support/testing/tests/package/test_ddrescue.py: new runtime test

Signed-off-by: Julien Olivain <ju.o@free.fr>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@bootlin.com>

DEVELOPERS

@@ -1729,6 +1729,8 @@ F:	support/testing/tests/package/sample_python_distro.py
 F:	support/testing/tests/package/sample_python_gnupg.py
 F:	support/testing/tests/package/sample_python_pyalsa.py
 F:	support/testing/tests/package/sample_python_spake2.py
+F:	support/testing/tests/package/test_ddrescue.py
+F:	support/testing/tests/package/test_ddrescue/
 F:	support/testing/tests/package/test_gnupg2.py
 F:	support/testing/tests/package/test_highway.py
 F:	support/testing/tests/package/test_hwloc.py

support/testing/tests/package/test_ddrescue.py

@@ -0,0 +1,94 @@
+import os
+
+import infra.basetest
+
+
+class TestDdrescue(infra.basetest.BRTest):
+
+    # A specific configuration is needed for testing ddrescue:
+    # - A kernel config fragment enables loop blk dev and device
+    #   mapper dm-dust, which are used to simulate a failing storage
+    #   block device.
+    # - dmraid user space package is needed to configure dm-dust
+    config = \
+        """
+        BR2_aarch64=y
+        BR2_TOOLCHAIN_EXTERNAL=y
+        BR2_TARGET_GENERIC_GETTY_PORT="ttyAMA0"
+        BR2_LINUX_KERNEL=y
+        BR2_LINUX_KERNEL_CUSTOM_VERSION=y
+        BR2_LINUX_KERNEL_CUSTOM_VERSION_VALUE="6.1.15"
+        BR2_LINUX_KERNEL_USE_CUSTOM_CONFIG=y
+        BR2_LINUX_KERNEL_CUSTOM_CONFIG_FILE="board/qemu/aarch64-virt/linux.config"
+        BR2_LINUX_KERNEL_CONFIG_FRAGMENT_FILES="{}"
+        BR2_LINUX_KERNEL_NEEDS_HOST_OPENSSL=y
+        BR2_PACKAGE_DDRESCUE=y
+        BR2_PACKAGE_DMRAID=y
+        BR2_TARGET_ROOTFS_CPIO=y
+        BR2_TARGET_ROOTFS_CPIO_GZIP=y
+        # BR2_TARGET_ROOTFS_TAR is not set
+        """.format(
+            infra.filepath("tests/package/test_ddrescue/linux-ddrescue.fragment")
+        )
+
+    def test_run(self):
+        img = os.path.join(self.builddir, "images", "rootfs.cpio.gz")
+        kern = os.path.join(self.builddir, "images", "Image")
+        self.emulator.boot(arch="aarch64",
+                           kernel=kern,
+                           kernel_cmdline=["console=ttyAMA0"],
+                           options=["-M", "virt", "-cpu", "cortex-a57", "-m", "256M", "-initrd", img])
+        self.emulator.login()
+
+        # Test variables:
+        dev_img = "/tmp/dev.img"
+        lo_dev = "/dev/loop0"
+        dm_dev_name = "dust0"
+        dm_dev = f"/dev/mapper/{dm_dev_name}"
+        ddrescue_img = "/tmp/ddrescue.img"
+
+        # Test the program can execute
+        self.assertRunOk("ddrescue --version")
+
+        # Create a 1MB file of zeroes for initial loopback block device
+        self.assertRunOk(f"dd if=/dev/zero of={dev_img} bs=1M count=1")
+
+        # Setup lookback block device
+        self.assertRunOk(f"losetup {lo_dev} {dev_img}")
+
+        # Create and setup dm-dust to simulate a failing block device
+        # The dev_img file is 1MB: 2048 blocks of 512 bytes each
+        self.assertRunOk(f"dmsetup create {dm_dev_name} --table '0 2048 dust {lo_dev} 0 512'")
+
+        # Add few bad blocks and enable I/O error emulation
+        for badblock in [30, 40, 50, 60]:
+            self.assertRunOk(f"dmsetup message {dm_dev_name} 0 addbadblock {badblock}")
+        self.assertRunOk(f"dmsetup message {dm_dev_name} 0 enable")
+
+        # Show device mapper status, to make debugging easier
+        self.assertRunOk(f"dmsetup status {dm_dev_name}")
+
+        # A normal 'dd' is expected to fail with I/O error
+        cmd = f"dd if={dm_dev} of=/dev/null bs=512"
+        _, exit_code = self.emulator.run(cmd)
+        self.assertNotEqual(exit_code, 0)
+
+        # Where a normal 'dd' fails, 'ddrescue' is expected to succeed
+        self.assertRunOk(f"ddrescue {dm_dev} {ddrescue_img}")
+
+        # ddrescue does not normaly write any output data when there
+        # is I/O error on the input. The intent is to preserve any
+        # data that could have been read in a previous pass. There is
+        # one exception, when the output is a non-existing regular
+        # file, ddrescue will initialize it with zeroes the first
+        # time. Since the original image file was also including
+        # zeroes, the recovered image is expected to be the same as
+        # the original one. See ddrescue manual:
+        # https://www.gnu.org/software/ddrescue/manual/ddrescue_manual.html#Introduction
+        # "Ddrescue does not write zeros to the output when it finds
+        # bad sectors in the input, and does not truncate the output
+        # file if not asked to."
+        # https://www.gnu.org/software/ddrescue/manual/ddrescue_manual.html#Algorithm
+        # "If the output file is a regular file created by ddrescue,
+        # the areas marked as bad-sector will contain zeros."
+        self.assertRunOk(f"cmp {dev_img} {ddrescue_img}")

support/testing/tests/package/test_ddrescue/linux-ddrescue.fragment

@@ -0,0 +1,4 @@
+CONFIG_BLK_DEV_LOOP=y
+CONFIG_MD=y
+CONFIG_BLK_DEV_DM=y
+CONFIG_DM_DUST=y