generator: Small fix for GODI users.

[libguestfs.git] / src / guestfs.c

diff --git a/src/guestfs.c b/src/guestfs.c
index af60699..e308044 100644 (file)
--- a/src/guestfs.c
+++ b/src/guestfs.c
@@ -792,9 +792,6 @@ int
 guestfs__add_drive_ro_with_if (guestfs_h *g, const char *filename,
                                const char *drive_if)
 {
-  size_t len = strlen (filename) + 64;
-  char buf[len];
-
   if (strchr (filename, ',') != NULL) {
     error (g, _("filename cannot contain ',' (comma) character"));
     return -1;
@@ -805,7 +802,24 @@ guestfs__add_drive_ro_with_if (guestfs_h *g, const char *filename,
     return -1;
   }
 
-  snprintf (buf, len, "file=%s,snapshot=on,if=%s", filename, drive_if);
+  if (qemu_supports (g, NULL) == -1)
+    return -1;
+
+  /* Only SCSI and virtio drivers support readonly mode.
+   * This is only supported as a QEMU feature since 2010/01.
+   */
+  int supports_ro = 0;
+  if ((STREQ (drive_if, "scsi") || STREQ (drive_if, "virtio")) &&
+      qemu_supports (g, "readonly=on"))
+    supports_ro = 1;
+
+  size_t len = strlen (filename) + 100;
+  char buf[len];
+
+  snprintf (buf, len, "file=%s,snapshot=on,%sif=%s",
+            filename,
+            supports_ro ? "readonly=on," : "",
+            drive_if);
 
   return guestfs__config (g, "-drive", buf);
 }
@@ -1606,7 +1620,7 @@ test_qemu (guestfs_h *g)
   char cmd[1024];
   FILE *fp;
 
-  snprintf (cmd, sizeof cmd, "LC_ALL=C '%s' -help", g->qemu);
+  snprintf (cmd, sizeof cmd, "LC_ALL=C '%s' -nographic -help", g->qemu);
 
   fp = popen (cmd, "r");
   /* qemu -help should always work (qemu -version OTOH wasn't
@@ -1628,7 +1642,8 @@ test_qemu (guestfs_h *g)
   if (pclose (fp) == -1)
     goto error;
 
-  snprintf (cmd, sizeof cmd, "LC_ALL=C '%s' -version 2>/dev/null", g->qemu);
+  snprintf (cmd, sizeof cmd, "LC_ALL=C '%s' -nographic -version 2>/dev/null",
+           g->qemu);
 
   fp = popen (cmd, "r");
   if (fp) {