Attached is a mergeable version. I'd be inclined to include this in the imminent release given the unlikely impact on existing code?
cheers, Pádraig.
>From d8889826af3f5eec1e19ef10f964c9b037f4b5a5 Mon Sep 17 00:00:00 2001 From: Harald Hoyer <[email protected]> Date: Thu, 23 Feb 2012 20:50:27 +0100 Subject: [PATCH] ln: add the --relative option MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit With the "--relative --symbolic" options, ln computes the relative symbolic link for the user. So, ln works just as cp, but creates relative symbolic links instead of copying the file. I miss this feature since the beginning of using ln. $ tree ./ / `-- usr |-- bin `-- lib `-- foo `-- foo 4 directories, 1 file $ ln -s -v --relative usr/lib/foo/foo usr/bin/foo âusr/bin/fooâ -> â../lib/foo/fooâ $ tree ./ / `-- usr |-- bin | `-- foo -> ../lib/foo/foo `-- lib `-- foo `-- foo 4 directories, 2 files $ ln -s -v --relative usr/bin/foo usr/lib/foo/link-to-foo âusr/lib/foo/link-to-fooâ -> âfooâ $ tree ./ / `-- usr |-- bin | `-- foo -> ../lib/foo/foo `-- lib `-- foo |-- link-to-foo -> foo `-- foo 4 directories, 3 files * src/relpath.c: Refactored from realpath.c and adjusted to support returning the relative path rather than just outputting. * src/relpath.h: Export the relpath function. * src/Makefile.am: Reference the refactored relpath module. * po/POTFILES.in: Likewise. * src/ln.c (usage): Mention the new option. (do_link): Call the relative conversion is specified. (convert_abs_rel): Perform the relative conversion using the refactored relpath module. * src/realpath.c: Adjust to the refactored relpath module. * tests/ln/relative: Add a new test. * tests/Makefile.am: Reference the new test. * doc/coreutils.texi: Document the new feature. * NEWS: Mention the new feature. --- NEWS | 3 + doc/coreutils.texi | 8 +++ po/POTFILES.in | 1 + src/Makefile.am | 2 + src/ln.c | 56 +++++++++++++++++++++- src/realpath.c | 96 ++----------------------------------- src/relpath.c | 134 ++++++++++++++++++++++++++++++++++++++++++++++++++++ src/relpath.h | 25 ++++++++++ tests/Makefile.am | 1 + tests/ln/relative | 32 ++++++++++++ 10 files changed, 265 insertions(+), 93 deletions(-) create mode 100644 src/relpath.c create mode 100644 src/relpath.h create mode 100755 tests/ln/relative diff --git a/NEWS b/NEWS index 5b53eb8..0fe75e5 100644 --- a/NEWS +++ b/NEWS @@ -25,6 +25,9 @@ GNU coreutils NEWS -*- outline -*- dd now accepts the conv=sparse flag to attempt to create sparse output, by seeking rather than writing to the output file. + ln now accepts the --relative option, to generate relative + symbolic links to a target, irrespective of how the target is specified. + split now accepts an optional "from" argument to --numeric-suffixes, which changes the start number from the default of 0. diff --git a/doc/coreutils.texi b/doc/coreutils.texi index 10be715..a8ed050 100644 --- a/doc/coreutils.texi +++ b/doc/coreutils.texi @@ -9389,6 +9389,14 @@ symbolic link with identical contents; since symbolic link contents cannot be edited, any file name resolution performed through either link will be the same as if a hard link had been created. +@item -r +@itemx --relative +@opindex -r +@opindex --relative +Make symbolic links relative to the link location. +@xref{realpath invocation}, which gives greater control +over relative path generation. + @item -s @itemx --symbolic @opindex -s diff --git a/po/POTFILES.in b/po/POTFILES.in index c92dd3c..7b3de0b 100644 --- a/po/POTFILES.in +++ b/po/POTFILES.in @@ -103,6 +103,7 @@ src/ptx.c src/pwd.c src/readlink.c src/realpath.c +src/relpath.c src/remove.c src/rm.c src/rmdir.c diff --git a/src/Makefile.am b/src/Makefile.am index b124064..06ab615 100644 --- a/src/Makefile.am +++ b/src/Makefile.am @@ -474,9 +474,11 @@ vdir_SOURCES = ls.c ls-vdir.c id_SOURCES = id.c