NAME
glob, globfree - generate pathnames matching a pattern
SYNOPSIS
#include <glob.h>
int glob(const char *restrict pattern, int flags,
int(*errfunc)(const char *epath, int eerrno),
glob_t *restrict pglob);
void globfree(glob_t *pglob);
DESCRIPTION
The glob() function is a pathname generator that shall implement the
rules defined in the Shell and Utilities volume of
IEEE Std 1003.1-2001, Section 2.13, Pattern Matching Notation, with
optional support for rule 3 in the Shell and Utilities volume of
IEEE Std 1003.1-2001, Section 2.13.3, Patterns Used for Filename
Expansion.
The structure type glob_t is defined in <glob.h> and includes at least
the following members:
Member Type Member Name Description
size_t gl_pathc Count of paths matched by pattern.
char ** gl_pathv Pointer to a list of matched pathnames.
size_t gl_offs Slots to reserve at the beginning of gl_pathv.
The argument pattern is a pointer to a pathname pattern to be expanded.
The glob() function shall match all accessible pathnames against this
pattern and develop a list of all pathnames that match. In order to
have access to a pathname, glob() requires search permission on every
component of a path except the last, and read permission on each
directory of any filename component of pattern that contains any of the
following special characters: ’*’ , ’?’ , and ’[’ .
The glob() function shall store the number of matched pathnames into
pglob->gl_pathc and a pointer to a list of pointers to pathnames into
pglob->gl_pathv. The pathnames shall be in sort order as defined by the
current setting of the LC_COLLATE category; see the Base Definitions
volume of IEEE Std 1003.1-2001, Section 7.3.2, LC_COLLATE. The first
pointer after the last pathname shall be a null pointer. If the pattern
does not match any pathnames, the returned number of matched paths is
set to 0, and the contents of pglob->gl_pathv are implementation-
defined.
It is the caller’s responsibility to create the structure pointed to by
pglob. The glob() function shall allocate other space as needed,
including the memory pointed to by gl_pathv. The globfree() function
shall free any space associated with pglob from a previous call to
glob().
The flags argument is used to control the behavior of glob(). The
value of flags is a bitwise-inclusive OR of zero or more of the
following constants, which are defined in <glob.h>:
GLOB_APPEND
Append pathnames generated to the ones from a previous call to
glob().
GLOB_DOOFFS
Make use of pglob->gl_offs. If this flag is set, pglob->gl_offs
is used to specify how many null pointers to add to the
beginning of pglob->gl_pathv. In other words, pglob->gl_pathv
shall point to pglob->gl_offs null pointers, followed by
pglob->gl_pathc pathname pointers, followed by a null pointer.
GLOB_ERR
Cause glob() to return when it encounters a directory that it
cannot open or read. Ordinarily, glob() continues to find
matches.
GLOB_MARK
Each pathname that is a directory that matches pattern shall
have a slash appended.
GLOB_NOCHECK
Supports rule 3 in the Shell and Utilities volume of
IEEE Std 1003.1-2001, Section 2.13.3, Patterns Used for Filename
Expansion. If pattern does not match any pathname, then glob()
shall return a list consisting of only pattern, and the number
of matched pathnames is 1.
GLOB_NOESCAPE
Disable backslash escaping.
GLOB_NOSORT
Ordinarily, glob() sorts the matching pathnames according to the
current setting of the LC_COLLATE category; see the Base
Definitions volume of IEEE Std 1003.1-2001, Section 7.3.2,
LC_COLLATE. When this flag is used, the order of pathnames
returned is unspecified.
The GLOB_APPEND flag can be used to append a new set of pathnames to
those found in a previous call to glob(). The following rules apply to
applications when two or more calls to glob() are made with the same
value of pglob and without intervening calls to globfree():
1. The first such call shall not set GLOB_APPEND. All subsequent calls
shall set it.
2. All the calls shall set GLOB_DOOFFS, or all shall not set it.
3. After the second call, pglob->gl_pathv points to a list containing
the following:
a. Zero or more null pointers, as specified by GLOB_DOOFFS and
pglob->gl_offs.
b. Pointers to the pathnames that were in the pglob->gl_pathv list
before the call, in the same order as before.
c. Pointers to the new pathnames generated by the second call, in
the specified order.
4. The count returned in pglob->gl_pathc shall be the total number of
pathnames from the two calls.
5. The application can change any of the fields after a call to
glob(). If it does, the application shall reset them to the
original value before a subsequent call, using the same pglob
value, to globfree() or glob() with the GLOB_APPEND flag.
If, during the search, a directory is encountered that cannot be opened
or read and errfunc is not a null pointer, glob() calls (*errfunc())
with two arguments:
1. The epath argument is a pointer to the path that failed.
2. The eerrno argument is the value of errno from the failure, as set
by opendir(), readdir(), or stat(). (Other values may be used to
report other errors not explicitly documented for those functions.)
