track of this as you grow
the object, because you can find out the length from the obstack
with obstack_object_size, before finishing the object.
size_t obstack_object_size (struct obstack *obstack-ptr) ¶This macro returns the current size of the growing object, in bytes.
Remember to call obstack_object_size before finishing the object.
After it is finished, obstack_object_size will return zero.
If you have started growing an object and wish to cancel it, you should finish it and then free it, like this:
obstack_free (obstack_ptr, obstack_finish (obstack_ptr));
This has no effect if no object was growing.
The usual macros for growing objects incur overhead for checking whether there is room for the new growth in the current chunk. If you are frequently constructing objects in small steps of growth, this overhead can be significant.
You can reduce the overhead by using special “fast growth” macros that grow the object without checking. In order to have a robust program, you must do the checking yourself. If you do this checking in the simplest way each time you are about to add data to the object, you have not saved anything, because that is what the ordinary growth macros do. But if you can arrange to check less often, or check more efficiently, then you make the program faster.
obstack_room returns the amount of room available
in the current chunk.
size_t obstack_room (struct obstack *obstack-ptr) ¶This returns the number of bytes that can be added safely to the current growing object (or to an object about to be started) in obstack obstack using the fast growth macros.
While you know there is room, you can use these fast growth macros for adding data to a growing object:
void obstack_1grow_fast (struct obstack *obstack-ptr, char c) ¶obstack_1grow_fast adds one byte containing the
character c to the growing object in obstack obstack-ptr.
void obstack_ptr_grow_fast (struct obstack *obstack-ptr, void *data) ¶obstack_ptr_grow_fast adds sizeof (void *)
bytes containing the value of data to the growing object in
obstack obstack-ptr.
void obstack_int_grow_fast (struct obstack *obstack-ptr, int data) ¶obstack_int_grow_fast adds sizeof (int) bytes
containing the value of data to the growing object in obstack
obstack-ptr.
void obstack_blank_fast (struct obstack *obstack-ptr, size_t size) ¶obstack_blank_fast adds size bytes to the
growing object in obstack obstack-ptr without initializing them.
When you check for space using obstack_room and there is not
enough room for what you want to add, the fast growth macros
are not safe. In this case, simply use the corresponding ordinary
growth macro instead. Very soon this will copy the object to a
new chunk; then there will be lots of room available again.
So, each time you use an ordinary growth macro, check afterward for
sufficient space using obstack_room. Once the object is copied
to a new chunk, there will be plenty of space again, so the program will
start using the fast growth macros again.
Here is an example:
void
add_string (struct obstack *obstack, const char *ptr, size_t len)
{
while (len > 0)
{
size_t room = obstack_room (obstack);
if (room == 0)
{
/* Not enough room. Add one character slowly,
which may copy to a new chunk and make room. */
obstack_1grow (obstack, *ptr++);
len--;
}
else
{
if (room > len)
room = len;
/* Add fast as much as we have room for. */
len -= room;
while (room-- > 0)
obstack_1grow_fast (obstack, *ptr++);
}
}
}
You can use obstack_blank_fast with a “negative” size
argument to make the current object smaller. Just don’t try to shrink
it beyond zero length—there’s no telling what will happen if you do
that. Earlier versions of obstacks allowed you to use
obstack_blank to shrink objects. This will no longer work.
Here are macros that provide information on the current status of allocation in an obstack. You can use them to learn about an object while still growing it.
void * obstack_base (struct obstack *obstack-ptr) ¶This macro returns the tentative address of the beginning of the currently growing object in obstack-ptr. If you finish the object immediately, it will have that address. If you make it larger first, it may outgrow the current chunk—then its address will change!
If no object is growing, this value says where the next object you allocate will start (once again assuming it fits in the current chunk).
void * obstack_next_free (struct obstack *obstack-ptr) ¶This macro returns the address of the first free byte in the current
chunk of obstack obstack-ptr. This is the end of the currently
growing object. If no object is growing, obstack_next_free
returns the same value as obstack_base.
size_t obstack_object_size (struct obstack *obstack-ptr) ¶This macro returns the size in bytes of the currently growing object. This is equivalent to
((size_t) (obstack_next_free (obstack-ptr) - obstack_base (obstack-ptr)))
Each obstack has an alignment boundary; each object allocated in the obstack automatically starts on an address that is a multiple of the specified boundary. By default, this boundary is aligned so that the object can hold any type of data.
To access an obstack’s alignment boundary, use the macro
obstack_alignment_mask.
size_t obstack_alignment_mask (struct obstack *obstack-ptr) ¶The value is a bit mask; a bit that is 1 indicates that the corresponding bit in the address of an object should be 0. The mask value should be one less than a power of 2; the effect is that all object addresses are multiples of that power of 2. The default value of the mask is a value that allows aligned objects to hold any type of data: for example, if its value is 3, any type of data can be stored at locations whose addresses are multiples of 4. A mask value of 0 means an object can start on any multiple of 1 (that is, no alignment is required).
The expansion of the macro obstack_alignment_mask is an lvalue,
so you can alter the mask by assignment. For example, this statement:
obstack_alignment_mask (obstack_ptr) = 0;
has the effect of turning off alignment processing in the specified obstack.
Note that a change in alignment mask does not take effect until
after the next time an object is allocated or finished in the
obstack. If you are not growing an object, you can make the new
alignment mask take effect immediately by calling obstack_finish.
This will finish a zero-length object and then do proper alignment for
the next object.
Obstacks work by allocating space for themselves in large chunks, and then parceling out space in the chunks to satisfy your requests. Chunks are normally 4096 bytes long unless you specify a different chunk size. The chunk size includes 8 bytes of overhead that are not actually used for storing objects. Regardless of the specified size, longer chunks will be allocated when necessary for long objects.
The obstack library allocates chunks by calling the function
obstack_chunk_alloc, which you must define. When a chunk is no
longer needed because you have freed all the objects in it, the obstack
library frees the chunk by calling obstack_chunk_free, which you
must also define.
These two must be defined (as macros) or declared (as functions) in each
source file that uses obstack_init (see Creating Obstacks).
Most often they are defined as macros like this:
#define obstack_chunk_alloc malloc #define obstack_chunk_free free
Note that these are simple macros (no arguments). Macro definitions with
arguments will not work! It is necessary that obstack_chunk_alloc
or obstack_chunk_free, alone, expand into a function name if it is
not itself a function name.
If you allocate chunks with malloc, the chunk size should be a
power of 2. The default chunk size, 4096, was chosen because it is long
enough to satisfy many typical requests on the obstack yet short enough
not to waste too much memory in the portion of the last chunk not yet used.
size_t obstack_chunk_size (struct obstack *obstack-ptr) ¶This returns the chunk size of the given obstack.
