GLOB(3C) Standard C Library Functions GLOB(3C)

glob, globfree - generate path names matching a pattern

#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 is a path name generator.

The globfree() function frees any memory allocated by glob() associated with pglob.

pattern Argument

The argument pattern is a pointer to a path name pattern to be expanded. The glob() function matches all accessible path names against this pattern and develops a list of all path names that match. In order to have access to a path name, 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:


*        ?        [

pglob Argument

The structure type glob_t is defined in the header <glob.h> and includes at least the following members:


size_t   gl_pathc;     /* Total count of paths matched by */


                       /* pattern */
char     **gl_pathv;   /* List of matched path names */
size_t   gl_offs;      /* # of slots reserved in gl_pathv */
int      gl_matchc;    /* Count of paths matching pattern. */
int      gl_flags;     /* Copy of flags parameter to glob. */

The glob() function stores the number of matched path names into pglob−>gl_pathc and a pointer to a list of pointers to path names into pglob−>gl_pathv. The path names are in sort order as defined by the current setting of the LC_COLLATE category. The first pointer after the last path name is a NULL pointer. If the pattern does not match any path names, the returned number of matched paths is set to 0, and the contents of pglob−>gl_pathv are implementation-dependent.

It is the caller's responsibility to create the structure pointed to by pglob. The glob() function allocates other space as needed, including the memory pointed to by gl_pathv. The globfree() function frees any space associated with pglob from a previous call to glob().

flags Argument

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 the header <glob.h>:

GLOB_APPEND

Append path names 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 will point to pglob−>gl_offs NULL pointers, followed by pglob−>gl_pathc path name pointers, followed by a NULL pointer.

GLOB_ERR

Causes glob() to return when it encounters a directory that it cannot open or read. Ordinarily, glob() continues to find matches.

GLOB_MARK

Each path name that is a directory that matches pattern has a slash appended.

GLOB_NOCHECK

If pattern does not match any path name, then glob() returns a list consisting of only pattern, and the number of matched path names is 1.

GLOB_NOESCAPE

Disable backslash escaping.

GLOB_NOSORT

Ordinarily, glob() sorts the matching path names according to the current setting of the LC_COLLATE category. When this flag is used the order of path names returned is unspecified.

GLOB_ALTDIRFUNC

The following additional fields in the pglob structure have been initialized with alternate functions for glob() to use to open, read, and close directories and to get stat information on names found in those directories: 

void *(*gl_opendir)(const char *);
struct dirent *(*gl_readdir)(void *);
void (*gl_closedir)(void *);
int (*gl_lstat)(const char *, struct stat *);
int (*gl_stat)(const char *, struct stat *);

This extension is provided to allow programs such as ufsrestore(8) to provide globbing from directories stored on tape.

GLOB_BRACE

Pre-process the pattern string to expand `{pat,pat,...}' strings like csh(1). The pattern `{}' is left unexpanded for historical reasons. (csh(1) does the same thing to ease typing of find(1) patterns.)

GLOB_MAGCHAR

Set by the glob() function if the pattern included globbing characters. See the description of the usage of the gl_matchc structure member for more details.

GLOB_NOMAGIC

Is the same as GLOB_NOCHECK but it only appends the pattern if it does not contain any of the special characters `*', `?', or `['. GLOB_NOMAGIC is provided to simplify implementing the historic csh(1) globbing behavior and should probably not be used anywhere else.

GLOB_QUOTE

This option has no effect and is included for backwards compatibility with older sources.

GLOB_TILDE

Expand patterns that start with `~' to user name home directories.

GLOB_LIMIT

Limit the amount of memory used by matches to ARG_MAX. This option should be set for programs that can be coerced to a denial of service attack via patterns that expand to a very large number of matches, such as a long string of `*/../*/..'.

GLOB_KEEPSTAT

Retain a copy of the stat(2) information retrieved for matching paths in the gl_statv array: 

struct stat **gl_statv;

This option may be used to avoid lstat(2) lookups in cases where they are expensive.

The GLOB_APPEND flag can be used to append a new set of path names to those found in a previous call to glob(). The following rules apply 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 must not set GLOB_APPEND. All subsequent calls must set it.
2.
All the calls must set GLOB_DOOFFS, or all must not set it.
3.
After the second call, pglob−>gl_pathv points to a list containing the following:
Zero or more NULL pointers, as specified by GLOB_DOOFFS and pglob−>gl_offs.
Pointers to the path names that were in the pglob−>gl_pathv list before the call, in the same order as before.
Pointers to the new path names generated by the second call, in the specified order.
4.
The count returned in pglob−>gl_pathc will be the total number of path names from the two calls.
5.
The application can change any of the fields after a call to glob(). If it does, it must reset them to the original value before a subsequent call, using the same pglob value, to globfree() or glob() with the GLOB_APPEND flag.

errfunc and epath Arguments

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 the opendir(3C), readdir(3C) or stat(2) functions. (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() stops the scan and returns 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 is ignored.

On successful completion, glob() returns zero. In addition the fields of pglob contain the values described below:

gl_pathc

Contains the total number of matched pathnames so far. This includes other matches from previous invocations of glob() if GLOB_APPEND was specified.

gl_matchc

Contains the number of matched pathnames in the current invocation of glob().

gl_flags

Contains a copy of the flags parameter with the bit GLOB_MAGCHAR set if pattern contained any of the special characters `*', `?', or `[', cleared if not.

gl_pathv

Contains a pointer to a null-terminated list of matched pathnames. However, if gl_pathc is zero, the contents of gl_pathv are undefined.

gl_statv

If the GLOB_KEEPSTAT flag was set, gl_statv contains a pointer to a null-terminated list of matched stat(2) objects corresponding to the paths in gl_pathc.

If glob() terminates due to an error, it sets errno and returns one of the following non-zero constants. defined in <glob.h>:

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 path name, and GLOB_NOCHECK was not set in flags.

GLOB_NOSPACE

An attempt to allocate memory failed.

GLOB_NOSYS

The requested function is not supported by this version of glob().

The arguments pglob−>gl_pathc and pglob−>gl_pathv are still set as specified above.

The globfree() function returns no value.

This function is not provided for the purpose of enabling utilities to perform path name 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 path name 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 path name matches a given pattern, it can use fnmatch(3C).

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 path name if wildcards are specified, but wants to treat the pattern as just a string otherwise.

The new path names generated by a subsequent call with GLOB_APPEND are not sorted together with the previous path names. This mirrors the way that the shell handles path name expansion when multiple expansions are done on a command line.

Applications that need tilde and parameter expansion should use the wordexp(3C) function.

Example 1 Example of glob_doofs function.

One use of the GLOB_DOOFFS flag is by applications that build an argument list for use with the execv(), execve(), or execvp() functions (see exec(2)). 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);
...

See attributes(7) for descriptions of the following attributes:

ATTRIBUTE TYPE ATTRIBUTE VALUE
Interface Stability Standard
MT-Level MT-Safe

execv(2), stat(2), fnmatch(3C), opendir(3C), readdir(3C), wordexp(3C), attributes(7), standards(7)

November 1, 2003 OmniOS