cups: parse cups-config output to reduce flags spew

On both Lucid and Natty, cups-config --libs includes cflags and other
unneeded output.  Parse the cups-config output to emit only the relevant
subsets of flags.

Review URL: http://codereview.chromium.org/7633022

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@96635 0039d316-1c4b-4281-b951-d872f2087c98

printing/cups_config_helper.py

+#!/usr/bin/python
+# Copyright (c) 2011 The Chromium Authors. All rights reserved.
+# Use of this source code is governed by a BSD-style license that can be
+# found in the LICENSE file.
+
+"""cups-config wrapper.
+
+cups-config, at least on Ubuntu Lucid and Natty, dumps all
+cflags/ldflags/libs when passed the --libs argument.  gyp would like
+to keep these separate: cflags are only needed when compiling files
+that use cups directly, while libs are only needed on the final link
+line.
+
+TODO(evan): remove me once
+  https://bugs.launchpad.net/ubuntu/+source/cupsys/+bug/163704
+is fixed.
+"""
+
+import subprocess
+import sys
+
+def usage():
+    print 'usage: %s {--cflags|--ldflags|--libs}' % sys.argv[0]
+    sys.exit(1)
+
+def run_cups_config(mode):
+    """Run cups-config with all --cflags etc modes, parse out the mode we want,
+    and return those flags as a list."""
+
+    cups = subprocess.Popen(['cups-config', '--cflags', '--ldflags', '--libs'],
+                            stdout=subprocess.PIPE)
+    flags = cups.communicate()[0].strip()
+
+    flags_subset = []
+    for flag in flags.split(' '):
+        flag_mode = None
+        if flag.startswith('-l'):
+            flag_mode = '--libs'
+        elif (flag.startswith('-L') or flag.startswith('-Wl,')):
+            flag_mode = '--ldflags'
+        elif (flag.startswith('-I') or flag.startswith('-D')):
+            flag_mode = '--cflags'
+
+        # Be conservative: for flags where we don't know which mode they
+        # belong in, always include them.
+        if flag_mode is None or flag_mode == mode:
+            flags_subset.append(flag)
+
+    return flags_subset
+
+if len(sys.argv) != 2:
+    usage()
+
+mode = sys.argv[1]
+if mode not in ('--cflags', '--libs', '--ldflags'):
+    usage()
+flags = run_cups_config(mode)
+print ' '.join(flags)

printing/printing.gyp

@@ -218,7 +218,7 @@
               }, {
                 'link_settings': {
                   'libraries': [
-                    '<!@(cups-config --libs)',
+                    '<!@(python cups_config_helper.py --libs)',
                   ],
                 },
               }],