[Xen-devel] [PATCH] libxl: improve error handling when saving device model state

[Ian Campbell <ian.campbell@xxxxxxxxxx>]

# HG changeset patch
# User Ian Campbell <ian.campbell@xxxxxxxxxx>
# Date 1323795995 0
# Node ID 64e48ae2ef6760db221fe1896f7571260b0fd6ba
# Parent  738c34b1b0450724c4b91b739d1e9cae09f26035
libxl: improve error handling when saving device model state.

Do not leak a file descriptor (fd2 when used with upstream qemu) or a file (the
save file which is leaked on failure).

Signed-off-by: Ian Campbell <ian.campbell@xxxxxxxxxx>

diff -r 738c34b1b045 -r 64e48ae2ef67 tools/libxl/libxl_dom.c
--- a/tools/libxl/libxl_dom.c   Tue Dec 13 17:06:35 2011 +0000
+++ b/tools/libxl/libxl_dom.c   Tue Dec 13 17:06:35 2011 +0000
@@ -605,7 +605,7 @@ out:
 int libxl__domain_save_device_model(libxl__gc *gc, uint32_t domid, int fd)
 {
     libxl_ctx *ctx = libxl__gc_owner(gc);
-    int fd2, c;
+    int ret, fd2, c;
     char buf[1024];
     const char *filename = libxl__device_model_savefile(gc, domid);
     struct stat st;
@@ -630,8 +630,10 @@ int libxl__domain_save_device_model(libx
             return ERROR_FAIL;
         }
         /* Save DM state into fd2 */
-        if (libxl__qmp_migrate(gc, domid, fd2))
-            return ERROR_FAIL;
+        ret = libxl__qmp_migrate(gc, domid, fd2);
+        close(fd2);
+        if (ret)
+            goto out_unlink;
         break;
     default:
         return ERROR_INVAL;
@@ -646,31 +648,35 @@ int libxl__domain_save_device_model(libx
     qemu_state_len = st.st_size;
     LIBXL__LOG(ctx, LIBXL__LOG_DEBUG, "Qemu state is %d bytes\n", 
qemu_state_len);
 
-    c = libxl_write_exactly(ctx, fd, QEMU_SIGNATURE, strlen(QEMU_SIGNATURE),
-                            "saved-state file", "qemu signature");
-    if (c)
-        return c;
+    ret = libxl_write_exactly(ctx, fd, QEMU_SIGNATURE, strlen(QEMU_SIGNATURE),
+                              "saved-state file", "qemu signature");
+    if (ret)
+        goto out_unlink;
 
-    c = libxl_write_exactly(ctx, fd, &qemu_state_len, sizeof(qemu_state_len),
+    ret = libxl_write_exactly(ctx, fd, &qemu_state_len, sizeof(qemu_state_len),
                             "saved-state file", "saved-state length");
-    if (c)
-        return c;
+    if (ret)
+        goto out_unlink;
 
     fd2 = open(filename, O_RDONLY);
     while ((c = read(fd2, buf, sizeof(buf))) != 0) {
         if (c < 0) {
             if (errno == EINTR)
                 continue;
-            return errno;
+            ret = errno;
+            goto out_close_fd2;
         }
-        c = libxl_write_exactly(
+        ret = libxl_write_exactly(
             ctx, fd, buf, c, "saved-state file", "qemu state");
-        if (c)
-            return c;
+        if (ret)
+            goto out_close_fd2;
     }
+    ret = 0;
+out_close_fd2:
     close(fd2);
+out_unlink:
     unlink(filename);
-    return 0;
+    return ret;
 }
 
 char *libxl__uuid2string(libxl__gc *gc, const libxl_uuid uuid)

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