NetBSD/lib/libc/gen/glob.3

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.\"     from: @(#)glob.3	5.7 (Berkeley) 12/2/92
.\"	$Id: glob.3,v 1.3 1993/07/30 08:36:56 mycroft Exp $
.\"
.Dd December 2, 1992
.Dt GLOB 3
.Os
.Sh NAME
.Nm glob ,
.Nm globfree
.Nd generate pathnames matching a pattern
.Sh SYNOPSIS
.Fd #include <glob.h>
.Ft int
.Fn glob "const char *pattern" "int flags" "const int (*errfunc)(char *, int)" "glob_t *pglob"
.Ft void 
.Fn globfree "glob_t *pglob"
.Sh DESCRIPTION
The
.Fn glob
function
is a pathname generator that implements the rules for file name pattern
matching used by the shell.
.Pp
The include file
.Pa glob.h
defines the structure type
.Fa glob_t ,
which contains at least the following fields:
.Bd -literal
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;
.Ed
.Pp
The argument
.Fa pattern
is a pointer to a pathname pattern to be expanded.
The
.Fn 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,
.Fn glob
requires search permission on every component of a path except the last
and read permission on each directory of any filename component of
.Fa pattern
that contains any of the special characters
.Ql * ,
.Ql ?
or
.Ql [ .
.Pp
The
.Fn glob
argument
stores the number of matched pathnames into the
.Fa gl_pathc
field, and a pointer to a list of pointers to pathnames into the
.Fa gl_pathv
field.
The first pointer after the last pathname is
.Dv NULL . 
If the pattern does not match any pathnames, the returned number of
matched paths is set to zero.
.Pp
It is the caller's responsibility to create the structure pointed to by
.Fa pglob .
The
.Fn glob
function allocates other space as needed, including the memory pointed
to by
.Fa gl_pathv .
.Pp
The argument
.Fa flags
is used to modify the behavior of
.Fn glob .
The value of
.Fa flags
is the bitwise inclusive
.Tn OR
of any of the following
values defined in
.Pa glob.h :
.Bl -tag -width GLOB_NOCHECK
.It Dv GLOB_APPEND
Append pathnames generated to the ones from a previous call (or calls)
to
.Fn glob .
The value of
.Fa 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
.Dv GLOB_DOOFFS
flag, nor change the value of
.Fa gl_offs
when
.Dv GLOB_DOOFFS
is set, nor (obviously) call
.Fn globfree
for
.Fa pglob .
.It Dv GLOB_DOOFFS
Make use of the
.Fa gl_offs
field.
If this flag is set,
.Fa gl_offs
is used to specify how many
.Dv NULL
pointers to prepend to the beginning
of the
.Fa gl_pathv
field.
In other words,
.Fa gl_pathv
will point to
.Fa gl_offs
.Dv NULL
pointers,
followed by
.Fa gl_pathc
pathname pointers, followed by a
.Dv NULL
pointer.
.It Dv GLOB_ERR
Causes
.Fn glob
to return when it encounters a directory that it cannot open or read.
Ordinarily,
.Fn glob
continues to find matches.
.It Dv GLOB_MARK
Each pathname that is a directory that matches
.Fa pattern
has a slash
appended.
.It Dv GLOB_NOCHECK
If
.Fa pattern
does not match any pathname, then
.Fn glob
returns a list
consisting of only
.Fa pattern ,
with the number of total pathnames is set to 1, and the number of matched
pathnames set to 0.
If
.Dv GLOB_QUOTE
is set, its effect is present in the pattern returned.
.It Dv GLOB_NOMAGIC
Is the same as 
.Dv GLOB_NOCHECK 
but it only appends the
.Fa pattern
if it does not contain any of the special characters ``*'', ``?'' or ``[''.
.Dv GLOB_NOMAGIC 
is provided to simplify implementing the historic
.Xr csh 1
globbing behavior and should probably not be used anywhere else.
.It Dv GLOB_NOSORT
By default, the pathnames are sorted in ascending
.Tn ASCII
order;
this flag prevents that sorting (speeding up
.Fn glob ) .
.It Dv GLOB_QUOTE
Use the backslash
.Pq Ql \e
character for quoting: every occurrence of
a backslash followed by a character in the pattern is replaced by that
character, avoiding any special interpretation of the character.
