From 0433f2d3bd818b83908636ae240ecbfd256e0a9c Mon Sep 17 00:00:00 2001
From: John Snow <jsnow@redhat.com>
Date: Wed, 10 Oct 2018 20:30:13 +0100
Subject: [PATCH 2/4] block/rbd: Attempt to parse legacy filenames

RH-Author: John Snow <jsnow@redhat.com>
Message-id: <20181010203015.11719-3-jsnow@redhat.com>
Patchwork-id: 82629
O-Subject: [RHEL8/rhel qemu-kvm PATCH 2/4] block/rbd: Attempt to parse legacy filenames
Bugzilla: 1635585
RH-Acked-by: Markus Armbruster <armbru@redhat.com>
RH-Acked-by: Stefan Hajnoczi <stefanha@redhat.com>
RH-Acked-by: Thomas Huth <thuth@redhat.com>

From: Jeff Cody <jcody@redhat.com>

When we converted rbd to get rid of the older key/value-centric
encoding format, we broke compatibility with image files with backing
file strings encoded in the old format.

This leaves a bit of an ugly conundrum, and a hacky solution.

If the initial attempt to parse the "proper" options fails, it assumes
that we may have an older key/value encoded filename.  Fall back to
attempting to parse the filename, and extract the required options from
it.  If that fails, pass along the original error message.

We do not support mixed modern usage alongside legacy keyvalue pair
usage.

A deprecation warning has been added, although care should be taken
when actually deprecating since the impact is not limited to
commandline or qapi usage, but also opening existing images.

Reviewed-by: Eric Blake <eblake@redhat.com>
Signed-off-by: Jeff Cody <jcody@redhat.com>
Message-id: 15b332e5432ad069441f7275a46080f465d789a0.1536704901.git.jcody@redhat.com
Signed-off-by: Jeff Cody <jcody@redhat.com>
(cherry picked from commit 084d1d13bdb753d558b991996e7686c077bd6d80)
Signed-off-by: John Snow <jsnow@redhat.com>
Signed-off-by: Danilo C. L. de Paula <ddepaula@redhat.com>
---
 block/rbd.c | 54 ++++++++++++++++++++++++++++++++++++++++++++++++++++--
 1 file changed, 52 insertions(+), 2 deletions(-)

diff --git a/block/rbd.c b/block/rbd.c
index 1e4d339..ebe0701 100644
--- a/block/rbd.c
+++ b/block/rbd.c
@@ -671,6 +671,33 @@ static int qemu_rbd_convert_options(QDict *options, BlockdevOptionsRbd **opts,
     return 0;
 }
 
+static int qemu_rbd_attempt_legacy_options(QDict *options,
+                                           BlockdevOptionsRbd **opts,
+                                           char **keypairs)
+{
+    char *filename;
+    int r;
+
+    filename = g_strdup(qdict_get_try_str(options, "filename"));
+    if (!filename) {
+        return -EINVAL;
+    }
+    qdict_del(options, "filename");
+
+    qemu_rbd_parse_filename(filename, options, NULL);
+
+    /* keypairs freed by caller */
+    *keypairs = g_strdup(qdict_get_try_str(options, "=keyvalue-pairs"));
+    if (*keypairs) {
+        qdict_del(options, "=keyvalue-pairs");
+    }
+
+    r = qemu_rbd_convert_options(options, opts, NULL);
+
+    g_free(filename);
+    return r;
+}
+
 static int qemu_rbd_open(BlockDriverState *bs, QDict *options, int flags,
                          Error **errp)
 {
@@ -693,8 +720,31 @@ static int qemu_rbd_open(BlockDriverState *bs, QDict *options, int flags,
 
     r = qemu_rbd_convert_options(options, &opts, &local_err);
     if (local_err) {
-        error_propagate(errp, local_err);
-        goto out;
+        /* If keypairs are present, that means some options are present in
+         * the modern option format.  Don't attempt to parse legacy option
+         * formats, as we won't support mixed usage. */
+        if (keypairs) {
+            error_propagate(errp, local_err);
+            goto out;
+        }
+
+        /* If the initial attempt to convert and process the options failed,
+         * we may be attempting to open an image file that has the rbd options
+         * specified in the older format consisting of all key/value pairs
+         * encoded in the filename.  Go ahead and attempt to parse the
+         * filename, and see if we can pull out the required options. */
+        r = qemu_rbd_attempt_legacy_options(options, &opts, &keypairs);
+        if (r < 0) {
+            /* Propagate the original error, not the legacy parsing fallback
+             * error, as the latter was just a best-effort attempt. */
+            error_propagate(errp, local_err);
+            goto out;
+        }
+        /* Take care whenever deciding to actually deprecate; once this ability
+         * is removed, we will not be able to open any images with legacy-styled
+         * backing image strings. */
+        error_report("RBD options encoded in the filename as keyvalue pairs "
+                     "is deprecated");
     }
 
     /* Remove the processed options from the QDict (the visitor processes
-- 
1.8.3.1