2908 if pyplatform.python_implementation() == b'CPython' and sys.version_info < (

  2907 

  2909     3,

  2908 # TODO delete since workaround variant for Python 2 no longer needed.

  2910     0,

  2909 def iterfile(fp):

  2911 ):

  2910     return fp

  2912     # There is an issue in CPython that some IO methods do not handle EINTR

  2913     # correctly. The following table shows what CPython version (and functions)

  2914     # are affected (buggy: has the EINTR bug, okay: otherwise):

  2915     #

  2916     #                | < 2.7.4 | 2.7.4 to 2.7.12 | >= 3.0

  2917     #   --------------------------------------------------

  2918     #    fp.__iter__ | buggy   | buggy           | okay

  2919     #    fp.read*    | buggy   | okay [1]        | okay

  2920     #

  2921     # [1]: fixed by changeset 67dc99a989cd in the cpython hg repo.

  2922     #

  2923     # Here we workaround the EINTR issue for fileobj.__iter__. Other methods

  2924     # like "read*" work fine, as we do not support Python < 2.7.4.

  2925     #

  2926     # Although we can workaround the EINTR issue for fp.__iter__, it is slower:

  2927     # "for x in fp" is 4x faster than "for x in iter(fp.readline, '')" in

  2928     # CPython 2, because CPython 2 maintains an internal readahead buffer for

  2929     # fp.__iter__ but not other fp.read* methods.

  2930     #

  2931     # On modern systems like Linux, the "read" syscall cannot be interrupted

  2932     # when reading "fast" files like on-disk files. So the EINTR issue only

  2933     # affects things like pipes, sockets, ttys etc. We treat "normal" (S_ISREG)

  2934     # files approximately as "fast" files and use the fast (unsafe) code path,

  2935     # to minimize the performance impact.

  2936 

  2937     def iterfile(fp):

  2938         fastpath = True

  2939         if type(fp) is file:

  2940             fastpath = stat.S_ISREG(os.fstat(fp.fileno()).st_mode)

  2941         if fastpath:

  2942             return fp

  2943         else:

  2944             # fp.readline deals with EINTR correctly, use it as a workaround.

  2945             return iter(fp.readline, b'')

  2946 

  2947 

  2948 else:

  2949     # PyPy and CPython 3 do not have the EINTR issue thus no workaround needed.

  2950     def iterfile(fp):

  2951         return fp