Originální popis anglicky:
glob, globfree - generate pathnames matching a pattern
Návod, kniha: POSIX Programmer's Manual
#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 pathname generator that shall implement the
rules defined in the Shell and Utilities volume of
IEEE Std 1003.1-2001, Section 2.13, Pattern Matching Notation,
with optional support for rule 3 in the Shell and Utilities volume of
IEEE Std 1003.1-2001, Section 2.13.3, Patterns Used for Filename
Expansion.
The structure type
glob_t is defined in
<glob.h> and
includes at least the following members:
| Member Type |
Member Name |
Description |
| size_t |
gl_pathc |
Count of paths matched by pattern. |
| char ** |
gl_pathv |
Pointer to a list of matched pathnames. |
| size_t |
gl_offs |
Slots to reserve at the beginning of gl_pathv. |
The argument
pattern is a pointer to a pathname pattern to be expanded.
The
glob() function shall match all accessible pathnames against this
pattern and develop a list of all 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 following
special characters:
'*' ,
'?' , and
'[' .
The
glob() function shall store the number of matched pathnames into
pglob->
gl_pathc and a pointer to a list of pointers to
pathnames into
pglob->
gl_pathv. The pathnames shall be in
sort order as defined by the current setting of the
LC_COLLATE
category; see the Base Definitions volume of
IEEE Std 1003.1-2001, Section 7.3.2, LC_COLLATE. The first
pointer after the last pathname shall be a null pointer. If the pattern does
not match any pathnames, the returned number of matched paths is set to 0, and
the contents of
pglob->
gl_pathv are implementation-defined.
It is the caller's responsibility to create the structure pointed to by
pglob. The
glob() function shall allocate other space as needed,
including the memory pointed to by
gl_pathv. The
globfree()
function shall free any space associated with
pglob from a previous
call to
glob().
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
<glob.h>:
- GLOB_APPEND
- Append pathnames 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 shall point to
pglob-> gl_offs null pointers, followed by
pglob-> gl_pathc pathname pointers, followed by a null
pointer.
- GLOB_ERR
- Cause 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 shall have a slash appended.
- GLOB_NOCHECK
- Supports rule 3 in the Shell and Utilities volume of
IEEE Std 1003.1-2001, Section 2.13.3, Patterns Used for
Filename Expansion. If pattern does not match any pathname, then
glob() shall return a list consisting of only pattern, and
the number of matched pathnames is 1.
- GLOB_NOESCAPE
- Disable backslash escaping.
- GLOB_NOSORT
- Ordinarily, glob() sorts the matching pathnames
according to the current setting of the LC_COLLATE category; see
the Base Definitions volume of IEEE Std 1003.1-2001, Section
7.3.2, LC_COLLATE. When this flag is used, the order of pathnames returned
is unspecified.
The GLOB_APPEND flag can be used to append a new set of pathnames to those found
in a previous call to
glob(). The following rules apply to applications
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 shall not set GLOB_APPEND. All
subsequent calls shall set it.
- 2.
- All the calls shall set GLOB_DOOFFS, or all shall 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 pathnames that were in the
pglob-> gl_pathv list before the call, in the same order
as before.
- c.
- Pointers to the new pathnames generated by the second call,
in the specified order.
- 4.
- The count returned in pglob->gl_pathc
shall be the total number of pathnames from the two calls.
- 5.
- The application can change any of the fields after a call
to glob(). If it does, the application shall reset them to the
original value before a subsequent call, using the same pglob
value, to globfree() or glob() with the GLOB_APPEND
flag.
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 opendir(), readdir(), or
stat(). (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() shall stop the scan and return
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
shall be ignored.
The
glob() function shall not fail because of large files.
Upon successful completion,
glob() shall return 0. The argument
pglob->
gl_pathc shall return the number of matched pathnames
and the argument
pglob->
gl_pathv shall contain a pointer to a
null-terminated list of matched and sorted pathnames. However, if
pglob->
gl_pathc is 0, the content of
pglob->
gl_pathv is undefined.
The
globfree() function shall not return a value.
If
glob() terminates due to an error, it shall return one of the non-zero
constants defined in
<glob.h>. The arguments
pglob->
gl_pathc and
pglob->
gl_pathv are
still set as defined above.
The
glob() function shall fail and return the corresponding value if:
- 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 pathname, and
GLOB_NOCHECK was not set in flags.
- GLOB_NOSPACE
- An attempt to allocate memory failed.
The following sections are informative.
One use of the GLOB_DOOFFS flag is by applications that build an argument list
for use with
execv(),
execve(), or
execvp(). Suppose, for
example, that an application wants to do the equivalent of:
but for some reason:
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:
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);
...
This function is not provided for the purpose of enabling utilities to perform
pathname 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 pathname 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 pathname matches a given pattern, it can use
fnmatch().
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
pathname if wildcards are specified, but wants to treat the pattern as just a
string otherwise. The
sh utility might use this for option-arguments,
for example.
The new pathnames generated by a subsequent call with GLOB_APPEND are not sorted
together with the previous pathnames. This mirrors the way that the shell
handles pathname expansion when multiple expansions are done on a command
line.
Applications that need tilde and parameter expansion should use
wordexp().
It was claimed that the GLOB_DOOFFS flag is unnecessary because it could be
simulated using:
new = (char **)malloc((n + pglob->gl_pathc + 1)
* sizeof(char *));
(void) memcpy(new+n, pglob->gl_pathv,
pglob->gl_pathc * sizeof(char *));
(void) memset(new, 0, n * sizeof(char *));
free(pglob->gl_pathv);
pglob->gl_pathv = new;
However, this assumes that the memory pointed to by
gl_pathv is a block
that was separately created using
malloc(). This is not necessarily the
case. An application should make no assumptions about how the memory
referenced by fields in
pglob was allocated. It might have been
obtained from
malloc() in a large chunk and then carved up within
glob(), or it might have been created using a different memory
allocator. It is not the intent of the standard developers to specify or imply
how the memory used by
glob() is managed.
The GLOB_APPEND flag would be used when an application wants to expand several
different patterns into a single list.
None.
exec() ,
fnmatch() ,
opendir() ,
readdir() ,
stat() ,
wordexp() , the Base Definitions volume of
IEEE Std 1003.1-2001,
<glob.h>, the Shell and
Utilities volume of IEEE Std 1003.1-2001
Portions of this text are reprinted and reproduced in electronic form from IEEE
Std 1003.1, 2003 Edition, Standard for Information Technology -- Portable
Operating System Interface (POSIX), The Open Group Base Specifications Issue
6, Copyright (C) 2001-2003 by the Institute of Electrical and Electronics
Engineers, Inc and The Open Group. In the event of any discrepancy between
this version and the original IEEE and The Open Group Standard, the original
IEEE and The Open Group Standard is the referee document. The original
Standard can be obtained online at http://www.opengroup.org/unix/online.html
.
