glob, globfree - find pathnames matching a pattern, free memory from glob()

#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);

The glob() function searches for all the pathnames matching pattern according to the rules used by the shell (see glob(7)). No tilde expansion or parameter substitution is done; if you want these, use wordexp(3).

The globfree() function frees the dynamically allocated storage from an earlier call to glob().

The results of a glob() call are stored in the structure pointed to by pglob. This structure is of type glob_t (declared in <glob.h>) and includes the following elements defined by POSIX.2 (more may be present as an extension):

typedef struct {
    size_t   gl_pathc;    /* Count of paths matched so far  */
    char   **gl_pathv;    /* List of matched pathnames.  */
    size_t   gl_offs;     /* Slots to reserve in gl_pathv.  */
} glob_t;

Results are stored in dynamically allocated storage.

The argument flags is made up of the bitwise OR of zero or more the following symbolic constants, which modify the behavior of glob():

GLOB_ERR

Return upon a read error (because a directory does not have read permission, for example). By default, glob() attempts carry on despite errors, reading all of the directories that it can.

GLOB_MARK

Append a slash to each path which corresponds to a directory.

GLOB_NOSORT

Don't sort the returned pathnames. The only reason to do this is to save processing time. By default, the returned pathnames are sorted.

GLOB_DOOFFS

Reserve pglob->gl_offs slots at the beginning of the list of strings in pglob->pathv. The reserved slots contain null pointers.

GLOB_NOCHECK

If no pattern matches, return the original pattern. By default, glob() returns GLOB_NOMATCH if there are no matches.

GLOB_APPEND

Append the results of this call to the vector of results returned by a previous call to glob(). Do not set this flag on the first invocation of glob().

GLOB_NOESCAPE

Don't allow backslash ('\') to be used as an escape character. Normally, a backslash can be used to quote the following character, providing a mechanism to turn off the special meaning metacharacters.

flags may also include any of the following, which are GNU extensions and not defined by POSIX.2:

GLOB_PERIOD

Allow a leading period to be matched by metacharacters. By default, metacharacters can't match a leading period.

GLOB_ALTDIRFUNC

Use alternative functions pglob->gl_closedir, pglob->gl_readdir, pglob->gl_opendir, pglob->gl_lstat, and pglob->gl_stat for filesystem access instead of the normal library functions.

GLOB_BRACE

Expand csh(1) style brace expressions of the form {a,b}. Brace expressions can be nested. Thus, for example, specifying the pattern "{foo/{,cat,dog},bar}" would return the same results as four separate glob() calls using the strings: "foo/", "foo/cat", "foo/dog", and "bar".

GLOB_NOMAGIC

If the pattern contains no metacharacters, then it should be returned as the sole matching word, even if there is no file with that name.

GLOB_TILDE

Carry out tilde expansion. If a tilde ('~') is the only character in the pattern, or an initial tilde is followed immediately by a slash ('/'), then the home directory of the caller is substituted for the tilde. If an initial tilde is followed by a username (e.g., "~andrea/bin"), then the tilde and username are substituted by the home directory of that user. If the username is invalid, or the home directory cannot be determined, then no substitution is performed.

GLOB_TILDE_CHECK

This provides behavior similar to that of GLOB_TILDE. The difference is that if the username is invalid, or the home directory cannot be determined, then instead of using the pattern itself as the name, glob() returns GLOB_NOMATCH to indicate an error.

GLOB_ONLYDIR

This is a hint to glob() that the caller is interested only in directories that match the pattern. If the implementation can easily determine file-type information, then nondirectory files are not returned to the caller. However, the caller must still check that returned files are directories. (The purpose of this flag is merely to optimize performance when the caller is interested only in directories.)

If errfunc is not NULL, it will be called in case of an error with the arguments epath, a pointer to the path which failed, and eerrno, the value of errno as returned from one of the calls to opendir(3), readdir(3), or stat(2). If errfunc returns nonzero, or if GLOB_ERR is set, glob() will terminate after the call to errfunc.

Upon successful return, pglob->gl_pathc contains the number of matched pathnames and pglob->gl_pathv contains a pointer to the list of pointers to matched pathnames. The list of pointers is terminated by a null pointer.

It is possible to call glob() several times. In that case, the GLOB_APPEND flag has to be set in flags on the second and later invocations.

As a GNU extension, pglob->gl_flags is set to the flags specified, ored with GLOB_MAGCHAR if any metacharacters were found.

On successful completion, glob() returns zero. Other possible returns are:

GLOB_NOSPACE

for running out of memory,

GLOB_ABORTED

for a read error, and

GLOB_NOMATCH

for no found matches.

One example of use is the following code, which simulates typing

ls -l *.c ../*.c

in the shell:

glob_t globbuf;
globbuf.gl_offs = 2;
glob("*.c", GLOB_DOOFFS, NULL, &globbuf);
glob("../*.c", GLOB_DOOFFS | GLOB_APPEND, NULL, &globbuf);
globbuf.gl_pathv[0] = "ls";
globbuf.gl_pathv[1] = "-l";
execvp("ls", &globbuf.gl_pathv[0]);

ls(1), sh(1), stat(2), exec(3), fnmatch(3), malloc(3), opendir(3), readdir(3), wordexp(3), glob(7)