The Tor Browser: python/which/which.py@b8a032363ba2 (annotated)

python/which/which.py@b8a032363ba2 (annotated)

python/which/which.py

Thu, 22 Jan 2015 13:21:57 +0100

author: Michael Schloh von Bennewitz <michael@schloh.com>
date: Thu, 22 Jan 2015 13:21:57 +0100
branch: TOR_BUG_9701
changeset 15: b8a032363ba2
permissions: -rw-r--r--

Incorporate requested changes from Mozilla in review:
https://bugzilla.mozilla.org/show_bug.cgi?id=1123480#c6

 #!/usr/bin/env python
 # Copyright (c) 2002-2005 ActiveState Corp.
 # See LICENSE.txt for license details.
 # Author:
 #   Trent Mick (TrentM@ActiveState.com)
 # Home:
 #   http://trentm.com/projects/which/
 r"""Find the full path to commands.
 which(command, path=None, verbose=0, exts=None)
     Return the full path to the first match of the given command on the
     path.
 whichall(command, path=None, verbose=0, exts=None)
     Return a list of full paths to all matches of the given command on
     the path.
 whichgen(command, path=None, verbose=0, exts=None)
     Return a generator which will yield full paths to all matches of the
     given command on the path.
 By default the PATH environment variable is searched (as well as, on
 Windows, the AppPaths key in the registry), but a specific 'path' list
 to search may be specified as well.  On Windows, the PATHEXT environment
 variable is applied as appropriate.
 If "verbose" is true then a tuple of the form
     (<fullpath>, <matched-where-description>)
 is returned for each match. The latter element is a textual description
 of where the match was found. For example:
     from PATH element 0
     from HKLM\SOFTWARE\...\perl.exe
 """
 _cmdlnUsage = """
     Show the full path of commands.
     Usage:
         which [<options>...] [<command-name>...]
     Options:
         -h, --help      Print this help and exit.
         -V, --version   Print the version info and exit.
         -a, --all       Print *all* matching paths.
         -v, --verbose   Print out how matches were located and
                         show near misses on stderr.
         -q, --quiet     Just print out matches. I.e., do not print out
                         near misses.
         -p <altpath>, --path=<altpath>
                         An alternative path (list of directories) may
                         be specified for searching.
         -e <exts>, --exts=<exts>
                         Specify a list of extensions to consider instead
                         of the usual list (';'-separate list, Windows
                         only).
     Show the full path to the program that would be run for each given
     command name, if any. Which, like GNU's which, returns the number of
     failed arguments, or -1 when no <command-name> was given.
     Near misses include duplicates, non-regular files and (on Un*x)
     files without executable access.
 """
 __revision__ = "$Id: which.py 430 2005-08-20 03:11:58Z trentm $"
 __version_info__ = (1, 1, 0)
 __version__ = '.'.join(map(str, __version_info__))
 import os
 import sys
 import getopt
 import stat
 #---- exceptions
 class WhichError(Exception):
     pass
 #---- internal support stuff
 def _getRegisteredExecutable(exeName):
     """Windows allow application paths to be registered in the registry."""
     registered = None
     if sys.platform.startswith('win'):
         if os.path.splitext(exeName)[1].lower() != '.exe':
             exeName += '.exe'
         import _winreg
         try:
             key = "SOFTWARE\\Microsoft\\Windows\\CurrentVersion\\App Paths\\" +\
                   exeName
             value = _winreg.QueryValue(_winreg.HKEY_LOCAL_MACHINE, key)
             registered = (value, "from HKLM\\"+key)
         except _winreg.error:
             pass
         if registered and not os.path.exists(registered[0]):
             registered = None
     return registered
 def _samefile(fname1, fname2):
     if sys.platform.startswith('win'):
         return ( os.path.normpath(os.path.normcase(fname1)) ==\
             os.path.normpath(os.path.normcase(fname2)) )
     else:
         return os.path.samefile(fname1, fname2)
 def _cull(potential, matches, verbose=0):
     """Cull inappropriate matches. Possible reasons:
         - a duplicate of a previous match
         - not a disk file
         - not executable (non-Windows)
     If 'potential' is approved it is returned and added to 'matches'.
     Otherwise, None is returned.
     """
     for match in matches:  # don't yield duplicates
         if _samefile(potential[0], match[0]):
             if verbose:
                 sys.stderr.write("duplicate: %s (%s)\n" % potential)
             return None
     else:
         if not stat.S_ISREG(os.stat(potential[0]).st_mode):
             if verbose:
                 sys.stderr.write("not a regular file: %s (%s)\n" % potential)
         elif not os.access(potential[0], os.X_OK):
             if verbose:
                 sys.stderr.write("no executable access: %s (%s)\n"\
                                  % potential)
         else:
             matches.append(potential)
             return potential
 #---- module API
 def whichgen(command, path=None, verbose=0, exts=None):
     """Return a generator of full paths to the given command.
     "command" is a the name of the executable to search for.
     "path" is an optional alternate path list to search. The default it
         to use the PATH environment variable.
     "verbose", if true, will cause a 2-tuple to be returned for each
         match. The second element is a textual description of where the
         match was found.
     "exts" optionally allows one to specify a list of extensions to use
         instead of the standard list for this system. This can
         effectively be used as an optimization to, for example, avoid
         stat's of "foo.vbs" when searching for "foo" and you know it is
         not a VisualBasic script but ".vbs" is on PATHEXT. This option
         is only supported on Windows.
     This method returns a generator which yields either full paths to
     the given command or, if verbose, tuples of the form (<path to
     command>, <where path found>).
     """
     matches = []
     if path is None:
         usingGivenPath = 0
         path = os.environ.get("PATH", "").split(os.pathsep)
         if sys.platform.startswith("win"):
             path.insert(0, os.curdir)  # implied by Windows shell
