[Qemu-devel] [PATCH 4/4] 9pfs: introduce v9fs_path_sprintf() helper

[Greg Kurz]

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 <address@hidden>
---
 hw/9pfs/9p-local.c |    7 ++-----
 hw/9pfs/9p-proxy.c |    7 ++-----
 hw/9pfs/9p.c       |   19 ++++++++++++++++---
 hw/9pfs/9p.h       |    1 +
 4 files changed, 21 insertions(+), 13 deletions(-)

diff --git a/hw/9pfs/9p-local.c b/hw/9pfs/9p-local.c
index 3f271fcbd2c5..845675e7a1bb 100644
--- a/hw/9pfs/9p-local.c
+++ b/hw/9pfs/9p-local.c
@@ -1058,17 +1058,14 @@ static int local_lremovexattr(FsContext *ctx, V9fsPath 
*fs_path,
 
 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",
-                            dir_path->data, name);
+        v9fs_path_sprintf(target, "%s/%s", 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;
 }
 
 static int local_renameat(FsContext *ctx, V9fsPath *olddir,
                           const char *old_name, V9fsPath *newdir,
diff --git a/hw/9pfs/9p-proxy.c b/hw/9pfs/9p-proxy.c
index d091564b6fd2..f2417b7fd73d 100644
--- a/hw/9pfs/9p-proxy.c
+++ b/hw/9pfs/9p-proxy.c
@@ -1021,17 +1021,14 @@ static int proxy_lremovexattr(FsContext *ctx, V9fsPath 
*fs_path,
 
 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",
-                            dir_path->data, name);
+        v9fs_path_sprintf(target, "%s/%s", 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;
 }
 
 static int proxy_renameat(FsContext *ctx, V9fsPath *olddir,
                           const char *old_name, V9fsPath *newdir,
diff --git a/hw/9pfs/9p.c b/hw/9pfs/9p.c
index d8f48ca76c47..639f93930285 100644
--- a/hw/9pfs/9p.c
+++ b/hw/9pfs/9p.c
@@ -10,10 +10,11 @@
  * the COPYING file in the top-level directory.
  *
  */
 
 #include "qemu/osdep.h"
+#include <glib/gprintf.h>
 #include "hw/virtio/virtio.h"
 #include "qapi/error.h"
 #include "qemu/error-report.h"
 #include "qemu/iov.h"
 #include "qemu/sockets.h"
@@ -177,10 +178,24 @@ void v9fs_path_free(V9fsPath *path)
     g_free(path->data);
     path->data = NULL;
     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);
     lhs->data = g_malloc(rhs->size);
     memcpy(lhs->data, rhs->data, rhs->size);
@@ -915,14 +930,12 @@ static void print_sg(struct iovec *sg, int cnt)
 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)
 {
     return ctx->export_flags & V9FS_RDONLY;
diff --git a/hw/9pfs/9p.h b/hw/9pfs/9p.h
index a38603398ef5..d539d2ebe9c0 100644
--- a/hw/9pfs/9p.h
+++ b/hw/9pfs/9p.h
@@ -325,10 +325,11 @@ 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);
 extern int v9fs_device_realize_common(V9fsState *s, Error **errp);
 extern void v9fs_device_unrealize_common(V9fsState *s, Error **errp);