Since this macro expands to an lvalue, you can specify a new chunk size by assigning it a new value. Doing so does not affect the chunks already allocated, but will change the size of chunks allocated for that particular obstack in the future. It is unlikely to be useful to make the chunk size smaller, but making it larger might improve efficiency if you are allocating many objects whose size is comparable to the chunk size. Here is how to do so cleanly:
if (obstack_chunk_size (obstack_ptr) < new-chunk-size) obstack_chunk_size (obstack_ptr) = new-chunk-size;
Here is a summary of all the macros associated with obstacks. Each
takes the address of an obstack (struct obstack *) as its first
argument.
int obstack_init (struct obstack *obstack-ptr)Initialize use of an obstack. See Creating Obstacks.
int obstack_begin (struct obstack *obstack-ptr, size_t chunk_size)Initialize use of an obstack, with an initial chunk of chunk_size bytes.
int obstack_specify_allocation (struct obstack *obstack-ptr, size_t chunk_size, size_t alignment, void *(*chunkfun) (size_t), void (*freefun) (void *))Initialize use of an obstack, specifying intial chunk size, chunk alignment, and memory allocation functions.
int obstack_specify_allocation_with_arg (struct obstack *obstack-ptr, size_t chunk_size, size_t alignment, void *(*chunkfun) (void *, size_t), void (*freefun) (void *, void *), void *arg)Like obstack_specify_allocation, but specifying memory
allocation functions that take an extra first argument, arg.
void *obstack_alloc (struct obstack *obstack-ptr, size_t size)Allocate an object of size uninitialized bytes. See Allocation in an Obstack.
void *obstack_copy (struct obstack *obstack-ptr, void *address, size_t size)Allocate an object of size bytes, with contents copied from address. See Allocation in an Obstack.
void *obstack_copy0 (struct obstack *obstack-ptr, void *address, size_t size)Allocate an object of size+1 bytes, with size of them copied from address, followed by a null character at the end. See Allocation in an Obstack.
void obstack_free (struct obstack *obstack-ptr, void *object)Free object (and everything allocated in the specified obstack more recently than object). See Freeing Objects in an Obstack.
void obstack_blank (struct obstack *obstack-ptr, size_t size)Add size uninitialized bytes to a growing object. See Growing Objects.
void obstack_grow (struct obstack *obstack-ptr, void *address, size_t size)Add size bytes, copied from address, to a growing object. See Growing Objects.
void obstack_grow0 (struct obstack *obstack-ptr, void *address, size_t size)Add size bytes, copied from address, to a growing object, and then add another byte containing a null character. See Growing Objects.
void obstack_1grow (struct obstack *obstack-ptr, char data-char)Add one byte containing data-char to a growing object. See Growing Objects.
void *obstack_finish (struct obstack *obstack-ptr)Finalize the object that is growing and return its permanent address. See Growing Objects.
size_t obstack_object_size (struct obstack *obstack-ptr)Get the current size of the currently growing object. See Growing Objects.
void obstack_blank_fast (struct obstack *obstack-ptr, size_t size)Add size uninitialized bytes to a growing object without checking that there is enough room. See Extra Fast Growing Objects.
void obstack_1grow_fast (struct obstack *obstack-ptr, char data-char)Add one byte containing data-char to a growing object without checking that there is enough room. See Extra Fast Growing Objects.
size_t obstack_room (struct obstack *obstack-ptr)Get the amount of room now available for growing the current object. See Extra Fast Growing Objects.
size_t obstack_alignment_mask (struct obstack *obstack-ptr)The mask used for aligning the beginning of an object. This is an lvalue. See Alignment of Data in Obstacks.
size_t obstack_chunk_size (struct obstack *obstack-ptr)The size for allocating chunks. This is an lvalue. See Obstack Chunks.
void *obstack_base (struct obstack *obstack-ptr)Tentative starting address of the currently growing object. See Status of an Obstack.
void *obstack_next_free (struct obstack *obstack-ptr)Address just after the end of the currently growing object. See Status of an Obstack.
void* alloca (size_t size) ¶This function allocates memory which will be automatically reclaimed
after the procedure exits. The libiberty implementation does not free
the memory immediately but will do so eventually during subsequent
calls to this function. Memory is allocated using xmalloc under
normal circumstances.
The header file alloca-conf.h can be used in conjunction with the
GNU Autoconf test AC_FUNC_ALLOCA to test for and properly make
available this function. The AC_FUNC_ALLOCA test requires that
client code use a block of preprocessor code to be safe (see the Autoconf
manual for more); this header incorporates that logic and more, including
the possibility of a GCC built-in function.
int asprintf (char **resptr, const char *format, ...) ¶Like sprintf, but instead of passing a pointer to a buffer, you
pass a pointer to a pointer. This function will compute the size of
the buffer needed, allocate memory with malloc, and store a
pointer to the allocated memory in *resptr. The value
returned is the same as sprintf would return. If memory could
not be allocated, minus one is returned and NULL is stored in
*resptr.
int atexit (void (*f)()) ¶Causes function f to be called at exit. Returns 0.
char* basename (const char *name) ¶Returns a pointer to the last component of pathname name. Behavior is undefined if the pathname ends in a directory separator.
int bcmp (char *x, char *y, int count) ¶Compares the first count bytes of two areas of memory. Returns zero if they are the same, nonzero otherwise. Returns zero if count is zero. A nonzero result only indicates a difference, it does not indicate any sorting order (say, by having a positive result mean x sorts before y).
void bcopy (char *in, char *out, int length) ¶Copies length bytes from memory region in to region
out. The use of bcopy is deprecated in new programs.
void* bsearch (const void *key, const void *base, size_t nmemb, size_t size, int (*compar)(const void *, const void *)) ¶Performs a search over an array of nmemb elements pointed to by base for a member that matches the object pointed to by key. The size of each member is specified by size. The array contents should be sorted in ascending order according to the compar comparison function. This routine should take two arguments pointing to the key and to an array member, in that order, and should return an integer less than, equal to, or greater than zero if the key object is respectively less than, matching, or greater than the array member.
void* bsearch_r (const void *key, const void *base, size_t nmemb, size_t size, int (*compar)(const void *, const void *, void *), void *arg) ¶Performs a search over an array of nmemb elements pointed to by
base for a member that matches the object pointed to by key.
The size of each member is specified by size. The array contents
should be sorted in ascending order according to the compar
comparison function. This routine should take three arguments: the first
two point to the key and to an array member, and the last is passed
down unchanged from bsearch_r’s last argument. It should return an
integer less than, equal to, or greater than zero if the key object
is respectively less than, matching, or greater than the array member.
char** buildargv (char *sp) ¶Given a pointer to a string, parse the string extracting fields
separated by whitespace and optionally enclosed within either single
or double quotes (which are stripped off), and build a vector of
pointers to copies of the string for each field. The input string
remains unchanged. The last element of the vector is followed by a
NULL element.
All of the memory for the pointer array and copies of the string
is obtained from xmalloc. All of the memory can be returned to the
system with the single function call freeargv, which takes the
returned result of buildargv, as it’s argument.
Returns a pointer to the argument vector if successful. Returns
NULL if sp is NULL or if there is insufficient
memory to complete building the argument vector.
If the input is a null string (as opposed to a NULL pointer),
then buildarg returns an argument vector that has one arg, a null
string.
void bzero (char *mem, int count) ¶Zeros count bytes starting at mem. Use of this function
is deprecated in favor of memset.
void* calloc (size_t nelem, size_t elsize) ¶Uses malloc to allocate storage for nelem objects of
elsize bytes each, then zeros the memory.
int canonical_filename_eq (const char *a, const char *b) ¶Return non-zero if file names a and b are equivalent.
This function compares the canonical versions of the filenames as returned by
lrealpath(), so that so that different file names pointing to the same
underlying file are treated as being identical.
char* choose_temp_base (void) ¶Return a prefix for temporary file names or NULL if unable to
find one. The current directory is chosen if all else fails so the
program is exited if a temporary directory can’t be found (mktemp
fails). The buffer for the result is obtained with xmalloc.
This function is provided for backwards compatibility only. Its use is not recommended.
const char* choose_tmpdir () ¶Returns a pointer to a directory path suitable for creating temporary files in.
long clock (void) ¶Returns an approximation of the CPU time used by the process as a
clock_t; divide this number by ‘CLOCKS_PER_SEC’ to get the
number of seconds used.
char* concat (const char *s1, const char *s2, …, NULL) ¶Concatenate zero or more of strings and return the result in freshly
xmalloced memory. The argument list is terminated by the first
NULL pointer encountered. Pointers to empty strings are ignored.
int countargv (char * const *argv) ¶Return the number of elements in argv. Returns zero if argv is NULL.
unsigned int crc32 (const unsigned char *buf, int len, unsigned int init) ¶Compute the 32-bit CRC of buf which has length len. The starting value is init; this may be used to compute the CRC of data split across multiple buffers by passing the return value of each call as the init parameter of the next.
