capitests: Add 'InitScratchFS' test environment.

This should allow us to perform filesystem-based write
tests much more quickly, because we don't need to recreate
the filesystem from scratch each time.

HACKING

@@ -168,36 +168,43 @@ Tests
 
 You can supply zero or as many tests as you want per API call.
 
-Note that the test environment has 3 block devices, of size 500MB,
-50MB and 10MB (respectively /dev/sda, /dev/sdb, /dev/sdc), and
-a fourth ISO block device with some known files on it (/dev/sdd).
+The test environment has 4 block devices:
+  /dev/sda   500MB   General block device for testing.
+  /dev/sdb    50MB   /dev/sdb1 is an ext2 filesystem used for testing
+                     filesystem write operations.
+  /dev/sdc    10MB   Used in a few tests where 2 block devices are needed.
+  /dev/sdd     -     ISO with fixed content (see images/test.iso).
 
-Note for partitioning purposes, the 500MB device has 1015 cylinders.
-Number of cylinders was 63 for IDE emulated disks with precisely
-the same size.  How exactly this is calculated is a mystery.
+To be able to run the tests in a reasonable amount of time, the
+virtual machine and block devices are reused between tests.  So don't
+try testing kill_subprocess :-x  Between each test we blockdev-setrw,
+umount-all, lvm-remove-all.
 
-The ISO block device (/dev/sdd) comes from images/test.iso.
+Each test starts with an initial scenario, selected using one of the
+'Init*' expressions, described in generator/generator_types.ml.  These
+initialize the disks in a particular way as described.  You should not
+assume anything about the previous contents of other disks that are
+not initialized.
 
-To be able to run the tests in a reasonable amount of time,
-the virtual machine and block devices are reused between tests.
-So don't try testing kill_subprocess :-x
-
-Between each test we blockdev-setrw, umount-all, lvm-remove-all.
-
-Don't assume anything about the previous contents of the block
-devices.  Use 'Init*' to create some initial scenarios.
-
-You can add a prerequisite clause to any individual test.  This
-is a run-time check, which, if it fails, causes the test to be
-skipped.  Useful if testing a command which might not work on
-all variations of libguestfs builds.  A test that has prerequisite
-of 'Always' is run unconditionally.
+You can add a prerequisite clause to any individual test.  This is a
+run-time check, which, if it fails, causes the test to be skipped.
+Useful if testing a command which might not work on all variations of
+libguestfs builds.  A test that has prerequisite of 'Always' is run
+unconditionally.
 
 In addition, packagers can skip individual tests by setting the
-environment variables:     eg:
+environment variables: eg:
+
   SKIP_TEST_<CMD>_<NUM>=1  SKIP_TEST_COMMAND_3=1  (skips test #3 of command)
   SKIP_TEST_<CMD>=1        SKIP_TEST_ZEROFREE=1   (skips all zerofree tests)
 
+and packagers can run only certain tests by setting eg:
+
+  TEST_ONLY="vfs_type zerofree"
+
+See capitests/tests.c for more details of how these environment
+variables work.
+
 Debugging
 ----------------------------------------------------------------------
 

generator/generator_actions.ml

@@ -1406,13 +1406,13 @@ See also C<guestfs_list_filesystems>.");
 
   ("list_partitions", (RStringList "partitions", [], []), 8, [],
    [InitBasicFS, Always, TestOutputListOfDevices (
-      [["list_partitions"]], ["/dev/sda1"]);
+      [["list_partitions"]], ["/dev/sda1"; "/dev/sdb1"]);
     InitEmpty, Always, TestOutputListOfDevices (
       [["part_init"; "/dev/sda"; "mbr"];
        ["part_add"; "/dev/sda"; "p"; "64"; "204799"];
        ["part_add"; "/dev/sda"; "p"; "204800"; "409599"];
        ["part_add"; "/dev/sda"; "p"; "409600"; "-64"];
-       ["list_partitions"]], ["/dev/sda1"; "/dev/sda2"; "/dev/sda3"])],
+       ["list_partitions"]], ["/dev/sda1"; "/dev/sda2"; "/dev/sda3"; "/dev/sdb1"])],
    "list the partitions",
    "\
 List all the partitions detected on all block devices.
@@ -5513,10 +5513,10 @@ error occurs.
 See also C<guestfs_download>, C<guestfs_pread>.");
 
