[Libguestfs] [PATCH] daemon: wipefs: Use --force option if available.

[Richard W.M. Jones]

From: "Richard W.M. Jones" <rjones at redhat.com>

See https://bugzilla.redhat.com/show_bug.cgi?id=872831
and https://bugzilla.redhat.com/show_bug.cgi?id=865961
---
 daemon/zero.c | 42 ++++++++++++++++++++++++++++++++++++++++--
 1 file changed, 40 insertions(+), 2 deletions(-)

diff --git a/daemon/zero.c b/daemon/zero.c
index 1a66881..4997583 100644
--- a/daemon/zero.c
+++ b/daemon/zero.c
@@ -82,14 +82,52 @@ optgroup_wipefs_available (void)
   return prog_exists (str_wipefs);
 }
 
+/* See RHBZ#872831 */
+static int
+wipefs_has_force_option (void)
+{
+  static int flag = -1;
+  int r;
+  char *out, *err;
+
+  if (flag == -1) {
+    r = command (&out, &err, "wipefs", "--help", NULL);
+    if (r == -1) {
+      reply_with_error ("%s", err);
+      free (out);
+      free (err);
+      return -1;
+    }
+    free (err);
+    flag = strstr (out, "--force") != NULL;
+    free (out);
+  }
+
+  return flag;
+}
+
 int
 do_wipefs (const char *device)
 {
+  int force;
   int r;
   char *err = NULL;
+  const size_t MAX_ARGS = 16;
+  const char *argv[MAX_ARGS];
+  size_t i = 0;
+
+  force = wipefs_has_force_option ();
+  if (force == -1)
+    return -1;
+
+  ADD_ARG (argv, i, str_wipefs);
+  ADD_ARG (argv, i, "-a");
+  if (force)
+    ADD_ARG (argv, i, "--force");
+  ADD_ARG (argv, i, device);
+  ADD_ARG (argv, i, NULL);
 
-  const char *wipefs[] = {str_wipefs, "-a", device, NULL};
-  r = commandv (NULL, &err, wipefs);
+  r = commandv (NULL, &err, argv);
   if (r == -1) {
     reply_with_error ("%s", err);
     free (err);
-- 
1.7.11.4