source: trunk/src/gcc/libiberty/functions.texi@ 1005

@c Automatically generated from *.c and others (the comments before
@c each entry tell you which file and where in that file).  DO NOT EDIT!
@c Edit the *.c files, configure with --enable-maintainer-mode,
@c and let gather-docs build you a new copy.

@c alloca.c:26
@deftypefn Replacement void* alloca (size_t @var{size})

This function allocates memory which will be automatically reclaimed
after the procedure exits.  The @libib{} implementation does not free
the memory immediately but will do so eventually during subsequent
calls to this function.  Memory is allocated using @code{xmalloc} under
normal circumstances.

The header file @file{alloca-conf.h} can be used in conjunction with the
GNU Autoconf test @code{AC_FUNC_ALLOCA} to test for and properly make
available this function.  The @code{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.

@end deftypefn

@c asprintf.c:33
@deftypefn Extension int asprintf (char **@var{resptr}, const char *@var{format}, ...)

Like @code{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 @code{malloc}, and store a
pointer to the allocated memory in @code{*@var{resptr}}.  The value
returned is the same as @code{sprintf} would return.  If memory could
not be allocated, zero is returned and @code{NULL} is stored in
@code{*@var{resptr}}.

@end deftypefn

@c atexit.c:6
@deftypefn Supplemental int atexit (void (*@var{f})())

Causes function @var{f} to be called at exit.  Returns 0.

@end deftypefn

@c basename.c:6
@deftypefn Supplemental char* basename (const char *@var{name})

Returns a pointer to the last component of pathname @var{name}.
Behavior is undefined if the pathname ends in a directory separator.

@end deftypefn

@c bcmp.c:6
@deftypefn Supplemental int bcmp (char *@var{x}, char *@var{y}, int @var{count})

Compares the first @var{count} bytes of two areas of memory.  Returns
zero if they are the same, nonzero otherwise.  Returns zero if
@var{count} is zero.  A nonzero result only indicates a difference,
it does not indicate any sorting order (say, by having a positive
result mean @var{x} sorts before @var{y}).

@end deftypefn

@c bcopy.c:3
@deftypefn Supplemental void bcopy (char *@var{in}, char *@var{out}, int @var{length})

Copies @var{length} bytes from memory region @var{in} to region
@var{out}.  The use of @code{bcopy} is deprecated in new programs.

@end deftypefn

@c bsearch.c:33
@deftypefn Supplemental void* bsearch (const void *@var{key}, const void *@var{base}, size_t @var{nmemb}, size_t @var{size}, int (*@var{compar})(const void *, const void *))

Performs a search over an array of @var{nmemb} elements pointed to by
@var{base} for a member that matches the object pointed to by @var{key}.
The size of each member is specified by @var{size}.  The array contents
should be sorted in ascending order according to the @var{compar}
comparison function.  This routine should take two arguments pointing to
the @var{key} and to an array member, in that order, and should return an
integer less than, equal to, or greater than zero if the @var{key} object
is respectively less than, matching, or greater than the array member.

@end deftypefn

@c argv.c:139
@deftypefn Extension char** buildargv (char *@var{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
@code{NULL} element.

All of the memory for the pointer array and copies of the string
is obtained from @code{malloc}.  All of the memory can be returned to the
system with the single function call @code{freeargv}, which takes the
returned result of @code{buildargv}, as it's argument.

Returns a pointer to the argument vector if successful.  Returns
@code{NULL} if @var{sp} is @code{NULL} or if there is insufficient
memory to complete building the argument vector.

If the input is a null string (as opposed to a @code{NULL} pointer),
then buildarg returns an argument vector that has one arg, a null
string.

@end deftypefn

@c bzero.c:6
@deftypefn Supplemental void bzero (char *@var{mem}, int @var{count})

Zeros @var{count} bytes starting at @var{mem}.  Use of this function
is deprecated in favor of @code{memset}.

@end deftypefn

@c calloc.c:6
@deftypefn Supplemental void* calloc (size_t @var{nelem}, size_t @var{elsize})

Uses @code{malloc} to allocate storage for @var{nelem} objects of
@var{elsize} bytes each, then zeros the memory.

