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1#!/usr/bin/env python
2
3# Copyright (c) 2016 Google Inc.
4#
5# Licensed under the Apache License, Version 2.0 (the "License");
6# you may not use this file except in compliance with the License.
7# You may obtain a copy of the License at
8#
9#     http://www.apache.org/licenses/LICENSE-2.0
10#
11# Unless required by applicable law or agreed to in writing, software
12# distributed under the License is distributed on an "AS IS" BASIS,
13# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14# See the License for the specific language governing permissions and
15# limitations under the License.
16
17# Updates an output file with version info unless the new content is the same
18# as the existing content.
19#
20# Args: <changes-file> <output-file>
21#
22# The output file will contain a line of text consisting of two C source syntax
23# string literals separated by a comma:
24#  - The software version deduced from the given CHANGES file.
25#  - A longer string with the project name, the software version number, and
26#    git commit information for the CHANGES file's directory.  The commit
27#    information is the output of "git describe" if that succeeds, or "git
28#    rev-parse HEAD" if that succeeds, or otherwise a message containing the
29#    phrase "unknown hash".
30# The string contents are escaped as necessary.
31
32import datetime
33import errno
34import os
35import os.path
36import re
37import subprocess
38import logging
39import sys
40import time
41
42# Format of the output generated by this script. Example:
43# "v2023.1", "SPIRV-Tools v2023.1 0fc5526f2b01a0cc89192c10cf8bef77f1007a62, 2023-01-18T14:51:49"
44OUTPUT_FORMAT = '"{version_tag}", "SPIRV-Tools {version_tag} {description}"\n'
45
46def mkdir_p(directory):
47    """Make the directory, and all its ancestors as required.  Any of the
48    directories are allowed to already exist."""
49
50    if directory == "":
51        # We're being asked to make the current directory.
52        return
53
54    try:
55        os.makedirs(directory)
56    except OSError as e:
57        if e.errno == errno.EEXIST and os.path.isdir(directory):
58            pass
59        else:
60            raise
61
62def command_output(cmd, directory):
63    """Runs a command in a directory and returns its standard output stream.
64
65    Captures the standard error stream.
66
67    Raises a RuntimeError if the command fails to launch or otherwise fails.
68    """
69    try:
70      # Set shell=True on Windows so that Chromium's git.bat can be found when
71      # 'git' is invoked.
72      p = subprocess.Popen(cmd,
73                           cwd=directory,
74                           stdout=subprocess.PIPE,
75                           stderr=subprocess.PIPE,
76                           shell=os.name == 'nt')
77      (stdout, stderr) = p.communicate()
78      if p.returncode != 0:
79        logging.error('Failed to run "{}" in "{}": {}'.format(cmd, directory, stderr.decode()))
80    except Exception as e:
81        logging.error('Failed to run "{}" in "{}": {}'.format(cmd, directory, str(e)))
82        return False, None
83    return p.returncode == 0, stdout
84
85def deduce_software_version(changes_file):
86    """Returns a tuple (success, software version number) parsed from the
87    given CHANGES file.
88
89    Success is set to True if the software version could be deduced.
90    Software version is undefined if success if False.
91    Function expects the CHANGES file to describes most recent versions first.
92    """
93
94    # Match the first well-formed version-and-date line
95    # Allow trailing whitespace in the checked-out source code has
96    # unexpected carriage returns on a linefeed-only system such as
97    # Linux.
98    pattern = re.compile(r'^(v\d+\.\d+(-dev)?) \d\d\d\d-\d\d-\d\d\s*$')
99    with open(changes_file, mode='r') as f:
100        for line in f.readlines():
101            match = pattern.match(line)
102            if match:
103                return True, match.group(1)
104    return False, None
105
106
107def describe(repo_path):
108    """Returns a string describing the current Git HEAD version as descriptively
109    as possible.
110
111    Runs 'git describe', or alternately 'git rev-parse HEAD', in directory.  If
112    successful, returns the output; otherwise returns 'unknown hash, <date>'."""
113
114    success, output = command_output(['git', 'describe'], repo_path)
115    if not success:
116      output = command_output(['git', 'rev-parse', 'HEAD'], repo_path)
117
118    if success:
119      # decode() is needed here for Python3 compatibility. In Python2,
120      # str and bytes are the same type, but not in Python3.
121      # Popen.communicate() returns a bytes instance, which needs to be
122      # decoded into text data first in Python3. And this decode() won't
123      # hurt Python2.
124      return output.rstrip().decode()
125
126    # This is the fallback case where git gives us no information,
127    # e.g. because the source tree might not be in a git tree.
128    # In this case, usually use a timestamp.  However, to ensure
129    # reproducible builds, allow the builder to override the wall
130    # clock time with environment variable SOURCE_DATE_EPOCH
131    # containing a (presumably) fixed timestamp.
132    timestamp = int(os.environ.get('SOURCE_DATE_EPOCH', time.time()))
133    iso_date = datetime.datetime.utcfromtimestamp(timestamp).isoformat()
134    return "unknown hash, {}".format(iso_date)
135
136def main():
137    FORMAT = '%(asctime)s %(message)s'
138    logging.basicConfig(format="[%(asctime)s][%(levelname)-8s] %(message)s", datefmt="%H:%M:%S")
139    if len(sys.argv) != 3:
140        logging.error("usage: {} <repo-path> <output-file>".format(sys.argv[0]))
141        sys.exit(1)
142
143    changes_file_path = os.path.realpath(sys.argv[1])
144    output_file_path = sys.argv[2]
145
146    success, version = deduce_software_version(changes_file_path)
147    if not success:
148      logging.error("Could not deduce latest release version from {}.".format(changes_file_path))
149      sys.exit(1)
150
151    repo_path = os.path.dirname(changes_file_path)
152    description = describe(repo_path)
153    content = OUTPUT_FORMAT.format(version_tag=version, description=description)
154
155    # Escape file content.
156    content.replace('"', '\\"')
157
158    if os.path.isfile(output_file_path):
159      with open(output_file_path, 'r') as f:
160        if content == f.read():
161          return
162
163    mkdir_p(os.path.dirname(output_file_path))
164    with open(output_file_path, 'w') as f:
165        f.write(content)
166
167if __name__ == '__main__':
168    main()
169