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| author | pixdamix@gmail.com <pixdamix@gmail.com@e8e0d7a0-c8d9-11dd-a880-a1081c7ac358> | 2012-11-22 07:24:42 (EST) |
|---|---|---|
| committer | pixdamix@gmail.com <pixdamix@gmail.com@e8e0d7a0-c8d9-11dd-a880-a1081c7ac358> | 2012-11-22 07:24:42 (EST) |
| commit | 6b576f0d9b00f78a60f4994b663fd8ce43b9f6da (patch) | |
| tree | 675af5651717547cdd513f4270a0229d701e0e4c | |
| parent | 5077685e6433d5609b9b82100e4dd18910d6affd (diff) | |
update-alternatives: use 'ln -n'
Using the '-n' option (--no-dereference) is a better way to solve the
do-not-link-into-directory issue. Using only 'ln -sf' can cause problems
on SELinux enabled hosts when target is inaccessible; e.g. when preparing
an offline rootsystem:
| $ cd <offline root>
| $ ln -sf /lib/systemd/systemd sbin/init # alternative #1
| $ ln -sf /bin/busybox sbin/init # alternative #2
| ln: accessing `sbin/init': Permission denied
|
| --> strace:
| brk(0) = 0x102b000
| stat("sbin/init", 0x7fffaa91c900) = -1 EACCES (Permission denied)
| ...
| exit_group(1) = ?
Now with '-n':
| $ ln -snf /bin/busybox sbin/init
| lstat("sbin/init", {st_mode=S_IFLNK|0777, st_size=20, ...}) = 0
| lstat("sbin/init", {st_mode=S_IFLNK|0777, st_size=20, ...}) = 0
| stat("/bin/busybox", 0x7fff8c1a3bd0) = -1 ENOENT (No such file or directory)
| symlink("/bin/busybox", "sbin/init") = -1 EEXIST (File exists)
| unlink("sbin/init") = 0
| symlink("/bin/busybox", "sbin/init") = 0
The '-n' flag is well supported (coreutils have it at least since
1999, busybox at least since 0.60.3 (2002)) and it obsoletes the
explicit check whether target is a directory.
Signed-off-by: Enrico Scholz <enrico.scholz@sigma-chemnitz.de>
git-svn-id: http://opkg.googlecode.com/svn/trunk@649 e8e0d7a0-c8d9-11dd-a880-a1081c7ac358
| -rw-r--r-- | utils/update-alternatives.in | 9 |
1 files changed, 1 insertions, 8 deletions
diff --git a/utils/update-alternatives.in b/utils/update-alternatives.in index 34d89f1..2a6f6cc 100644 --- a/utils/update-alternatives.in +++ b/utils/update-alternatives.in @@ -113,14 +113,7 @@ find_best_alt() { if [ ! -d $link_dir ]; then mkdir -p $link_dir fi - if [ -h $link -a -d $link ]; then - # If $link exists and the target is a directory, - # 'ln -sf $path $link' doesn't replace the link to - # that directory, it creates new link inside. - echo "update-alternatives: Removing $link". - rm -f $link - fi - ln -sf $path $link + ln -snf $path $link echo "update-alternatives: Linking $link to $path" else echo "update-alternatives: Error: not linking $link to $path since $link exists and is not a link" |