1#!/usr/bin/env python
2
3# Copyright (c) 2020 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
17import datetime
18import errno
19import os
20import os.path
21import re
22import subprocess
23import sys
24import time
25
26usage = """{} emits a string to stdout or file with project version information.
27
28args: <project-dir> [<input-string>] [-i <input-file>] [-o <output-file>]
29
30Either <input-string> or -i <input-file> needs to be provided.
31
32The tool will output the provided string or file content with the following
33tokens substituted:
34
35 <major>   - The major version point parsed from the CHANGES.md file.
36 <minor>   - The minor version point parsed from the CHANGES.md file.
37 <patch>   - The point version point parsed from the CHANGES.md file.
38 <flavor>  - The optional dash suffix parsed from the CHANGES.md file (excluding
39             dash prefix).
40 <-flavor> - The optional dash suffix parsed from the CHANGES.md file (including
41             dash prefix).
42 <date>    - The optional date of the release in the form YYYY-MM-DD
43 <commit>  - The git commit information for the directory taken from
44             "git describe" if that succeeds, or "git rev-parse HEAD"
45             if that succeeds, or otherwise a message containing the phrase
46             "unknown hash".
47
48-o is an optional flag for writing the output string to the given file. If
49   ommitted then the string is printed to stdout.
50"""
51
52def mkdir_p(directory):
53    """Make the directory, and all its ancestors as required.  Any of the
54    directories are allowed to already exist."""
55
56    if directory == "":
57        # We're being asked to make the current directory.
58        return
59
60    try:
61        os.makedirs(directory)
62    except OSError as e:
63        if e.errno == errno.EEXIST and os.path.isdir(directory):
64            pass
65        else:
66            raise
67
68
69def command_output(cmd, directory):
70    """Runs a command in a directory and returns its standard output stream.
71
72    Captures the standard error stream.
73
74    Raises a RuntimeError if the command fails to launch or otherwise fails.
75    """
76    p = subprocess.Popen(cmd,
77                         cwd=directory,
78                         stdout=subprocess.PIPE,
79                         stderr=subprocess.PIPE)
80    (stdout, _) = p.communicate()
81    if p.returncode != 0:
82        raise RuntimeError('Failed to run %s in %s' % (cmd, directory))
83    return stdout
84
85
86def deduce_software_version(directory):
87    """Returns a software version number parsed from the CHANGES.md file
88    in the given directory.
89
90    The CHANGES.md file describes most recent versions first.
91    """
92
93    # Match the first well-formed version-and-date line.
94    # Allow trailing whitespace in the checked-out source code has
95    # unexpected carriage returns on a linefeed-only system such as
96    # Linux.
97    pattern = re.compile(r'^#* +(\d+)\.(\d+)\.(\d+)(-\w+)? (\d\d\d\d-\d\d-\d\d)? *$')
98    changes_file = os.path.join(directory, 'CHANGES.md')
99    with open(changes_file, mode='r') as f:
100        for line in f.readlines():
101            match = pattern.match(line)
102            if match:
103                flavor = match.group(4)
104                if flavor == None:
105                    flavor = ""
106                return {
107                    "major": match.group(1),
108                    "minor": match.group(2),
109                    "patch": match.group(3),
110                    "flavor": flavor.lstrip("-"),
111                    "-flavor": flavor,
112                    "date": match.group(5),
113                }
114    raise Exception('No version number found in {}'.format(changes_file))
115
116
117def describe(directory):
118    """Returns a string describing the current Git HEAD version as descriptively
119    as possible.
120
121    Runs 'git describe', or alternately 'git rev-parse HEAD', in directory.  If
122    successful, returns the output; otherwise returns 'unknown hash, <date>'."""
123    try:
124        # decode() is needed here for Python3 compatibility. In Python2,
125        # str and bytes are the same type, but not in Python3.
126        # Popen.communicate() returns a bytes instance, which needs to be
127        # decoded into text data first in Python3. And this decode() won't
128        # hurt Python2.
129        return command_output(['git', 'describe'], directory).rstrip().decode()
130    except:
131        try:
132            return command_output(
133                ['git', 'rev-parse', 'HEAD'], directory).rstrip().decode()
134        except:
135            # This is the fallback case where git gives us no information,
136            # e.g. because the source tree might not be in a git tree.
137            # In this case, usually use a timestamp.  However, to ensure
138            # reproducible builds, allow the builder to override the wall
139            # clock time with environment variable SOURCE_DATE_EPOCH
140            # containing a (presumably) fixed timestamp.
141            timestamp = int(os.environ.get('SOURCE_DATE_EPOCH', time.time()))
142            formatted = datetime.datetime.utcfromtimestamp(timestamp).isoformat()
143            return 'unknown hash, {}'.format(formatted)
144
145def parse_args():
146    directory = None
147    input_string = None
148    input_file = None
149    output_file = None
150
151    if len(sys.argv) < 2:
152        raise Exception("Invalid number of arguments")
153
154    directory = sys.argv[1]
155    i = 2
156
157    if not sys.argv[i].startswith("-"):
158        input_string = sys.argv[i]
159        i = i + 1
160
161    while i < len(sys.argv):
162        opt = sys.argv[i]
163        i = i + 1
164
165        if opt == "-i" or opt == "-o":
166            if i == len(sys.argv):
167                raise Exception("Expected path after {}".format(opt))
168            val = sys.argv[i]
169            i = i + 1
170            if (opt == "-i"):
171                input_file = val
172            elif (opt == "-o"):
173                output_file = val
174            else:
175                raise Exception("Unknown flag {}".format(opt))
176
177    return {
178        "directory": directory,
179        "input_string": input_string,
180        "input_file": input_file,
181        "output_file": output_file,
182    }
183
184def main():
185    args = None
186    try:
187        args = parse_args()
188    except Exception as e:
189        print(e)
190        print("\nUsage:\n")
191        print(usage.format(sys.argv[0]))
192        sys.exit(1)
193
194    directory = args["directory"]
195    template = args["input_string"]
196    if template == None:
197        with open(args["input_file"], 'r') as f:
198            template = f.read()
199    output_file = args["output_file"]
200
201    software_version = deduce_software_version(directory)
202    commit = describe(directory)
203    output = template \
204        .replace("@major@", software_version["major"]) \
205        .replace("@minor@", software_version["minor"]) \
206        .replace("@patch@", software_version["patch"]) \
207        .replace("@flavor@", software_version["flavor"]) \
208        .replace("@-flavor@", software_version["-flavor"]) \
209        .replace("@date@", software_version["date"]) \
210        .replace("@commit@", commit)
211
212    if output_file is None:
213        print(output)
214    else:
215        mkdir_p(os.path.dirname(output_file))
216
217        if os.path.isfile(output_file):
218            with open(output_file, 'r') as f:
219                if output == f.read():
220                    return
221
222        with open(output_file, 'w') as f:
223            f.write(output)
224
225if __name__ == '__main__':
226    main()
227