wic: Add --exclude-path option to rootfs source plugin.

It will omit the given path from the resulting partition, and if the
given path ends in a slash, it will only delete the content, and keep
the directory.

Since mkfs only accepts whole directories as input, we need to copy
the rootfs directory to the workdir so that we can selectively delete
files from it.

Since we want to use the copyhardlinktree() function, we need to put
the generic oe lib in the module search path.

Signed-off-by: Kristian Amlie <kristian.amlie@mender.io>
Signed-off-by: Ross Burton <ross.burton@intel.com>

4 files changed, 50 insertions, 1 deletions

diff --git a/scripts/lib/wic/help.py b/scripts/lib/wic/help.py
index 1bd411deeb..63bbc23a83 100644
--- a/scripts/lib/wic/help.py
+++ b/scripts/lib/wic/help.py
@@ -721,6 +721,12 @@ DESCRIPTION
                      partition table. It may be useful for
                      bootloaders.
 
+         --exclude-path: This option is specific to wic. It excludes the given
+                         absolute path from the resulting image. If the path
+                         ends with a slash, only the content of the directory
+                         is omitted, not the directory itself. This option only
+                         has an effect with the rootfs source plugin.
+
          --extra-space: This option is specific to wic. It adds extra
                         space after the space filled by the content
                         of the partition. The final size can go
diff --git a/scripts/lib/wic/ksparser.py b/scripts/lib/wic/ksparser.py
index 41d3cc667f..f0aa5d0389 100644
--- a/scripts/lib/wic/ksparser.py
+++ b/scripts/lib/wic/ksparser.py
@@ -130,6 +130,7 @@ class KickStart():
         part.add_argument('mountpoint', nargs='?')
         part.add_argument('--active', action='store_true')
         part.add_argument('--align', type=int)
+        part.add_argument('--exclude-path', nargs='+')
         part.add_argument("--extra-space", type=sizetype)
         part.add_argument('--fsoptions', dest='fsopts')
         part.add_argument('--fstype')
diff --git a/scripts/lib/wic/partition.py b/scripts/lib/wic/partition.py
index 754ad757d0..1221f691dc 100644
--- a/scripts/lib/wic/partition.py
+++ b/scripts/lib/wic/partition.py
@@ -40,6 +40,7 @@ class Partition():
         self.disk = args.disk
         self.device = None
         self.extra_space = args.extra_space
+        self.exclude_path = args.exclude_path
         self.fsopts = args.fsopts
         self.fstype = args.fstype
         self.label = args.label
diff --git a/scripts/lib/wic/plugins/source/rootfs.py b/scripts/lib/wic/plugins/source/rootfs.py
index 9d959fa7d7..c57a4341d1 100644
--- a/scripts/lib/wic/plugins/source/rootfs.py
+++ b/scripts/lib/wic/plugins/source/rootfs.py
@@ -26,10 +26,13 @@
 #
 
 import os
+import shutil
+
+from oe.path import copyhardlinktree
 
 from wic import msger
 from wic.pluginbase import SourcePlugin
-from wic.utils.misc import get_bitbake_var
+from wic.utils.misc import get_bitbake_var, exec_cmd
 
 class RootfsPlugin(SourcePlugin):
     """
@@ -78,6 +81,44 @@ class RootfsPlugin(SourcePlugin):
 
         real_rootfs_dir = cls.__get_rootfs_dir(rootfs_dir)
 
+        # Handle excluded paths.
+        if part.exclude_path is not None:
+            # We need a new rootfs directory we can delete files from. Copy to
+            # workdir.
+            new_rootfs = os.path.realpath(os.path.join(cr_workdir, "rootfs"))
+
+            if os.path.lexists(new_rootfs):
+                shutil.rmtree(os.path.join(new_rootfs))
+
+            copyhardlinktree(real_rootfs_dir, new_rootfs)
+
+            real_rootfs_dir = new_rootfs
+
+            for orig_path in part.exclude_path:
+                path = orig_path
+                if os.path.isabs(path):
+                    msger.error("Must be relative: --exclude-path=%s" % orig_path)
+
+                full_path = os.path.realpath(os.path.join(new_rootfs, path))
+
+                # Disallow climbing outside of parent directory using '..',
+                # because doing so could be quite disastrous (we will delete the
+                # directory).
+                if not full_path.startswith(new_rootfs):
+                    msger.error("'%s' points to a path outside the rootfs" % orig_path)
+
+                if path.endswith(os.sep):
+                    # Delete content only.
+                    for entry in os.listdir(full_path):
+                        full_entry = os.path.join(full_path, entry)
+                        if os.path.isdir(full_entry) and not os.path.islink(full_entry):
+                            shutil.rmtree(full_entry)
+                        else:
+                            os.remove(full_entry)
+                else:
+                    # Delete whole directory.
+                    shutil.rmtree(full_path)
+
         part.rootfs_dir = real_rootfs_dir
         part.prepare_rootfs(cr_workdir, oe_builddir,
                             real_rootfs_dir, native_sysroot)