From: Bruno Haible Date: Mon, 17 Mar 2003 09:32:25 +0000 (+0000) Subject: gnulib module 'xreadlink'. X-Git-Tag: v0.12~151 X-Git-Url: http://git.ipfire.org/gitweb/?a=commitdiff_plain;h=cd3ade379d0b291ac50f1b763e7f9113cbeb547e;p=thirdparty%2Fgettext.git gnulib module 'xreadlink'. --- diff --git a/gettext-tools/lib/xreadlink.c b/gettext-tools/lib/xreadlink.c new file mode 100644 index 000000000..0322ca797 --- /dev/null +++ b/gettext-tools/lib/xreadlink.c @@ -0,0 +1,143 @@ +/* xreadlink.c -- readlink wrapper to return the link name in malloc'd storage + + Copyright 2001, 2003 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 2, 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; see the file COPYING. + If not, write to the Free Software Foundation, + 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. */ + +/* Written by Jim Meyering + and Bruno Haible . */ + +#if HAVE_CONFIG_H +# include +#endif + +/* Specification. */ +#include "xreadlink.h" + +#include +#include +#include +#ifndef errno +extern int errno; +#endif + +#if HAVE_LIMITS_H +# include +#endif +#if HAVE_SYS_TYPES_H +# include +#endif +#if HAVE_STDLIB_H +# include +#endif +#if HAVE_UNISTD_H +# include +#endif + +#ifndef SIZE_MAX +# define SIZE_MAX ((size_t) -1) +#endif +#ifndef SSIZE_MAX +# define SSIZE_MAX ((ssize_t) (SIZE_MAX / 2)) +#endif + +#ifdef NO_XMALLOC +# define xmalloc malloc +#else +# include "xmalloc.h" +#endif + +/* Call readlink to get the symbolic link value of FILENAME. + Return a pointer to that NUL-terminated string in malloc'd storage. + If readlink fails, return NULL (caller may use errno to diagnose). + If realloc fails, or if the link value is longer than SIZE_MAX :-), + give a diagnostic and exit. */ + +char * +xreadlink (char const *filename) +{ + /* The initial buffer size for the link value. A power of 2 + detects arithmetic overflow earlier, but is not required. */ +#define INITIAL_BUF_SIZE 1024 + + /* Allocate the initial buffer on the stack. This way, in the common + case of a symlink of small size, we get away with a single small malloc() + instead of a big malloc() followed by a shrinking realloc(). */ + char initial_buf[INITIAL_BUF_SIZE]; + + char *buffer = initial_buf; + size_t buf_size = sizeof (initial_buf); + + while (1) + { + /* Attempt to read the link into the current buffer. */ + ssize_t link_length = readlink (filename, buffer, buf_size); + + if (link_length < 0) + { + if (buffer != initial_buf) + { + int saved_errno = errno; + free (buffer); + errno = saved_errno; + } + return NULL; + } + + if ((size_t) link_length < buf_size) + { + buffer[link_length++] = '\0'; + + /* Return it in a chunk of memory as small as possible. */ + if (buffer == initial_buf) + { + buffer = (char *) xmalloc (link_length); +#ifdef NO_XMALLOC + if (buffer == NULL) + return NULL; +#endif + memcpy (buffer, initial_buf, link_length); + } + else + { + /* Shrink buffer before returning it. */ + if ((size_t) link_length < buf_size) + { + char *smaller_buffer = (char *) realloc (buffer, link_length); + + if (smaller_buffer != NULL) + buffer = smaller_buffer; + } + } + return buffer; + } + + if (buffer != initial_buf) + free (buffer); + buf_size *= 2; + if (SSIZE_MAX < buf_size || (SIZE_MAX / 2 < SSIZE_MAX && buf_size == 0)) +#ifdef NO_XMALLOC + return NULL; +#else + xalloc_die (); +#endif + buffer = (char *) xmalloc (buf_size); +#ifdef NO_XMALLOC + if (buffer == NULL) + return NULL; +#endif + } +} diff --git a/gettext-tools/lib/xreadlink.h b/gettext-tools/lib/xreadlink.h new file mode 100644 index 000000000..2b35106a5 --- /dev/null +++ b/gettext-tools/lib/xreadlink.h @@ -0,0 +1,21 @@ +/* Reading symbolic links without size limitation. + Copyright (C) 2001, 2003 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 2, 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, write to the Free Software Foundation, + Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA. */ + +/* Call readlink to get the symbolic link value of FILENAME. + Return a pointer to that NUL-terminated string in malloc'd storage. + If readlink fails, return NULL and set errno. */ +extern char *xreadlink (char const *filename); diff --git a/gettext-tools/m4/xreadlink.m4 b/gettext-tools/m4/xreadlink.m4 new file mode 100644 index 000000000..cc9eeb430 --- /dev/null +++ b/gettext-tools/m4/xreadlink.m4 @@ -0,0 +1,13 @@ +# xreadlink.m4 serial 1 (gettext-0.12) +dnl Copyright (C) 2002 Free Software Foundation, Inc. +dnl This file is free software, distributed under the terms of the GNU +dnl General Public License. As a special exception to the GNU General +dnl Public License, this file may be distributed as part of a program +dnl that contains a configuration script generated by Autoconf, under +dnl the same distribution terms as the rest of that program. + +AC_DEFUN([gl_XREADLINK], +[ + dnl Prerequisites of lib/xreadlink.c. + AC_CHECK_HEADERS_ONCE(limits.h stdlib.h sys/types.h unistd.h) +])