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According to Pádraig Brady on 9/24/2009 5:13 PM:
> Eric Blake wrote:
>
>> + -L, --logical make hard links to symbolic link references\n\
>
> s/references/targets/ is a bit clearer to me?
I thought about that, but we already specify:
ln source target
as the synopsis, so I didn't want to confuse target (the file being
created) with target (the contents of the symlink being linked through).
>
>> + -P, --physical make hard links directly to symblic links\n\
>
> s/symblic/symbolic/
Thanks. I folded that in, then added a patch to fix copy.c to use linkat
(pushed). I also noticed a cleanup for stdbuf while searching through
instances of 'link (', although I haven't been able to test that yet,
since stdbuf doesn't compile on cygwin. I've pushed my work to:
git pull git://repo.or.cz/coreutils/ericb.git master
to make it easier to review.
- --
Don't work too hard, make some time for fun as well!
Eric Blake e...@byu.net
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>From 4b9126696dfa293986640556960ef4bbf0be442b Mon Sep 17 00:00:00 2001
From: Eric Blake <e...@byu.net>
Date: Thu, 24 Sep 2009 17:11:26 -0600
Subject: [PATCH 1/2] cp, mv: use linkat to guarantee semantics
* src/copy.c (copy_internal): Use linkat, not link.
---
src/copy.c | 29 +++++++++++------------------
1 files changed, 11 insertions(+), 18 deletions(-)
diff --git a/src/copy.c b/src/copy.c
index e3c5c52..49e620a 100644
--- a/src/copy.c
+++ b/src/copy.c
@@ -1687,7 +1687,9 @@ copy_internal (char const *src_name, char const *dst_name,
}
else
{
- bool link_failed = (link (earlier_file, dst_name) != 0);
+ /* We want to guarantee that symlinks are not followed. */
+ bool link_failed = (linkat (AT_FDCWD, earlier_file, AT_FDCWD,
+ dst_name, 0) != 0);
/* If the link failed because of an existing destination,
remove that file and then call link again. */
@@ -1700,7 +1702,8 @@ copy_internal (char const *src_name, char const *dst_name,
}
if (x->verbose)
printf (_("removed %s\n"), quote (dst_name));
- link_failed = (link (earlier_file, dst_name) != 0);
+ link_failed = (linkat (AT_FDCWD, earlier_file, AT_FDCWD,
+ dst_name, 0) != 0);
}
if (link_failed)
@@ -1990,25 +1993,15 @@ copy_internal (char const *src_name, char const
*dst_name,
}
}
- /* POSIX 2008 states that it is implementation-defined whether
- link() on a symlink creates a hard-link to the symlink, or only
- to the referent (effectively dereferencing the symlink) (POSIX
- 2001 required the latter behavior, although many systems provided
- the former). Yet cp, invoked with `--link --no-dereference',
- should not follow the link. We can approximate the desired
- behavior by skipping this hard-link creating block and instead
- copying the symlink, via the `S_ISLNK'- copying code below.
- LINK_FOLLOWS_SYMLINKS is tri-state; if it is -1, we don't know
- how link() behaves, so we use the fallback case for safety.
-
- FIXME - use a gnulib linkat emulation for more fine-tuned
- emulation, particularly when LINK_FOLLOWS_SYMLINKS is -1. */
+ /* cp, invoked with `--link --no-dereference', should not follow the
+ link; we guarantee this with gnulib's linkat module (on systems
+ where link(2) follows the link, gnulib creates a symlink with
+ identical contents, which is good enough for our purposes). */
else if (x->hard_link
- && (!LINK_FOLLOWS_SYMLINKS
- || !S_ISLNK (src_mode)
+ && (!S_ISLNK (src_mode)
|| x->dereference != DEREF_NEVER))
{
- if (link (src_name, dst_name))
+ if (linkat (AT_FDCWD, src_name, AT_FDCWD, dst_name, 0))
{
error (0, errno, _("cannot create link %s"), quote (dst_name));
goto un_backup;
--
1.6.5.rc1
>From d7b4703e46ef2b377704f56dac6e57f0648637d4 Mon Sep 17 00:00:00 2001
From: Eric Blake <e...@byu.net>
Date: Thu, 24 Sep 2009 17:18:47 -0600
Subject: [PATCH 2/2] stdbuf: improve path search
* src/stdbuf.c (set_program_path): use gnulib methods for better
file name handling.
---
src/stdbuf.c | 26 +++++++++-----------------
1 files changed, 9 insertions(+), 17 deletions(-)
diff --git a/src/stdbuf.c b/src/stdbuf.c
index afb7821..c33cdfa 100644
--- a/src/stdbuf.c
+++ b/src/stdbuf.c
@@ -145,34 +145,26 @@ set_program_path (const char *arg)
}
else
{
- char *path;
- char tmppath[PATH_MAX + 1];
- ssize_t len = readlink ("/proc/self/exe", tmppath, sizeof (tmppath) - 1);
- if (len > 0)
- {
- tmppath[len] = '\0';
- program_path = dir_name (tmppath);
- }
+ char *path = areadlink ("/proc/self/exe");
+ if (path)
+ program_path = dir_name (path);
else if ((path = getenv ("PATH")))
{
char *dir;
path = xstrdup (path);
for (dir = strtok (path, ":"); dir != NULL; dir = strtok (NULL, ":"))
{
- int req = snprintf (tmppath, sizeof (tmppath), "%s/%s", dir,
arg);
- if (req >= sizeof (tmppath))
- {
- error (0, 0, _("path truncated when looking for %s"),
- quote (arg));
- }
- else if (access (tmppath, X_OK) == 0)
+ char *candidate = file_name_concat (dir, arg);
+ if (access (candidate, X_OK) == 0)
{
- program_path = dir_name (tmppath);
+ program_path = dir_name (candidate);
+ free (candidate);
break;
}
+ free (candidate);
}
- free (path);
}
+ free (path);
}
}
--
1.6.5.rc1
