From: Jim Meyering Date: Mon, 18 Jun 2007 12:21:16 +0000 (+0000) Subject: New module: mreadlink-with-size. X-Git-Tag: cvs-readonly~232 X-Git-Url: http://erislabs.net/gitweb/?a=commitdiff_plain;h=07b83208ad50ccf613a769c0c06d145f4f828b40;p=gnulib.git New module: mreadlink-with-size. * MODULES.html.sh: Add mreadlink-with-size. * modules/mreadlink-with-size: New module * modules/canonicalize (Depends-on): Depend on mreadlink-with-size, not xreadlink-with-size. * lib/mreadlink-with-size.c, lib/mreadlink.h: New files. --- diff --git a/ChangeLog b/ChangeLog index 60ca7dbce..12fd89f5b 100644 --- a/ChangeLog +++ b/ChangeLog @@ -1,3 +1,12 @@ +2007-06-18 Jim Meyering + + New module: mreadlink-with-size. + * MODULES.html.sh: Add mreadlink-with-size. + * modules/mreadlink-with-size: New module + * modules/canonicalize (Depends-on): Depend on mreadlink-with-size, + not xreadlink-with-size. + * lib/mreadlink-with-size.c, lib/mreadlink.h: New files. + 2007-06-16 Bruno Haible * m4/frexpl.m4 (gl_FUNC_FREXPL_WORKS): Catch the MacOS X 10.4 bug. diff --git a/MODULES.html.sh b/MODULES.html.sh index ae39dc207..a77b4d012 100755 --- a/MODULES.html.sh +++ b/MODULES.html.sh @@ -2149,6 +2149,7 @@ func_all_modules () func_module mkdir-p func_module modechange func_module mountlist + func_module mreadlink-with-size func_module openat func_module pathmax func_module same diff --git a/lib/mreadlink-with-size.c b/lib/mreadlink-with-size.c new file mode 100644 index 000000000..e18d5c43f --- /dev/null +++ b/lib/mreadlink-with-size.c @@ -0,0 +1,110 @@ +/* readlink wrapper to return the link name in malloc'd storage. + Unlike xreadlink and xreadlink_with_size, don't ever call exit. + + Copyright (C) 2001, 2003-2007 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, + 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA. */ + +/* Written by Jim Meyering */ + +#include + +#include "mreadlink.h" + +#include +#include +#include +#include +#include +#include + +#ifndef SIZE_MAX +# define SIZE_MAX ((size_t) -1) +#endif +#ifndef SSIZE_MAX +# define SSIZE_MAX ((ssize_t) (SIZE_MAX / 2)) +#endif + +/* SYMLINK_MAX is used only for an initial memory-allocation sanity + check, so it's OK to guess too small on hosts where there is no + arbitrary limit to symbolic link length. */ +#ifndef SYMLINK_MAX +# define SYMLINK_MAX 1024 +#endif + +#define MAXSIZE (SIZE_MAX < SSIZE_MAX ? SIZE_MAX : SSIZE_MAX) + +/* Call readlink to get the symbolic link value of FILE. + SIZE is a hint as to how long the link is expected to be; + typically it is taken from st_size. It need not be correct. + Return a pointer to that NUL-terminated string in malloc'd storage. + If readlink fails, malloc fails, or if the link value is longer + than SSIZE_MAX, return NULL (caller may use errno to diagnose). */ + +char * +mreadlink_with_size (char const *file, size_t size) +{ + /* Some buggy file systems report garbage in st_size. Defend + against them by ignoring outlandish st_size values in the initial + memory allocation. */ + size_t symlink_max = SYMLINK_MAX; + size_t INITIAL_LIMIT_BOUND = 8 * 1024; + size_t initial_limit = (symlink_max < INITIAL_LIMIT_BOUND + ? symlink_max + 1 + : INITIAL_LIMIT_BOUND); + + /* The initial buffer size for the link value. */ + size_t buf_size = size < initial_limit ? size + 1 : initial_limit; + + while (1) + { + ssize_t r; + size_t link_length; + char *buffer = malloc (buf_size); + + if (buffer == NULL) + return NULL; + r = readlink (file, buffer, buf_size); + link_length = r; + + /* On AIX 5L v5.3 and HP-UX 11i v2 04/09, readlink returns -1 + with errno == ERANGE if the buffer is too small. */ + if (r < 0 && errno != ERANGE) + { + int saved_errno = errno; + free (buffer); + errno = saved_errno; + return NULL; + } + + if (link_length < buf_size) + { + buffer[link_length] = 0; + return buffer; + } + + free (buffer); + if (buf_size <= MAXSIZE / 2) + buf_size *= 2; + else if (buf_size < MAXSIZE) + buf_size = MAXSIZE; + else + { + errno = ENOMEM; + return NULL; + } + } +} diff --git a/lib/mreadlink.h b/lib/mreadlink.h new file mode 100644 index 000000000..28d3eec9e --- /dev/null +++ b/lib/mreadlink.h @@ -0,0 +1,24 @@ +/* Read symbolic links without size limitation. + + Copyright (C) 2001, 2003, 2004, 2007 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, + 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA. */ + +/* Written by Jim Meyering */ + +#include + +extern char *mreadlink_with_size (char const *filename, size_t size_hint); diff --git a/modules/canonicalize b/modules/canonicalize index 4d7174a31..cb135daf8 100644 --- a/modules/canonicalize +++ b/modules/canonicalize @@ -13,7 +13,7 @@ filenamecat sys_stat xalloc xgetcwd -xreadlink-with-size +mreadlink-with-size configure.ac: AC_FUNC_CANONICALIZE_FILE_NAME diff --git a/modules/mreadlink-with-size b/modules/mreadlink-with-size new file mode 100644 index 000000000..70c88e731 --- /dev/null +++ b/modules/mreadlink-with-size @@ -0,0 +1,25 @@ +Description: +Return the contents of a symbolic link, without size limitations. + +Files: +lib/mreadlink.h +lib/mreadlink-with-size.c + +Depends-on: +readlink +ssize_t +unistd + +configure.ac: + +Makefile.am: +lib_SOURCES += mreadlink-with-size.c + +Include: +"mreadlink.h" + +License: +GPL + +Maintainer: +Jim Meyering