avoid leak upon failed realloc

[libguestfs.git] / daemon / guestfsd.c

diff --git a/daemon/guestfsd.c b/daemon/guestfsd.c
index 0a3e64f..87065b9 100644 (file)
--- a/daemon/guestfsd.c
+++ b/daemon/guestfsd.c
@@ -1,5 +1,5 @@
 /* libguestfs - the guestfsd daemon
- * Copyright (C) 2009 Red Hat Inc. 
+ * Copyright (C) 2009 Red Hat Inc.
  *
  * This program is free software; you can redistribute it and/or modify
  * it under the terms of the GNU General Public License as published by
@@ -572,19 +572,23 @@ commandrv (char **stdoutput, char **stderror, char * const* const argv)
    * trailing \n characters from the error buffer (not from stdout).
    */
   if (stdoutput) {
-    *stdoutput = realloc (*stdoutput, so_size+1);
-    if (*stdoutput == NULL) {
+    void *q = realloc (*stdoutput, so_size+1);
+    if (q == NULL) {
       perror ("realloc");
-      *stdoutput = NULL;
-    } else
+      free (*stdoutput);
+    }
+    *stdoutput = q;
+    if (*stdoutput)
       (*stdoutput)[so_size] = '\0';
   }
   if (stderror) {
-    *stderror = realloc (*stderror, se_size+1);
-    if (*stderror == NULL) {
+    void *q = realloc (*stderror, se_size+1);
+    if (q == NULL) {
       perror ("realloc");
-      *stderror = NULL;
-    } else {
+      free (*stderror);
+    }
+    *stderror = q;
+    if (*stderror) {
       (*stderror)[se_size] = '\0';
       se_size--;
       while (se_size >= 0 && (*stderror)[se_size] == '\n')
@@ -741,3 +745,16 @@ device_name_translation (char *device, const char *func)
   device[5] = 's';             /* Restore original device name. */
   goto error;
 }
+
+/* LVM and other commands aren't synchronous, especially when udev is
+ * involved.  eg. You can create or remove some device, but the /dev
+ * device node won't appear until some time later.  This means that
+ * you get an error if you run one command followed by another.
+ * Use 'udevadm settle' after certain commands, but don't be too
+ * fussed if it fails.
+ */
+void
+udev_settle (void)
+{
+  command (NULL, NULL, "/sbin/udevadm", "settle", NULL);
+}