1 #!/usr/bin/env python 2 # Copyright (c) 2011 The Chromium Authors. All rights reserved. 3 # Use of this source code is governed by a BSD-style license that can be 4 # found in the LICENSE file. 5 6 """ 7 lastchange.py -- Chromium revision fetching utility. 8 """ 9 10 import re 11 import optparse 12 import os 13 import subprocess 14 import sys 15 16 class VersionInfo(object): 17 def __init__(self, url, root, revision): 18 self.url = url 19 self.root = root 20 self.revision = revision 21 22 23 def FetchSVNRevision(directory): 24 """ 25 Fetch the Subversion branch and revision for a given directory. 26 27 Errors are swallowed. 28 29 Returns: 30 a VersionInfo object or None on error. 31 """ 32 try: 33 proc = subprocess.Popen(['svn', 'info'], 34 stdout=subprocess.PIPE, 35 stderr=subprocess.PIPE, 36 cwd=directory, 37 shell=(sys.platform=='win32')) 38 except OSError: 39 # command is apparently either not installed or not executable. 40 return None 41 if not proc: 42 return None 43 44 attrs = {} 45 for line in proc.stdout: 46 line = line.strip() 47 if not line: 48 continue 49 key, val = line.split(': ', 1) 50 attrs[key] = val 51 52 try: 53 url = attrs['URL'] 54 root = attrs['Repository Root'] 55 revision = attrs['Revision'] 56 except KeyError: 57 return None 58 59 return VersionInfo(url, root, revision) 60 61 62 def RunGitCommand(directory, command): 63 """ 64 Launches git subcommand. 65 66 Errors are swallowed. 67 68 Returns: 69 process object or None. 70 """ 71 command = ['git'] + command 72 # Force shell usage under cygwin & win32. This is a workaround for 73 # mysterious loss of cwd while invoking cygwin's git. 74 # We can't just pass shell=True to Popen, as under win32 this will 75 # cause CMD to be used, while we explicitly want a cygwin shell. 76 if sys.platform in ('cygwin', 'win32'): 77 command = ['sh', '-c', ' '.join(command)] 78 try: 79 proc = subprocess.Popen(command, 80 stdout=subprocess.PIPE, 81 stderr=subprocess.PIPE, 82 cwd=directory) 83 return proc 84 except OSError: 85 return None 86 87 88 def FetchGitRevision(directory): 89 """ 90 Fetch the Git hash for a given directory. 91 92 Errors are swallowed. 93 94 Returns: 95 a VersionInfo object or None on error. 96 """ 97 proc = RunGitCommand(directory, ['rev-parse', 'HEAD']) 98 if proc: 99 output = proc.communicate()[0].strip() 100 if proc.returncode == 0 and output: 101 return VersionInfo('git', 'git', output[:7]) 102 return None 103 104 105 def IsGitSVN(directory): 106 """ 107 Checks whether git-svn has been set up. 108 109 Errors are swallowed. 110 111 Returns: 112 whether git-svn has been set up. 113 """ 114 # To test whether git-svn has been set up, query the config for any 115 # svn-related configuration. This command exits with an error code 116 # if there aren't any matches, so ignore its output. 117 proc = RunGitCommand(directory, ['config', '--get-regexp', '^svn']) 118 if proc: 119 return (proc.wait() == 0) 120 return False 121 122 123 def FetchGitSVNURL(directory): 124 """ 125 Fetch URL of SVN repository bound to git. 126 127 Errors are swallowed. 128 129 Returns: 130 SVN URL. 131 """ 132 if IsGitSVN(directory): 133 proc = RunGitCommand(directory, ['svn', 'info', '--url']) 134 if proc: 135 output = proc.communicate()[0].strip() 136 if proc.returncode == 0: 137 match = re.search(r'^\w+://.*$', output, re.M) 138 if match: 139 return match.group(0) 140 return '' 141 142 143 def FetchGitSVNRoot(directory): 144 """ 145 Fetch root of SVN repository bound to git. 146 147 Errors are swallowed. 148 149 Returns: 150 SVN root repository. 151 """ 152 if IsGitSVN(directory): 153 git_command = ['config', '--get-regexp', '^svn-remote.svn.url$'] 154 proc = RunGitCommand(directory, git_command) 155 if proc: 156 output = proc.communicate()[0].strip() 157 if proc.returncode == 0: 158 # Zero return code implies presence of requested configuration variable. 