If (*errfunc()) is called and returns non-zero, or if the GLOB_ERR flag
is set in flags, glob() shall stop the scan and return GLOB_ABORTED
after setting gl_pathc and gl_pathv in pglob to reflect the paths
already scanned. If GLOB_ERR is not set and either errfunc is a null
pointer or (*errfunc()) returns 0, the error shall be ignored.
The glob() function shall not fail because of large files.
RETURN VALUE
Upon successful completion, glob() shall return 0. The argument
pglob->gl_pathc shall return the number of matched pathnames and the
argument pglob->gl_pathv shall contain a pointer to a null-terminated
list of matched and sorted pathnames. However, if pglob->gl_pathc is 0,
the content of pglob->gl_pathv is undefined.
The globfree() function shall not return a value.
If glob() terminates due to an error, it shall return one of the non-
zero constants defined in <glob.h>. The arguments pglob->gl_pathc and
pglob->gl_pathv are still set as defined above.
ERRORS
The glob() function shall fail and return the corresponding value if:
GLOB_ABORTED
The scan was stopped because GLOB_ERR was set or (*errfunc())
returned non-zero.
GLOB_NOMATCH
The pattern does not match any existing pathname, and
GLOB_NOCHECK was not set in flags.
GLOB_NOSPACE
An attempt to allocate memory failed.
The following sections are informative.
EXAMPLES
One use of the GLOB_DOOFFS flag is by applications that build an
argument list for use with execv(), execve(), or execvp(). Suppose,
for example, that an application wants to do the equivalent of:
ls -l *.c
but for some reason:
system("ls -l *.c")
is not acceptable. The application could obtain approximately the same
result using the sequence:
globbuf.gl_offs = 2;
glob("*.c", GLOB_DOOFFS, NULL, &globbuf);
globbuf.gl_pathv[0] = "ls";
globbuf.gl_pathv[1] = "-l";
execvp("ls", &globbuf.gl_pathv[0]);
Using the same example:
ls -l *.c *.h
could be approximately simulated using GLOB_APPEND as follows:
globbuf.gl_offs = 2;
glob("*.c", GLOB_DOOFFS, NULL, &globbuf);
glob("*.h", GLOB_DOOFFS|GLOB_APPEND, NULL, &globbuf);
...
APPLICATION USAGE
This function is not provided for the purpose of enabling utilities to
perform pathname expansion on their arguments, as this operation is
performed by the shell, and utilities are explicitly not expected to
redo this. Instead, it is provided for applications that need to do
pathname expansion on strings obtained from other sources, such as a
pattern typed by a user or read from a file.
If a utility needs to see if a pathname matches a given pattern, it can
use fnmatch().
Note that gl_pathc and gl_pathv have meaning even if glob() fails. This
allows glob() to report partial results in the event of an error.
However, if gl_pathc is 0, gl_pathv is unspecified even if glob() did
not return an error.
The GLOB_NOCHECK option could be used when an application wants to
expand a pathname if wildcards are specified, but wants to treat the
pattern as just a string otherwise. The sh utility might use this for
option-arguments, for example.
The new pathnames generated by a subsequent call with GLOB_APPEND are
not sorted together with the previous pathnames. This mirrors the way
that the shell handles pathname expansion when multiple expansions are
done on a command line.
Applications that need tilde and parameter expansion should use
wordexp().
RATIONALE
It was claimed that the GLOB_DOOFFS flag is unnecessary because it
could be simulated using:
new = (char **)malloc((n + pglob->gl_pathc + 1)
* sizeof(char *));
(void) memcpy(new+n, pglob->gl_pathv,
pglob->gl_pathc * sizeof(char *));
(void) memset(new, 0, n * sizeof(char *));
free(pglob->gl_pathv);
pglob->gl_pathv = new;
However, this assumes that the memory pointed to by gl_pathv is a block
that was separately created using malloc(). This is not necessarily the
case. An application should make no assumptions about how the memory
referenced by fields in pglob was allocated. It might have been
obtained from malloc() in a large chunk and then carved up within
glob(), or it might have been created using a different memory
allocator. It is not the intent of the standard developers to specify
or imply how the memory used by glob() is managed.
The GLOB_APPEND flag would be used when an application wants to expand
several different patterns into a single list.
FUTURE DIRECTIONS
None.
SEE ALSO
exec() , fnmatch() , opendir() , readdir() , stat() , wordexp() , the
Base Definitions volume of IEEE Std 1003.1-2001, <glob.h>, the Shell
and Utilities volume of IEEE Std 1003.1-2001
COPYRIGHT
Portions of this text are reprinted and reproduced in electronic form
from IEEE Std 1003.1, 2003 Edition, Standard for Information Technology
-- Portable Operating System Interface (POSIX), The Open Group Base
Specifications Issue 6, Copyright (C) 2001-2003 by the Institute of
Electrical and Electronics Engineers, Inc and The Open Group. In the
event of any discrepancy between this version and the original IEEE and
The Open Group Standard, the original IEEE and The Open Group Standard
is the referee document. The original Standard can be obtained online
at http://www.opengroup.org/unix/online.html .