group-list.c groups_SOURCES = groups.c group-list.c ls_SOURCES = ls.c ls-ls.c +ln_SOURCES = ln.c relpath.c relpath.h chown_SOURCES = chown.c chown-core.c chgrp_SOURCES = chgrp.c chown-core.c kill_SOURCES = kill.c operand2sig.c +realpath_SOURCES = realpath.c relpath.c relpath.h timeout_SOURCES = timeout.c operand2sig.c mv_SOURCES = mv.c remove.c $(copy_sources) diff --git a/src/ln.c b/src/ln.c index d984fd7..95b3be3 100644 --- a/src/ln.c +++ b/src/ln.c @@ -29,8 +29,10 @@ #include "hash.h" #include "hash-triple.h" #include "quote.h" +#include "relpath.h" #include "same.h" #include "yesno.h" +#include "canonicalize.h" /* The official name of this program (e.g., no 'g' prefix). */ #define PROGRAM_NAME "ln" @@ -45,6 +47,9 @@ static enum backup_type backup_type; /* If true, make symbolic links; otherwise, make hard links. */ static bool symbolic_link; +/* If true, make symbolic links relative */ +static bool relative; + /* If true, hard links are logical rather than physical. */ static bool logical = !!LINK_FOLLOWS_SYMLINKS; @@ -90,6 +95,7 @@ static struct option const long_options[] = {"target-directory", required_argument, NULL, 't'}, {"logical", no_argument, NULL, 'L'}, {"physical", no_argument, NULL, 'P'}, + {"relative", no_argument, NULL, 'r'}, {"symbolic", no_argument, NULL, 's'}, {"verbose", no_argument, NULL, 'v'}, {GETOPT_HELP_OPTION_DECL}, @@ -120,6 +126,37 @@ target_directory_operand (char const *file) return is_a_dir; } +/* Return FROM represented as relative to the dir of TARGET. + The result is malloced. */ + +static char * +convert_abs_rel (const char *from, const char *target) +{ + char *realtarget = canonicalize_filename_mode (target, CAN_MISSING); + char *realfrom = canonicalize_filename_mode (from, CAN_MISSING); + + /* Write to a PATH_MAX buffer, guarding against very large values. */ + size_t nalloc = MIN (PATH_MAX, 32 * 1024); + char *relative_from = xmalloc (nalloc); + + /* Get dirname to generate paths relative to. */ + realtarget[dir_len (realtarget)] = '\0'; + + if (!relpath (realfrom, realtarget, relative_from, nalloc)) + { + free (relative_from); + relative_from = NULL; + } + + free (realtarget); + free (realfrom); + + if (relative_from) + return relative_from; + else + return xstrdup (from); +} + /* Make a link DEST to the (usually) existing file SOURCE. Symbolic links to nonexistent files are allowed. Return true if successful. */ @@ -130,6 +167,7 @@ do_link (const char *source, const char *dest) struct stat source_stats; struct stat dest_stats; char *dest_backup = NULL; + char *rel_source = NULL; bool dest_lstat_ok = false; bool source_is_dir = false; bool ok; @@ -246,6 +284,9 @@ do_link (const char *source, const char *dest) } } + if (relative) + source = rel_source = convert_abs_rel (source, dest); + ok = ((symbolic_link ? symlink (source, dest) : linkat (AT_FDCWD, source, AT_FDCWD, dest, logical ? AT_SYMLINK_FOLLOW : 0)) @@ -276,6 +317,7 @@ do_link (const char *source, const char *dest) { error (0, errno, _("cannot remove %s"), quote (dest)); free (dest_backup); + free (rel_source); return false; } @@ -322,6 +364,7 @@ do_link (const char *source, const char *dest) } free (dest_backup); + free (rel_source); return ok; } @@ -367,6 +410,7 @@ Mandatory arguments to long options are mandatory for short options too.