Add a snapshot of flutter/engine/src/build to our sdk

build/config/linux/pkg-config.py

Index: build/config/linux/pkg-config.py
diff --git a/build/config/linux/pkg-config.py b/build/config/linux/pkg-config.py
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+++ b/build/config/linux/pkg-config.py
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+# 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
+from optparse import OptionParser
+
+# This script runs pkg-config, optionally filtering out some results, and
+# returns the result.
+#
+# The result will be [ <includes>, <cflags>, <libs>, <lib_dirs>, <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.
+#
+# You can specify a sysroot using "-s <sysroot>" where sysroot is the absolute
+# system path to the sysroot used for compiling. This script will attempt to
+# generate correct paths for the sysroot.
+#
+# When using a sysroot, you must also specify the architecture via
+# "-a <arch>" where arch is either "x86" or "x64".
+#
+# 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.
+
+# 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)
+
+
+def SetConfigPath(options):
+  """Set the PKG_CONFIG_PATH environment variable.
+  This takes into account any sysroot and architecture specification from the
+  options on the given command line."""
+
+  sysroot = options.sysroot
+  if not sysroot:
+    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)
+  if arch == 'x64':
+    libpath = 'lib64'
+  else:
+    libpath = 'lib'
+
+  # Add the sysroot path to the environment's PKG_CONFIG_PATH
+  config_path = sysroot + '/usr/' + libpath + '/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
+
+
+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)
+  # instead of relative to /path/to/chroot/build/x86-generic (i.e prefix=/usr).
+  # To support this correctly, it's necessary to extract the prefix to strip
+  # from pkg-config's |prefix| variable.
+  prefix = subprocess.check_output(["pkg-config", "--variable=prefix"] + args,
+      env=os.environ)
+  if prefix[-4] == '/usr':
+    return prefix[4:]
+  return prefix
+
+
+def MatchesAnyRegexp(flag, list_of_regexps):
+  """Returns true if the first argument matches any regular expression in the
+  given list."""
+  for regexp in list_of_regexps:
+    if regexp.search(flag) != None:
+      return True
+  return False
+
+
+def RewritePath(path, strip_prefix, sysroot):
+  """Rewrites a path by stripping the prefix and prepending the sysroot."""
+  if os.path.isabs(path) and not path.startswith(sysroot):
+    if path.startswith(strip_prefix):
+      path = path[len(strip_prefix):]
+    path = path.lstrip('/')
+    return os.path.join(sysroot, path)
+  else:
+    return path
+
+
+parser = OptionParser()
+parser.add_option('-p', action='store', dest='pkg_config', type='string',
+                  default='pkg-config')
+parser.add_option('-v', action='append', dest='strip_out', type='string')
+parser.add_option('-s', action='store', dest='sysroot', type='string')
+parser.add_option('-a', action='store', dest='arch', type='string')
+parser.add_option('--atleast-version', action='store',
+                  dest='atleast_version', type='string')
+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))
+
+SetConfigPath(options)
+if options.sysroot:
+  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,
+                         env=os.environ):
+    print "true"
+  else:
+    print "false"
+  sys.exit(0)
+
+if options.libdir:
+  try:
+    libdir = subprocess.check_output([options.pkg_config,
+                                      "--variable=libdir"] +
+                                     args,
+                                     env=os.environ)
+  except:
+    print "Error from pkg-config."
+    sys.exit(1)
+  sys.stdout.write(libdir.strip())
+  sys.exit(0)
+
+try:
+  flag_string = subprocess.check_output(
+      [ options.pkg_config, "--cflags", "--libs-only-l", "--libs-only-L" ] +
+      args, env=os.environ)
+  # 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)
+
+
+sysroot = options.sysroot
+if not sysroot:
+  sysroot = ''
+
+includes = []
+cflags = []
+libs = []
+lib_dirs = []
+ldflags = []
+
+for flag in all_flags[:]:
+  if len(flag) == 0 or MatchesAnyRegexp(flag, strip_out):
+    continue;
+
+  if flag[:2] == '-l':
+    libs.append(RewritePath(flag[2:], prefix, sysroot))
+  elif flag[:2] == '-L':
+    lib_dirs.append(RewritePath(flag[2:], prefix, sysroot))
+  elif flag[:2] == '-I':
+    includes.append(RewritePath(flag[2:], prefix, sysroot))
+  elif flag[:3] == '-Wl':
+    ldflags.append(flag)
+  elif flag == '-pthread':
+    # Many libs specify "-pthread" which we don't need since we always include
+    # this anyway. Removing it here prevents a bunch of duplicate inclusions on
+    # the command line.
+    pass
+  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, lib_dirs, ldflags])