engine: implement listing wic images

Implemented 'wic ls' functionality:
 - list image partitions
 - list directory content of vfat partitions

[YOCTO #11283]

(From OE-Core rev: 61667fabd5746caf773f73b3aeb2a04db13cba38)

Signed-off-by: Ed Bartosh <ed.bartosh@linux.intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

scripts/lib/wic/engine.py

@@ -30,10 +30,15 @@
 
 import logging
 import os
+import tempfile
+
+from collections import namedtuple, OrderedDict
+from distutils.spawn import find_executable
 
 from wic import WicError
+from wic.filemap import sparse_copy
 from wic.pluginbase import PluginMgr
-from wic.utils.misc import get_bitbake_var
+from wic.utils.misc import get_bitbake_var, exec_cmd
 
 logger = logging.getLogger('wic')
 
@@ -225,9 +230,84 @@ def wic_list(args, scripts_path):
 
     return False
 
+
+class Disk:
+    def __init__(self, imagepath, native_sysroot):
+        self.imagepath = imagepath
+        self.native_sysroot = native_sysroot
+        self._partitions = None
+        self._mdir = None
+        self._partimages = {}
+
+        # find parted
+        self.paths = "/bin:/usr/bin:/usr/sbin:/sbin/"
+        if native_sysroot:
+            for path in self.paths.split(':'):
+                self.paths = "%s%s:%s" % (native_sysroot, path, self.paths)
+
+        self.parted = find_executable("parted", self.paths)
+        if not self.parted:
+            raise WicError("Can't find executable parted")
+
+    def __del__(self):
+        for path in self._partimages.values():
+            os.unlink(path)
+
+    @property
+    def partitions(self):
+        if self._partitions is None:
+            self._partitions = OrderedDict()
+            out = exec_cmd("%s -sm %s unit B print" % (self.parted, self.imagepath))
+            parttype = namedtuple("Part", "pnum start end size fstype")
+            for line in out.splitlines()[2:]:
+                pnum, start, end, size, fstype = line.split(':')[:5]
+                partition = parttype(pnum, int(start[:-1]), int(end[:-1]),
+                                     int(size[:-1]), fstype)
+                self._partitions[pnum] = partition
+
+        return self._partitions
+
+    @property
+    def mdir(self):
+        if self._mdir is None:
+            self._mdir = find_executable("mdir", self.paths)
+            if not self._mdir:
+                raise WicError("Can't find executable mdir")
+        return self._mdir
+
+    def _get_part_image(self, pnum):
+        if pnum not in self.partitions:
+            raise WicError("Partition %s is not in the image")
+        part = self.partitions[pnum]
+        if not part.fstype.startswith("fat"):
+            raise WicError("Not supported fstype: {}".format(part.fstype))
+        if pnum not in self._partimages:
+            tmpf = tempfile.NamedTemporaryFile(prefix="wic-part")
+            dst_fname = tmpf.name
+            tmpf.close()
+            sparse_copy(self.imagepath, dst_fname, skip=part.start, length=part.size)
+            self._partimages[pnum] = dst_fname
+
+        return self._partimages[pnum]
+
+    def dir(self, pnum, path):
+        return exec_cmd("{} -i {} ::{}".format(self.mdir,
+                                               self._get_part_image(pnum),
+                                               path))
+
 def wic_ls(args, native_sysroot):
     """List contents of partitioned image or vfat partition."""
-    pass
+    disk = Disk(args.path.image, native_sysroot)
+    if not args.path.part:
+        if disk.partitions:
+            print('Num     Start        End          Size      Fstype')
+            for part in disk.partitions.values():
+                print("{:2s}  {:12d} {:12d} {:12d}  {}".format(\
+                          part.pnum, part.start, part.end,
+                          part.size, part.fstype))
+    else:
+        path = args.path.path or '/'
+        print(disk.dir(args.path.part, path))
 
 def find_canned(scripts_path, file_name):
     """