diff options
Diffstat (limited to 'src/guestfs.c')
| -rw-r--r-- | src/guestfs.c | 22 |
1 files changed, 18 insertions, 4 deletions
diff --git a/src/guestfs.c b/src/guestfs.c index af60699d..02d5fdbf 100644 --- 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); } |