   ("pwrite_device", (RInt "nbytes", [Device "device"; BufferIn "content"; Int64 "offset"], []), 275, [ProtocolLimitWarning],
-   [InitPartition, Always, TestOutputList (
+   [InitPartition, Always, TestOutputListOfDevices (
       [["pwrite_device"; "/dev/sda"; "\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000\000"; "446"];
        ["blockdev_rereadpt"; "/dev/sda"];
-       ["list_partitions"]], [])],
+       ["list_partitions"]], ["/dev/sdb1"])],
    "write to part of a device",
    "\
 This command writes to part of a device.  It writes the data

generator/generator_capitests.ml

@@ -257,6 +257,16 @@ int main (int argc, char *argv[])
   /* Cancel previous alarm. */
   alarm (0);
 
+  /* Create ext2 filesystem on /dev/sdb1 partition. */
+  if (guestfs_part_disk (g, \"/dev/sdb\", \"mbr\") == -1) {
+    printf (\"guestfs_part_disk FAILED\\n\");
+    exit (EXIT_FAILURE);
+  }
+  if (guestfs_mkfs (g, \"ext2\", \"/dev/sdb1\") == -1) {
+    printf (\"guestfs_mkfs (/dev/sdb1) FAILED\\n\");
+    exit (EXIT_FAILURE);
+  }
+
   nr_tests = %d;
 
 " (500 * 1024 * 1024) (50 * 1024 * 1024) (10 * 1024 * 1024) nr_tests;
@@ -435,6 +445,13 @@ and generate_one_test_body name i test_name init test =
           ["umount_all"];
           ["lvm_remove_all"];
           ["mount_ro"; "/dev/sdd"; "/"]]
+   | InitScratchFS ->
+       pr "  /* InitScratchFS for %s */\n" test_name;
+       List.iter (generate_test_command_call test_name)
+         [["blockdev_setrw"; "/dev/sda"];
+          ["umount_all"];
+          ["lvm_remove_all"];
+          ["mount_options"; ""; "/dev/sdb1"; "/"]]
   );
 
   let get_seq_last = function

generator/generator_types.ml

@@ -334,15 +334,16 @@ and test_init =
   | InitEmpty
 
     (* /dev/sda contains a single partition /dev/sda1, with random
-     * content.  /dev/sdb and /dev/sdc may have random content.
-     * No LVM.
+     * content.  No LVM.
      *)
   | InitPartition
 
     (* /dev/sda contains a single partition /dev/sda1, which is formatted
      * as ext2, empty [except for lost+found] and mounted on /.
-     * /dev/sdb and /dev/sdc may have random content.
      * No LVM.
+     *
+     * Note: for testing filesystem operations, it is quicker to use
+     * InitScratchFS
      *)
   | InitBasicFS
 
@@ -350,7 +351,9 @@ and test_init =
      *   /dev/sda1 (is a PV):
      *     /dev/VG/LV (size 8MB):
      *       formatted as ext2, empty [except for lost+found], mounted on /
-     * /dev/sdb and /dev/sdc may have random content.
+     *
+     * Note: only use this if you really need a freshly created filesystem
+     * on LVM.  Normally you should use InitScratchFS instead.
      *)
   | InitBasicFSonLVM
 
@@ -359,6 +362,16 @@ and test_init =
      *)
   | InitISOFS
 
+    (* /dev/sdb1 (write scratch disk) is mounted on /.  The filesystem
+     * will be empty.
+     *
+     * Note that this filesystem is not recreated between tests, and
+     * could contain random files and directories from previous tests.
+     * Therefore it is recommended that you create uniquely named files
+     * and directories for your tests.
+     *)
+  | InitScratchFS
+
 (* Sequence of commands for testing. *)
 and seq = cmd list
 and cmd = string list