This is used by the gdb remote protocol for the ‘qCRC’
command. In order to get the same results as gdb for a block of data,
you must pass the first CRC parameter as 0xffffffff.
This CRC can be specified as:
Width : 32 Poly : 0x04c11db7 Init : parameter, typically 0xffffffff RefIn : false RefOut : false XorOut : 0
This differs from the "standard" CRC-32 algorithm in that the values are not reflected, and there is no final XOR value. These differences make it easy to compose the values of multiple blocks.
char** dupargv (char * const *vector) ¶Duplicate an argument vector. Simply scans through vector,
duplicating each argument until the terminating NULL is found.
Returns a pointer to the argument vector if successful. Returns
NULL if there is insufficient memory to complete building the
argument vector.
int errno_max (void) ¶Returns the maximum errno value for which a corresponding
symbolic name or message is available. Note that in the case where we
use the sys_errlist supplied by the system, it is possible for
there to be more symbolic names than messages, or vice versa. In
fact, the manual page for perror(3C) explicitly warns that one
should check the size of the table (sys_nerr) before indexing
it, since new error codes may be added to the system before they are
added to the table. Thus sys_nerr might be smaller than value
implied by the largest errno value defined in <errno.h>.
We return the maximum value that can be used to obtain a meaningful symbolic name or message.
void expandargv (int *argcp, char ***argvp) ¶The argcp and argvp arguments are pointers to the usual
argc and argv arguments to main. This function
looks for arguments that begin with the character ‘@’. Any such
arguments are interpreted as “response files”. The contents of the
response file are interpreted as additional command line options. In
particular, the file is separated into whitespace-separated strings;
each such string is taken as a command-line option. The new options
are inserted in place of the option naming the response file, and
*argcp and *argvp will be updated. If the value of
*argvp is modified by this function, then the new value has
been dynamically allocated and can be deallocated by the caller with
freeargv. However, most callers will simply call
expandargv near the beginning of main and allow the
operating system to free the memory when the program exits.
int fdmatch (int fd1, int fd2) ¶Check to see if two open file descriptors refer to the same file.
This is useful, for example, when we have an open file descriptor for
an unnamed file, and the name of a file that we believe to correspond
to that fd. This can happen when we are exec’d with an already open
file (stdout for example) or from the SVR4 /proc calls
that return open file descriptors for mapped address spaces. All we
have to do is open the file by name and check the two file descriptors
for a match, which is done by comparing major and minor device numbers
and inode numbers.
FILE * fdopen_unlocked (int fildes, const char * mode) ¶Opens and returns a FILE pointer via fdopen. If the
operating system supports it, ensure that the stream is setup to avoid
any multi-threaded locking. Otherwise return the FILE pointer
unchanged.
int ffs (int valu) ¶Find the first (least significant) bit set in valu. Bits are numbered from right to left, starting with bit 1 (corresponding to the value 1). If valu is zero, zero is returned.
int filename_cmp (const char *s1, const char *s2) ¶Return zero if the two file names s1 and s2 are equivalent.
If not equivalent, the returned value is similar to what strcmp
would return. In other words, it returns a negative value if s1
is less than s2, or a positive value if s2 is greater than
s2.
This function does not normalize file names. As a result, this function will treat filenames that are spelled differently as different even in the case when the two filenames point to the same underlying file. However, it does handle the fact that on DOS-like file systems, forward and backward slashes are equal.
int filename_eq (const void *s1, const void *s2) ¶Return non-zero if file names s1 and s2 are equivalent. This function is for use with hashtab.c hash tables.
hashval_t filename_hash (const void *s) ¶Return the hash value for file name s that will be compared using filename_cmp. This function is for use with hashtab.c hash tables.
int filename_ncmp (const char *s1, const char *s2, size_t n) ¶Return zero if the two file names s1 and s2 are equivalent
in range n.
If not equivalent, the returned value is similar to what strncmp
would return. In other words, it returns a negative value if s1
is less than s2, or a positive value if s2 is greater than
s2.
This function does not normalize file names. As a result, this function will treat filenames that are spelled differently as different even in the case when the two filenames point to the same underlying file. However, it does handle the fact that on DOS-like file systems, forward and backward slashes are equal.
int fnmatch (const char *pattern, const char *string, int flags) ¶Matches string against pattern, returning zero if it
matches, FNM_NOMATCH if not. pattern may contain the
wildcards ? to match any one character, * to match any
zero or more characters, or a set of alternate characters in square
brackets, like ‘[a-gt8]’, which match one character (a
through g, or t, or 8, in this example) if that one
character is in the set. A set may be inverted (i.e., match anything
except what’s in the set) by giving ^ or ! as the first
character in the set. To include those characters in the set, list them
as anything other than the first character of the set. To include a
dash in the set, list it last in the set. A backslash character makes
the following character not special, so for example you could match
against a literal asterisk with ‘\*’. To match a literal
backslash, use ‘\\’.
flags controls various aspects of the matching process, and is a
boolean OR of zero or more of the following values (defined in
<fnmatch.h>):
FNM_PATHNAMEFNM_FILE_NAMEstring is assumed to be a path name. No wildcard will ever match
/.
FNM_NOESCAPEDo not interpret backslashes as quoting the following special character.
FNM_PERIODA leading period (at the beginning of string, or if
FNM_PATHNAME after a slash) is not matched by * or
? but must be matched explicitly.
FNM_LEADING_DIRMeans that string also matches pattern if some initial part
of string matches, and is followed by / and zero or more
characters. For example, ‘foo*’ would match either ‘foobar’
or ‘foobar/grill’.
FNM_CASEFOLDIgnores case when performing the comparison.
FILE * fopen_unlocked (const char *path, const char * mode) ¶Opens and returns a FILE pointer via fopen. If the
operating system supports it, ensure that the stream is setup to avoid
any multi-threaded locking. Otherwise return the FILE pointer
unchanged.
void freeargv (char **vector) ¶Free an argument vector that was built using buildargv. Simply
scans through vector, freeing the memory for each argument until
the terminating NULL is found, and then frees vector
itself.
FILE * freopen_unlocked (const char * path, const char * mode, FILE * stream) ¶Opens and returns a FILE pointer via freopen. If the
operating system supports it, ensure that the stream is setup to avoid
any multi-threaded locking. Otherwise return the FILE pointer
unchanged.
long get_run_time (void) ¶Returns the time used so far, in microseconds. If possible, this is the time used by this process, else it is the elapsed time since the process started.
char* getcwd (char *pathname, int len) ¶Copy the absolute pathname for the current working directory into
pathname, which is assumed to point to a buffer of at least
len bytes, and return a pointer to the buffer. If the current
directory’s path doesn’t fit in len characters, the result is
NULL and errno is set. If pathname is a null pointer,
getcwd will obtain len bytes of space using
malloc.
int getpagesize (void) ¶Returns the number of bytes in a page of memory. This is the granularity of many of the system memory management routines. No guarantee is made as to whether or not it is the same as the basic memory management hardware page size.
char* getpwd (void) ¶Returns the current working directory. This implementation caches the
result on the assumption that the process will not call chdir
between calls to getpwd.
int gettimeofday (struct timeval *tp, void *tz) ¶Writes the current time to tp. This implementation requires that tz be NULL. Returns 0 on success, -1 on failure.
void hex_init (void) ¶Initializes the array mapping the current character set to
corresponding hex values. This function must be called before any
call to hex_p or hex_value. If you fail to call it, a
default ASCII-based table will normally be used on ASCII systems.
int hex_p (int c) ¶Evaluates to non-zero if the given character is a valid hex character,
or zero if it is not. Note that the value you pass will be cast to
unsigned char within the macro.
unsigned int hex_value (int c) ¶Returns the numeric equivalent of the given character when interpreted
as a hexadecimal digit. The result is undefined if you pass an
invalid hex digit. Note that the value you pass will be cast to
unsigned char within the macro.
