Lib/posixfile.py

   1 #
   2 # Start of posixfile.py
   3 #
   4
   5 #
   6 # Extended file operations
   7 #
   8 # f = posixfile.open(filename, [mode, [bufsize]])
   9 #       will create a new posixfile object
  10 #
  11 # f = posixfile.fileopen(fileobject)
  12 #       will create a posixfile object from a builtin file object
  13 #
  14 # f.file()
  15 #       will return the original builtin file object
  16 #
  17 # f.dup()
  18 #       will return a new file object based on a new filedescriptor
  19 #
  20 # f.dup2(fd)
  21 #       will return a new file object based on the given filedescriptor
  22 #
  23 # f.flags(mode)
  24 #       will turn on the associated flag (merge)
  25 #       mode can contain the following characters:
  26 #
  27 #   (character representing a flag)
  28 #       a       append only flag
  29 #       c       close on exec flag
  30 #       n       no delay flag
  31 #       s       synchronization flag
  32 #   (modifiers)
  33 #       !       turn flags 'off' instead of default 'on'
  34 #       =       copy flags 'as is' instead of default 'merge'
  35 #       ?       return a string in which the characters represent the flags
  36 #               that are set
  37 #
  38 #       note: - the '!' and '=' modifiers are mutually exclusive.
  39 #             - the '?' modifier will return the status of the flags after they
  40 #               have been changed by other characters in the mode string
  41 #
  42 # f.lock(mode [, len [, start [, whence]]])
  43 #       will (un)lock a region
  44 #       mode can contain the following characters:
  45 #
  46 #   (character representing type of lock)
  47 #       u       unlock
  48 #       r       read lock
  49 #       w       write lock
  50 #   (modifiers)
  51 #       |       wait until the lock can be granted
  52 #       ?       return the first lock conflicting with the requested lock
  53 #               or 'None' if there is no conflict. The lock returned is in the
  54 #               format (mode, len, start, whence, pid) where mode is a
  55 #               character representing the type of lock ('r' or 'w')
  56 #
  57 #       note: - the '?' modifier prevents a region from being locked; it is
  58 #               query only
  59 #
  60
  61 class _posixfile_:
  62     states = ['open', 'closed']
  63
  64     #
  65     # Internal routines
  66     #
  67     def __repr__(self):
  68         file = self._file_
  69         return "<%s posixfile '%s', mode '%s' at %s>" % \
  70                 (self.states[file.closed], file.name, file.mode, \
  71                  hex(id(self))[2:])
  72
  73     def __del__(self):
  74         self._file_.close()
  75
  76     #
  77     # Initialization routines
  78     #
  79     def open(self, name, mode='r', bufsize=-1):
  80         import __builtin__
  81         return self.fileopen(__builtin__.open(name, mode, bufsize))
  82
  83     def fileopen(self, file):
  84         if `type(file)` != "<type 'file'>":
  85             raise TypeError, 'posixfile.fileopen() arg must be file object'
  86         self._file_  = file
  87         # Copy basic file methods
  88         for method in file.__methods__:
  89             setattr(self, method, getattr(file, method))
  90         return self
  91
  92     #
  93     # New methods
  94     #
  95     def file(self):
  96         return self._file_
  97
  98     def dup(self):
  99         import posix
 100
 101         try: ignore = posix.fdopen
 102         except: raise AttributeError, 'dup() method unavailable'
 103
 104         return posix.fdopen(posix.dup(self._file_.fileno()), self._file_.mode)
 105
 106     def dup2(self, fd):
 107         import posix
 108
 109         try: ignore = posix.fdopen
 110         except: raise AttributeError, 'dup() method unavailable'
 111
 112         posix.dup2(self._file_.fileno(), fd)
 113         return posix.fdopen(fd, self._file_.mode)
 114
 115     def flags(self, *which):
 116         import fcntl, FCNTL
 117
 118         if which:
 119             if len(which) > 1:
 120                 raise TypeError, 'Too many arguments'
 121             which = which[0]
 122         else: which = '?'
