Allow chromium to be built with some system libs by introducing

a variable called SYSTEM_LIBS, consisting of a comma-separated
list of system libraries. So far, bzip2, libpng, libjpeg,
libxml, libxslt, lzma_sdk, zlib, hunspell, sqlite, libevent are recognized.

BUG=4321

Review URL: http://codereview.chromium.org/10626
Patch from Fabien Tassin <fta@sofaraway.org>.


git-svn-id: svn://svn.chromium.org/chrome/trunk/src@5320 0039d316-1c4b-4281-b951-d872f2087c98

7 files changed, 75 insertions, 18 deletions

diff --git a/AUTHORS b/AUTHORS
index 0df32b5..925742d 100644
--- a/AUTHORS
+++ b/AUTHORS
@@ -20,3 +20,4 @@ Comodo CA Limited
 Torchmobile Inc.
 Craig Schlenter <craig.schlenter@gmail.com>
 Ibrar Ahmed <ibrar.ahmad@gmail.com>
+Fabien Tassin <fta@sofaraway.org>
diff --git a/build/SConscript.main b/build/SConscript.main
index 0209417..60e86a9 100644
--- a/build/SConscript.main
+++ b/build/SConscript.main
@@ -29,6 +29,12 @@ else:
 root_env = Environment(
     tools = ['component_setup'],
 
+    # Requested list of system (shared) libraries, from the comma separated
+    # SYSTEM_LIBS command-line argument
+    req_system_libs = [],
+    # All supported system libraries, for the help message
+    all_system_libs = [],
+
     CHROME_SRC_DIR = '$MAIN_DIR/..',
     DESTINATION_ROOT = '$MAIN_DIR/Hammer',
     TARGET_ROOT = '$DESTINATION_ROOT',
@@ -96,6 +102,16 @@ root_env = Environment(
                              '__env__, RDirs, TARGET, SOURCE)}'),
 )
 
+root_env['req_system_libs'] = ARGUMENTS.get('SYSTEM_LIBS', '').split(',')
+
+def WantSystemLib(env, lib):
+  """
+  Return true if lib has been requested as a system library in SYSTEM_LIBS.
+  """
+  if lib not in env['all_system_libs']:
+    env['all_system_libs'].append(lib)
+  return (lib in env['req_system_libs'])
+root_env.AddMethod(WantSystemLib, "WantSystemLib")
 
 def ChromeProgram(env, *args, **kw):
   return env.ComponentProgram(*args, **kw)
@@ -209,18 +225,34 @@ if LoadComponent('testing'):
   sconscripts.append('$TESTING_DIR/SConscript.gtest')
 
 if LoadComponent('third_party'):
+  if not root_env.WantSystemLib('bzip2'):
+    sconscripts.append('$BZIP2_DIR/bzip2.scons')
+    root_env.Append(BZIP2_LIB = ['bzip2'])
+  else:
+    root_env.Append(BZIP2_LIB = ['bz2'])
+  if not root_env.WantSystemLib('libpng'):
+    sconscripts.append('$LIBPNG_DIR/libpng.scons')
+  if not root_env.WantSystemLib('libjpeg'):
+    sconscripts.append('$LIBJPEG_DIR/SConscript')
+  if not root_env.WantSystemLib('libxml'):
+    sconscripts.append('$LIBXML_DIR/SConscript')
+    root_env.Append(XML_LIB = ['libxml'])
+  else:
+    root_env.Append(XML_LIB = ['xml2'])
+  if not root_env.WantSystemLib('libxslt'):
+    sconscripts.append('$LIBXSLT_DIR/SConscript')
+  if not root_env.WantSystemLib('lzma_sdk'):
+    sconscripts.append('$LZMA_SDK_DIR/SConscript')
+  if not root_env.WantSystemLib('zlib'):
+    sconscripts.append('$ZLIB_DIR/zlib.scons')
+    root_env.Append(ZLIB_LIB = ['zlib'])
+  else:
+    root_env.Append(ZLIB_LIB = ['z'])
   sconscripts.extend([
       '$BSDIFF_DIR/SConscript',
-      '$BZIP2_DIR/bzip2.scons',
       '$DMG_FP_DIR/dmg_fp.scons',
       '$ICU38_DIR/icu38.scons',
-      '$LIBPNG_DIR/libpng.scons',
-      '$LZMA_SDK_DIR/SConscript',
       '$MODP_B64_DIR/modp_b64.scons',
-      '$ZLIB_DIR/zlib.scons',
-      '$LIBJPEG_DIR/SConscript',
-      '$LIBXML_DIR/SConscript',
-      '$LIBXSLT_DIR/SConscript',
       '$BSPATCH_DIR/SConscript',
   ])
 