\n\ -n, --no-dereference treat LINK_NAME as a normal file if\n\ it is a symbolic link to a directory\n\ -P, --physical make hard links directly to symbolic links\n\ + -r, --relative create symbolic links relative to link location\n\ -s, --symbolic make symbolic links instead of hard links\n\ "), stdout); fputs (_("\ @@ -429,7 +473,7 @@ main (int argc, char **argv) symbolic_link = remove_existing_files = interactive = verbose = hard_dir_link = false; - while ((c = getopt_long (argc, argv, "bdfinst:vFLPS:T", long_options, NULL)) + while ((c = getopt_long (argc, argv, "bdfinrst:vFLPS:T", long_options, NULL)) != -1) { switch (c) @@ -460,6 +504,9 @@ main (int argc, char **argv) case 'P': logical = false; break; + case 'r': + relative = true; + break; case 's': symbolic_link = true; break; @@ -539,6 +586,13 @@ main (int argc, char **argv) ? xget_version (_("backup type"), version_control_string) : no_backups); + if (relative && !symbolic_link) + { + error (EXIT_FAILURE, 0, + _("cannot do --relative without --symbolic")); + } + + if (target_directory) { int i; diff --git a/src/realpath.c b/src/realpath.c index 206f800..cd595b8 100644 --- a/src/realpath.c +++ b/src/realpath.c @@ -25,6 +25,7 @@ #include "canonicalize.h" #include "error.h" #include "quote.h" +#include "relpath.h" /* The official name of this program (e.g., no 'g' prefix). */ #define PROGRAM_NAME "realpath" @@ -136,97 +137,6 @@ path_prefix (const char *prefix, const char *path) return (!*prefix && (*path == '/' || !*path)); } -/* Return the length of the longest common prefix - of canonical PATH1 and PATH2, ensuring only full path components - are matched. Return 0 on no match. */ -static int _GL_ATTRIBUTE_PURE -path_common_prefix (const char *path1, const char *path2) -{ - int i = 0; - int ret = 0; - - /* We already know path1[0] and path2[0] are '/'. Special case - '//', which is only present in a canonical name on platforms - where it is distinct. */ - if ((path1[1] == '/') != (path2[1] == '/')) - return 0; - - while (*path1 && *path2) - { - if (*path1 != *path2) - break; - if (*path1 == '/') - ret = i + 1; - path1++; - path2++; - i++; - } - - if (!*path1 && !*path2) - ret = i; - if (!*path1 && *path2 == '/') - ret = i; - if (!*path2 && *path1 == '/') - ret = i; - - return ret; -} - -/* Output the relative representation if requested. */ -static bool -relpath (const char *can_fname) -{ - if (can_relative_to) - { - /* Enforce --relative-base. */ - if (can_relative_base && !path_prefix (can_relative_base, can_fname)) - return false; - - /* Skip the prefix common to --relative-to and path. */ - int common_index = path_common_prefix (can_relative_to, can_fname); - if (!common_index) - return false; - - const char *relto_suffix = can_relative_to + common_index; - const char *fname_suffix = can_fname + common_index; - - /* skip over extraneous '/'. */ - if (*relto_suffix == '/') - relto_suffix++; - if (*fname_suffix == '/') - fname_suffix++; - - /* Replace remaining components of --relative-to with '..', to get - to a common directory. Then output the remainder of fname. */ - if (*relto_suffix) - { - fputs ("..", stdout); - for (; *relto_suffix; ++relto_suffix) - { - if (*relto_suffix == '/') - fputs ("/..", stdout); - } - - if (*fname_suffix) - { - putchar ('/'); - fputs (fname_suffix, stdout); - } - } - else - { - if (*fname_suffix) - fputs (fname_suffix, stdout); - else - putchar ('.'); - } - - return true; - } - - return false; -} - static bool isdir (const char *path) { @@ -247,7 +157,9 @@ process_path (const char *fname, int can_mode) return false; } - if (!relpath (can_fname)) + if (!can_relative_to + || (can_relative_base && !path_prefix (can_relative_base, can_fname)) + || (can_relative_to && !relpath (can_fname, can_relative_to, NULL, 0))) fputs (can_fname, stdout); putchar (use_nuls ? '\0' : '\n'); diff --git a/src/relpath.c b/src/relpath.c new file mode 100644 index 0000000..75cd9ea --- /dev/null +++ b/src/relpath.c @@ -0,0 +1,134 @@ +/* relpath - print the relative path + Copyright (C) 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 Pádraig Brady. */ + +#include <config.h> + +#include "error.h" +#include "system.h" +#include "relpath.h" + + +/* Return the length of the longest common prefix + of canonical PATH1 and PATH2, ensuring only full path components + are matched. Return 0 on no match. */ +static int _GL_ATTRIBUTE_PURE +path_common_prefix (const char *path1, const char *path2) +{ + int i = 0; + int ret = 0; + + /* We already know path1[0] and path2[0] are '/'. Special case + '//', which is only present in a canonical name on platforms + where it is distinct. */ + if ((path1[1] == '/') != (path2[1] == '/')) + return 0; + + while (*path1 && *path2) + { + if (*path1 != *path2) + break; + if (*path1 == '/') + ret = i + 1; + path1++; + path2++; + i++; + } + + if (!