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GLOB(3) |
FreeBSD Library Functions Manual |
GLOB(3) |
glob , globfree —
generate pathnames matching a pattern
Standard C Library (libc, -lc)
#include <glob.h>
int
glob (const
char * restrict pattern,
int flags,
int (*errfunc)(const char *,
int), glob_t * restrict
pglob);
void
globfree (glob_t
*pglob);
The glob () function is a pathname generator that
implements the rules for file name pattern matching used by the shell.
The include file
<glob.h> defines the
structure type glob_t, which contains at least the
following fields:
typedef struct {
size_t gl_pathc; /* count of total paths so far */
size_t gl_matchc; /* count of paths matching pattern */
size_t gl_offs; /* reserved at beginning of gl_pathv */
int gl_flags; /* returned flags */
char **gl_pathv; /* list of paths matching pattern */
} glob_t;
The argument pattern is a pointer to a
pathname pattern to be expanded. The glob () argument
matches all accessible pathnames against the pattern and creates a list of
the 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
special characters ‘* ’,
‘? ’ or
‘[ ’.
The glob () argument stores the number of
matched pathnames into the gl_pathc field, and a
pointer to a list of pointers to pathnames into the
gl_pathv field. The first pointer after the last
pathname is NULL . If the pattern does not match any
pathnames, the returned number of matched paths is set to zero.
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 argument flags is used to modify the
behavior of glob (). The value of
flags is the bitwise inclusive OR of any of the
following values defined in
<glob.h> :
GLOB_APPEND
- Append pathnames generated to the ones from a previous call (or calls) to
glob (). The value of
gl_pathc will be the total matches found by this
call and the previous call(s). The pathnames are appended to, not merged
with the pathnames returned by the previous call(s). Between calls, the
caller must not change the setting of the
GLOB_DOOFFS flag, nor change the value of
gl_offs when GLOB_DOOFFS is
set, nor (obviously) call globfree () for
pglob.
GLOB_DOOFFS
- Make use of the gl_offs field. If this flag is set,
gl_offs is used to specify how many
NULL pointers to prepend to the beginning of the
gl_pathv field. In other words,
gl_pathv will point to gl_offs
NULL pointers, followed by
gl_pathc pathname 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 pathname that is a directory that matches
pattern has a slash appended.
GLOB_NOCHECK
- If pattern does not match any pathname, then
glob () returns a list consisting of only
pattern, with the number of total pathnames set to
1, and the number of matched pathnames set to 0. The effect of backslash
escaping is present in the pattern returned.
GLOB_NOESCAPE
- By default, a backslash (‘
\ ’)
character is used to escape the following character in the pattern,
avoiding any special interpretation of the character. If
GLOB_NOESCAPE is set, backslash escaping is
disabled.
GLOB_NOSORT
- By default, the pathnames are sorted in ascending collation order; this
flag prevents that sorting (speeding up
glob ()).
The following values may also be included in
flags, however, they are non-standard extensions to
IEEE Std 1003.2 (“POSIX.2”).
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 * name);
struct dirent *(*gl_readdir)(void *);
void (*gl_closedir)(void *);
int (*gl_lstat)(const char *name, struct stat *st);
int (*gl_stat)(const char *name, struct stat *st);
This extension is provided to allow programs such as
restore(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 (and
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_TILDE
- Expand patterns that start with ‘
~ ’
to user name home directories.
GLOB_LIMIT
- Limit the total number of returned pathnames to the value provided in
gl_matchc (default
ARG_MAX ).
This option should be set for programs that can be coerced into a denial
of service attack via patterns that expand to a very large number of
matches, such as a long string of
‘*/../*/.. ’.
If, during the search, a directory is encountered that cannot be
opened or read and errfunc is
non-NULL , glob () calls
(*errfunc)(path,
errno), however, the GLOB_ERR
flag will cause an immediate return when this happens.
If errfunc returns non-zero,
glob () stops the scan and returns
GLOB_ABORTED after setting
gl_pathc and gl_pathv to reflect
any paths already matched. This also happens if an error is encountered and
GLOB_ERR is set in flags,
regardless of the return value of errfunc, if called.
If GLOB_ERR is not set and either
errfunc is NULL or
errfunc returns zero, the error is ignored.
The globfree () function frees any space
associated with pglob from a previous call(s) to
glob ().
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 argument 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.
If glob () terminates due to an error, it
sets errno and returns one of the following non-zero constants, which are
defined in the include file
<glob.h> :
GLOB_NOSPACE
- An attempt to allocate memory failed, or if errno
was E2BIG,
GLOB_LIMIT was specified in the flags
and pglob->gl_matchc or more patterns were
matched.
GLOB_ABORTED
- The scan was stopped because an error was encountered and either
GLOB_ERR was set or
(*errfunc)() returned non-zero.
GLOB_NOMATCH
- The pattern did not match a pathname and
GLOB_NOCHECK was not set.
The arguments pglob->gl_pathc and
pglob->gl_pathv are still set as specified
above.
A rough equivalent of ‘ls -l *.c *.h ’ can
be obtained with the following code:
glob_t g;
g.gl_offs = 2;
glob("*.c", GLOB_DOOFFS, NULL, &g);
glob("*.h", GLOB_DOOFFS | GLOB_APPEND, NULL, &g);
g.gl_pathv[0] = "ls";
g.gl_pathv[1] = "-l";
execvp("ls", g.gl_pathv);
The current implementation of the glob () function
does not conform to IEEE Std 1003.2
(“POSIX.2”). Collating symbol expressions, equivalence
class expressions and character class expressions are not supported.
The flags GLOB_ALTDIRFUNC ,
GLOB_BRACE , GLOB_LIMIT ,
GLOB_MAGCHAR , GLOB_NOMAGIC ,
and GLOB_TILDE , and the fields
gl_matchc and gl_flags are
extensions to the POSIX standard and should not be used by applications
striving for strict conformance.
The glob () and globfree ()
functions first appeared in 4.4BSD.
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