On 21 August 2014 22:28, Bernhard Voelker <mail@xxxxxxxxxxxxxxxxxxx> wrote:
> On 08/21/2014 08:03 PM, Sami Kerola wrote:
>> Earlier the mountpoint(1) followed symlinks
>
> IMO this is correct as symlinks only have to be treated
> as such when explicitly not de-referencing.
> As mountpoint(1) does not have a --no-dereference option,
> symlinks should always be transparent for this tool.
>
> Furthermore, the patch would break scripts relying on existing
> behavior:
>
> $ ln -s / slink
>
> $ /usr/bin/mountpoint slink
> slink is a mountpoint
>
> $ # ~berny/util-linux/mountpoint slink
> slink is not a mountpoint
Hi Berny,
I don't share view symlinks are mount points. In my mind they are
pointers, much like street signs, giving a direction to somewhere without
understanding what is there if anything at all. But not breaking
existing behavior is good point, so I changed the patch and added
--no-dereference.
--->8----
From: Sami Kerola <kerolasa@xxxxxx>
Date: Fri, 22 Aug 2014 00:16:57 +0300
Subject: [PATCH] mountpoint: add --no-dereference option
By default the mountpoint follows symlinks.
$ ls -l /tmp/this-is-symlink
lrwxrwxrwx 1 kerolasa kerolasa 1 Aug 21 19:54 /tmp/this-is-symlink -> /
$ mountpoint /tmp/this-is-symlink
/tmp/this-is-symlink is a mountpoint
When use --no-dereference is used symlinks will not be reported as mount
points, even when they are pointing to such.
CC: Bernhard Voelker <mail@xxxxxxxxxxxxxxxxxxx>
Signed-off-by: Sami Kerola <kerolasa@xxxxxx>
---
sys-utils/mountpoint.1 | 3 +++
sys-utils/mountpoint.c | 14 +++++++++++---
2 files changed, 14 insertions(+), 3 deletions(-)
diff --git a/sys-utils/mountpoint.1 b/sys-utils/mountpoint.1
index 29c153c..c99ba41 100644
--- a/sys-utils/mountpoint.1
+++ b/sys-utils/mountpoint.1
@@ -28,6 +28,9 @@ Be quiet - don't print anything.
.BR \-x , " \-\-devno"
Show the major/minor numbers of the given blockdevice on standard output.
.TP
+.BR \-\-no\-dereference
+Do not follow symbolic links.
+.TP
.BR \-V , " \-\-version"
Display version information and exit.
.TP
diff --git a/sys-utils/mountpoint.c b/sys-utils/mountpoint.c
index 3919ab7..c34fbee 100644
--- a/sys-utils/mountpoint.c
+++ b/sys-utils/mountpoint.c
@@ -123,6 +123,7 @@ static void __attribute__((__noreturn__)) usage(FILE *out)
fputs(_(" -q, --quiet quiet mode - don't print anything\n"
" -d, --fs-devno print maj:min device number of the filesystem\n"
" -x, --devno print maj:min device number of the block device\n"), out);
+ fputs(_(" --no-dereference never follow symbolic links\n"), out);
fputs(USAGE_SEPARATOR, out);
fputs(USAGE_HELP, out);
fputs(USAGE_VERSION, out);
@@ -133,14 +134,18 @@ static void __attribute__((__noreturn__)) usage(FILE *out)
int main(int argc, char **argv)
{
- int c, fs_devno = 0, dev_devno = 0, rc = 0;
+ int c, fs_devno = 0, dev_devno = 0, no_dereference = 0, rc = 0;
char *spec;
struct stat st;
+ enum {
+ OPT_NO_DEREFERENCE = CHAR_MAX + 1
+ };
static const struct option longopts[] = {
{ "quiet", 0, 0, 'q' },
{ "fs-devno", 0, 0, 'd' },
{ "devno", 0, 0, 'x' },
+ { "no-dereference", 0, 0, OPT_NO_DEREFERENCE},
{ "help", 0, 0, 'h' },
{ "version", 0, 0, 'V' },
{ NULL, 0, 0, 0 }
@@ -165,6 +170,9 @@ int main(int argc, char **argv)
case 'x':
dev_devno = 1;
break;
+ case OPT_NO_DEREFERENCE:
+ no_dereference = 1;
+ break;
case 'h':
usage(stdout);
break;
@@ -182,7 +190,7 @@ int main(int argc, char **argv)
spec = argv[optind++];
- if (stat(spec, &st)) {
+ if (lstat(spec, &st)) {
if (!quiet)
err(EXIT_FAILURE, "%s", spec);
return EXIT_FAILURE;
@@ -192,7 +200,7 @@ int main(int argc, char **argv)
else {
dev_t src;
- if ( dir_to_device(spec, &src)) {
+ if (dir_to_device(spec, &src) || (no_dereference && S_ISLNK(st.st_mode))) {
if (!quiet)
printf(_("%s is not a mountpoint\n"), spec);
return EXIT_FAILURE;
--
2.1.0
--
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