The hex_value macro returns unsigned int, rather than
signed int, to make it easier to use in parsing addresses from
hex dump files: a signed int would be sign-extended when
converted to a wider unsigned type — like bfd_vma, on some
systems.
This macro indicates the basic character set and encoding used by the host: more precisely, the encoding used for character constants in preprocessor ‘#if’ statements (the C "execution character set"). It is defined by safe-ctype.h, and will be an integer constant with one of the following values:
HOST_CHARSET_UNKNOWN ¶The host character set is unknown - that is, not one of the next two possibilities.
HOST_CHARSET_ASCII ¶The host character set is ASCII.
HOST_CHARSET_EBCDIC ¶The host character set is some variant of EBCDIC. (Only one of the nineteen EBCDIC varying characters is tested; exercise caution.)
htab_t htab_create_typed_alloc (size_t size, htab_hash hash_f, htab_eq eq_f, htab_del del_f, htab_alloc alloc_tab_f, htab_alloc alloc_f, htab_free free_f) ¶This function creates a hash table that uses two different allocators alloc_tab_f and alloc_f to use for allocating the table itself and its entries respectively. This is useful when variables of different types need to be allocated with different allocators.
The created hash table is slightly larger than size and it is
initially empty (all the hash table entries are HTAB_EMPTY_ENTRY).
The function returns the created hash table, or NULL if memory
allocation fails.
char* index (char *s, int c) ¶Returns a pointer to the first occurrence of the character c in
the string s, or NULL if not found. The use of index is
deprecated in new programs in favor of strchr.
void insque (struct qelem *elem, struct qelem *pred) ¶void remque (struct qelem *elem) ¶Routines to manipulate queues built from doubly linked lists. The
insque routine inserts elem in the queue immediately
after pred. The remque routine removes elem from
its containing queue. These routines expect to be passed pointers to
structures which have as their first members a forward pointer and a
back pointer, like this prototype (although no prototype is provided):
struct qelem {
struct qelem *q_forw;
struct qelem *q_back;
char q_data[];
};
These twelve macros are defined by safe-ctype.h. Each has the
same meaning as the corresponding macro (with name in lowercase)
defined by the standard header ctype.h. For example,
ISALPHA returns true for alphabetic characters and false for
others. However, there are two differences between these macros and
those provided by ctype.h:
signed char and unsigned char, and
for EOF.
ALPHA | A-Za-z |
ALNUM | A-Za-z0-9 |
BLANK | space tab |
CNTRL | !PRINT |
DIGIT | 0-9 |
GRAPH | ALNUM || PUNCT |
LOWER | a-z |
PRINT | GRAPH || space |
PUNCT | `~!@#$%^&*()_-=+[{]}\|;:'",<.>/? |
SPACE | space tab \n \r \f \v |
UPPER | A-Z |
XDIGIT | 0-9A-Fa-f |
Note that, if the host character set is ASCII or a superset thereof,
all these macros will return false for all values of char outside
the range of 7-bit ASCII. In particular, both ISPRINT and ISCNTRL return
false for characters with numeric values from 128 to 255.
These six macros are defined by safe-ctype.h and provide additional character classes which are useful when doing lexical analysis of C or similar languages. They are true for the following sets of characters:
IDNUM | A-Za-z0-9_ |
IDST | A-Za-z_ |
VSPACE | \r \n |
NVSPACE | space tab \f \v \0 |
SPACE_OR_NUL | VSPACE || NVSPACE |
ISOBASIC | VSPACE || NVSPACE || PRINT |
const char* lbasename (const char *name) ¶Given a pointer to a string containing a typical pathname (‘/usr/src/cmd/ls/ls.c’ for example), returns a pointer to the last component of the pathname (‘ls.c’ in this case). The returned pointer is guaranteed to lie within the original string. This latter fact is not true of many vendor C libraries, which return special strings or modify the passed strings for particular input.
In particular, the empty string returns the same empty string,
and a path ending in / returns the empty string after it.
const char* lrealpath (const char *name) ¶Given a pointer to a string containing a pathname, returns a canonical
version of the filename. Symlinks will be resolved, and “.” and “..”
components will be simplified. The returned value will be allocated using
malloc, or NULL will be returned on a memory allocation error.
const char* make_relative_prefix (const char *progname, const char *bin_prefix, const char *prefix) ¶Given three paths progname, bin_prefix, prefix, return the path that is in the same position relative to progname’s directory as prefix is relative to bin_prefix. That is, a string starting with the directory portion of progname, followed by a relative pathname of the difference between bin_prefix and prefix.
If progname does not contain any directory separators,
make_relative_prefix will search PATH to find a program
named progname. Also, if progname is a symbolic link,
the symbolic link will be resolved.
For example, if bin_prefix is /alpha/beta/gamma/gcc/delta,
prefix is /alpha/beta/gamma/omega/, and progname is
/red/green/blue/gcc, then this function will return
/red/green/blue/../../omega/.
The return value is normally allocated via malloc. If no
relative prefix can be found, return NULL.
char* make_temp_file (const char *suffix) ¶Return a temporary file name (as a string) or NULL if unable to
create one. suffix is a suffix to append to the file name. The
string is malloced, and the temporary file has been created.
void* memchr (const void *s, int c, size_t n) ¶This function searches memory starting at *s for the
character c. The search only ends with the first occurrence of
c, or after length characters; in particular, a null
character does not terminate the search. If the character c is
found within length characters of *s, a pointer
to the character is returned. If c is not found, then NULL is
returned.
int memcmp (const void *x, const void *y, size_t count) ¶Compares the first count bytes of two areas of memory. Returns zero if they are the same, a value less than zero if x is lexically less than y, or a value greater than zero if x is lexically greater than y. Note that lexical order is determined as if comparing unsigned char arrays.
void* memcpy (void *out, const void *in, size_t length) ¶Copies length bytes from memory region in to region out. Returns a pointer to out.
void* memmem (const void *haystack, size_t haystack_len const void *needle, size_t needle_len) ¶Returns a pointer to the first occurrence of needle (length
needle_len) in haystack (length haystack_len).
