NAME
glob
, globfree
— generate pathnames matching a
pattern
SYNOPSIS
#include
<glob.h>
int
glob
(const
char *pattern, int
flags, const int
(*errfunc)(const char *, int),
glob_t *pglob);
void
globfree
(glob_t
*pglob);
DESCRIPTION
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 { int gl_pathc; /* count of total paths so far */ int gl_matchc; /* count of paths matching pattern */ int 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.
glob
()
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 number of matched pathnames is stored in the
gl_pathc field, and a pointer to a list of pointers to
pathnames in 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 theGLOB_DOOFFS
flag, nor change the value of gl_offs whenGLOB_DOOFFS
is set, nor (obviously) callglobfree
() 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. GLOB_NOESCAPE
- Normally, every occurrence of a backslash
(‘
\
’) followed by a character in pattern is replaced by that character. This is done to negate any special meaning for the character. If theGLOB_NOESCAPE
flag is set, a backslash character is treated as an ordinary character. GLOB_NOSORT
- By default, the pathnames are sorted in ascending ASCII 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 *); 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 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. (csh(1) does the same thing to ease typing of find(1) patterns.) 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.
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 to store matched strings to
64K
, the number of stat(2) calls to 2048, and the number of readdir(3) calls to 16K. 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 ‘*/../*/..
’.
If, during the search, a directory is encountered that
cannot be opened or read and errfunc is non-null,
glob
() calls
(*errfunc)(path, errno). This may be unintuitive: a
pattern like “*/Makefile” will try to
stat(2) “foo/Makefile” even if “foo” is
not a directory, resulting in a call to errfunc. The
error routine can suppress this action by testing for
ENOENT
and ENOTDIR
; however,
the GLOB_ERR
flag will still 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
().
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
() ifGLOB_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, which are defined in the include file
⟨glob.h⟩:
GLOB_NOSPACE
- An attempt to allocate memory failed, or if errno
was 0
GLOB_LIMIT
was specified in the flags andARG_MAX 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. 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.
EXAMPLES
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);
ERRORS
The glob
() function may fail and set
errno for any of the errors specified for the library
routines stat(2),
closedir(3),
opendir(3),
readdir(3),
malloc(3), and
free(3).
SEE ALSO
STANDARDS
The glob
() function is expected to conform
to IEEE Std 1003.2 (“POSIX.2”) and
X/Open Portability Guide Issue 4, Version 2
(“XPG4.2”). Note, however, that the flags
GLOB_ALTDIRFUNC
, GLOB_BRACE
,
GLOB_KEEPSTAT
, GLOB_MAGCHAR
,
GLOB_NOMAGIC
, GLOB_QUOTE
,
GLOB_TILDE
, and GLOB_LIMIT
and the fields gl_matchc,
gl_statv and gl_flags should not
be used by applications striving for strict standards conformance.
HISTORY
The glob
() and
globfree
() functions first appeared in
4.4BSD.
BUGS
Patterns longer than MAXPATHLEN
may cause
unchecked errors.