(Patch updated to report symlinks similar to Fabio's suggestion)

When using symlinks with mkfs.gfs2 it reports what the symlink points
to instead of the contents of the device, like so:

# ./mkfs.gfs2 -p lock_nolock /dev/vg/test
This will destroy any data on /dev/vg/test.
It appears to contain: symbolic link to `../dm-3'

This patch resolves symlinks before checking the device contents to make
the output more informative:

# ./mkfs.gfs2 -p lock_nolock /dev/vg/test
/dev/vg/test is a symlink to /dev/dm-3
This will destroy any data on /dev/dm-3.
It appears to contain: GFS2 Filesystem (blocksize 4096, lockproto lock_nolock)

Signed-off-by: Andrew Price <anprice@redhat.com>
---
gfs2/mkfs/main_mkfs.c | 35 ++++++++++++++++++++++++++++++++---
1 files changed, 32 insertions(+), 3 deletions(-)

diff --git a/gfs2/mkfs/main_mkfs.c b/gfs2/mkfs/main_mkfs.c
index e6b00a0..957b144 100644
--- a/gfs2/mkfs/main_mkfs.c
+++ b/gfs2/mkfs/main_mkfs.c
@@ -518,19 +518,46 @@ print_results(struct gfs2_sbd *sdp, uint64_t real_device_size,
printf("
");
}

+
+/**
+ * If path is a symlink, return 1 with *abspath pointing to the absolute path,
+ * otherwise return 0. Exit on errors. The caller must free the memory pointed
+ * to by *abspath.
+ */
+static int is_symlink(char *path, char **abspath)
+{
+ struct stat lnkstat;
+
+ if (lstat(path, &lnkstat) == -1) {
+ perror("Failed to lstat the device");
+ exit(EXIT_FAILURE);
+ }
+ if (!S_ISLNK(lnkstat.st_mode)) {
+ return 0;
+ }
+ *abspath = canonicalize_file_name(path);
+ if (*abspath == NULL) {
+ perror(_("Could not find the absolute path of the device"));
+ exit(EXIT_FAILURE);
+ }
+ printf( _("%s is a symlink to %s
"), path, *abspath);
+ return 1;
+}
+
/**
* main_mkfs - do everything
* @argc:
* @argv:
*
*/
-
void main_mkfs(int argc, char *argv[])
{
struct gfs2_sbd sbd, *sdp = &sbd;
int error;
int rgsize_specified = 0;
unsigned char uuid[16];
+ char *absname = NULL;
+ int islnk = 0;

memset(sdp, 0, sizeof(struct gfs2_sbd));
sdp->bsize = -1;
@@ -561,8 +588,10 @@ void main_mkfs(int argc, char *argv[])
}

if (!sdp->override) {
- printf( _("This will destroy any data on %s.
"), sdp->device_name);
- check_dev_content(sdp->device_name);
+ islnk = is_symlink(sdp->device_name, &absname);
+ printf(_("This will destroy any data on %s.
"), islnk ? absname : sdp->device_name);
+ check_dev_content(islnk ? absname : sdp->device_name);
+ free(absname);
are_you_sure();
}

--
1.7.7.6