Re: [PATCH v3 2/2] block/rbd: Add an escape-aware strchr helper
Hi Connor,
On Wed, Apr 21, 2021 at 04:15:42PM -0500, Connor Kuehl wrote:
On 4/21/21 6:04 AM, Stefano Garzarella wrote:
+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;
+}
+
IIUC this is similar to the code used in qemu_rbd_next_tok().
To avoid code duplication can we use this new function inside it?
Hi Stefano! Good catch. I think you're right. I've incorporated your
suggestion into my next revision. The only thing I changed was the
if-statement from:
if (end && *end == delim) {
to:
if (end) {
Since qemu_rbd_strchr() will only ever return a non-NULL pointer if it
was able to find 'delim'.
Yeah, definitely better :-)
Thanks,
Stefano
Re: [PATCH v3 2/2] block/rbd: Add an escape-aware strchr helper
On 4/21/21 6:04 AM, Stefano Garzarella wrote:
>> +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;
>> +}
>> +
>
> IIUC this is similar to the code used in qemu_rbd_next_tok().
> To avoid code duplication can we use this new function inside it?
Hi Stefano! Good catch. I think you're right. I've incorporated your
suggestion into my next revision. The only thing I changed was the
if-statement from:
if (end && *end == delim) {
to:
if (end) {
Since qemu_rbd_strchr() will only ever return a non-NULL pointer if it
was able to find 'delim'.
Connor
>
> I mean something like this (not tested):
>
> diff --git a/block/rbd.c b/block/rbd.c
> index f098a89c7b..eb6a839362 100644
> --- a/block/rbd.c
> +++ b/block/rbd.c
> @@ -119,15 +119,8 @@ static char *qemu_rbd_next_tok(char *src, char delim,
> char **p)
>
> *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 && *end == delim) {
> *p = end + 1;
> *end = '\0';
> }
>
>
> The rest LGTM!
>
> Thanks for fixing this issue,
> Stefano
>
Re: [PATCH v3 2/2] block/rbd: Add an escape-aware strchr helper
On Fri, Apr 09, 2021 at 09:38:54AM -0500, 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
Fixes: https://bugzilla.redhat.com/1873913
Signed-off-by: Connor Kuehl
---
v2 -> v3:
* Update qemu_rbd_strchr to only skip if there's a delimiter AND the
next character is not the NUL terminator
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..291e3f09e1 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[1] != '\0') {
+++p;
+}
+}
+
+return NULL;
+}
+
IIUC this is similar to the code used in qemu_rbd_next_tok().
To avoid code duplication can we use this new function inside it?
I mean something like this (not tested):
diff --git a/block/rbd.c b/block/rbd.c
index f098a89c7b..eb6a839362 100644
--- a/block/rbd.c
+++ b/block/rbd.c
@@ -119,15 +119,8 @@ static char *qemu_rbd_next_tok(char *src, char delim, char
**p)
*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 && *end == delim) {
*p = end + 1;
*end = '\0';
}
The rest LGTM!
Thanks for fixing this issue,
Stefano
[PATCH v3 2/2] 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.
Reported-by: Han Han
Fixes: https://bugzilla.redhat.com/1873913
Signed-off-by: Connor Kuehl
---
v2 -> v3:
* Update qemu_rbd_strchr to only skip if there's a delimiter AND the
next character is not the NUL terminator
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..291e3f09e1 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[1] != '\0') {
+++p;
+}
+}
+
+return NULL;
+}
+
static void qemu_rbd_unescape(char *src)
{
char *p;
@@ -171,7 +187,7 @@ 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, '@', );
found_str = qemu_rbd_next_tok(p, ':', );
@@ -181,7 +197,7 @@ static void qemu_rbd_parse_filename(const char *filename,
QDict *options,
image_name = qemu_rbd_next_tok(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, '/', _name);
qemu_rbd_unescape(found_str);
qdict_put_str(options, "namespace", found_str);
diff --git a/tests/qemu-iotests/231 b/tests/qemu-iotests/231
index 0f66d0ca36..8e6c6447c1 100755
--- a/tests/qemu-iotests/231
+++ b/tests/qemu-iotests/231
@@ -55,6 +55,10 @@ _filter_conf()
$QEMU_IMG info
"json:{'file.driver':'rbd','file.filename':'rbd:rbd/bogus:conf=${BOGUS_CONF}'}"
2>&1 | _filter_conf
$QEMU_IMG info
"json:{'file.driver':'rbd','file.pool':'rbd','file.image':'bogus','file.conf':'${BOGUS_CONF}'}"
2>&1 | _filter_conf
+# Regression test: the qemu-img invocation is expected to fail, but it should
+# not seg fault the parser.
+$QEMU_IMG create "rbd:rbd/aa\/bb:conf=${BOGUS_CONF}" 1M 2>&1 | _filter_conf
+
# success, all done
echo "*** done"
rm -f $seq.full
diff --git a/tests/qemu-iotests/231.out b/tests/qemu-iotests/231.out
index 747dd221bb..a785a6e859 100644
--- a/tests/qemu-iotests/231.out
+++ b/tests/qemu-iotests/231.out
@@ -4,4 +4,7 @@ unable to get monitor info from DNS SRV with service name:
ceph-mon
qemu-img: Could not open
'json:{'file.driver':'rbd','file.filename':'rbd:rbd/bogus:conf=BOGUS_CONF'}':
error connecting: No such file or directory
unable to get monitor info from DNS SRV with service name: ceph-mon
qemu-img: Could not open
'json:{'file.driver':'rbd','file.pool':'rbd','file.image':'bogus','file.conf':'BOGUS_CONF'}':
error connecting: No such file or directory
+Formatting 'rbd:rbd/aa\/bb:conf=BOGUS_CONF', fmt=raw size=1048576
+unable to get monitor info from DNS SRV with service name: ceph-mon
+qemu-img: rbd:rbd/aa\/bb:conf=BOGUS_CONF: error connecting: No such file or
directory
*** done
--
2.30.2
