9pfs: introduce v9fs_path_sprintf() helper

This helper is similar to v9fs_string_sprintf(), but it includes the
terminating NUL character in the size field.

This is to avoid doing v9fs_string_sprintf((V9fsString *) &path) and
then bumping the size.

Affected users are changed to use this new helper.

Signed-off-by: Greg Kurz <groug@kaod.org>
Reviewed-by: Cédric Le Goater <clg@kaod.org>

hw/9pfs/9p-local.c

@@ -1060,13 +1060,10 @@ static int local_name_to_path(FsContext *ctx, V9fsPath *dir_path,
                               const char *name, V9fsPath *target)
 {
     if (dir_path) {
-        v9fs_string_sprintf((V9fsString *)target, "%s/%s",
+        v9fs_path_sprintf(target, "%s/%s", dir_path->data, name);
-                            dir_path->data, name);
     } else {
-        v9fs_string_sprintf((V9fsString *)target, "%s", name);
+        v9fs_path_sprintf(target, "%s", name);
     }
-    /* Bump the size for including terminating NULL */
-    target->size++;
     return 0;
 }
 

hw/9pfs/9p-proxy.c

@@ -1023,13 +1023,10 @@ static int proxy_name_to_path(FsContext *ctx, V9fsPath *dir_path,
                               const char *name, V9fsPath *target)
 {
     if (dir_path) {
-        v9fs_string_sprintf((V9fsString *)target, "%s/%s",
+        v9fs_path_sprintf(target, "%s/%s", dir_path->data, name);
-                            dir_path->data, name);
     } else {
-        v9fs_string_sprintf((V9fsString *)target, "%s", name);
+        v9fs_path_sprintf(target, "%s", name);
     }
-    /* Bump the size for including terminating NULL */
-    target->size++;
     return 0;
 }
 

hw/9pfs/9p.c

@@ -12,6 +12,7 @@
  */
 
 #include "qemu/osdep.h"
+#include <glib/gprintf.h>
 #include "hw/virtio/virtio.h"
 #include "qapi/error.h"
 #include "qemu/error-report.h"
@@ -179,6 +180,20 @@ void v9fs_path_free(V9fsPath *path)
     path->size = 0;
 }
 
+
+void GCC_FMT_ATTR(2, 3)
+v9fs_path_sprintf(V9fsPath *path, const char *fmt, ...)
+{
+    va_list ap;
+
+    v9fs_path_free(path);
+
+    va_start(ap, fmt);
+    /* Bump the size for including terminating NULL */
+    path->size = g_vasprintf(&path->data, fmt, ap) + 1;
+    va_end(ap);
+}
+
 void v9fs_path_copy(V9fsPath *lhs, V9fsPath *rhs)
 {
     v9fs_path_free(lhs);
@@ -917,10 +932,8 @@ static void v9fs_fix_path(V9fsPath *dst, V9fsPath *src, int len)
     V9fsPath str;
     v9fs_path_init(&str);
     v9fs_path_copy(&str, dst);
-    v9fs_string_sprintf((V9fsString *)dst, "%s%s", src->data, str.data+len);
+    v9fs_path_sprintf(dst, "%s%s", src->data, str.data + len);
     v9fs_path_free(&str);
-    /* +1 to include terminating NULL */
-    dst->size++;
 }
 
 static inline bool is_ro_export(FsContext *ctx)

hw/9pfs/9p.h

@@ -327,6 +327,7 @@ static inline uint8_t v9fs_request_cancelled(V9fsPDU *pdu)
 extern void v9fs_reclaim_fd(V9fsPDU *pdu);
 extern void v9fs_path_init(V9fsPath *path);
 extern void v9fs_path_free(V9fsPath *path);
+extern void v9fs_path_sprintf(V9fsPath *path, const char *fmt, ...);
 extern void v9fs_path_copy(V9fsPath *lhs, V9fsPath *rhs);
 extern int v9fs_name_to_path(V9fsState *s, V9fsPath *dirpath,
                              const char *name, V9fsPath *path);