[libvirt] [PATCH] fix index creation for disks > {sd,hd,xvd,vd}z

[Chris Wright]

Calling virDiskNameToIndex with a disk name > {sd,hd,xvd,vd}z, such as
vdaa, generates a bogus index.  Account for iterations through the loop.

Old behaviour:
vda -> 0
vdz -> 25
vdaa -> 0
vdaz -> 25

New behaviour:
vda -> 0
vdz -> 25
vdaa -> 26
vdaz -> 51

This was discovered by Sanjay Rao, thanks for the report.

Signed-off-by: Chris Wright <chrisw at redhat.com>
Cc: Mark Wagner <mwagner at redhat.com>
Cc: Sanjay Rao <srao at redhat.com>
---
 src/domain_conf.c |    2 +-
 src/util.c        |    6 +++---
 2 files changed, 4 insertions(+), 4 deletions(-)

diff --git a/src/domain_conf.c b/src/domain_conf.c
index 6a35064..b5897a7 100644
--- a/src/domain_conf.c
+++ b/src/domain_conf.c
@@ -3395,7 +3395,7 @@ char *virDomainConfigFile(virConnectPtr conn,
 
 /* Translates a device name of the form (regex) "[fhv]d[a-z]+" into
  * the corresponding bus,index combination (e.g. sda => (0,0), sdi (1,1),
- *                                               hdd => (1,1), vdaa => (0,27))
+ *                                               hdd => (1,1), vdaa => (0,26))
  * @param disk The disk device
  * @param busIdx parsed bus number
  * @param devIdx parsed device number
diff --git a/src/util.c b/src/util.c
index ca14be1..56390d7 100644
--- a/src/util.c
+++ b/src/util.c
@@ -1055,7 +1055,7 @@ const char *virEnumToString(const char *const*types,
 }
 
 /* Translates a device name of the form (regex) "[fhv]d[a-z]+" into
- * the corresponding index (e.g. sda => 1, hdz => 26, vdaa => 27)
+ * the corresponding index (e.g. sda => 0, hdz => 25, vdaa => 26)
  * @param name The name of the device
  * @return name's index, or -1 on failure
  */
@@ -1075,8 +1075,8 @@ int virDiskNameToIndex(const char *name) {
     if (!ptr)
         return -1;
 
-    while (*ptr) {
-        idx = idx * 26;
+    for (i = 0; *ptr; i++) {
+        idx = (idx + i) * 26;
 
         if (!c_islower(*ptr))
             return -1;