@end deftypefn

@c choose-temp.c:42
@deftypefn Extension char* choose_temp_base (void)

Return a prefix for temporary file names or @code{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 (@code{mktemp}
fails).  The buffer for the result is obtained with @code{xmalloc}.

This function is provided for backwards compatability only.  Its use is
not recommended.

@end deftypefn

@c make-temp-file.c:88
@deftypefn Replacement char* choose_tmpdir ()

Returns a pointer to a directory path suitable for creating temporary
files in.

@end deftypefn

@c clock.c:27
@deftypefn Supplemental long clock (void)

Returns an approximation of the CPU time used by the process as a
@code{clock_t}; divide this number by @samp{CLOCKS_PER_SEC} to get the
number of seconds used.

@end deftypefn

@c concat.c:24
@deftypefn Extension char* concat (const char *@var{s1}, const char *@var{s2}, @dots{}, @code{NULL})

Concatenate zero or more of strings and return the result in freshly
@code{xmalloc}ed memory.  Returns @code{NULL} if insufficient memory is
available.  The argument list is terminated by the first @code{NULL}
pointer encountered.  Pointers to empty strings are ignored.

@end deftypefn

@c argv.c:65
@deftypefn Extension char** dupargv (char **@var{vector})

Duplicate an argument vector.  Simply scans through @var{vector},
duplicating each argument until the terminating @code{NULL} is found.
Returns a pointer to the argument vector if successful.  Returns
@code{NULL} if there is insufficient memory to complete building the
argument vector.

@end deftypefn

@c strerror.c:566
@deftypefn Extension int errno_max (void)

Returns the maximum @code{errno} value for which a corresponding
symbolic name or message is available.  Note that in the case where we
use the @code{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 @code{perror(3C)} explicitly warns that one
should check the size of the table (@code{sys_nerr}) before indexing
it, since new error codes may be added to the system before they are
added to the table.  Thus @code{sys_nerr} might be smaller than value
implied by the largest @code{errno} value defined in @code{<errno.h>}.

We return the maximum value that can be used to obtain a meaningful
symbolic name or message.

@end deftypefn

@c fdmatch.c:23
@deftypefn Extension int fdmatch (int @var{fd1}, int @var{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 (@code{stdout} for example) or from the SVR4 @file{/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.

@end deftypefn

@c ffs.c:3
@deftypefn Supplemental int ffs (int @var{valu})

Find the first (least significant) bit set in @var{valu}.  Bits are
numbered from right to left, starting with bit 1 (corresponding to the
value 1).  If @var{valu} is zero, zero is returned.

@end deftypefn

@c fnmatch.txh:1
@deftypefn Replacement int fnmatch (const char *@var{pattern}, const char *@var{string}, int @var{flags})

Matches @var{string} against @var{pattern}, returning zero if it
matches, @code{FNM_NOMATCH} if not.  @var{pattern} may contain the
wildcards @code{?} to match any one character, @code{*} to match any
zero or more characters, or a set of alternate characters in square
brackets, like @samp{[a-gt8]}, which match one character (@code{a}
through @code{g}, or @code{t}, or @code{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 @code{^} or @code{!} 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 @samp{\*}.  To match a literal
backslash, use @samp{\\}.

@code{flags} controls various aspects of the matching process, and is a
boolean OR of zero or more of the following values (defined in
@code{<fnmatch.h>}):

@table @code

@item FNM_PATHNAME
@itemx FNM_FILE_NAME
@var{string} is assumed to be a path name.  No wildcard will ever match
@code{/}.

@item FNM_NOESCAPE
Do not interpret backslashes as quoting the following special character.

@item FNM_PERIOD
A leading period (at the beginning of @var{string}, or if
@code{FNM_PATHNAME} after a slash) is not matched by @code{*} or
@code{?} but must be matched explicitly.

@item FNM_LEADING_DIR
Means that @var{string} also matches @var{pattern} if some initial part
of @var{string} matches, and is followed by @code{/} and zero or more
characters.  For example, @samp{foo*} would match either @samp{foobar}
or @samp{foobar/grill}.

@item FNM_CASEFOLD
Ignores case when performing the comparison.

