New commands: 'mkmountpoint' and 'rmmountpoint'

These specialized commands are used to create additional mountpoints
before mounting filesystems.  They are only used where you want to
mount several unrelated or read-only filesystems together, and need
additional care to use correctly.

Here is how to use these calls to unpack the "Russian doll" nest
of a Fedora 11 live CD:

 add-ro Fedora-11-i686-Live.iso
 run
 mkmountpoint /cd
 mkmountpoint /squash
 mkmountpoint /ext3
 mount /dev/sda /cd
 mount-loop /cd/LiveOS/squashfs.img /squash
 mount-loop /squash/LiveOS/ext3fs.img /ext3

The inner filesystem is now unpacked under the /ext3 mountpoint.

daemon/mount.c

@@ -22,6 +22,8 @@
 #include <stdlib.h>
 #include <string.h>
 #include <unistd.h>
+#include <sys/stat.h>
+#include <sys/types.h>
 
 #include "daemon.h"
 #include "actions.h"
@@ -349,3 +351,52 @@ do_mount_loop (char *file, char *mountpoint)
 
   return 0;
 }
+
+/* Specialized calls mkmountpoint and rmmountpoint are really
+ * variations on mkdir and rmdir which do no checking and (in the
+ * mkmountpoint case) set the root_mounted flag.
+ */
+int
+do_mkmountpoint (char *path)
+{
+  int r;
+
+  /* NEED_ROOT (-1); - we don't want this test for this call. */
+  ABS_PATH (path, -1);
+
+  CHROOT_IN;
+  r = mkdir (path, 0777);
+  CHROOT_OUT;
+
+  if (r == -1) {
+    reply_with_perror ("mkmountpoint: %s", path);
+    return -1;
+  }
+
+  /* Set the flag so that filesystems can be mounted here,
+   * not just on /sysroot.
+   */
+  root_mounted = 1;
+
+  return 0;
+}
+
+int
+do_rmmountpoint (char *path)
+{
+  int r;
+
+  NEED_ROOT (-1);
+  ABS_PATH (path, -1);
+
+  CHROOT_IN;
+  r = rmdir (path);
+  CHROOT_OUT;
+
+  if (r == -1) {
+    reply_with_perror ("rmmountpoint: %s", path);
+    return -1;
+  }
+
+  return 0;
+}

src/MAX_PROC_NR

@@ -1 +1 @@
-147
+149

src/generator.ml

@@ -2937,6 +2937,42 @@ This call is similar to C<guestfs_mounts>.  That call returns
 a list of devices.  This one returns a hash table (map) of
 device name to directory where the device is mounted.");
 
+  ("mkmountpoint", (RErr, [String "path"]), 148, [],
+   [],
+   "create a mountpoint",
+   "\
+C<guestfs_mkmountpoint> and C<guestfs_rmmountpoint> are
+specialized calls that can be used to create extra mountpoints
+before mounting the first filesystem.
+
+These calls are I<only> necessary in some very limited circumstances,
+mainly the case where you want to mount a mix of unrelated and/or
+read-only filesystems together.
+
+For example, live CDs often contain a \"Russian doll\" nest of
+filesystems, an ISO outer layer, with a squashfs image inside, with
+an ext2/3 image inside that.  You can unpack this as follows
+in guestfish:
+
+ add-ro Fedora-11-i686-Live.iso
+ run
+ mkmountpoint /cd
+ mkmountpoint /squash
+ mkmountpoint /ext3
+ mount /dev/sda /cd
+ mount-loop /cd/LiveOS/squashfs.img /squash
+ mount-loop /squash/LiveOS/ext3fs.img /ext3
+
+The inner filesystem is now unpacked under the /ext3 mountpoint.");
+
+  ("rmmountpoint", (RErr, [String "path"]), 149, [],
+   [],
+   "remove a mountpoint",
+   "\
+This calls removes a mountpoint that was previously created
+with C<guestfs_mkmountpoint>.  See C<guestfs_mkmountpoint>
+for full details.");
+
 ]
 
 let all_functions = non_daemon_functions @ daemon_functions