path: root/man3p/glob.3p

.\" Copyright (c) 2001-2003 The Open Group, All Rights Reserved 
.TH "GLOB" 3P 2003 "IEEE/The Open Group" "POSIX Programmer's Manual"
.\" glob 
.SH PROLOG
This manual page is part of the POSIX Programmer's Manual.
The Linux implementation of this interface may differ (consult
the corresponding Linux manual page for details of Linux behavior),
or the interface may not be implemented on Linux.
.SH NAME
glob, globfree \- generate pathnames matching a pattern
.SH SYNOPSIS
.LP
\fB#include <glob.h>
.br
.sp
int glob(const char *restrict\fP \fIpattern\fP\fB, int\fP \fIflags\fP\fB,
.br
\ \ \ \ \ \  int(*\fP\fIerrfunc\fP\fB)(const char *\fP\fIepath\fP\fB,
int\fP
\fIeerrno\fP\fB),
.br
\ \ \ \ \ \  glob_t *restrict\fP \fIpglob\fP\fB);
.br
void globfree(glob_t *\fP\fIpglob\fP\fB);
.br
\fP
.SH DESCRIPTION
.LP
The \fIglob\fP() 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.
.LP
The structure type \fBglob_t\fP is defined in \fI<glob.h>\fP and includes
at least
the following members:
.TS C
center; l1 l1 l.
\fBMember Type\fP	\fBMember Name\fP	\fBDescription\fP
\fBsize_t\fP	\fIgl_pathc\fP	Count of paths matched by \fIpattern\fP.
\fBchar **\fP	\fIgl_pathv\fP	Pointer to a list of matched pathnames.
\fBsize_t\fP	\fIgl_offs\fP	Slots to reserve at the beginning of \fIgl_pathv\fP.
.TE
.LP
The argument \fIpattern\fP is a pointer to a pathname pattern to be
expanded. The \fIglob\fP() 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,
\fIglob\fP() requires search permission on every component of a path
except the last, and read permission on each directory of any
filename component of \fIpattern\fP that contains any of the following
special characters: \fB'*'\fP , \fB'?'\fP , and
\fB'['\fP .
.LP
The \fIglob\fP() function shall store the number of matched pathnames
into \fIpglob\fP->\fIgl_pathc\fP and a pointer to a
list of pointers to pathnames into \fIpglob\fP->\fIgl_pathv\fP. The
pathnames shall be in sort order as defined by the current
setting of the \fILC_COLLATE\fP 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
\fIpglob\fP->\fIgl_pathv\fP are implementation-defined.
.LP
It is the caller's responsibility to create the structure pointed
to by \fIpglob\fP. The \fIglob\fP() function shall allocate
other space as needed, including the memory pointed to by \fIgl_pathv\fP.
The \fIglobfree\fP() function shall free any space
associated with \fIpglob\fP from a previous call to \fIglob\fP().
.LP
The \fIflags\fP argument is used to control the behavior of \fIglob\fP().
The value of \fIflags\fP is a bitwise-inclusive OR
of zero or more of the following constants, which are defined in \fI<glob.h>\fP:
.TP 7
GLOB_APPEND
Append pathnames generated to the ones from a previous call to \fIglob\fP().
.TP 7
GLOB_DOOFFS
Make use of \fIpglob\fP->\fIgl_offs\fP. If this flag is set, \fIpglob\fP->\fIgl_offs\fP
is used to specify how many
null pointers to add to the beginning of \fIpglob\fP->\fIgl_pathv\fP.
In other words, \fIpglob\fP->\fIgl_pathv\fP shall
point to \fIpglob\fP->\fIgl_offs\fP null pointers, followed by \fIpglob\fP->\fIgl_pathc\fP
pathname pointers, followed by
a null pointer.
.TP 7
GLOB_ERR
Cause \fIglob\fP() to return when it encounters a directory that it
cannot open or read. Ordinarily, \fIglob\fP() continues
to find matches.
.TP 7
GLOB_MARK
Each pathname that is a directory that matches \fIpattern\fP shall
have a slash appended.
.TP 7
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 \fIpattern\fP
does not
match any pathname, then \fIglob\fP() shall return a list consisting
of only \fIpattern\fP, and the number of matched pathnames
is 1.
.TP 7
GLOB_NOESCAPE
Disable backslash escaping.
.TP 7
GLOB_NOSORT
Ordinarily, \fIglob\fP() sorts the matching pathnames according to
the current setting of the \fILC_COLLATE\fP 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.
.sp
.LP
The GLOB_APPEND flag can be used to append a new set of pathnames
to those found in a previous call to \fIglob\fP(). The
following rules apply to applications when two or more calls to \fIglob\fP()
are made with the same value of \fIpglob\fP and
without intervening calls to \fIglobfree\fP():
.IP " 1." 4
The first such call shall not set GLOB_APPEND. All subsequent calls
shall set it.
.LP
.IP " 2." 4
All the calls shall set GLOB_DOOFFS, or all shall not set it.
.LP
.IP " 3." 4
After the second call, \fIpglob\fP->\fIgl_pathv\fP points to a list
containing the following:
.RS
.IP " a." 4
Zero or more null pointers, as specified by GLOB_DOOFFS and \fIpglob\fP->\fIgl_offs\fP.
.LP
.IP " b." 4
Pointers to the pathnames that were in the \fIpglob\fP->\fIgl_pathv\fP
list before the call, in the same order as
before.
.LP
.IP " c." 4
Pointers to the new pathnames generated by the second call, in the
specified order.
.LP
.RE
.LP
.IP " 4." 4
The count returned in \fIpglob\fP->\fIgl_pathc\fP shall be the total
number of pathnames from the two calls.
.LP
.IP " 5." 4
The application can change any of the fields after a call to \fIglob\fP().
If it does, the application shall reset them to the
original value before a subsequent call, using the same \fIpglob\fP
value, to \fIglobfree\fP() or \fIglob\fP() with the
GLOB_APPEND flag.
.LP
.LP
If, during the search, a directory is encountered that cannot be opened
or read and \fIerrfunc\fP is not a null pointer,
\fIglob\fP() calls (\fI*errfunc\fP()) with two arguments:
.IP " 1." 4
The \fIepath\fP argument is a pointer to the path that failed.
.LP
.IP " 2." 4
The \fIeerrno\fP argument is the value of \fIerrno\fP from the failure,
as set by \fIopendir\fP(), \fIreaddir\fP(), or \fIstat\fP(). (Other
values may be used to report other errors not explicitly documented
for those
functions.)
.LP
.LP
If (\fI*errfunc\fP()) is called and returns non-zero, or if the GLOB_ERR
flag is set in \fIflags\fP, \fIglob\fP() shall stop
the scan and return GLOB_ABORTED after setting \fIgl_pathc\fP and
\fIgl_pathv\fP in \fIpglob\fP to reflect the paths already
scanned. If GLOB_ERR is not set and either \fIerrfunc\fP is a null
pointer or (\fI*errfunc\fP()) returns 0, the error shall be
ignored.
.LP
The \fIglob\fP() function shall not fail because of large files.
.SH RETURN VALUE
.LP
Upon successful completion, \fIglob\fP() shall return 0. The argument
\fIpglob\fP->\fIgl_pathc\fP shall return the number
of matched pathnames and the argument \fIpglob\fP->\fIgl_pathv\fP
shall contain a pointer to a null-terminated list of matched
and sorted pathnames. However, if \fIpglob\fP->\fIgl_pathc\fP is 0,
the content of \fIpglob\fP->\fIgl_pathv\fP is
undefined.
.LP
The \fIglobfree\fP() function shall not return a value.
.LP
If \fIglob\fP() terminates due to an error, it shall return one of
the non-zero constants defined in \fI<glob.h>\fP. The arguments \fIpglob\fP->\fIgl_pathc\fP
and
\fIpglob\fP->\fIgl_pathv\fP are still set as defined above.
.SH ERRORS
.LP
The \fIglob\fP() function shall fail and return the corresponding
value if:
.TP 7
GLOB_ABORTED
The scan was stopped because GLOB_ERR was set or (\fI*errfunc\fP())
returned non-zero.
.TP 7
GLOB_NOMATCH
The pattern does not match any existing pathname, and GLOB_NOCHECK
was not set in flags.
.TP 7
GLOB_NOSPACE
An attempt to allocate memory failed.
.sp
.LP
\fIThe following sections are informative.\fP
.SH EXAMPLES
.LP
One use of the GLOB_DOOFFS flag is by applications that build an argument
list for use with \fIexecv\fP(), \fIexecve\fP(), or \fIexecvp\fP().
Suppose, for example, that an application wants to do the equivalent
of:
.sp
.RS
.nf

