partx: fix --update ranges and out of order tables

partx --update DEVICE NUMBER
was broken in 2 cases:
 * if NUMBER != 1
 * if the partition table was "out of order".
   Ie, where sda2 came after sda3.

References: https://bugs.launchpad.net/ubuntu/+source/cloud-utils/+bug/1244662
Signed-off-by: Scott Moser <smoser@ubuntu.com>
Signed-off-by: Karel Zak <kzak@redhat.com>

diff --git a/disk-utils/partx.c b/disk-utils/partx.c
index 880d779621c6e3c76a26505cb92b996021995571..df03e591e3fcd7365dd5cd06a9f41514e8d8d017 100644 (file)
--- a/disk-utils/partx.c
+++ b/disk-utils/partx.c
@@ -412,10 +412,41 @@ static void upd_parts_warnx(const char *device, int first, int last)
                                device, first, last);
 }
 
+/**
+ * get_partition_by_partno:
+ * @ls: partitions list
+ * @n: the partition number (e.g. 'N' from sda'N')
+ *
+ * This does not assume any order of the input blkid_partlist.
+ * And correctly handles "out of order" partition tables.
+ * partition N is located after partition N+1 on the disk.
+ *
+ * Returns: partition object or NULL in case or error.
+ */
+blkid_partition get_partition_by_partno(blkid_partlist ls, int n)
+{
+       int i, nparts;
+       blkid_partition par;
+       if (!ls)
+               return NULL;
+
+       nparts = blkid_partlist_numof_partitions(ls);
+       if (nparts < 0)
+               return NULL;
+
+       for (i = 0; i < nparts; i++) {
+               par = blkid_partlist_get_partition(ls, i);
+               if (n == blkid_partition_get_partno(par)) {
+                       return par;
+               }
+       }
+       return NULL;
+}
+
 static int upd_parts(int fd, const char *device, dev_t devno,
                     blkid_partlist ls, int lower, int upper)
 {
-       int i, n, an, nparts, rc = 0, errfirst = 0, errlast = 0, err;
+       int n, nparts, rc = 0, errfirst = 0, errlast = 0, err;
        blkid_partition par;
        uintmax_t start, size;
 
@@ -441,18 +472,16 @@ static int upd_parts(int fd, const char *device, dev_t devno,
                return -1;
        }
 
-       for (i = 0, n = lower; n <= upper; n++) {
-               par = blkid_partlist_get_partition(ls, i);
-               an = blkid_partition_get_partno(par);
-
-               if (lower && n < lower)
-                       continue;
-               if (upper && n > upper)
+       for (n = lower; n <= upper; n++) {
+               par = get_partition_by_partno(ls, n);
+               if (!par) {
+                       if (verbose)
+                               warn(_("%s: no partition #%d"), device, n);
                        continue;
+               }
 
                start = blkid_partition_get_start(par);
                size =  blkid_partition_get_size(par);
-
                if (blkid_partition_is_extended(par))
                        /*
                         * Let's follow the Linux kernel and reduce
@@ -463,25 +492,21 @@ static int upd_parts(int fd, const char *device, dev_t devno,
                err = partx_del_partition(fd, n);
                if (err == -1 && errno == ENXIO)
                        err = 0; /* good, it already doesn't exist */
-               if (an == n)
+               if (err == -1 && errno == EBUSY)
                {
-                       if (i < nparts)
-                               i++;
-                       if (err == -1 && errno == EBUSY)
-                       {
-                               /* try to resize */
-                               err = partx_resize_partition(fd, n, start, size);
-                               if (verbose)
-                                       printf(_("%s: partition #%d resized\n"), device, n);
-                               if (err == 0)
-                                       continue;
-                       }
-                       if (err == 0 && partx_add_partition(fd, n, start, size) == 0) {
-                               if (verbose)
-                                       printf(_("%s: partition #%d added\n"), device, n);
+                       /* try to resize */
+                       err = partx_resize_partition(fd, n, start, size);
+                       if (verbose)
+                               printf(_("%s: partition #%d resized\n"), device, n);
+                       if (err == 0)
                                continue;
-                       }
                }
+               if (err == 0 && partx_add_partition(fd, n, start, size) == 0) {
+                       if (verbose)
+                               printf(_("%s: partition #%d added\n"), device, n);
+                       continue;
+               }
+
                if (err == 0)
                        continue;
                rc = -1;