 123
 124         l_flags = 0
 125         if 'n' in which: l_flags = l_flags | FCNTL.O_NDELAY
 126         if 'a' in which: l_flags = l_flags | FCNTL.O_APPEND
 127         if 's' in which: l_flags = l_flags | FCNTL.O_SYNC
 128
 129         file = self._file_
 130
 131         if '=' not in which:
 132             cur_fl = fcntl.fcntl(file.fileno(), FCNTL.F_GETFL, 0)
 133             if '!' in which: l_flags = cur_fl & ~ l_flags
 134             else: l_flags = cur_fl | l_flags
 135
 136         l_flags = fcntl.fcntl(file.fileno(), FCNTL.F_SETFL, l_flags)
 137
 138         if 'c' in which:
 139             arg = ('!' not in which)    # 0 is don't, 1 is do close on exec
 140             l_flags = fcntl.fcntl(file.fileno(), FCNTL.F_SETFD, arg)
 141
 142         if '?' in which:
 143             which = ''                  # Return current flags
 144             l_flags = fcntl.fcntl(file.fileno(), FCNTL.F_GETFL, 0)
 145             if FCNTL.O_APPEND & l_flags: which = which + 'a'
 146             if fcntl.fcntl(file.fileno(), FCNTL.F_GETFD, 0) & 1:
 147                 which = which + 'c'
 148             if FCNTL.O_NDELAY & l_flags: which = which + 'n'
 149             if FCNTL.O_SYNC & l_flags: which = which + 's'
 150             return which
 151
 152     def lock(self, how, *args):
 153         import struct, fcntl, FCNTL
 154
 155         if 'w' in how: l_type = FCNTL.F_WRLCK
 156         elif 'r' in how: l_type = FCNTL.F_RDLCK
 157         elif 'u' in how: l_type = FCNTL.F_UNLCK
 158         else: raise TypeError, 'no type of lock specified'
 159
 160         if '|' in how: cmd = FCNTL.F_SETLKW
 161         elif '?' in how: cmd = FCNTL.F_GETLK
 162         else: cmd = FCNTL.F_SETLK
 163
 164         l_whence = 0
 165         l_start = 0
 166         l_len = 0
 167
 168         if len(args) == 1:
 169             l_len = args[0]
 170         elif len(args) == 2:
 171             l_len, l_start = args
 172         elif len(args) == 3:
 173             l_len, l_start, l_whence = args
 174         elif len(args) > 3:
 175             raise TypeError, 'too many arguments'
 176
 177         # Hack by davem@magnet.com to get locking to go on freebsd;
 178         # additions for AIX by Vladimir.Marangozov@imag.fr
 179         import sys, os
 180         if sys.platform in ('netbsd1', 'freebsd2', 'freebsd3'):
 181             flock = struct.pack('lxxxxlxxxxlhh', \
 182                   l_start, l_len, os.getpid(), l_type, l_whence)
 183         elif sys.platform in ['aix3', 'aix4']:
 184             flock = struct.pack('hhlllii', \
 185                   l_type, l_whence, l_start, l_len, 0, 0, 0)
 186         else:
 187             flock = struct.pack('hhllhh', \
 188                   l_type, l_whence, l_start, l_len, 0, 0)
 189
 190         flock = fcntl.fcntl(self._file_.fileno(), cmd, flock)
 191
 192         if '?' in how:
 193             if sys.platform in ('netbsd1', 'freebsd2', 'freebsd3'):
 194                 l_start, l_len, l_pid, l_type, l_whence = \
 195                     struct.unpack('lxxxxlxxxxlhh', flock)
 196             elif sys.platform in ['aix3', 'aix4']:
 197                 l_type, l_whence, l_start, l_len, l_sysid, l_pid, l_vfs = \
 198                     struct.unpack('hhlllii', flock)
 199             elif sys.platform == "linux2":
 200                 l_type, l_whence, l_start, l_len, l_pid, l_sysid = \
 201                     struct.unpack('hhllhh', flock)
 202             else:
 203                 l_type, l_whence, l_start, l_len, l_sysid, l_pid = \
 204                     struct.unpack('hhllhh', flock)
 205
 206             if l_type != FCNTL.F_UNLCK:
 207                 if l_type == FCNTL.F_RDLCK:
 208                     return 'r', l_len, l_start, l_whence, l_pid
 209                 else:
 210                     return 'w', l_len, l_start, l_whence, l_pid
 211
 212 #
 213 # Public routine to obtain a posixfile object
 214 #
 215 def open(name, mode='r', bufsize=-1):
 216     return _posixfile_().open(name, mode, bufsize)
 217
 218 def fileopen(file):
 219     return _posixfile_().fileopen(file)
 220
 221 #
 222 # Constants
 223 #
 224 SEEK_SET = 0
 225 SEEK_CUR = 1
 226 SEEK_END = 2
 227
 228 #
 229 # End of posixfile.py
 230 #