Extract a library from create_embedded_tools.py

We'll use the extracted functions in the upcoming
Python-based reincarnation of the
//:bazel-distfile rule.

Change-Id: I5140938ae4af50f62fb695b5b96cd41f3cd939ef
PiperOrigin-RevId: 164950515

3 files changed, 113 insertions, 47 deletions

diff --git a/src/BUILD b/src/BUILD
index 15b7502910..d788f1f644 100644
--- a/src/BUILD
+++ b/src/BUILD
@@ -122,9 +122,15 @@ filegroup(
     ],
 )
 
+py_library(
+    name = "create_embedded_tools_lib",
+    srcs = ["create_embedded_tools_lib.py"],
+)
+
 py_binary(
     name = "create_embedded_tools",
     srcs = ["create_embedded_tools.py"],
+    deps = [":create_embedded_tools_lib"],
 )
 
 # TODO(philwo): Clean this up, once a Bazel that can run py_binary and sh_binary
diff --git a/src/create_embedded_tools.py b/src/create_embedded_tools.py
index a4ba83a06e..a29e013627 100644
--- a/src/create_embedded_tools.py
+++ b/src/create_embedded_tools.py
@@ -1,3 +1,4 @@
+# pylint: disable=g-direct-third-party-import
 # pylint: disable=g-bad-file-header
 # Copyright 2017 The Bazel Authors. All rights reserved.
 #
@@ -19,11 +20,13 @@ import fnmatch
 import os
 import os.path
 import re
-import stat
 import sys
-import tarfile
 import zipfile
 
+from src.create_embedded_tools_lib import copy_tar_to_zip
+from src.create_embedded_tools_lib import copy_zip_to_zip
+from src.create_embedded_tools_lib import is_executable
+
 output_paths = [
     ('*tools/jdk/BUILD*', lambda x: 'tools/jdk/BUILD'),
     ('*tools/platforms/platforms.BUILD', lambda x: 'platforms/BUILD'),
@@ -69,14 +72,6 @@ def get_output_path(path):
       return transformer(path).replace('/BUILD.tools', '/BUILD')
 
 
-def is_mode_executable(mode):
-  return mode & (stat.S_IXUSR | stat.S_IXGRP | stat.S_IXOTH) > 0
-
-
-def is_executable(path):
-  return is_mode_executable(os.stat(path)[stat.ST_MODE])
-
-
 def get_input_files(argsfile):
   """Returns a sorted list of tuples (archive_file, input_file).
 
@@ -106,46 +101,17 @@ def get_input_files(argsfile):
 
 
 def copy_jdk_into_archive(output_zip, archive_file, input_file):
+
+  def _replace_dirname(filename):
+    # Rename the first folder to 'jdk', because Bazel looks for a
+    # bundled JDK in the embedded tools using that folder name.
+    return 'jdk/' + '/'.join(filename.split('/')[1:])
+
   # The JDK is special - it's extracted instead of copied.
   if archive_file.endswith('.tar.gz'):
-    with tarfile.open(input_file, 'r', errorlevel=2) as jdk_tar:
-      while True:
-        jdk_tarinfo = jdk_tar.next()
-        if jdk_tarinfo is None:
-          break
-        # Rename the first folder to 'jdk', because Bazel looks for a
-        # bundled JDK in the embedded tools using that folder name.
-        filename = 'jdk/' + '/'.join(jdk_tarinfo.name.split('/')[1:])
-        zipinfo = zipfile.ZipInfo(filename, (1980, 1, 1, 0, 0, 0))
-        if jdk_tarinfo.isreg():
-          if is_mode_executable(jdk_tarinfo.mode):
-            zipinfo.external_attr = 0o755 << 16
-          else:
-            zipinfo.external_attr = 0o644 << 16
-          zipinfo.compress_type = zipfile.ZIP_DEFLATED
-          output_zip.writestr(zipinfo, jdk_tar.extractfile(jdk_tarinfo).read())
-        elif jdk_tarinfo.issym():
-          # 0120000 originally comes from the definition of S_IFLNK and
-          # marks a symbolic link in the Zip file format.
-          zipinfo.external_attr = 0o120000 << 16
-          output_zip.writestr(zipinfo, jdk_tarinfo.linkname)
-        else:
-          # Ignore directories, hard links, special files, ...
-          pass
+    copy_tar_to_zip(output_zip, input_file, _replace_dirname)
   elif archive_file.endswith('.zip'):
-    # Adding contextlib.closing to be python 2.6 (for centos 6.7) compatible
-    with contextlib.closing(zipfile.ZipFile(input_file, 'r')) as jdk_zip:
-      for jdk_zipinfo in jdk_zip.infolist():
-        # Rename the first folder to 'jdk', because Bazel looks for a
-        # bundled JDK in the embedded tools using that folder name.
-        filename = 'jdk/' + '/'.join(jdk_zipinfo.filename.split('/')[1:])
-        zipinfo = zipfile.ZipInfo(filename, (1980, 1, 1, 0, 0, 0))
-        if is_mode_executable(jdk_zipinfo.external_attr >> 16 & 0xFFFF):
-          zipinfo.external_attr = 0o755 << 16
-        else:
-          zipinfo.external_attr = 0o644 << 16
-        zipinfo.compress_type = jdk_zipinfo.compress_type
-        output_zip.writestr(zipinfo, jdk_zip.read(jdk_zipinfo))
+    copy_zip_to_zip(output_zip, input_file, _replace_dirname)
 
