Add support for generating nmfs for pnacl pexes with glibc (vs pnacl nexes).

SConstruct

Index: SConstruct
diff --git a/SConstruct b/SConstruct
index 7529deb3519967a396b9ccff52d1dd5eda0b3d6c..72f6e0a1cb6fe8a463df05260af8098bf4c3f6e9 100755
--- a/SConstruct
+++ b/SConstruct
@@ -1308,6 +1308,9 @@ def CopyLibsForExtensionCommand(target, source, env):
     lib_info = ParseLibInfoInRunnableLdLog(line)
     if lib_info:
       lib_name, lib_path = lib_info
+      # Note: This probably work with pnacl _pexes_ right now, because
+      # the NEEDED metadata in the bitcode doesn't have the original file paths.
+      # It probably shouldn't have the original file paths anyway...
       shutil.copyfile(lib_path, os.path.join(target_dir, lib_name))
   shutil.copyfile(env.subst('${NACL_SDK_LIB}/runnable-ld.so'),
                   os.path.join(target_dir, 'runnable-ld.so'))
@@ -1334,9 +1337,11 @@ pre_base_env.AddMethod(CopyLibsForExtension)
 # Generate manifest from newlib manifest and the list of libs generated by
 # runnable-ld.so.
 def GenerateManifestFunc(target, source, env):
+  # Open the original manifest and parse it.
   source_file = open(str(source[0]), 'r')
   obj = json.load(source_file)
   source_file.close()
+  # Open the file with ldd-format list of NEEDED libs and parse it.
   libs_file = open(str(source[1]), 'r')
   lib_names = []
   arch = env.subst('${TARGET_FULLARCH}')
@@ -1346,62 +1351,90 @@ def GenerateManifestFunc(target, source, env):
       lib_name, _ = lib_info
       lib_names.append(lib_name)
   libs_file.close()
+  # Inject the NEEDED libs into the manifest.
   if 'files' not in obj:
     obj['files'] = {}
   for lib_name in lib_names:
     obj['files'][lib_name] = {}
     obj['files'][lib_name][arch] = {}
     obj['files'][lib_name][arch]['url'] = lib_name
+  # Put what used to be specified under 'program' into 'main.nexe'.
   obj['files']['main.nexe'] = {}
   for k, v in obj['program'].items():
     obj['files']['main.nexe'][k] = v.copy()
     v['url'] = 'runnable-ld.so'
+  # Put runnable-ld.so into the 'program' field, for all known
+  # NMF architectures (besides 'portable').
+  new_program_dict = {}
+  obj['program'] = new_program_dict
+  for arch in ['x86-32', 'x86-64', 'arm']:
+    new_program_dict[arch] = {}
+    new_program_dict[arch]['url'] = 'runnable-ld.so'
+  # Write the new manifest!
   target_file = open(str(target[0]), 'w')
   json.dump(obj, target_file)
   target_file.close()
   return 0
 
 
-# Returns nexe specified in manifest file.
-def GetNexeFromManifest(env, manifest):
+# Returns a pair (main program, is_portable), based on the program
+# specified in manifest file.
+def GetMainProgramFromManifest(env, manifest):
   manifest_file = open(str(env.File(manifest)), 'r')
   obj = json.load(manifest_file)
   manifest_file.close()
-  nexe = obj['program'][env.subst('${TARGET_FULLARCH}')]['url']
-  return nexe
-
+  program_dict = obj['program']
+  if env.Bit('bitcode'):
+    # For Pnacl we are not yet always using the 'portable' key in the manifest.
+    # Sometimes we translate to a native nexe for testing.
+    if 'portable' in program_dict.keys():
+      return (program_dict['portable']['url'], True)
+    # otherwise, fall through to nexe case.
+  return (program_dict[env.subst('${TARGET_FULLARCH}')]['url'], False)
+
+# Is this for detecting if we've staged a manifest file yet or not?
 manifest_map = {}
 
-
 # Returns scons node for generated manifest.
 def GeneratedManifestNode(env, manifest):
   manifest = env.subst(manifest)
   manifest_base_name = os.path.basename(manifest)
-  nexe = GetNexeFromManifest(env, manifest)
+  main_program, is_portable = GetMainProgramFromManifest(env, manifest)
   result = env.File('${STAGING_DIR}/' + manifest_base_name)
   if not env.Bit('nacl_glibc'):
     if manifest_base_name not in manifest_map:
       env.Install('${STAGING_DIR}', manifest)
-      manifest_map[manifest_base_name] = nexe
+      manifest_map[manifest_base_name] = main_program
     # fall through
   if manifest_base_name in manifest_map:
-    if manifest_map[manifest_base_name] != nexe:
-      print nexe
+    if manifest_map[manifest_base_name] != main_program:
+      print main_program
       print manifest_map[manifest_base_name]
       raise Exception("Two manifest files with the same name")
     return result
-  manifest_map[manifest_base_name] = nexe
-  lib_list_node = env.Command(
-      '${STAGING_DIR}/' + manifest_base_name + '.libs',
-      [GetSelLdr(env),
-       '${NACL_SDK_LIB}/runnable-ld.so',
-       env.File('${STAGING_DIR}/' + os.path.basename(nexe)),
-       '${SCONSTRUCT_DIR}/DEPS'],
-      # We ignore return code using '-' in order to build tests where binaries
-      # do not validate. This is the scons feature.
-      '-${SOURCES[0]} -a -E LD_TRACE_LOADED_OBJECTS=1 ${SOURCES[1]} '
-      '--library-path ${NACL_SDK_LIB}:${LIB_DIR} ${SOURCES[2].posix} '
-      '> ${TARGET}')
+  manifest_map[manifest_base_name] = main_program
+  lib_list_filename = '${STAGING_DIR}/' + manifest_base_name + '.libs'
+  if is_portable:
+    # Use pnacl-meta to extract the NEEDED libraries.
+    # Note: This relies on the pexe containing the transitive dependencies.
+    lib_list_node = env.Command(
+        lib_list_filename,
+        ['${READMETA}',
+         env.File('${STAGING_DIR}/' + os.path.basename(main_program))],
+        '${SOURCES[0]} --format=ldd ${SOURCES[1]} > ${TARGET}')
+  else:
+    # Run sel_ldr on the nexe to trace the NEEDED libraries.
+    lib_list_node = env.Command(
+        lib_list_filename,
+        [GetSelLdr(env),
+         '${NACL_SDK_LIB}/runnable-ld.so',
+         env.File('${STAGING_DIR}/' + os.path.basename(main_program)),
+         '${SCONSTRUCT_DIR}/DEPS'],
+        # We ignore return code using '-' in order to build tests where binaries
+        # do not validate. This is the scons feature.
+        '-${SOURCES[0]} -a -E LD_TRACE_LOADED_OBJECTS=1 ${SOURCES[1]} '
+        '--library-path ${NACL_SDK_LIB}:${LIB_DIR} ${SOURCES[2].posix} '
+        '> ${TARGET}')
   nmf_node = env.Command(
       '${STAGING_DIR}/' + manifest_base_name,
       [manifest, lib_list_node],