\fBls -l *.c
\fP
.fi
.RE
.LP
but for some reason:
.sp
.RS
.nf

\fBsystem("ls -l *.c")
\fP
.fi
.RE
.LP
is not acceptable. The application could obtain approximately the
same result using the sequence:
.sp
.RS
.nf

\fBglobbuf.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]);
\fP
.fi
.RE
.LP
Using the same example:
.sp
.RS
.nf

\fBls -l *.c *.h
\fP
.fi
.RE
.LP
could be approximately simulated using GLOB_APPEND as follows:
.sp
.RS
.nf

\fBglobbuf.gl_offs = 2;
glob("*.c", GLOB_DOOFFS, NULL, &globbuf);
glob("*.h", GLOB_DOOFFS|GLOB_APPEND, NULL, &globbuf);
\&...
\fP
.fi
.RE
.SH APPLICATION USAGE
.LP
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.
.LP
If a utility needs to see if a pathname matches a given pattern, it
can use \fIfnmatch\fP().
.LP
Note that \fIgl_pathc\fP and \fIgl_pathv\fP have meaning even if \fIglob\fP()
fails. This allows \fIglob\fP() to report
partial results in the event of an error. However, if \fIgl_pathc\fP
is 0, \fIgl_pathv\fP is unspecified even if \fIglob\fP()
did not return an error.
.LP
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 \fIsh\fP utility
might use this for
option-arguments, for example.
.LP
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.
.LP
Applications that need tilde and parameter expansion should use \fIwordexp\fP().
.SH RATIONALE
.LP
It was claimed that the GLOB_DOOFFS flag is unnecessary because it
could be simulated using:
.sp
.RS
.nf

\fBnew = (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;
\fP
.fi
.RE
.LP
However, this assumes that the memory pointed to by \fIgl_pathv\fP
is a block that was separately created using \fImalloc\fP(). This
is not necessarily the case. An application should make no assumptions
about
how the memory referenced by fields in \fIpglob\fP was allocated.
It might have been obtained from \fImalloc\fP() in a large chunk and
then carved up within \fIglob\fP(), 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 \fIglob\fP() is managed.
.LP
The GLOB_APPEND flag would be used when an application wants to expand
several different patterns into a single list.
.SH FUTURE DIRECTIONS
.LP
None.
.SH SEE ALSO
.LP
\fIexec\fP() , \fIfnmatch\fP() , \fIopendir\fP() , \fIreaddir\fP()
, \fIstat\fP() , \fIwordexp\fP() , the Base Definitions volume of
IEEE\ Std\ 1003.1-2001, \fI<glob.h>\fP, the Shell and Utilities volume
of IEEE\ Std\ 1003.1-2001
.SH COPYRIGHT
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 .