@end table

@end deftypefn

@c argv.c:111
@deftypefn Extension void freeargv (char **@var{vector})

Free an argument vector that was built using @code{buildargv}.  Simply
scans through @var{vector}, freeing the memory for each argument until
the terminating @code{NULL} is found, and then frees @var{vector}
itself.

@end deftypefn

@c getruntime.c:78
@deftypefn Replacement 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.

@end deftypefn

@c getcwd.c:6
@deftypefn Supplemental char* getcwd (char *@var{pathname}, int @var{len})

Copy the absolute pathname for the current working directory into
@var{pathname}, which is assumed to point to a buffer of at least
@var{len} bytes, and return a pointer to the buffer.  If the current
directory's path doesn't fit in @var{len} characters, the result is
@code{NULL} and @code{errno} is set.  If @var{pathname} is a null pointer,
@code{getcwd} will obtain @var{len} bytes of space using
@code{malloc}.

@end deftypefn

@c getpagesize.c:5
@deftypefn Supplemental 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.

@end deftypefn

@c getpwd.c:5
@deftypefn Supplemental char* getpwd (void)

Returns the current working directory.  This implementation caches the
result on the assumption that the process will not call @code{chdir}
between calls to @code{getpwd}.

@end deftypefn

@c index.c:5
@deftypefn Supplemental char* index (char *@var{s}, int @var{c})

Returns a pointer to the first occurrence of the character @var{c} in
the string @var{s}, or @code{NULL} if not found.  The use of @code{index} is
deprecated in new programs in favor of @code{strchr}.

@end deftypefn

@c insque.c:6
@deftypefn Supplemental void insque (struct qelem *@var{elem}, struct qelem *@var{pred})
@deftypefnx Supplemental void remque (struct qelem *@var{elem})

Routines to manipulate queues built from doubly linked lists.  The
@code{insque} routine inserts @var{elem} in the queue immediately
after @var{pred}.  The @code{remque} routine removes @var{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):

@example
struct qelem @{
  struct qelem *q_forw;
  struct qelem *q_back;
  char q_data[];
@};
@end example

@end deftypefn

@c lbasename.c:23
@deftypefn Replacement {const char*} lbasename (const char *@var{name})

Given a pointer to a string containing a typical pathname
(@samp{/usr/src/cmd/ls/ls.c} for example), returns a pointer to the
last component of the pathname (@samp{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 @code{/} returns the empty string after it.

@end deftypefn

@c make-temp-file.c:138
@deftypefn Replacement char* make_temp_file (const char *@var{suffix})

Return a temporary file name (as a string) or @code{NULL} if unable to
create one.  @var{suffix} is a suffix to append to the file name.  The
string is @code{malloc}ed, and the temporary file has been created.

@end deftypefn

@c memchr.c:3
@deftypefn Supplemental void* memchr (const void *@var{s}, int @var{c}, size_t @var{n})

This function searches memory starting at @code{*@var{s}} for the
character @var{c}.  The search only ends with the first occurrence of
@var{c}, or after @var{length} characters; in particular, a null
character does not terminate the search.  If the character @var{c} is
found within @var{length} characters of @code{*@var{s}}, a pointer
to the character is returned.  If @var{c} is not found, then @code{NULL} is
returned.

@end deftypefn

@c memcmp.c:6
@deftypefn Supplemental int memcmp (const void *@var{x}, const void *@var{y}, size_t @var{count})

Compares the first @var{count} bytes of two areas of memory.  Returns
zero if they are the same, a value less than zero if @var{x} is
lexically less than @var{y}, or a value greater than zero if @var{x}
is lexically greater than @var{y}.  Note that lexical order is determined
as if comparing unsigned char arrays.

@end deftypefn

@c memcpy.c:6
@deftypefn Supplemental void* memcpy (void *@var{out}, const void *@var{in}, size_t @var{length})

Copies @var{length} bytes from memory region @var{in} to region
@var{out}.  Returns a pointer to @var{out}.

@end deftypefn

@c memmove.c:6
@deftypefn Supplemental void* memmove (void *@var{from}, const void *@var{to}, size_t @var{count})

Copies @var{count} bytes from memory area @var{from} to memory area
@var{to}, returning a pointer to @var{to}.

