1 #! /usr/bin/env python

     2 

     3 # Change the #! line occurring in Python scripts.  The new interpreter

     4 # pathname must be given with a -i option.

     5 #

     6 # Command line arguments are files or directories to be processed.

     7 # Directories are searched recursively for files whose name looks

     8 # like a python module.

     9 # Symbolic links are always ignored (except as explicit directory

    10 # arguments).  Of course, the original file is kept as a back-up

    11 # (with a "~" attached to its name).

    12 #

    13 # Undoubtedly you can do this using find and sed or perl, but this is

    14 # a nice example of Python code that recurses down a directory tree

    15 # and uses regular expressions.  Also note several subtleties like

    16 # preserving the file's mode and avoiding to even write a temp file

    17 # when no changes are needed for a file.

    18 #

    19 # NB: by changing only the function fixfile() you can turn this

    20 # into a program for a different change to Python programs...

    21 

    22 import sys

    23 import re

    24 import os

    25 from stat import *

    26 import getopt

    27 

    28 err = sys.stderr.write

    29 dbg = err

    30 rep = sys.stdout.write

    31 

    32 new_interpreter = None

    33 

    34 def main():

    35     global new_interpreter

    36     usage = ('usage: %s -i /interpreter file-or-directory ...\n' %

    37              sys.argv[0])

    38     try:

    39         opts, args = getopt.getopt(sys.argv[1:], 'i:')

    40     except getopt.error, msg:

    41         err(msg + '\n')

    42         err(usage)

    43         sys.exit(2)

    44     for o, a in opts:

    45         if o == '-i':

    46             new_interpreter = a

    47     if not new_interpreter or new_interpreter[0] != '/' or not args:

    48         err('-i option or file-or-directory missing\n')

    49         err(usage)

    50         sys.exit(2)

    51     bad = 0

    52     for arg in args:

    53         if os.path.isdir(arg):

    54             if recursedown(arg): bad = 1

    55         elif os.path.islink(arg):

    56             err(arg + ': will not process symbolic links\n')

    57             bad = 1

    58         else:

    59             if fix(arg): bad = 1

    60     sys.exit(bad)

    61 

    62 ispythonprog = re.compile('^[a-zA-Z0-9_]+\.py$')

    63 def ispython(name):

    64     return ispythonprog.match(name) >= 0

    65 

    66 def recursedown(dirname):

    67     dbg('recursedown(%r)\n' % (dirname,))

    68     bad = 0

    69     try:

    70         names = os.listdir(dirname)

    71     except os.error, msg:

    72         err('%s: cannot list directory: %r\n' % (dirname, msg))

    73         return 1

    74     names.sort()

    75     subdirs = []

    76     for name in names:

    77         if name in (os.curdir, os.pardir): continue

    78         fullname = os.path.join(dirname, name)

    79         if os.path.islink(fullname): pass

    80         elif os.path.isdir(fullname):

    81             subdirs.append(fullname)

    82         elif ispython(name):

    83             if fix(fullname): bad = 1

    84     for fullname in subdirs:

    85         if recursedown(fullname): bad = 1

    86     return bad

    87 

    88 def fix(filename):

    89 ##  dbg('fix(%r)\n' % (filename,))

    90     try:

    91         f = open(filename, 'r')

    92     except IOError, msg:

    93         err('%s: cannot open: %r\n' % (filename, msg))

    94         return 1

    95     line = f.readline()

    96     fixed = fixline(line)

    97     if line == fixed:

    98         rep(filename+': no change\n')

    99         f.close()

   100         return

   101     head, tail = os.path.split(filename)

   102     tempname = os.path.join(head, '@' + tail)

   103     try:

   104         g = open(tempname, 'w')

   105     except IOError, msg:

   106         f.close()

   107         err('%s: cannot create: %r\n' % (tempname, msg))

   108         return 1

   109     rep(filename + ': updating\n')

   110     g.write(fixed)

   111     BUFSIZE = 8*1024

   112     while 1:

   113         buf = f.read(BUFSIZE)

   114         if not buf: break

   115         g.write(buf)

   116     g.close()

   117     f.close()

   118 

   119     # Finishing touch -- move files

   120 

   121     # First copy the file's mode to the temp file

   122     try:

   123         statbuf = os.stat(filename)

   124         os.chmod(tempname, statbuf[ST_MODE] & 07777)

   125     except os.error, msg:

   126         err('%s: warning: chmod failed (%r)\n' % (tempname, msg))

   127     # Then make a backup of the original file as filename~

   128     try:

   129         os.rename(filename, filename + '~')

   130     except os.error, msg:

   131         err('%s: warning: backup failed (%r)\n' % (filename, msg))

   132     # Now move the temp file to the original file

   133     try:

   134         os.rename(tempname, filename)

   135     except os.error, msg:

   136         err('%s: rename failed (%r)\n' % (filename, msg))

   137         return 1

   138     # Return succes

   139     return 0

   140 

   141 def fixline(line):

   142     if not line.startswith('#!'):

   143         return line

   144     if "python" not in line:

   145         return line

   146     return '#! %s\n' % new_interpreter

   147 

   148 if __name__ == '__main__':

   149     main()