     else:
         usingGivenPath = 1
     # Windows has the concept of a list of extensions (PATHEXT env var).
     if sys.platform.startswith("win"):
         if exts is None:
             exts = os.environ.get("PATHEXT", "").split(os.pathsep)
             # If '.exe' is not in exts then obviously this is Win9x and
             # or a bogus PATHEXT, then use a reasonable default.
             for ext in exts:
                 if ext.lower() == ".exe":
                     break
             else:
                 exts = ['.COM', '.EXE', '.BAT']
         elif not isinstance(exts, list):
             raise TypeError("'exts' argument must be a list or None")
     else:
         if exts is not None:
             raise WhichError("'exts' argument is not supported on "\
                              "platform '%s'" % sys.platform)
         exts = []
     # File name cannot have path separators because PATH lookup does not
     # work that way.
     if os.sep in command or os.altsep and os.altsep in command:
         pass
     else:
         for i in range(len(path)):
             dirName = path[i]
             # On windows the dirName *could* be quoted, drop the quotes
             if sys.platform.startswith("win") and len(dirName) >= 2\
                and dirName[0] == '"' and dirName[-1] == '"':
                 dirName = dirName[1:-1]
             for ext in ['']+exts:
                 absName = os.path.abspath(
                     os.path.normpath(os.path.join(dirName, command+ext)))
                 if os.path.isfile(absName):
                     if usingGivenPath:
                         fromWhere = "from given path element %d" % i
                     elif not sys.platform.startswith("win"):
                         fromWhere = "from PATH element %d" % i
                     elif i == 0:
                         fromWhere = "from current directory"
                     else:
                         fromWhere = "from PATH element %d" % (i-1)
                     match = _cull((absName, fromWhere), matches, verbose)
                     if match:
                         if verbose:
                             yield match
                         else:
                             yield match[0]
         match = _getRegisteredExecutable(command)
         if match is not None:
             match = _cull(match, matches, verbose)
             if match:
                 if verbose:
                     yield match
                 else:
                     yield match[0]
 def which(command, path=None, verbose=0, exts=None):
     """Return the full path to the first match of the given command on
     the path.
     "command" is a the name of the executable to search for.
     "path" is an optional alternate path list to search. The default it
         to use the PATH environment variable.
     "verbose", if true, will cause a 2-tuple to be returned. The second
         element is a textual description of where the match was found.
     "exts" optionally allows one to specify a list of extensions to use
         instead of the standard list for this system. This can
         effectively be used as an optimization to, for example, avoid
         stat's of "foo.vbs" when searching for "foo" and you know it is
         not a VisualBasic script but ".vbs" is on PATHEXT. This option
         is only supported on Windows.
     If no match is found for the command, a WhichError is raised.
     """
     try:
         match = whichgen(command, path, verbose, exts).next()
     except StopIteration:
         raise WhichError("Could not find '%s' on the path." % command)
     return match
 def whichall(command, path=None, verbose=0, exts=None):
     """Return a list of full paths to all matches of the given command
     on the path.
     "command" is a the name of the executable to search for.
     "path" is an optional alternate path list to search. The default it
         to use the PATH environment variable.
     "verbose", if true, will cause a 2-tuple to be returned for each
         match. The second element is a textual description of where the
         match was found.
     "exts" optionally allows one to specify a list of extensions to use
         instead of the standard list for this system. This can
         effectively be used as an optimization to, for example, avoid
         stat's of "foo.vbs" when searching for "foo" and you know it is
         not a VisualBasic script but ".vbs" is on PATHEXT. This option
         is only supported on Windows.
     """
     return list( whichgen(command, path, verbose, exts) )
 #---- mainline
 def main(argv):
     all = 0
     verbose = 0
     altpath = None
     exts = None
     try:
         optlist, args = getopt.getopt(argv[1:], 'haVvqp:e:',
             ['help', 'all', 'version', 'verbose', 'quiet', 'path=', 'exts='])
     except getopt.GetoptError, msg:
         sys.stderr.write("which: error: %s. Your invocation was: %s\n"\
                          % (msg, argv))
         sys.stderr.write("Try 'which --help'.\n")
         return 1
     for opt, optarg in optlist:
         if opt in ('-h', '--help'):
             print _cmdlnUsage
             return 0
         elif opt in ('-V', '--version'):
             print "which %s" % __version__
             return 0
         elif opt in ('-a', '--all'):
             all = 1
         elif opt in ('-v', '--verbose'):
             verbose = 1
         elif opt in ('-q', '--quiet'):
             verbose = 0
         elif opt in ('-p', '--path'):
             if optarg:
                 altpath = optarg.split(os.pathsep)
             else:
                 altpath = []
         elif opt in ('-e', '--exts'):
             if optarg:
                 exts = optarg.split(os.pathsep)
             else:
                 exts = []
     if len(args) == 0:
         return -1
     failures = 0
     for arg in args:
         #print "debug: search for %r" % arg
         nmatches = 0
         for match in whichgen(arg, path=altpath, verbose=verbose, exts=exts):
             if verbose:
                 print "%s (%s)" % match
             else:
                 print match
             nmatches += 1
             if not all:
                 break
         if not nmatches:
             failures += 1
     return failures
 if __name__ == "__main__":
     sys.exit( main(sys.argv) )

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