@end deftypefn

@c memset.c:6
@deftypefn Supplemental void* memset (void *@var{s}, int @var{c}, size_t @var{count})

Sets the first @var{count} bytes of @var{s} to the constant byte
@var{c}, returning a pointer to @var{s}.

@end deftypefn

@c mkstemps.c:54
@deftypefn Replacement int mkstemps (char *@var{template}, int @var{suffix_len})

Generate a unique temporary file name from @var{template}.
@var{template} has the form:

@example
   @var{path}/ccXXXXXX@var{suffix}
@end example

@var{suffix_len} tells us how long @var{suffix} is (it can be zero
length).  The last six characters of @var{template} before @var{suffix}
must be @samp{XXXXXX}; they are replaced with a string that makes the
filename unique.  Returns a file descriptor open on the file for
reading and writing.

@end deftypefn

@c pexecute.c:67
@deftypefn Extension int pexecute (const char *@var{program}, char * const *@var{argv}, const char *@var{this_pname}, const char *@var{temp_base}, char **@var{errmsg_fmt}, char **@var{errmsg_arg}, int flags)

Executes a program.

@var{program} and @var{argv} are the arguments to
@code{execv}/@code{execvp}.

@var{this_pname} is name of the calling program (i.e., @code{argv[0]}).

@var{temp_base} is the path name, sans suffix, of a temporary file to
use if needed.  This is currently only needed for MS-DOS ports that
don't use @code{go32} (do any still exist?).  Ports that don't need it
can pass @code{NULL}.

(@code{@var{flags} & PEXECUTE_SEARCH}) is non-zero if @env{PATH} should be searched
(??? It's not clear that GCC passes this flag correctly).  (@code{@var{flags} &
PEXECUTE_FIRST}) is nonzero for the first process in chain.
(@code{@var{flags} & PEXECUTE_FIRST}) is nonzero for the last process
in chain.  The first/last flags could be simplified to only mark the
last of a chain of processes but that requires the caller to always
mark the last one (and not give up early if some error occurs).
It's more robust to require the caller to mark both ends of the chain.

The result is the pid on systems like Unix where we
@code{fork}/@code{exec} and on systems like WIN32 and OS/2 where we
use @code{spawn}.  It is up to the caller to wait for the child.

The result is the @code{WEXITSTATUS} on systems like MS-DOS where we
@code{spawn} and wait for the child here.

Upon failure, @var{errmsg_fmt} and @var{errmsg_arg} are set to the
text of the error message with an optional argument (if not needed,
@var{errmsg_arg} is set to @code{NULL}), and @minus{}1 is returned.
@code{errno} is available to the caller to use.

@end deftypefn

@c strsignal.c:547
@deftypefn Supplemental void psignal (unsigned @var{signo}, char *@var{message})

Print @var{message} to the standard error, followed by a colon,
followed by the description of the signal specified by @var{signo},
followed by a newline.

@end deftypefn

@c putenv.c:21
@deftypefn Supplemental int putenv (const char *@var{string})

Uses @code{setenv} or @code{unsetenv} to put @var{string} into
the environment or remove it.  If @var{string} is of the form
@samp{name=value} the string is added; if no @samp{=} is present the
name is unset/removed.

@end deftypefn

@c pexecute.c:104
@deftypefn Extension int pwait (int @var{pid}, int *@var{status}, int @var{flags})

Waits for a program started by @code{pexecute} to finish.

@var{pid} is the process id of the task to wait for. @var{status} is
the `status' argument to wait. @var{flags} is currently unused (allows
future enhancement without breaking upward compatibility).  Pass 0 for now.

The result is the pid of the child reaped, or -1 for failure
(@code{errno} says why).

On systems that don't support waiting for a particular child, @var{pid} is
ignored.  On systems like MS-DOS that don't really multitask @code{pwait}
is just a mechanism to provide a consistent interface for the caller.

@end deftypefn

@c random.c:39
@deftypefn Supplement {long int} random (void)
@deftypefnx Supplement void srandom (unsigned int @var{seed})
@deftypefnx Supplement void* initstate (unsigned int @var{seed}, void *@var{arg_state}, unsigned long @var{n})
@deftypefnx Supplement void* setstate (void *@var{arg_state})