kvmtool: 9p: fix overapping snprintf
GCC 8.2 gives this warning:
virtio/9p.c: In function ‘virtio_p9_create’:
virtio/9p.c:335:21: error: passing argument 1 to restrict-qualified parameter aliases with argument 4 [-Werror=restrict]
ret = snprintf(dfid->path, size, "%s/%s", dfid->path, name);
~~~~^~~~~~ ~~~~~~~~~~
Fix it by allocating a temporary string with dfid->path content instead
of overwriting it in-place, which is limited in glibc snprintf with the
__restrict qualifier.
Reviewed-by: Andre Przywara <andre.przywara@arm.com>
Signed-off-by: Anisse Astier <aastier@freebox.fr>
Signed-off-by: Will Deacon <will.deacon@arm.com>
diff --git a/virtio/9p.c b/virtio/9p.c
index 6bae403..ac70dbc 100644
--- a/virtio/9p.c
+++ b/virtio/9p.c
@@ -322,6 +322,7 @@
struct p9_qid qid;
struct p9_fid *dfid;
char full_path[PATH_MAX];
+ char *tmp_path;
u32 dfid_val, flags, mode, gid;
virtio_p9_pdu_readf(pdu, "dsddd", &dfid_val,
@@ -332,7 +333,13 @@
goto err_out;
size = sizeof(dfid->abs_path) - (dfid->path - dfid->abs_path);
- ret = snprintf(dfid->path, size, "%s/%s", dfid->path, name);
+
+ tmp_path = strdup(dfid->path);
+ if (!tmp_path)
+ goto err_out;
+
+ ret = snprintf(dfid->path, size, "%s/%s", tmp_path, name);
+ free(tmp_path);
if (ret >= (int)size) {
errno = ENAMETOOLONG;
if (size > 0)
