GN: Return array from pkgconfig wrapper

tools/gn/secondary/build/config/linux/pkg-config.py

 # Copyright (c) 2013 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.
 
+import json
 import subprocess
 import sys
+import re
+from optparse import OptionParser
 
-sys.exit(subprocess.call(["pkg-config"] + sys.argv[1:]))
+# This script runs pkg-config, optionally filtering out some results, and
+# returns the result.
+#
+# The result will be [ <includes>, <cflags>, <ldflags> ] where each member is
+# itself a list of strings.
+#
+# You can filter out matches using "-v <regexp>" where all results from
+# pkgconfig matching the given regular expression will be ignored. You can
+# specify more than one regular expression my specifying "-v" more than once.
+
+# If this is run on non-Linux platforms, just return nothing and indicate
+# success. This allows us to "kind of emulate" a Linux build from other
+# platforms.
+if sys.platform.find("linux") == -1:
+  print "[[],[],[]]"
+  sys.exit(0)
+
+parser = OptionParser()
+parser.add_option('-v', action='append', dest='strip_out', type='string')
+(options, args) = parser.parse_args()
+
+# Make a list of regular expressions to strip out.
+strip_out = []
+if options.strip_out != None:
+  for regexp in options.strip_out:
+    strip_out.append(re.compile(regexp))
+
+try:
+  flag_string = subprocess.check_output(["pkg-config", "--cflags", "--libs"] +
+      args)
+  # For now just split on spaces to get the args out. This will break if
+  # pkgconfig returns quoted things with spaces in them, but that doesn't seem
+  # to happen in practice.
+  all_flags = flag_string.strip().split(' ')
+except:
+  print "Could not run pkg-config."
+  sys.exit(1)
+
+includes = []
+cflags = []
+libs = []
+
+def MatchesAnyRegexp(flag, list_of_regexps):
+  for regexp in list_of_regexps:
+    if regexp.search(flag) != None:
+      return True
+  return False
+
+for flag in all_flags[:]:
+  if len(flag) == 0 or MatchesAnyRegexp(flag, strip_out):
+    continue;
+
+  if flag[:2] == '-l':
+    libs.append(flag)
+  elif flag[:2] == '-I':
+    includes.append(flag[2:])
+  else:
+    cflags.append(flag)
+
+# Output a GN array, the first one is the cflags, the second are the libs. The
+# JSON formatter prints GN compatible lists when everything is a list of
+# strings.
+print json.dumps([includes, cflags, libs])