Returns NULL if not found.
void* memmove (void *from, const void *to, size_t count) ¶Copies count bytes from memory area from to memory area to, returning a pointer to to.
void* mempcpy (void *out, const void *in, size_t length) ¶Copies length bytes from memory region in to region out. Returns a pointer to out + length.
void* memset (void *s, int c, size_t count) ¶Sets the first count bytes of s to the constant byte c, returning a pointer to s.
int mkstemps (char *pattern, int suffix_len) ¶Generate a unique temporary file name from pattern. pattern has the form:
path/ccXXXXXXsuffix
suffix_len tells us how long suffix is (it can be zero length). The last six characters of pattern before suffix must be ‘XXXXXX’; they are replaced with a string that makes the filename unique. Returns a file descriptor open on the file for reading and writing.
void pex_free (struct pex_obj obj) ¶Clean up and free all data associated with obj. If you have not
yet called pex_get_times or pex_get_status, this will
try to kill the subprocesses.
int pex_get_status (struct pex_obj *obj, int count, int *vector) ¶Returns the exit status of all programs run using obj.
count is the number of results expected. The results will be
placed into vector. The results are in the order of the calls
to pex_run. Returns 0 on error, 1 on success.
int pex_get_times (struct pex_obj *obj, int count, struct pex_time *vector) ¶Returns the process execution times of all programs run using
obj. count is the number of results expected. The
results will be placed into vector. The results are in the
order of the calls to pex_run. Returns 0 on error, 1 on
success.
struct pex_time has the following fields of the type
unsigned long: user_seconds,
user_microseconds, system_seconds,
system_microseconds. On systems which do not support reporting
process times, all the fields will be set to 0.
struct pex_obj * pex_init (int flags, const char *pname, const char *tempbase) ¶Prepare to execute one or more programs, with standard output of each program fed to standard input of the next. This is a system independent interface to execute a pipeline.
flags is a bitwise combination of the following:
PEX_RECORD_TIMES ¶Record subprocess times if possible.
PEX_USE_PIPES ¶Use pipes for communication between processes, if possible.
PEX_SAVE_TEMPS ¶Don’t delete temporary files used for communication between processes.
pname is the name of program to be executed, used in error
messages. tempbase is a base name to use for any required
temporary files; it may be NULL to use a randomly chosen name.
FILE * pex_input_file (struct pex_obj *obj, int flags, const char *in_name) ¶Return a stream for a temporary file to pass to the first program in the pipeline as input.
The name of the input file is chosen according to the same rules
pex_run uses to choose output file names, based on
in_name, obj and the PEX_SUFFIX bit in flags.
Don’t call fclose on the returned stream; the first call to
pex_run closes it automatically.
If flags includes PEX_BINARY_OUTPUT, open the stream in
binary mode; otherwise, open it in the default mode. Including
PEX_BINARY_OUTPUT in flags has no effect on Unix.
FILE * pex_input_pipe (struct pex_obj *obj, int binary) ¶Return a stream fp for a pipe connected to the standard input of
the first program in the pipeline; fp is opened for writing.
You must have passed PEX_USE_PIPES to the pex_init call
that returned obj.
You must close fp using fclose yourself when you have
finished writing data to the pipeline.
The file descriptor underlying fp is marked not to be inherited by child processes.
On systems that do not support pipes, this function returns
NULL, and sets errno to EINVAL. If you would
like to write code that is portable to all systems the pex
functions support, consider using pex_input_file instead.
There are two opportunities for deadlock using
pex_input_pipe:
pex_input_pipe makes no promises about the
size of the pipe’s buffer, so if you need to write any data at all
before starting the first process in the pipeline, consider using
pex_input_file instead.
pex_input_pipe and pex_read_output together
may also cause deadlock. If the output pipe fills up, so that each
program in the pipeline is waiting for the next to read more data, and
you fill the input pipe by writing more data to fp, then there
is no way to make progress: the only process that could read data from
the output pipe is you, but you are blocked on the input pipe.
const char * pex_one (int flags, const char *executable, char * const *argv, const char *pname, const char *outname, const char *errname, int *status, int *err) ¶An interface to permit the easy execution of a
single program. The return value and most of the parameters are as
for a call to pex_run. flags is restricted to a
combination of PEX_SEARCH, PEX_STDERR_TO_STDOUT, and
PEX_BINARY_OUTPUT. outname is interpreted as if
PEX_LAST were set. On a successful return, *status will
be set to the exit status of the program.
FILE * pex_read_err (struct pex_obj *obj, int binary) ¶Returns a FILE pointer which may be used to read the standard
error of the last program in the pipeline. When this is used,
PEX_LAST should not be used in a call to pex_run. After
this is called, pex_run may no longer be called with the same
obj. binary should be non-zero if the file should be
opened in binary mode. Don’t call fclose on the returned file;
it will be closed by pex_free.
FILE * pex_read_output (struct pex_obj *obj, int binary) ¶Returns a FILE pointer which may be used to read the standard
output of the last program in the pipeline. When this is used,
PEX_LAST should not be used in a call to pex_run. After
this is called, pex_run may no longer be called with the same
obj. binary should be non-zero if the file should be
opened in binary mode. Don’t call fclose on the returned file;
it will be closed by pex_free.
const char * pex_run (struct pex_obj *obj, int flags, const char *executable, char * const *argv, const char *outname, const char *errname, int *err) ¶Execute one program in a pipeline. On success this returns
NULL. On failure it returns an error message, a statically
allocated string.
obj is returned by a previous call to pex_init.
flags is a bitwise combination of the following:
PEX_LAST ¶This must be set on the last program in the pipeline. In particular,
it should be set when executing a single program. The standard output
of the program will be sent to outname, or, if outname is
NULL, to the standard output of the calling program. Do not
set this bit if you want to call pex_read_output
(described below). After a call to pex_run with this bit set,
pex_run may no longer be called with the same obj.
PEX_SEARCH ¶Search for the program using the user’s executable search path.
PEX_SUFFIX ¶outname is a suffix. See the description of outname, below.
PEX_STDERR_TO_STDOUT ¶Send the program’s standard error to standard output, if possible.
PEX_BINARY_INPUT ¶PEX_BINARY_OUTPUTPEX_BINARY_ERRORThe standard input (output or error) of the program should be read (written) in
binary mode rather than text mode. These flags are ignored on systems
which do not distinguish binary mode and text mode, such as Unix. For
proper behavior these flags should match appropriately—a call to
pex_run using PEX_BINARY_OUTPUT should be followed by a
call using PEX_BINARY_INPUT.
PEX_STDERR_TO_PIPE ¶Send the program’s standard error to a pipe, if possible. This flag
cannot be specified together with PEX_STDERR_TO_STDOUT. This
flag can be specified only on the last program in pipeline.
executable is the program to execute. argv is the set of
arguments to pass to the program; normally argv[0] will
be a copy of executable.
outname is used to set the name of the file to use for standard output. There are two cases in which no output file will be used:
PEX_LAST is not set in flags, and PEX_USE_PIPES
was set in the call to pex_init, and the system supports pipes
PEX_LAST is set in flags, and outname is
NULL
Otherwise the code will use a file to hold standard
output. If PEX_LAST is not set, this file is considered to be
a temporary file, and it will be removed when no longer needed, unless
PEX_SAVE_TEMPS was set in the call to pex_init.
There are two cases to consider when setting the name of the file to hold standard output.
PEX_SUFFIX is set in flags. In this case
outname may not be NULL. If the tempbase parameter
to pex_init was not NULL, then the output file name is
the concatenation of tempbase and outname. If
tempbase was NULL, then the output file name is a random
file name ending in outname.
PEX_SUFFIX was not set in flags. In this
case, if outname is not NULL, it is used as the output
file name. If outname is NULL, and tempbase was
not NULL, the output file name is randomly chosen using
tempbase. Otherwise the output file name is chosen completely
at random.
errname is the file name to use for standard error output. If
it is NULL, standard error is the same as the caller’s.
Otherwise, standard error is written to the named file.