 
 def main():
diff --git a/src/create_embedded_tools_lib.py b/src/create_embedded_tools_lib.py
new file mode 100644
index 0000000000..a730ce6b9a
--- /dev/null
+++ b/src/create_embedded_tools_lib.py
@@ -0,0 +1,94 @@
+# pylint: disable=g-bad-file-header
+# Copyright 2017 The Bazel Authors. All rights reserved.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#    http:#www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+"""Utils to the contents of a tar or zip file into another zip file."""
+
+import contextlib
+import os.path
+import stat
+import tarfile
+import zipfile
+
+
+def is_mode_executable(mode):
+  """Returns true if `mode` has any of the executable bits set."""
+  return mode & (stat.S_IXUSR | stat.S_IXGRP | stat.S_IXOTH) > 0
+
+
+def is_executable(path):
+  """Returns true if `path` is an executable file/directory."""
+  return is_mode_executable(os.stat(path)[stat.ST_MODE])
+
+
+def copy_tar_to_zip(output_zip, input_file, process_filename=None):
+  """Copy a tar file's contents into a zip file.
+
+  This function unpacks every file from `input_file` and puts them into
+  `output_zip`. The unpacking is performed in-memory.
+
+  Args:
+    output_zip: zipfile.ZipFile; the destination archive
+    input_file: string; path to the source tar file
+    process_filename: function(str) -> str; optional; for a packed file entry in
+      `input_file` it computes the path in `output_zip`
+  """
+  with tarfile.open(input_file, 'r', errorlevel=2) as tar_file:
+    while True:
+      tar_entry = tar_file.next()
+      if tar_entry is None:
+        break
+      filename = (process_filename(tar_entry.name)
+                  if process_filename else tar_entry.name)
+      zipinfo = zipfile.ZipInfo(filename, (1980, 1, 1, 0, 0, 0))
+      if tar_entry.isreg():
+        if is_mode_executable(tar_entry.mode):
+          zipinfo.external_attr = 0o755 << 16
+        else:
+          zipinfo.external_attr = 0o644 << 16
+        zipinfo.compress_type = zipfile.ZIP_DEFLATED
+        output_zip.writestr(zipinfo, tar_file.extractfile(tar_entry).read())
+      elif tar_entry.issym():
+        # 0120000 originally comes from the definition of S_IFLNK and
+        # marks a symbolic link in the Zip file format.
+        zipinfo.external_attr = 0o120000 << 16
+        output_zip.writestr(zipinfo, tar_entry.linkname)
+      else:
+        # Ignore directories, hard links, special files, ...
+        pass
+
+
+def copy_zip_to_zip(output_zip, input_file, process_filename=None):
+  """Copy a zip file's contents into another zip file.
+
+  This function unpacks every file from `input_file` and puts them into
+  `output_zip`. The unpacking is performed in-memory.
+
+  Args:
+    output_zip: zipfile.ZipFile; the destination archive
+    input_file: string; path to the source tar file
+    process_filename: function(str) -> str; optional; for a packed file entry in
+      `input_file` it computes the path in `output_zip`
+  """
+  # Adding contextlib.closing to be python 2.6 (for centos 6.7) compatible
+  with contextlib.closing(zipfile.ZipFile(input_file, 'r')) as zip_file:
+    for zip_entry in zip_file.infolist():
+      filename = (process_filename(zip_entry.filename)
+                  if process_filename else zip_entry.filename)
+      zipinfo = zipfile.ZipInfo(filename, (1980, 1, 1, 0, 0, 0))
+      if is_mode_executable(zip_entry.external_attr >> 16 & 0xFFFF):
+        zipinfo.external_attr = 0o755 << 16
+      else:
+        zipinfo.external_attr = 0o644 << 16
+      zipinfo.compress_type = zip_entry.compress_type
+      output_zip.writestr(zipinfo, zip_file.read(zip_entry))