.It Dv 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.
.Bd -literal
	void *(*gl_opendir)();
	struct dirent *(*gl_readdir)();
	void (*gl_closedir)();
	int (*gl_lstat)();
	int (*gl_stat)();
.Ed
.Pp
This non-standard extension is provided to allow programs such
as restore to provide globbing from directories stored on tape.
.El
.Pp
If, during the search, a directory is encountered that cannot be opened
or read and
.Fa errfunc
is
.Pf non- Dv NULL , 
.Fn glob
calls
.Fa (*errfunc)(path,errno) .
This may be unintuitive: a pattern like
.Ql */Makefile
will try to
.Xr stat 2
.Ql foo/Makefile
even if
.Ql foo
is not a directory, resulting in a
call to
.Fa errfunc .
The error routine can suppress this action by testing for
.Dv ENOENT
and
.Dv ENOTDIR ; 
however, the
.Dv GLOB_ERR
flag will still cause an immediate
return when this happens.
.Pp
If
.Fa errfunc
returns non-zero,
.Fn glob
stops the scan and returns
.Dv GLOB_ABEND
after setting
.Fa gl_pathc
and
.Fa gl_pathv
to reflect any paths already matched.
This also happens if an error is encountered and
.Dv GLOB_ERR
is set in
.Fa flags ,
regardless of the return value of
.Fa errfunc ,
if called.
If
.Dv GLOB_ERR
is not set and either
.Fa errfunc
is
.Dv NULL
or
.Fa errfunc
returns zero, the error is ignored.
.Pp
The
.Fn globfree
function frees any space associated with
.Fa pglob
from a previous call(s) to
.Fn glob .
.Sh RETURN VALUES
On successful completion,
.Fn glob
returns zero.
In addition the fields of
.Fa pglob
contain the values described below:
.Bl -tag -width GLOB_NOCHECK
.It Fa gl_pathc
contains the total number of matched pathnames so far.
This includes other matches from previous invocations of 
.Fn glob
if 
.Dv GLOB_APPEND
was specified.
.It Fa gl_matchc
contains the number of matched pathnames in the current invocation of
.Fn glob .
.It Fa gl_flags
contains a copy of the 
.Fa flags
parameter with the bit
.Dv GLOB_MAGCHAR
set if
.Fa pattern
contained any of the special characters ``*'', ``?'' or ``['', cleared
if not.
.It Fa gl_pathv
contains a pointer to a
.Dv NULL Ns -terminated 
list of matched pathnames.
However, if
.Fa gl_pathc
is zero, the contents of
.Fa gl_pathv
are undefined.
.El
.Pp
If
.Fn 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
.Aq Pa glob.h :
.Bl -tag -width GLOB_NOCHECK
.It Dv GLOB_NOSPACE
An attempt to allocate memory failed.
.It Dv GLOB_ABEND
The scan was stopped because an error was encountered and either
.Dv GLOB_ERR
was set or
.Fa (*errfunc)()
returned non-zero.
.El
.Pp
The arguments
.Fa pglob\->gl_pathc
and
.Fa pglob\->gl_pathv
are still set as specified above.
.Sh SEE ALSO
.Xr sh 1 ,
.Xr fnmatch 3 ,
.Xr wordexp 3 ,
.Xr regexp 3
.Sh STANDARDS
The
.Fn glob
function is expected to be
.St -p1003.2
compatible with the exception
that the flags
.Dv GLOB_ALTDIRFUNC
and
.Dv GLOB_QUOTE
and the fields 
.Fa gl_matchc
and 
.Fa gl_flags
should not be used by applications striving for strict
.Tn POSIX
conformance.
.Sh EXAMPLE
A rough equivalent of
.Ql "ls -l *.c *.h"
can be obtained with the
following code:
.Bd -literal -offset indent
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);
.Ed
.Sh HISTORY
The
.Fn glob
and
.Fn globfree
functions are
.Ud .
.Sh BUGS
Patterns longer than
.Dv MAXPATHLEN
may cause unchecked errors.
.Pp
The
.Fn glob
argument
may fail and set errno for any of the errors specified for the
library routines
.Xr stat 2 ,
.Xr closedir 3 ,
.Xr opendir 3 ,
.Xr readdir 3 ,
.Xr malloc 3 ,
and
.Xr free 3 .