check_whence: error if symlinks are in-tree

Currently we have no symlinks in-tree. Add a simple check, ensuring they
don't get added in the future.

This allows us to remove the clunky symlink checking code in
copy-firmware.sh

v2:
 - tweak helper to produce link and target (based off Adam's patch)

v3:
 - honour quoted target/linkname

Signed-off-by: Emil Velikov <emil.l.velikov@gmail.com>
Signed-off-by: Josh Boyer <jwboyer@kernel.org>

check_whence.py

@@ -36,6 +36,23 @@ def list_whence_files():
                 yield match.group(1).replace("\ ", " ").replace("\"", "")
                 continue
 
+def list_links_list():
+    with open('WHENCE', encoding='utf-8') as whence:
+        for line in whence:
+            match = re.match(r'Link:\s*(.*)', line)
+            if match:
+                linkname, target = match.group(1).split("->")
+
+                linkname = linkname.strip().replace("\ ", " ").replace("\"", "")
+                target = target.strip().replace("\ ", " ").replace("\"", "")
+
+                # Link target is relative to the link
+                target = os.path.join(os.path.dirname(linkname), target)
+                target = os.path.normpath(target)
+
+                yield (linkname, target)
+                continue
+
 def list_git():
     with os.popen('git ls-files') as git_files:
         for line in git_files:
@@ -45,6 +62,7 @@ def main():
     ret = 0
     whence_list = list(list_whence())
     whence_files = list(list_whence_files())
+    links_list = list(list_links_list())
     known_files = set(name for name in whence_list if not name.endswith('/')) | \
                   set(['check_whence.py', 'configure', 'Makefile',
                        'README', 'copy-firmware.sh', 'WHENCE'])
@@ -65,6 +83,10 @@ def main():
                          name)
         ret = 1
 
+    for name in set(link[0] for link in links_list if os.path.islink(link[0])):
+        sys.stderr.write('E: %s listed in WHENCE as Link, is in tree\n' % name)
+        ret = 1
+
     for name in sorted(list(known_files - git_files)):
         sys.stderr.write('E: %s listed in WHENCE does not exist\n' % name)
         ret = 1