binman: Write the original input fdtmap to a file

When reading an image in, write its fdtmap to a file in the output
directory. This is useful for debugging. Update the 'ls' command to set up
the output directory; otherwise it will fail.

Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/tools/binman/control.py b/tools/binman/control.py
index ab94f9d..f9680e3 100644
--- a/tools/binman/control.py
+++ b/tools/binman/control.py
@@ -342,7 +342,11 @@
         return 0
 
     if args.cmd == 'ls':
-        ListEntries(args.image, args.paths)
+        try:
+            tools.PrepareOutputDir(None)
+            ListEntries(args.image, args.paths)
+        finally:
+            tools.FinaliseOutputDir()
         return 0
 
     if args.cmd == 'extract':
diff --git a/tools/binman/image.py b/tools/binman/image.py
index c81f7e3..893e8cb 100644
--- a/tools/binman/image.py
+++ b/tools/binman/image.py
@@ -94,7 +94,10 @@
             data[pos + fdtmap.FDTMAP_HDR_LEN:pos + 256])
         dtb_size = probe_dtb.GetFdtObj().totalsize()
         fdtmap_data = data[pos:pos + dtb_size + fdtmap.FDTMAP_HDR_LEN]
-        dtb = fdt.Fdt.FromData(fdtmap_data[fdtmap.FDTMAP_HDR_LEN:])
+        fdt_data = fdtmap_data[fdtmap.FDTMAP_HDR_LEN:]
+        out_fname = tools.GetOutputFilename('fdtmap.in.dtb')
+        tools.WriteFile(out_fname, fdt_data)
+        dtb = fdt.Fdt.FromData(fdt_data, out_fname)
         dtb.Scan()
 
         # Return an Image with the associated nodes