On 01.04.21 23:01, Connor Kuehl wrote:
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.
Reported-by: Han Han <h...@redhat.com>
Fixes: https://bugzilla.redhat.com/1873913
Signed-off-by: Connor Kuehl <cku...@redhat.com>
---
block/rbd.c | 20 ++++++++++++++++++--
tests/qemu-iotests/231 | 4 ++++
tests/qemu-iotests/231.out | 3 +++
3 files changed, 25 insertions(+), 2 deletions(-)
diff --git a/block/rbd.c b/block/rbd.c
index 9071a00e3f..c0e4d4a952 100644
--- a/block/rbd.c
+++ b/block/rbd.c
@@ -134,6 +134,22 @@ static char *qemu_rbd_next_tok(char *src, char delim, char
**p)
return src;
}
+static char *qemu_rbd_strchr(char *src, char delim)
+{
+ char *p;
+
+ for (p = src; *p; ++p) {
+ if (*p == delim) {
+ return p;
+ }
+ if (*p == '\\') {
+ ++p;
+ }
+ }
+
+ return NULL;
+}
+
So I thought you could make qemu_rbd_do_next_tok() to do this. (I
didn’t say you should, but bear with me.) That would be possible by
giving it a new parameter (e.g. @find), and if that is set, return @end
if *end == delim after the loop, and NULL otherwise.
Now, if you add wrapper functions to make it nice, there’s not much more
difference in lines added compared to just adding a new function, but it
does mean your function should basically be the same as
qemu_rbd_next_tok(), except that no splitting happens, that there is no
*p, and that @end is returned instead of @src.
So there is one difference, and that is that qemu_rbd_next_tok() has
this condition to skip escaped characters:
if (*end == '\\' && end[1] != '\0') {
where qemu_rbd_strchr() has only:
if (*p == '\\') {
And I think qemu_rbd_next_tok() is right; if the string in question has
a trailing backslash, qemu_rbd_strchr() will ignore the final NUL and
continue searching past the end of the string.
Max
