[bpt/emacs.git] / lib / careadlinkat.h

/* Read symbolic links into a buffer without size limitation, relative to fd.

   Copyright (C) 2011-2012 Free Software Foundation, Inc.

   This program is free software: you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation; either version 3 of the License, or
   (at your option) any later version.

   This program is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU General Public License for more details.

   You should have received a copy of the GNU General Public License
   along with this program.  If not, see <http://www.gnu.org/licenses/>.  */

/* Written by Paul Eggert, Bruno Haible, and Jim Meyering.  */

#ifndef _GL_CAREADLINKAT_H
#define _GL_CAREADLINKAT_H

#include <fcntl.h>
#include <unistd.h>

struct allocator;

/* Assuming the current directory is FD, get the symbolic link value
   of FILENAME as a null-terminated string and put it into a buffer.
   If FD is AT_FDCWD, FILENAME is interpreted relative to the current
   working directory, as in openat.

   If the link is small enough to fit into BUFFER put it there.
   BUFFER's size is BUFFER_SIZE, and BUFFER can be null
   if BUFFER_SIZE is zero.

   If the link is not small, put it into a dynamically allocated
   buffer managed by ALLOC.  It is the caller's responsibility to free
   the returned value if it is nonnull and is not BUFFER.

   The PREADLINKAT function specifies how to read links.  It operates
   like POSIX readlinkat()
   <http://pubs.opengroup.org/onlinepubs/9699919799/functions/readlink.html>
   but can assume that its first argument is the same as FD.

   If successful, return the buffer address; otherwise return NULL and
   set errno.  */

char *careadlinkat (int fd, char const *filename,
                    char *buffer, size_t buffer_size,
                    struct allocator const *alloc,
                    ssize_t (*preadlinkat) (int, char const *,
                                            char *, size_t));

/* Suitable values for careadlinkat's FD and PREADLINKAT arguments,
   when doing a plain readlink:
   Pass FD = AT_FDCWD and PREADLINKAT = careadlinkatcwd.  */
#if HAVE_READLINKAT
/* AT_FDCWD is declared in <fcntl.h>.  */
#else
/* Define AT_FDCWD independently, so that the careadlinkat module does
   not depend on the fcntl-h module.  The value does not matter, since
   careadlinkatcwd ignores it, but we might as well use the same value
   as fcntl-h.  */
# ifndef AT_FDCWD
#  define AT_FDCWD (-3041965)
# endif
#endif
ssize_t careadlinkatcwd (int fd, char const *filename,
                         char *buffer, size_t buffer_size);

#endif /* _GL_CAREADLINKAT_H */
Commit	Line	Data
d1fdcab7 PE	1	/* Read symbolic links into a buffer without size limitation, relative to fd.
d1fdcab7 PE	2
caf8a9b2	3	Copyright (C) 2011-2012 Free Software Foundation, Inc.
d1fdcab7 PE	4
	5	This program is free software: you can redistribute it and/or modify
	6	it under the terms of the GNU General Public License as published by
	7	the Free Software Foundation; either version 3 of the License, or
	8	(at your option) any later version.
	9
	10	This program is distributed in the hope that it will be useful,
	11	but WITHOUT ANY WARRANTY; without even the implied warranty of
	12	MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
	13	GNU General Public License for more details.
	14
	15	You should have received a copy of the GNU General Public License
	16	along with this program. If not, see <http://www.gnu.org/licenses/>. */
	17
	18	/* Written by Paul Eggert, Bruno Haible, and Jim Meyering. */
	19
	20	#ifndef _GL_CAREADLINKAT_H
e5b28a7a	21	#define _GL_CAREADLINKAT_H
d1fdcab7 PE	22
	23	#include <fcntl.h>
	24	#include <unistd.h>
	25
	26	struct allocator;
	27
	28	/* Assuming the current directory is FD, get the symbolic link value
	29	of FILENAME as a null-terminated string and put it into a buffer.
	30	If FD is AT_FDCWD, FILENAME is interpreted relative to the current
	31	working directory, as in openat.
	32
	33	If the link is small enough to fit into BUFFER put it there.
	34	BUFFER's size is BUFFER_SIZE, and BUFFER can be null
	35	if BUFFER_SIZE is zero.
	36
	37	If the link is not small, put it into a dynamically allocated
	38	buffer managed by ALLOC. It is the caller's responsibility to free
	39	the returned value if it is nonnull and is not BUFFER.
	40
e5b28a7a PE	41	The PREADLINKAT function specifies how to read links. It operates
	42	like POSIX readlinkat()
	43	<http://pubs.opengroup.org/onlinepubs/9699919799/functions/readlink.html>
	44	but can assume that its first argument is the same as FD.
d1fdcab7 PE	45
	46	If successful, return the buffer address; otherwise return NULL and
	47	set errno. */
	48
	49	char careadlinkat (int fd, char const filename,
	50	char *buffer, size_t buffer_size,
	51	struct allocator const *alloc,
	52	ssize_t (preadlinkat) (int, char const ,
	53	char *, size_t));
	54
	55	/* Suitable values for careadlinkat's FD and PREADLINKAT arguments,
e5b28a7a PE	56	when doing a plain readlink:
e5b28a7a PE	57	Pass FD = AT_FDCWD and PREADLINKAT = careadlinkatcwd. */
d1fdcab7	58	#if HAVE_READLINKAT
9afafefb	59	/* AT_FDCWD is declared in <fcntl.h>. */
d1fdcab7 PE	60	#else
	61	/* Define AT_FDCWD independently, so that the careadlinkat module does
	62	not depend on the fcntl-h module. The value does not matter, since
	63	careadlinkatcwd ignores it, but we might as well use the same value
	64	as fcntl-h. */
	65	# ifndef AT_FDCWD
	66	# define AT_FDCWD (-3041965)
	67	# endif
9afafefb	68	#endif
d1fdcab7 PE	69	ssize_t careadlinkatcwd (int fd, char const *filename,
d1fdcab7 PE	70	char *buffer, size_t buffer_size);
d1fdcab7 PE	71
d1fdcab7 PE	72	#endif /* _GL_CAREADLINKAT_H */