From b60af444ccc7ae2655af6753d62c7ee611a628b8 Mon Sep 17 00:00:00 2001
From: Peter Krempa <pkrempa@redhat.com>
Date: Thu, 11 Feb 2016 09:57:45 +0100
Subject: [PATCH] conf: snapshot: Avoid autogenerating duplicate snapshot names

The snapshot name generator truncates the original file name after a '.'
and replaces the suffix with the snapshot name. If two disks source
images differ only in the suffix portion, the generated name will be
duplicate.

Since this is a corner case just error out stating that a duplicate name
was generated. The user can work around this situation by providing
the file names explicitly.

Resolves: https://bugzilla.redhat.com/show_bug.cgi?id=1283085
---
 src/conf/snapshot_conf.c | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/src/conf/snapshot_conf.c b/src/conf/snapshot_conf.c
index f8a1aed19c..58646bd982 100644
--- a/src/conf/snapshot_conf.c
+++ b/src/conf/snapshot_conf.c
@@ -445,6 +445,7 @@ virDomainSnapshotDefAssignExternalNames(virDomainSnapshotDefPtr def)
     char *tmp;
     struct stat sb;
     size_t i;
+    size_t j;
 
     for (i = 0; i < def->ndisks; i++) {
         virDomainSnapshotDiskDefPtr disk = &def->disks[i];
@@ -491,6 +492,17 @@ virDomainSnapshotDefAssignExternalNames(virDomainSnapshotDefPtr def)
         }
 
         VIR_FREE(tmppath);
+
+        /* verify that we didn't generate a duplicate name */
+        for (j = 0; j < i; j++) {
+            if (STREQ_NULLABLE(disk->src->path, def->disks[j].src->path)) {
+                virReportError(VIR_ERR_CONFIG_UNSUPPORTED,
+                               _("cannot generate external snapshot name for "
+                                 "disk '%s': collision with disk '%s'"),
+                               disk->name, def->disks[j].name);
+                return -1;
+            }
+        }
     }
 
     return 0;