@@ -519,7 +551,20 @@ if root_env['PLATFORM'] in ['linux', 'linux2', 'posix']:
         '#Software_Requirements')
 
     sys.exit(1)
-
+  if root_env.WantSystemLib('libxml'):
+    try:
+      linux_env.ParseConfig('pkg-config --cflags --libs libxml-2.0')
+    except OSError, e:
+      print ('\n'
+          'libxml requested in SYSTEM_LIBS but not found\n')
+      sys.exit(1)
+  if root_env.WantSystemLib('libxslt'):
+    try:
+      linux_env.ParseConfig('pkg-config --cflags --libs libxslt')
+    except OSError, e:
+      print ('\n'
+          'libxslt requested in SYSTEM_LIBS but not found\n')
+      sys.exit(1)
 
 # --------------------------------------------------------------------------
 # Mac specific
@@ -560,10 +605,13 @@ mac_env.FilterOut(
     ],
 )
 
-mac_env.Append(
+if not root_env.WantSystemLib('libevent'):
+  mac_env.Append(
     BUILD_SCONSCRIPTS = [
         '$LIBEVENT_DIR/libevent.scons',
     ],
+  )
+mac_env.Append(
     CFLAGS = [
         '-std=c99',
     ],
@@ -640,6 +688,10 @@ Supported build variables:
   LOAD=[module,...]         Comma-separated list of components to load in the
                               dependency graph ('-' prefix excludes):
 %s
+  SYSTEM_LIBS=[lib,...]     Comma-separated list of system libraries to link
+                              dynamically (by default they are built in from
+                              included sources):
+%s
   PROGRESS=type             Display a progress indicator:
                               name:  print each evaluated target name
                               spinner:  print a spinner every 5 targets
@@ -654,8 +706,9 @@ if GetOption('help'):
     subsequent_indent = ' '*32,
   )
   components = tw.fill(', '.join(components))
+  all_system_libs = tw.fill(', '.join(env['all_system_libs']))
 
-  Help(help_fmt % components)
+  Help(help_fmt % (components, all_system_libs))
 
 
 Import('build_component')
diff --git a/chrome/SConscript b/chrome/SConscript
index d691dd9..e87e38d 100644
--- a/chrome/SConscript
+++ b/chrome/SConscript
@@ -392,10 +392,13 @@ if env_flat['PLATFORM'] == 'win32':
 sconscript_files = [
     'test/chrome_plugin/SConscript',
     'tools/test/image_diff/SConscript',
-    'third_party/hunspell/SConscript',
-    '$THIRD_PARTY_DIR/sqlite/SConscript',
 ]
 
+if not env.WantSystemLib('hunspell'):
+  sconscript_files.append('third_party/hunspell/SConscript')
+if not env.WantSystemLib('sqlite'):
+  sconscript_files.append('$THIRD_PARTY_DIR/sqlite/SConscript')
+
 # TODO(port)
 if env['PLATFORM'] == 'win32':
   sconscript_files.extend([
diff --git a/chrome/tools/test/image_diff/SConscript b/chrome/tools/test/image_diff/SConscript
index 4a77cc2..b1cccf5 100644
--- a/chrome/tools/test/image_diff/SConscript
+++ b/chrome/tools/test/image_diff/SConscript
@@ -23,7 +23,7 @@ env_test.Prepend(
         'libpng',
         'base_gfx',
         env_test['ICU_LIBS'],  # TODO(sgk):  '$ICU_LIBS' when scons is fixed
-        'zlib',
+        env_test['ZLIB_LIB'],
         'base',
     ],
 )
diff --git a/third_party/bzip2/using_bzip2.scons b/third_party/bzip2/using_bzip2.scons
index a7706f5..b41bca2 100644
--- a/third_party/bzip2/using_bzip2.scons
+++ b/third_party/bzip2/using_bzip2.scons
@@ -10,6 +10,6 @@ Import("env")
 
 env.Append(
     LIBS = [
-        'bzip2',
+        env['BZIP2_LIB'],
     ],
 )
diff --git a/third_party/libxml/using_libxml.scons b/third_party/libxml/using_libxml.scons
index 7c7d7da..4a5c1329 100644
--- a/third_party/libxml/using_libxml.scons
+++ b/third_party/libxml/using_libxml.scons
@@ -17,7 +17,7 @@ env.Append(
         'LIBXML_STATIC',
     ],
     LIBS = [
-        'libxml',
+        env['XML_LIB'],
     ],
 )
 # Copyright (c) 2006-2008 The Chromium Authors. All rights reserved.
@@ -39,6 +39,6 @@ env.Append(
         'LIBXML_STATIC',
     ],
     LIBS = [
-        'libxml',
+        env['XML_LIB'],
     ],
 )
diff --git a/webkit/tools/test_shell/SConscript b/webkit/tools/test_shell/SConscript
index 66b252d..640e5b2 100644
--- a/webkit/tools/test_shell/SConscript
+++ b/webkit/tools/test_shell/SConscript
@@ -38,14 +38,14 @@ env.Append(
         'sdch',
         'skia',
         'gtest',
-        'bzip2',
+        env['BZIP2_LIB'],
         'V8Bindings',
         'WebCore',
         'WTF',
         env['ICU_LIBS'],  # TODO(sgk):  '$ICU_LIBS' when scons is fixed
         'libjpeg',
         'libpng',
-        'libxml',
+        env['XML_LIB'],
         'libxslt',
         'modp_b64',
         'zlib',