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 preserve_timestamps = False 34 35 def main(): 36 global new_interpreter 37 global preserve_timestamps 38 usage = ('usage: %s -i /interpreter -p file-or-directory ...\n' % 39 sys.argv[0]) 40 try: 41 opts, args = getopt.getopt(sys.argv[1:], 'i:p') 42 except getopt.error as msg: 43 err(str(msg) + '\n') 44 err(usage) 45 sys.exit(2) 46 for o, a in opts: 47 if o == '-i': 48 new_interpreter = a.encode() 49 if o == '-p': 50 preserve_timestamps = True 51 if not new_interpreter or not new_interpreter.startswith(b'/') or \ 52 not args: 53 err('-i option or file-or-directory missing\n') 54 err(usage) 55 sys.exit(2) 56 bad = 0 57 for arg in args: 58 if os.path.isdir(arg): 59 if recursedown(arg): bad = 1 60 elif os.path.islink(arg): 61 err(arg + ': will not process symbolic links\n') 62 bad = 1 63 else: 64 if fix(arg): bad = 1 65 sys.exit(bad) 66 67 ispythonprog = re.compile(r'^[a-zA-Z0-9_]+\.py$') 68 def ispython(name): 69 return bool(ispythonprog.match(name)) 70 71 def recursedown(dirname): 72 dbg('recursedown(%r)\n' % (dirname,)) 73 bad = 0 74 try: 75 names = os.listdir(dirname) 76 except OSError as msg: 77 err('%s: cannot list directory: %r\n' % (dirname, msg)) 78 return 1 79 names.sort() 80 subdirs = [] 81 for name in names: 82 if name in (os.curdir, os.pardir): continue 83 fullname = os.path.join(dirname, name) 84 if os.path.islink(fullname): pass 85 elif os.path.isdir(fullname): 86 subdirs.append(fullname) 87 elif ispython(name): 88 if fix(fullname): bad = 1 89 for fullname in subdirs: 90 if recursedown(fullname): bad = 1 91 return bad 92 93 def fix(filename): 94 ## dbg('fix(%r)\n' % (filename,)) 95 try: 96 f = open(filename, 'rb') 97 except IOError as msg: 98 err('%s: cannot open: %r\n' % (filename, msg)) 99 return 1 100 line = f.readline() 101 fixed = fixline(line) 102 if line == fixed: 103 rep(filename+': no change\n') 104 f.close() 105 return 106 head, tail = os.path.split(filename) 107 tempname = os.path.join(head, '@' + tail) 108 try: 109 g = open(tempname, 'wb') 110 except IOError as msg: 111 f.close() 112 err('%s: cannot create: %r\n' % (tempname, msg)) 113 return 1 114 rep(filename + ': updating\n') 115 g.write(fixed) 116 BUFSIZE = 8*1024 117 while 1: 118 buf = f.read(BUFSIZE) 119 if not buf: break 120 g.write(buf) 121 g.close() 122 f.close() 123 124 # Finishing touch -- move files 125 126 mtime = None 127 atime = None 128 # First copy the file's mode to the temp file 129 try: 130 statbuf = os.stat(filename) 131 mtime = statbuf.st_mtime 132 atime = statbuf.st_atime 133 os.chmod(tempname, statbuf[ST_MODE] & 0o7777) 134 except OSError as msg: 135 err('%s: warning: chmod failed (%r)\n' % (tempname, msg)) 136 # Then make a backup of the original file as filename~ 137 try: 138 os.rename(filename, filename + '~') 139 except OSError as msg: 140 err('%s: warning: backup failed (%r)\n' % (filename, msg)) 141 # Now move the temp file to the original file 142 try: 143 os.rename(tempname, filename) 144 except OSError as msg: 145 err('%s: rename failed (%r)\n' % (filename, msg)) 146 return 1 147 if preserve_timestamps: 148 if atime and mtime: 149 try: 150 os.utime(filename, (atime, mtime)) 151 except OSError as msg: 152 err('%s: reset of timestamp failed (%r)\n' % (filename, msg)) 153 return 1 154 # Return success 155 return 0 156 157 def fixline(line): 158 if not line.startswith(b'#!'): 159 return line 160 if b"python" not in line: 161 return line 162 return b'#! ' + new_interpreter + b'\n' 163 164 if __name__ == '__main__': 165 main() 166