*path1 && !*path2) + ret = i; + if (!*path1 && *path2 == '/') + ret = i; + if (!*path2 && *path1 == '/') + ret = i; + + return ret; +} + +/* Either output STR to stdout or + if *PBUF is not NULL then append STR to *PBUF + and update *PBUF to point to the end of the buffer + and adjust *PLEN to reflect the remaining space. */ +static bool +buffer_or_output (const char* str, char **pbuf, size_t *plen) +{ + if (*pbuf) + { + size_t slen = strlen (str); + if (slen >= *plen) + return true; + memcpy (*pbuf, str, slen + 1); + *pbuf += slen; + *plen -= slen; + } + else + fputs (str, stdout); + + return false; +} + +/* Output the relative representation if possible. + If BUF is non NULL, output is to that buffer rather than stdout. */ +bool +relpath (const char *can_fname, const char *can_reldir, char *buf, size_t len) +{ + bool buf_err = false; + + /* Skip the prefix common to --relative-to and path. */ + int common_index = path_common_prefix (can_reldir, can_fname); + if (!common_index) + return false; + + const char *relto_suffix = can_reldir + common_index; + const char *fname_suffix = can_fname + common_index; + + /* skip over extraneous '/'. */ + if (*relto_suffix == '/') + relto_suffix++; + if (*fname_suffix == '/') + fname_suffix++; + + /* Replace remaining components of --relative-to with '..', to get + to a common directory. Then output the remainder of fname. */ + if (*relto_suffix) + { + buf_err |= buffer_or_output ("..", &buf, &len); + for (; *relto_suffix; ++relto_suffix) + { + if (*relto_suffix == '/') + buf_err |= buffer_or_output ("/..", &buf, &len); + } + + if (*fname_suffix) + { + buf_err |= buffer_or_output ("/", &buf, &len); + buf_err |= buffer_or_output (fname_suffix, &buf, &len); + } + } + else + { + if (*fname_suffix) + buf_err |= buffer_or_output (fname_suffix, &buf, &len); + else + buf_err |= buffer_or_output (".", &buf, &len); + } + + if (buf_err) + error (0, ENAMETOOLONG, "%s", _("generating relative path")); + + return !buf_err; +} diff --git a/src/relpath.h b/src/relpath.h new file mode 100644 index 0000000..e25f82b --- /dev/null +++ b/src/relpath.h @@ -0,0 +1,25 @@ +/* relpath - print the relative path + Copyright (C) 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 Pádraig Brady. */ + +#ifndef _RELPATH_H +# define _RELPATH_H + +extern bool +relpath (const char *can_fname, const char *can_reldir, char *buf, size_t len); + +#endif diff --git a/tests/Makefile.am b/tests/Makefile.am index c72b175..011051a 100644 --- a/tests/Makefile.am +++ b/tests/Makefile.am @@ -420,6 +420,7 @@ TESTS = \ ln/hard-backup \ ln/hard-to-sym \ ln/misc \ + ln/relative \ ln/sf-1 \ ln/slash-decorated-nonexistent-dest \ ln/target-1 \ diff --git a/tests/ln/relative b/tests/ln/relative new file mode 100755 index 0000000..cfc3469 --- /dev/null +++ b/tests/ln/relative @@ -0,0 +1,32 @@ +#!/bin/sh +# Test "ln --relative". + +# Copyright (C) 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/>. + +. "${srcdir=.}/init.sh"; path_prepend_ ../src +print_ver_ ln + +mkdir -p usr/bin || framework_failure_ +mkdir -p usr/lib/foo || framework_failure_ +touch usr/lib/foo/foo || framework_failure_ + +ln -sr usr/lib/foo/foo usr/bin/foo +test $(readlink usr/bin/foo) = '../lib/foo/foo' || fail=1 + +ln -sr usr/bin/foo usr/lib/foo/link-to-foo +test $(readlink usr/lib/foo/link-to-foo) = 'foo' || fail=1 + +Exit $fail -- 1.7.6.4