On an error return, the code sets *err to an errno
value, or to 0 if there is no relevant errno.
const char * pex_run_in_environment (struct pex_obj *obj, int flags, const char *executable, char * const *argv, char * const *env, int env_size, const char *outname, const char *errname, int *err) ¶Execute one program in a pipeline, permitting the environment for the
program to be specified. Behaviour and parameters not listed below are
as for pex_run.
env is the environment for the child process, specified as an array of
character pointers. Each element of the array should point to a string of the
form VAR=VALUE, with the exception of the last element that must be
NULL.
int pexecute (const char *program, char * const *argv, const char *this_pname, const char *temp_base, char **errmsg_fmt, char **errmsg_arg, int flags) ¶This is the old interface to execute one or more programs. It is still supported for compatibility purposes, but is no longer documented.
void psignal (int signo, char *message) ¶Print message to the standard error, followed by a colon, followed by the description of the signal specified by signo, followed by a newline.
int putenv (const char *string) ¶Uses setenv or unsetenv to put string into
the environment or remove it. If string is of the form
‘name=value’ the string is added; if no ‘=’ is present the
name is unset/removed.
int pwait (int pid, int *status, int flags) ¶Another part of the old execution interface.
long int random (void) ¶void srandom (unsigned int seed) ¶void* initstate (unsigned int seed, void *arg_state, unsigned long n) ¶void* setstate (void *arg_state) ¶Random number functions. random returns a random number in the
range 0 to LONG_MAX. srandom initializes the random
number generator to some starting point determined by seed
(else, the values returned by random are always the same for each
run of the program). initstate and setstate allow fine-grained
control over the state of the random number generator.
char* reconcat (char *optr, const char *s1, …, NULL) ¶Same as concat, except that if optr is not NULL it
is freed after the string is created. This is intended to be useful
when you’re extending an existing string or building up a string in a
loop:
str = reconcat (str, "pre-", str, NULL);
int rename (const char *old, const char *new) ¶Renames a file from old to new. If new already exists, it is removed.
char* rindex (const char *s, int c) ¶Returns a pointer to the last occurrence of the character c in
the string s, or NULL if not found. The use of rindex is
deprecated in new programs in favor of strrchr.
int setenv (const char *name, const char *value, int overwrite) ¶void unsetenv (const char *name) ¶setenv adds name to the environment with value
value. If the name was already present in the environment,
the new value will be stored only if overwrite is nonzero.
The companion unsetenv function removes name from the
environment. This implementation is not safe for multithreaded code.
void setproctitle (const char *fmt, ...) ¶Set the title of a process to fmt. va args not supported for now, but defined for compatibility with BSD.
int signo_max (void) ¶Returns the maximum signal value for which a corresponding symbolic
name or message is available. Note that in the case where we use the
sys_siglist supplied by the system, it is possible for there to
be more symbolic names than messages, or vice versa. In fact, the
manual page for psignal(3b) explicitly warns that one should
check the size of the table (NSIG) before indexing it, since
new signal codes may be added to the system before they are added to
the table. Thus NSIG might be smaller than value implied by
the largest signo value defined in <signal.h>.
We return the maximum value that can be used to obtain a meaningful symbolic name or message.
int sigsetmask (int set) ¶Sets the signal mask to the one provided in set and returns
the old mask (which, for libiberty’s implementation, will always
be the value 1).
const char * simple_object_attributes_compare (simple_object_attributes *attrs1, simple_object_attributes *attrs2, int *err) ¶Compare attrs1 and attrs2. If they could be linked
together without error, return NULL. Otherwise, return an
error message and set *err to an errno value or 0
if there is no relevant errno.
simple_object_attributes * simple_object_fetch_attributes (simple_object_read *simple_object, const char **errmsg, int *err) ¶Fetch the attributes of simple_object. The attributes are
internal information such as the format of the object file, or the
architecture it was compiled for. This information will persist until
simple_object_attributes_release is called, even if
simple_object itself is released.
On error this returns NULL, sets *errmsg to an
error message, and sets *err to an errno value or
0 if there is no relevant errno.
int simple_object_find_section (simple_object_read *simple_object off_t *offset, off_t *length, const char **errmsg, int *err) ¶Look for the section name in simple_object. This returns information for the first section with that name.
If found, return 1 and set *offset to the offset in the
file of the section contents and set *length to the
length of the section contents. The value in *offset
will be relative to the offset passed to
simple_object_open_read.
If the section is not found, and no error occurs,
simple_object_find_section returns 0 and set
*errmsg to NULL.
If an error occurs, simple_object_find_section returns
0, sets *errmsg to an error message, and sets
*err to an errno value or 0 if there is no
relevant errno.
const char * simple_object_find_sections (simple_object_read *simple_object, int (*pfn) (void *data, const char *name, off_t offset, off_t length), void *data, int *err) ¶This function calls pfn for each section in simple_object.
It calls pfn with the section name, the offset within the file
of the section contents, and the length of the section contents. The
offset within the file is relative to the offset passed to
simple_object_open_read. The data argument to this
function is passed along to pfn.
If pfn returns 0, the loop over the sections stops and
simple_object_find_sections returns. If pfn returns some
other value, the loop continues.
On success simple_object_find_sections returns. On error it
returns an error string, and sets *err to an errno value
or 0 if there is no relevant errno.
simple_object_read * simple_object_open_read (int descriptor, off_t offset, const char *segment_name, const char **errmsg, int *err) ¶Opens an object file for reading. Creates and returns an
simple_object_read pointer which may be passed to other
functions to extract data from the object file.
descriptor holds a file descriptor which permits reading.
offset is the offset into the file; this will be 0 in the
normal case, but may be a different value when reading an object file
in an archive file.
segment_name is only used with the Mach-O file format used on Darwin aka Mac OS X. It is required on that platform, and means to only look at sections within the segment with that name. The parameter is ignored on other systems.
If an error occurs, this functions returns NULL and sets
*errmsg to an error string and sets *err to
an errno value or 0 if there is no relevant errno.
void simple_object_release_attributes (simple_object_attributes *attrs) ¶Release all resources associated with attrs.
void simple_object_release_read (simple_object_read *simple_object) ¶Release all resources associated with simple_object. This does not close the file descriptor.
void simple_object_release_write (simple_object_write *simple_object) ¶Release all resources associated with simple_object.
simple_object_write * simple_object_start_write (simple_object_attributes attrs, const char *segment_name, const char **errmsg, int *err) ¶Start creating a new object file using the object file format described in attrs. You must fetch attribute information from an existing object file before you can create a new one. There is currently no support for creating an object file de novo.
segment_name is only used with Mach-O as found on Darwin aka Mac OS X. The parameter is required on that target. It means that all sections are created within the named segment. It is ignored for other object file formats.
On error simple_object_start_write returns NULL, sets
*ERRMSG to an error message, and sets *err
to an errno value or 0 if there is no relevant errno.
const char * simple_object_write_add_data (simple_object_write *simple_object, simple_object_write_section *section, const void *buffer, size_t size, int copy, int *err) ¶Add data buffer/size to section in
simple_object. If copy is non-zero, the data will be
copied into memory if necessary. If copy is zero, buffer
must persist until simple_object_write_to_file is called. is
released.
On success this returns NULL. On error this returns an error
message, and sets *err to an errno value or 0 if there is
no relevant erro.
simple_object_write_section * simple_object_write_create_section (simple_object_write *simple_object, const char *name, unsigned int align, const char **errmsg, int *err) ¶Add a section to simple_object. name is the name of the new section. align is the required alignment expressed as the number of required low-order 0 bits (e.g., 2 for alignment to a 32-bit boundary).
The section is created as containing data, readable, not writable, not
executable, not loaded at runtime. The section is not written to the
file until simple_object_write_to_file is called.
On error this returns NULL, sets *errmsg to an
error message, and sets *err to an errno value or
0 if there is no relevant errno.
const char * simple_object_write_to_file (simple_object_write *simple_object, int descriptor, int *err) ¶Write the complete object file to descriptor, an open file
descriptor. This writes out all the data accumulated by calls to
simple_object_write_create_section and
simple_object_write_add_data.
