Tools/scripts/pathfix.py

   1 #!/usr/bin/env python3
   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 as 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.encode()
  47     if not new_interpreter or not new_interpreter.startswith(b'/') or \
  48            not args:
  49         err('-i option or file-or-directory missing\n')
  50         err(usage)
  51         sys.exit(2)
  52     bad = 0
  53     for arg in args:
  54         if os.path.isdir(arg):
  55             if recursedown(arg): bad = 1
  56         elif os.path.islink(arg):
  57             err(arg + ': will not process symbolic links\n')
  58             bad = 1
  59         else:
  60             if fix(arg): bad = 1
  61     sys.exit(bad)
  62
  63 ispythonprog = re.compile('^[a-zA-Z0-9_]+\.py$')
  64 def ispython(name):
  65     return bool(ispythonprog.match(name))
  66
  67 def recursedown(dirname):
  68     dbg('recursedown(%r)\n' % (dirname,))
  69     bad = 0
  70     try:
  71         names = os.listdir(dirname)
  72     except os.error as msg:
  73         err('%s: cannot list directory: %r\n' % (dirname, msg))
  74         return 1
  75     names.sort()
  76     subdirs = []
  77     for name in names:
  78         if name in (os.curdir, os.pardir): continue
  79         fullname = os.path.join(dirname, name)
  80         if os.path.islink(fullname): pass
  81         elif os.path.isdir(fullname):
  82             subdirs.append(fullname)
  83         elif ispython(name):
  84             if fix(fullname): bad = 1
  85     for fullname in subdirs:
  86         if recursedown(fullname): bad = 1
  87     return bad
  88
  89 def fix(filename):
  90 ##  dbg('fix(%r)\n' % (filename,))
  91     try:
  92         f = open(filename, 'rb')
  93     except IOError as msg:
  94         err('%s: cannot open: %r\n' % (filename, msg))
  95         return 1
  96     line = f.readline()
  97     fixed = fixline(line)
  98     if line == fixed:
  99         rep(filename+': no change\n')
 100         f.close()
 101         return
 102     head, tail = os.path.split(filename)
 103     tempname = os.path.join(head, '@' + tail)
 104     try:
 105         g = open(tempname, 'wb')
 106     except IOError as msg:
 107         f.close()
 108         err('%s: cannot create: %r\n' % (tempname, msg))
 109         return 1
 110     rep(filename + ': updating\n')
 111     g.write(fixed)
 112     BUFSIZE = 8*1024
 113     while 1:
 114         buf = f.read(BUFSIZE)
 115         if not buf: break
 116         g.write(buf)
 117     g.close()
 118     f.close()
 119
 120     # Finishing touch -- move files
 121
 122     # First copy the file's mode to the temp file
 123     try:
 124         statbuf = os.stat(filename)
 125         os.chmod(tempname, statbuf[ST_MODE] & 0o7777)
 126     except os.error as msg:
 127         err('%s: warning: chmod failed (%r)\n' % (tempname, msg))
 128     # Then make a backup of the original file as filename~
 129     try:
 130         os.rename(filename, filename + '~')
 131     except os.error as msg:
 132         err('%s: warning: backup failed (%r)\n' % (filename, msg))
 133     # Now move the temp file to the original file
 134     try:
 135         os.rename(tempname, filename)
 136     except os.error as msg:
 137         err('%s: rename failed (%r)\n' % (filename, msg))
 138         return 1
 139     # Return succes
 140     return 0
 141
 142 def fixline(line):
 143     if not line.startswith(b'#!'):
 144         return line
 145     if b"python" not in line:
 146         return line
 147     return b'#! ' + new_interpreter + b'\n'
 148
 149 if __name__ == '__main__':
 150     main()