e2fsprogs: fix blkid whole-disk scanning heuristics

The heuristics in blkid/devname.c probe_all() for scanning whole disks
with no partitions assume that a device name with no digit on the end
will always be present as a delineator, i.e.:

sda
sda1
sdb
sdc

In this case, when sdc is seen, it's the clue to go back and scan sdb.
However, for something like:

sda
sda1
sdb
loop0

this falls down, and sdb is never scanned.
(thanks to Karel Zak for pointing this out).

Addresses-Red-Hat-Bugzilla: #400321

Signed-off-by: Eric Sandeen <sandeen@redhat.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>

diff --git a/lib/blkid/devname.c b/lib/blkid/devname.c
index 13500768e25722453fd49c1fd4d20e0733982a78..fd646960c5ce39e07e64d447dd2c53a991b0b064 100644 (file)
--- a/lib/blkid/devname.c
+++ b/lib/blkid/devname.c
@@ -490,10 +490,11 @@ static int probe_all(blkid_cache cache, int only_if_new)
 
                DBG(DEBUG_DEVNAME, printf("read partition name %s\n", ptname));
 
-               /* Skip whole disk devs unless they have no partitions
-                * If we don't have a partition on this dev, also
+               /* Skip whole disk devs unless they have no partitions.
+                * If base name of device has changed, also
                 * check previous dev to see if it didn't have a partn.
-                * heuristic: partition name ends in a digit.
+                * heuristic: partition name ends in a digit, & partition
+                * names contain whole device name as substring.
                 *
                 * Skip extended partitions.
                 * heuristic: size is 1
@@ -502,6 +503,8 @@ static int probe_all(blkid_cache cache, int only_if_new)
                 */
 
                lens[which] = strlen(ptname);
+
+               /* ends in a digit, clearly a partition, so check */
                if (isdigit(ptname[lens[which] - 1])) {
                        DBG(DEBUG_DEVNAME,
                            printf("partition dev %s, devno 0x%04X\n",
@@ -510,10 +513,15 @@ static int probe_all(blkid_cache cache, int only_if_new)
                        if (sz > 1)
                                probe_one(cache, ptname, devs[which], 0, 
                                          only_if_new);
-                       lens[which] = 0;
-                       lens[last] = 0;
-               } else if (lens[last] && strncmp(ptnames[last], ptname,
-                                                lens[last])) {
+                       lens[which] = 0;        /* mark as checked */
+               }
+
+               /*
+                * If last was not checked because it looked like a whole-disk
+                * dev, and the device's base name has changed,
+                * check last as well.
+                */
+               if (lens[last] && strncmp(ptnames[last], ptname, lens[last])) {
                        DBG(DEBUG_DEVNAME,
                            printf("whole dev %s, devno 0x%04X\n",
                                   ptnames[last], (unsigned int) devs[last]));