This returns NULL on success. On error this returns an error
message and sets *err to an errno value or 0 if
there is no relevant errno.
int snprintf (char *buf, size_t n, const char *format, ...) ¶This function is similar to sprintf, but it will write to
buf at most n-1 bytes of text, followed by a
terminating null byte, for a total of n bytes.
On error the return value is -1, otherwise it returns the number of
bytes, not including the terminating null byte, that would have been
written had n been sufficiently large, regardless of the actual
value of n. Note some pre-C99 system libraries do not implement
this correctly so users cannot generally rely on the return value if
the system version of this function is used.
char* spaces (int count) ¶Returns a pointer to a memory region filled with the specified number of spaces and null terminated. The returned pointer is valid until at least the next call.
splay_tree splay_tree_new_with_typed_alloc (splay_tree_compare_fn compare_fn, splay_tree_delete_key_fn delete_key_fn, splay_tree_delete_value_fn delete_value_fn, splay_tree_allocate_fn tree_allocate_fn, splay_tree_allocate_fn node_allocate_fn, splay_tree_deallocate_fn deallocate_fn, void * allocate_data) ¶This function creates a splay tree that uses two different allocators tree_allocate_fn and node_allocate_fn to use for allocating the tree itself and its nodes respectively. This is useful when variables of different types need to be allocated with different allocators.
The splay tree will use compare_fn to compare nodes, delete_key_fn to deallocate keys, and delete_value_fn to deallocate values. Keys and values will be deallocated when the tree is deleted using splay_tree_delete or when a node is removed using splay_tree_remove. splay_tree_insert will release the previously inserted key and value using delete_key_fn and delete_value_fn if the inserted key is already found in the tree.
void stack_limit_increase (unsigned long pref) ¶Attempt to increase stack size limit to pref bytes if possible.
char* stpcpy (char *dst, const char *src) ¶Copies the string src into dst. Returns a pointer to dst + strlen(src).
char* stpncpy (char *dst, const char *src, size_t len) ¶Copies the string src into dst, copying exactly len and padding with zeros if necessary. If len < strlen(src) then return dst + len, otherwise returns dst + strlen(src).
int strcasecmp (const char *s1, const char *s2) ¶A case-insensitive strcmp.
char* strchr (const char *s, int c) ¶Returns a pointer to the first occurrence of the character c in
the string s, or NULL if not found. If c is itself the
null character, the results are undefined.
char* strdup (const char *s) ¶Returns a pointer to a copy of s in memory obtained from
malloc, or NULL if insufficient memory was available.
const char* strerrno (int errnum) ¶Given an error number returned from a system call (typically returned
in errno), returns a pointer to a string containing the
symbolic name of that error number, as found in <errno.h>.
If the supplied error number is within the valid range of indices for symbolic names, but no name is available for the particular error number, then returns the string ‘Error num’, where num is the error number.
If the supplied error number is not within the range of valid
indices, then returns NULL.
The contents of the location pointed to are only guaranteed to be
valid until the next call to strerrno.
char* strerror (int errnoval) ¶Maps an errno number to an error message string, the contents
of which are implementation defined. On systems which have the
external variables sys_nerr and sys_errlist, these
strings will be the same as the ones used by perror.
If the supplied error number is within the valid range of indices for
the sys_errlist, but no message is available for the particular
error number, then returns the string ‘Error num’, where
num is the error number.
If the supplied error number is not a valid index into
sys_errlist, returns NULL.
The returned string is only guaranteed to be valid only until the
next call to strerror.
int strncasecmp (const char *s1, const char *s2) ¶A case-insensitive strncmp.
int strncmp (const char *s1, const char *s2, size_t n) ¶Compares the first n bytes of two strings, returning a value as
strcmp.
char* strndup (const char *s, size_t n) ¶Returns a pointer to a copy of s with at most n characters
in memory obtained from malloc, or NULL if insufficient
memory was available. The result is always NUL terminated.
size_t strnlen (const char *s, size_t maxlen) ¶Returns the length of s, as with strlen, but never looks
past the first maxlen characters in the string. If there is no
’\0’ character in the first maxlen characters, returns
maxlen.
char* strrchr (const char *s, int c) ¶Returns a pointer to the last occurrence of the character c in
the string s, or NULL if not found. If c is itself the
null character, the results are undefined.
const char * strsignal (int signo) ¶Maps an signal number to an signal message string, the contents of
which are implementation defined. On systems which have the external
variable sys_siglist, these strings will be the same as the
ones used by psignal().
If the supplied signal number is within the valid range of indices for
the sys_siglist, but no message is available for the particular
signal number, then returns the string ‘Signal num’, where
num is the signal number.
If the supplied signal number is not a valid index into
sys_siglist, returns NULL.
The returned string is only guaranteed to be valid only until the next
call to strsignal.
const char* strsigno (int signo) ¶Given an signal number, returns a pointer to a string containing the
symbolic name of that signal number, as found in <signal.h>.
If the supplied signal number is within the valid range of indices for symbolic names, but no name is available for the particular signal number, then returns the string ‘Signal num’, where num is the signal number.
If the supplied signal number is not within the range of valid
indices, then returns NULL.
The contents of the location pointed to are only guaranteed to be
valid until the next call to strsigno.
char* strstr (const char *string, const char *sub) ¶This function searches for the substring sub in the string
string, not including the terminating null characters. A pointer
to the first occurrence of sub is returned, or NULL if the
substring is absent. If sub points to a string with zero
length, the function returns string.
double strtod (const char *string, char **endptr) ¶This ISO C function converts the initial portion of string to a
double. If endptr is not NULL, a pointer to the
character after the last character used in the conversion is stored in
the location referenced by endptr. If no conversion is
performed, zero is returned and the value of string is stored in
the location referenced by endptr.
int strtoerrno (const char *name) ¶Given the symbolic name of a error number (e.g., EACCES), map it
to an errno value. If no translation is found, returns 0.
long int strtol (const char *string, char **endptr, int base) ¶unsigned long int strtoul (const char *string, char **endptr, int base) ¶The strtol function converts the string in string to a
long integer value according to the given base, which must be
between 2 and 36 inclusive, or be the special value 0. If base
is 0, strtol will look for the prefixes 0 and 0x
to indicate bases 8 and 16, respectively, else default to base 10.
When the base is 16 (either explicitly or implicitly), a prefix of
0x is allowed. The handling of endptr is as that of
strtod above. The strtoul function is the same, except
that the converted value is unsigned.
long long int strtoll (const char *string, char **endptr, int base) ¶unsigned long long int strtoul ( const char *string, char **endptr, int base) ¶The strtoll function converts the string in string to a
long long integer value according to the given base, which must be
between 2 and 36 inclusive, or be the special value 0. If base
is 0, strtoll will look for the prefixes 0 and 0x
to indicate bases 8 and 16, respectively, else default to base 10.
When the base is 16 (either explicitly or implicitly), a prefix of
0x is allowed. The handling of endptr is as that of
strtod above. The strtoull function is the same, except
that the converted value is unsigned.
int strtosigno (const char *name) ¶Given the symbolic name of a signal, map it to a signal number. If no translation is found, returns 0.
int strverscmp (const char *s1, const char *s2) ¶The strverscmp function compares the string s1 against
s2, considering them as holding indices/version numbers. Return
value follows the same conventions as found in the strverscmp
function. In fact, if s1 and s2 contain no digits,
strverscmp behaves like strcmp.
