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authorEric Blake <ebb9@byu.net>2009-09-24 11:57:11 -0600
committerEric Blake <ebb9@byu.net>2009-09-25 07:03:03 -0600
commitefcee783e4d576898130ccbf1cb2d7d6bf1b8420 (patch)
tree401900376fd200b55ebede212a2b777b1d3fa0d4 /src
parentfb59d72f0a48ef6bc45d795ab96131368157c59f (diff)
downloadcoreutils-efcee783e4d576898130ccbf1cb2d7d6bf1b8420.tar.xz
ln: add -L/-P options
* src/ln.c (STAT_LIKE_LINK): Delete. (logical): New flag. (long_options): Add -L, -P. (usage): Mention them. (main): Choose between them. (do_link): Perform correct action. * tests/ln/misc: Move hard-to-sym portion of test... * tests/ln/hard-to-sym: ...into new test, and add more. * tests/Makefile.am (TESTS): Run new test. * NEWS: Document this. * doc/coreutils.texi (link invocation, ln invocation): Likewise. * bootstrap.conf (gnulib_modules): Add linkat.
Diffstat (limited to 'src')
-rw-r--r--src/ln.c63
1 files changed, 34 insertions, 29 deletions
diff --git a/src/ln.c b/src/ln.c
index 0c35338f2..4f75c1919 100644
--- a/src/ln.c
+++ b/src/ln.c
@@ -39,26 +39,15 @@
proper_name ("Mike Parker"), \
proper_name ("David MacKenzie")
-/* In being careful not even to try to make hard links to directories,
- we have to know whether link(2) follows symlinks. If it does, then
- we have to *stat* the `source' to see if the resulting link would be
- to a directory. Otherwise, we have to use *lstat* so that we allow
- users to make hard links to symlinks-that-point-to-directories. */
-
-#if LINK_FOLLOWS_SYMLINKS
-# define STAT_LIKE_LINK(File, Stat_buf) \
- stat (File, Stat_buf)
-#else
-# define STAT_LIKE_LINK(File, Stat_buf) \
- lstat (File, Stat_buf)
-#endif
-
/* FIXME: document */
static enum backup_type backup_type;
/* If true, make symbolic links; otherwise, make hard links. */
static bool symbolic_link;
+/* If true, hard links are logical rather than physical. */
+static bool logical = !!LINK_FOLLOWS_SYMLINKS;
+
/* If true, ask the user before removing existing files. */
static bool interactive;
@@ -71,7 +60,7 @@ static bool verbose;
/* If true, allow the superuser to *attempt* to make hard links
to directories. However, it appears that this option is not useful
in practice, since even the superuser is prohibited from hard-linking
- directories on most (all?) existing systems. */
+ directories on most existing systems (Solaris being an exception). */
static bool hard_dir_link;
/* If nonzero, and the specified destination is a symbolic link to a
@@ -99,6 +88,8 @@ static struct option const long_options[] =
{"interactive", no_argument, NULL, 'i'},
{"suffix", required_argument, NULL, 'S'},
{"target-directory", required_argument, NULL, 't'},
+ {"logical", no_argument, NULL, 'L'},
+ {"physical", no_argument, NULL, 'P'},
{"symbolic", no_argument, NULL, 's'},
{"verbose", no_argument, NULL, 'v'},
{GETOPT_HELP_OPTION_DECL},
@@ -143,18 +134,15 @@ do_link (const char *source, const char *dest)
bool source_is_dir = false;
bool ok;
- /* Use stat here instead of lstat.
- On SVR4, link does not follow symlinks, so this check disallows
- making hard links to symlinks that point to directories. Big deal.
- On other systems, link follows symlinks, so this check is right.
-
- FIXME - POSIX 2008 added the AT_SYMLINK_FOLLOW flag to linkat so
- that we can specify either behavior, via the new options -L
- (hard-link to symlinks) and -P (hard-link to the referent). Once
- gnulib has a decent implementation, we should use it here. */
if (!symbolic_link)
{
- if (STAT_LIKE_LINK (source, &source_stats) != 0)
+ /* Which stat to use depends on whether linkat will follow the
+ symlink. We can't use the shorter
+ (logical ? stat : lstat) (source, &source_stats)
+ since stat might be a function-like macro. */
+ if ((logical ? stat (source, &source_stats)
+ : lstat (source, &source_stats))
+ != 0)
{
error (0, errno, _("accessing %s"), quote (source));
return false;
@@ -258,7 +246,9 @@ do_link (const char *source, const char *dest)
}
}
- ok = ((symbolic_link ? symlink (source, dest) : link (source, dest))
+ ok = ((symbolic_link ? symlink (source, dest)
+ : linkat (AT_FDCWD, source, AT_FDCWD, dest,
+ logical ? AT_SYMLINK_FOLLOW : 0))
== 0);
/* If the attempt to create a link failed and we are removing or
@@ -289,7 +279,9 @@ do_link (const char *source, const char *dest)
return false;
}
- ok = ((symbolic_link ? symlink (source, dest) : link (source, dest))
+ ok = ((symbolic_link ? symlink (source, dest)
+ : linkat (AT_FDCWD, source, AT_FDCWD, dest,
+ logical ? AT_SYMLINK_FOLLOW : 0))
== 0);
}
@@ -370,9 +362,11 @@ Mandatory arguments to long options are mandatory for short options too.\n\
-f, --force remove existing destination files\n\
"), stdout);
fputs (_("\
+ -i, --interactive prompt whether to remove destinations\n\
+ -L, --logical make hard links to symbolic link references\n\
-n, --no-dereference treat destination that is a symlink to a\n\
directory as if it were a normal file\n\
- -i, --interactive prompt whether to remove destinations\n\
+ -P, --physical make hard links directly to symbolic links\n\
-s, --symbolic make symbolic links instead of hard links\n\
"), stdout);
fputs (_("\
@@ -391,6 +385,11 @@ The version control method may be selected via the --backup option or through\n\
the VERSION_CONTROL environment variable. Here are the values:\n\
\n\
"), stdout);
+ printf (_("\
+Using -s ignores -L and -P. Otherwise, the last option specified controls\n\
+behavior when the source is a symbolic link, defaulting to %s.\n\
+\n\
+"), LINK_FOLLOWS_SYMLINKS ? "-L" : "-P");
fputs (_("\
none, off never make backups (even if --backup is given)\n\
numbered, t make numbered backups\n\
@@ -430,7 +429,7 @@ main (int argc, char **argv)
symbolic_link = remove_existing_files = interactive = verbose
= hard_dir_link = false;
- while ((c = getopt_long (argc, argv, "bdfinst:vFS:T", long_options, NULL))
+ while ((c = getopt_long (argc, argv, "bdfinst:vFLPS:T", long_options, NULL))
!= -1)
{
switch (c)
@@ -452,9 +451,15 @@ main (int argc, char **argv)
remove_existing_files = false;
interactive = true;
break;
+ case 'L':
+ logical = true;
+ break;
case 'n':
dereference_dest_dir_symlinks = false;
break;
+ case 'P':
+ logical = false;
+ break;
case 's':
symbolic_link = true;
break;