block/rbd: Add an escape-aware strchr helper

Sometimes the parser needs to further split a token it has collected
from the token input stream. Right now, it does a cursory check to see
if the relevant characters appear in the token to determine if it should
break it down further.

However, qemu_rbd_next_tok() will escape characters as it removes tokens
from the token stream and plain strchr() won't. This can make the
initial strchr() check slightly misleading since it implies
qemu_rbd_next_tok() will find the token and split on it, except the
reality is that qemu_rbd_next_tok() will pass over it if it is escaped.

Use a custom strchr to avoid mixing escaped and unescaped string
operations. Furthermore, this code is identical to how
qemu_rbd_next_tok() seeks its next token, so incorporate this custom
strchr into the body of that function to reduce duplication.

Reported-by: Han Han <hhan@redhat.com>
Fixes: https://bugzilla.redhat.com/1873913
Signed-off-by: Connor Kuehl <ckuehl@redhat.com>
Message-Id: <20210421212343.85524-3-ckuehl@redhat.com>
Reviewed-by: Stefano Garzarella <sgarzare@redhat.com>
Signed-off-by: Max Reitz <mreitz@redhat.com>

1 files changed, 21 insertions, 11 deletions

diff --git a/block/rbd.c b/block/rbd.c
index f098a89c7b..26f64cce7c 100644
--- a/block/rbd.c
+++ b/block/rbd.c
@@ -113,21 +113,31 @@ static int qemu_rbd_connect(rados_t *cluster, rados_ioctx_t *io_ctx,
                             const char *keypairs, const char *secretid,
                             Error **errp);
 
+static char *qemu_rbd_strchr(char *src, char delim)
+{
+    char *p;
+
+    for (p = src; *p; ++p) {
+        if (*p == delim) {
+            return p;
+        }
+        if (*p == '\\' && p[1] != '\0') {
+            ++p;
+        }
+    }
+
+    return NULL;
+}
+
+
 static char *qemu_rbd_next_tok(char *src, char delim, char **p)
 {
     char *end;
 
     *p = NULL;
 
-    for (end = src; *end; ++end) {
-        if (*end == delim) {
-            break;
-        }
-        if (*end == '\\' && end[1] != '\0') {
-            end++;
-        }
-    }
-    if (*end == delim) {
+    end = qemu_rbd_strchr(src, delim);
+    if (end) {
         *p = end + 1;
         *end = '\0';
     }
@@ -171,7 +181,7 @@ static void qemu_rbd_parse_filename(const char *filename, QDict *options,
     qemu_rbd_unescape(found_str);
     qdict_put_str(options, "pool", found_str);
 
-    if (strchr(p, '@')) {
+    if (qemu_rbd_strchr(p, '@')) {
         image_name = qemu_rbd_next_tok(p, '@', &p);
 
         found_str = qemu_rbd_next_tok(p, ':', &p);
@@ -181,7 +191,7 @@ static void qemu_rbd_parse_filename(const char *filename, QDict *options,
         image_name = qemu_rbd_next_tok(p, ':', &p);
     }
     /* Check for namespace in the image_name */
-    if (strchr(image_name, '/')) {
+    if (qemu_rbd_strchr(image_name, '/')) {
         found_str = qemu_rbd_next_tok(image_name, '/', &image_name);
         qemu_rbd_unescape(found_str);
         qdict_put_str(options, "namespace", found_str);