Basically, we compare strings normally (character by character), until we find a digit in each string - then we enter a special comparison mode, where each sequence of digits is taken as a whole. If we reach the end of these two parts without noticing a difference, we return to the standard comparison mode. There are two types of numeric parts: "integral" and "fractional" (those begin with a ’0’). The types of the numeric parts affect the way we sort them:
strverscmp ("no digit", "no digit")
⇒ 0 // same behavior as strcmp.
strverscmp ("item#99", "item#100")
⇒ <0 // same prefix, but 99 < 100.
strverscmp ("alpha1", "alpha001")
⇒ >0 // fractional part inferior to integral one.
strverscmp ("part1_f012", "part1_f01")
⇒ >0 // two fractional parts.
strverscmp ("foo.009", "foo.0")
⇒ <0 // idem, but with leading zeroes only.
This function is especially useful when dealing with filename sorting, because filenames frequently hold indices/version numbers.
void timeval_add (struct timeval *a, struct timeval *b, struct timeval *result) ¶Adds a to b and stores the result in result.
void timeval_sub (struct timeval *a, struct timeval *b, struct timeval *result) ¶Subtracts b from a and stores the result in result.
char* tmpnam (char *s) ¶This function attempts to create a name for a temporary file, which
will be a valid file name yet not exist when tmpnam checks for
it. s must point to a buffer of at least L_tmpnam bytes,
or be NULL. Use of this function creates a security risk, and it must
not be used in new projects. Use mkstemp instead.
int unlink_if_ordinary (const char*) ¶Unlinks the named file, unless it is special (e.g. a device file). Returns 0 when the file was unlinked, a negative value (and errno set) when there was an error deleting the file, and a positive value if no attempt was made to unlink the file because it is special.
void unlock_std_streams (void) ¶If the OS supports it, ensure that the standard I/O streams,
stdin, stdout and stderr are setup to avoid any
multi-threaded locking. Otherwise do nothing.
void unlock_stream (FILE * stream) ¶If the OS supports it, ensure that the supplied stream is setup to
avoid any multi-threaded locking. Otherwise leave the FILE
pointer unchanged. If the stream is NULL do nothing.
int vasprintf (char **resptr, const char *format, va_list args) ¶Like vsprintf, but instead of passing a pointer to a buffer,
you pass a pointer to a pointer. This function will compute the size
of the buffer needed, allocate memory with malloc, and store a
pointer to the allocated memory in *resptr. The value
returned is the same as vsprintf would return. If memory could
not be allocated, minus one is returned and NULL is stored in
*resptr.
int vfork (void) ¶Emulates vfork by calling fork and returning its value.
int vprintf (const char *format, va_list ap) ¶int vfprintf (FILE *stream, const char *format, va_list ap) ¶int vsprintf (char *str, const char *format, va_list ap) ¶These functions are the same as printf, fprintf, and
sprintf, respectively, except that they are called with a
va_list instead of a variable number of arguments. Note that
they do not call va_end; this is the application’s
responsibility. In libiberty they are implemented in terms of the
nonstandard but common function _doprnt.
int vsnprintf (char *buf, size_t n, const char *format, va_list ap) ¶This function is similar to vsprintf, but it will write to
buf at most n-1 bytes of text, followed by a
terminating null byte, for a total of n bytes. On error the
return value is -1, otherwise it returns the number of characters that
would have been printed had n been sufficiently large,
regardless of the actual value of n. Note some pre-C99 system
libraries do not implement this correctly so users cannot generally
rely on the return value if the system version of this function is
used.
int waitpid (int pid, int *status, int) ¶This is a wrapper around the wait function. Any “special”
values of pid depend on your implementation of wait, as
does the return value. The third argument is unused in libiberty.
int writeargv (char * const *argv, FILE *file) ¶Write each member of ARGV, handling all necessary quoting, to the file associated with FILE, separated by whitespace. Return 0 on success, non-zero if an error occurred while writing to FILE.
char* xasprintf (const char *format, ...) ¶Print to allocated string without fail. If xasprintf fails,
this will print a message to stderr (using the name set by
xmalloc_set_program_name, if any) and then call xexit.
int xatexit (void (*fn) (void)) ¶Behaves as the standard atexit function, but with no limit on
the number of registered functions. Returns 0 on success, or −1 on
failure. If you use xatexit to register functions, you must use
xexit to terminate your program.
void* xcalloc (size_t nelem, size_t elsize) ¶Allocate memory without fail, and set it to zero. This routine functions
like calloc, but will behave the same as xmalloc if memory
cannot be found.
void xexit (int code) ¶Terminates the program. If any functions have been registered with
the xatexit replacement function, they will be called first.
Termination is handled via the system’s normal exit call.
void* xmalloc (size_t) ¶Allocate memory without fail. If malloc fails, this will print
a message to stderr (using the name set by
xmalloc_set_program_name,
if any) and then call xexit. Note that it is therefore safe for
a program to contain #define malloc xmalloc in its source.
void xmalloc_failed (size_t) ¶This function is not meant to be called by client code, and is listed here for completeness only. If any of the allocation routines fail, this function will be called to print an error message and terminate execution.
void xmalloc_set_program_name (const char *name) ¶You can use this to set the name of the program used by
xmalloc_failed when printing a failure message.
void* xmemdup (void *input, size_t copy_size, size_t alloc_size) ¶Duplicates a region of memory without fail. First, alloc_size bytes are allocated, then copy_size bytes from input are copied into it, and the new memory is returned. If fewer bytes are copied than were allocated, the remaining memory is zeroed.
void* xrealloc (void *ptr, size_t size) ¶Reallocate memory without fail. This routine functions like realloc,
but will behave the same as xmalloc if memory cannot be found.
char* xstrdup (const char *s) ¶Duplicates a character string without fail, using xmalloc to
obtain memory.
char* xstrerror (int errnum) ¶Behaves exactly like the standard strerror function, but
will never return a NULL pointer.
char* xstrndup (const char *s, size_t n) ¶Returns a pointer to a copy of s with at most n characters
without fail, using xmalloc to obtain memory. The result is
always NUL terminated.
char* xvasprintf (const char *format, va_list args) ¶Print to allocated string without fail. If xvasprintf fails,
this will print a message to stderr (using the name set by
xmalloc_set_program_name, if any) and then call xexit.
Copyright © 1991-2024 Free Software Foundation, Inc. 51 Franklin Street - Fifth Floor, Boston, MA 02110-1301, USA Everyone is permitted to copy and distribute verbatim copies of this license document, but changing it is not allowed. [This is the first released version of the Lesser GPL. It also counts as the successor of the GNU Library Public License, version 2, hence the version number 2.1.]
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To apply these terms, attach the following notices to the library. It is safest to attach them to the start of each source file to most effectively convey the exclusion of warranty; and each file should have at least the “copyright” line and a pointer to where the full notice is found.
one line to give the library's name and an idea of what it does. Copyright (C) year name of author This library is free software; you can redistribute it and/or modify it under the terms of the GNU Lesser General Public License as published by the Free Software Foundation; either version 2.1 of the License, or (at your option) any later version. This library is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License for more details. You should have received a copy of the GNU Lesser General Public License along with this library; if not, write to the Free Software Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
Also add information on how to contact you by electronic and paper mail.
You should also get your employer (if you work as a programmer) or your school, if any, to sign a “copyright disclaimer” for the library, if necessary. Here is a sample; alter the names:
Yoyodyne, Inc., hereby disclaims all copyright interest in the library `Frob' (a library for tweaking knobs) written by James Random Hacker. signature of Ty Coon, 1 April 1990 Ty Coon, President of Vice
That’s all there is to it!
Copyright © 1990 Regents of the University of California. All rights reserved.
Redistribution and use in source and binary forms, with or without modification, are permitted provided that the following conditions are met:
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