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

   Copyright (C) 2011-2017 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 value for careadlinkat's FD argument.  */

#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.  We might as well use the same value

   as fcntl-h.  */

# ifndef AT_FDCWD

#  define AT_FDCWD (-3041965)

# endif

#endif

#endif /* _GL_CAREADLINKAT_H */