Use PKG_CONFIG_LIBDIR to force pkg-config to use sysroot only

build/config/linux/pkg-config.py

 #!/usr/bin/env python
 # 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 os
 import subprocess
 import sys
 import re
@@ skipping 24 matching lines @@
 # variable to this script with the "--system_libdir <system_libdir>" flag. If no
 # flag is provided, then pkgconfig files are assumed to come from
 # <systemroot>/usr/lib/pkgconfig.
 #
 # Additionally, you can specify the option --atleast-version. This will skip
 # the normal outputting of a dictionary and instead print true or false,
 # depending on the return value of pkg-config for the given package.
 
 
 def SetConfigPath(options):
-  """Set the PKG_CONFIG_PATH environment variable.
+  """Set the PKG_CONFIG_LIBDIR environment variable.
   This takes into account any sysroot and architecture specification from the
   options on the given command line."""
 
   sysroot = options.sysroot
   assert sysroot
 
   # Compute the library path name based on the architecture.
   arch = options.arch
   if sysroot and not arch:
     print "You must specify an architecture via -a if using a sysroot."
     sys.exit(1)
 
-  # Add the sysroot path to the environment's PKG_CONFIG_PATH
+  # Add the sysroot path to the environment's PKG_CONFIG_LIBDIR

[Lei Zhang, 2016/01/12 23:01:50]

More like overwrite than add.

[Sam Clegg, 2016/01/12 23:25:12]

Done

   config_path = sysroot + '/usr/' + options.system_libdir + '/pkgconfig'
   config_path += ':' + sysroot + '/usr/share/pkgconfig'
-  if 'PKG_CONFIG_PATH' in os.environ:
-    os.environ['PKG_CONFIG_PATH'] += ':' + config_path
-  else:
-    os.environ['PKG_CONFIG_PATH'] = config_path
+  os.environ['PKG_CONFIG_LIBDIR'] = config_path
+  return config_path
 
 
 def GetPkgConfigPrefixToStrip(args):
   """Returns the prefix from pkg-config where packages are installed.
   This returned prefix is the one that should be stripped from the beginning of
   directory names to take into account sysroots."""
   # Some sysroots, like the Chromium OS ones, may generate paths that are not
   # relative to the sysroot. For example,
   # /path/to/chroot/build/x86-generic/usr/lib/pkgconfig/pkg.pc may have all
   # paths relative to /path/to/chroot (i.e. prefix=/build/x86-generic/usr)
@@ skipping 49 matching lines @@
   parser.add_option('--libdir', action='store_true', dest='libdir')
   (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))
 
   if options.sysroot:
-    SetConfigPath(options)
+    libdir = SetConfigPath(options)
     if options.debug:
-      sys.stderr.write('PKG_CONFIG_PATH=%s\n' % os.environ['PKG_CONFIG_PATH'])
+      sys.stderr.write('PKG_CONFIG_LIBDIR=%s\n' % libdir)
     prefix = GetPkgConfigPrefixToStrip(args)
   else:
     prefix = ''
 
   if options.atleast_version:
     # When asking for the return value, just run pkg-config and print the return
     # value, no need to do other work.
     if not subprocess.call([options.pkg_config,
                             "--atleast-version=" + options.atleast_version] +
                             args):
       print "true"
     else:
       print "false"
     return 0
 
   if options.libdir:
+    cmd = [options.pkg_config, "--variable=libdir"] + args
+    if options.debug:
+      sys.stderr.write('Running: %s\n' % cmd)
     try:
-      libdir = subprocess.check_output([options.pkg_config,
-                                        "--variable=libdir"] +
-                                       args)
+      libdir = subprocess.check_output(cmd)
     except:
       print "Error from pkg-config."
       return 1
     sys.stdout.write(libdir.strip())
     return 0
 
+  cmd = [options.pkg_config, "--cflags", "--libs"] + args
+  if options.debug:
+    sys.stderr.write('Running: %s\n' % ' '.join(cmd))
+
   try:
-    flag_string = subprocess.check_output(
-        [ options.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(' ')
+    flag_string = subprocess.check_output(cmd)
   except:
-    print "Could not run pkg-config."
+    sys.stderr.write('Could not run pkg-config.\n')
     return 1
 
+  # 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(' ')
+
 
   sysroot = options.sysroot
   if not sysroot:
     sysroot = ''
 
   includes = []
   cflags = []
   libs = []
   lib_dirs = []
   ldflags = []
@@ skipping 20 matching lines @@
 
   # 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, lib_dirs, ldflags])
   return 0
 
 
 if __name__ == '__main__':
   sys.exit(main())