159 # Its value is second (last) field of output. 160 match = re.search(r'\S+$', output) 161 if match: 162 return match.group(0) 163 return '' 164 165 166 def LookupGitSVNRevision(directory, depth): 167 """ 168 Fetch the Git-SVN identifier for the local tree. 169 Parses first |depth| commit messages. 170 171 Errors are swallowed. 172 """ 173 if not IsGitSVN(directory): 174 return None 175 git_re = re.compile(r'^\s*git-svn-id:\s+(\S+)@(\d+)') 176 proc = RunGitCommand(directory, ['log', '-' + str(depth)]) 177 if proc: 178 for line in proc.stdout: 179 match = git_re.match(line) 180 if match: 181 id = match.group(2) 182 if id: 183 proc.stdout.close() # Cut pipe for fast exit. 184 return id 185 return None 186 187 188 def IsGitSVNDirty(directory): 189 """ 190 Checks whether our git-svn tree contains clean trunk or some branch. 191 192 Errors are swallowed. 193 """ 194 # For git branches the last commit message is either 195 # some local commit or a merge. 196 return LookupGitSVNRevision(directory, 1) is None 197 198 199 def FetchGitSVNRevision(directory): 200 """ 201 Fetch the Git-SVN identifier for the local tree. 202 203 Errors are swallowed. 204 """ 205 # We assume that at least first 999 commit messages contain svn evidence. 206 revision = LookupGitSVNRevision(directory, 999) 207 if not revision: 208 return None 209 if IsGitSVNDirty(directory): 210 revision = revision + '-dirty' 211 url = FetchGitSVNURL(directory) 212 root = FetchGitSVNRoot(directory) 213 return VersionInfo(url, root, revision) 214 215 216 def FetchVersionInfo(default_lastchange, directory=None): 217 """ 218 Returns the last change (in the form of a branch, revision tuple), 219 from some appropriate revision control system. 220 """ 221 version_info = (FetchSVNRevision(directory) or 222 FetchGitSVNRevision(directory) or FetchGitRevision(directory)) 223 if not version_info: 224 if default_lastchange and os.path.exists(default_lastchange): 225 revision = open(default_lastchange, 'r').read().strip() 226 version_info = VersionInfo(None, None, revision) 227 else: 228 version_info = VersionInfo('unknown', '', '0') 229 return version_info 230 231 232 def WriteIfChanged(file_name, contents): 233 """ 234 Writes the specified contents to the specified file_name 235 iff the contents are different than the current contents. 236 """ 237 try: 238 old_contents = open(file_name, 'r').read() 239 except EnvironmentError: 240 pass 241 else: 242 if contents == old_contents: 243 return 244 os.unlink(file_name) 245 open(file_name, 'w').write(contents) 246 247 248 def main(argv=None): 249 if argv is None: 250 argv = sys.argv 251 252 parser = optparse.OptionParser(usage="lastchange.py [options]") 253 parser.add_option("-d", "--default-lastchange", metavar="FILE", 254 help="default last change input FILE") 255 parser.add_option("-o", "--output", metavar="FILE", 256 help="write last change to FILE") 257 parser.add_option("--revision-only", action='store_true', 258 help="just print the SVN revision number") 259 opts, args = parser.parse_args(argv[1:]) 260 261 out_file = opts.output 262 263 while len(args) and out_file is None: 264 if out_file is None: 265 out_file = args.pop(0) 266 if args: 267 sys.stderr.write('Unexpected arguments: %r\n\n' % args) 268 parser.print_help() 269 sys.exit(2) 270 271 version_info = FetchVersionInfo(opts.default_lastchange) 272 273 if opts.revision_only: 274 print version_info.revision 275 else: 276 contents = "LASTCHANGE=%s\n" % version_info.revision 277 if out_file: 278 WriteIfChanged(out_file, contents) 279 else: 280 sys.stdout.write(contents) 281 282 return 0 283 284 285 if __name__ == '__main__': 286 sys.exit(main()) 287
