check_deps: handle "include" directives in ld.so.conf

The ld.so.conf file supports an "include" directive where it'll include
all the files matched by the following glob.  Since Gentoo has started
using this, we need to support parsing of it too.  So move the parsing
code into a dedicated function and recursively call ourselves when we
hit an include directive.

BUG=chromium-os:20636
TEST=`./check_deps /build/amd64-generic /bin/bash` now finds libs
TEST=`./build_image --board=x86-alex` still works

Change-Id: I8894ca42358d91d8f2ee6e95b47faf9334ccdd26
Reviewed-on: http://gerrit.chromium.org/gerrit/8494
Reviewed-by: David James <davidjames@chromium.org>
Commit-Ready: Mike Frysinger <vapier@chromium.org>
Tested-by: Mike Frysinger <vapier@chromium.org>

build_library/check_deps

@@ -7,6 +7,7 @@
 import os
 import re
 import sys
+import glob
 
 _SHARED_RE = re.compile(r"Shared library: \[([^\]]+)\]")
 _RPATH_RE = re.compile(r"Library rpath: \[([^\]]+)\]")
@@ -15,6 +16,43 @@ _RPATH_RE = re.compile(r"Library rpath: \[([^\]]+)\]")
 class CheckDependencies(object):
   """Check that dependencies for binaries can be found in the specified dir."""
 
+  def _ReadLdSoConf(self, path):
+    """Parse ld.so.conf files.
+
+    Starting with the file at PATH (searched relative to self._root), return
+    all the valid libdirs found. Include directives are handled recursively.
+
+    Args:
+      path: the path to the ld.so.conf file (inside of the root).
+
+    Returns:
+      A list of valid libdirs.
+    """
+
+    libdirs = []
+
+    ld_so_conf = self._root + path
+    if os.path.exists(ld_so_conf):
+      f = file(ld_so_conf)
+
+      for line in f:
+        line = line.rstrip()
+
+        if line.startswith("/"):
+          libpath = self._root + line
+          if os.path.exists(libpath):
+            libdirs.append(libpath)
+
+        elif line.startswith("include "):
+          # Includes are absolute or relative to the file itself.
+          line = os.path.join(os.path.dirname(path), line[8:])
+          for p in glob.glob(self._root + line):
+            libdirs.extend(self._ReadLdSoConf(os.path.relpath(p, self._root)))
+
+      f.close()
+
+    return libdirs
+
   def __init__(self, root, verbose=False):
     """Initializer.
 
@@ -38,15 +76,7 @@ class CheckDependencies(object):
     ]
 
     # Read more directories from ld.so.conf.
-    ld_so_conf = "%s/etc/ld.so.conf" % root
-    if os.path.exists(ld_so_conf):
-      f = file(ld_so_conf)
-      for line in f:
-        if line.startswith("/"):
-          path = root + line[:-1]
-          if os.path.exists(path):
-            libdirs.append(path)
-      f.close()
+    libdirs.extend(self._ReadLdSoConf("/etc/ld.so.conf"))
 
     self._ReadLibs(libdirs, self._libcache)