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


NAME


glob, globfree - generate path names 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 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(1M) 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:

a. Zero or more NULL pointers, as specified by GLOB_DOOFFS
and pglob->gl_offs.

b. Pointers to the path names that were in the
pglob->gl_pathv list before the call, in the same order as
before.

c. 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.

RETURN VALUES


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.

USAGE


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.

EXAMPLES


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);
...


ATTRIBUTES


See attributes(5) for descriptions of the following attributes:


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

SEE ALSO


execv(2), stat(2), fnmatch(3C), opendir(3C), readdir(3C), wordexp(3C),
attributes(5), standards(5)


November 1, 2003 GLOB(3C)