Windows binary stdin goes EOF after \x1a character

Dan daniel.goertzen at gmail.com
Fri Oct 15 21:28:49 CEST 2010


I am writing a Windows program in Python 3.1.2 that reads binary data
from stdin.  Whenever it hits a \x1a character, stdin goes EOF and no
more data can be read.  A short program that exhibits this problem is:

#listing of main.pyw
import sys
def go():
    bb=sys.stdin.buffer.raw.read(10000)
    print(bb,file=sys.stderr)
    sys.stderr.flush()
go()
go()


The program is run as "pythonw.exe main.pyw"


When fed with a block of bytes equivalent to "bytes(range(1,255))",
the following output is observed...

b'\x01\x02\x03\x04\x05\x06\x07\x08\t\n\x0b\x0c\r\x0e\x0f
\x10\x11\x12\x13\x14\x15\x16\x17\x18\x19'
b''

...and according to the documentation, the empty bytes object means
EOF.

I wrote an equivalent program in C++ using the win32 ReadFile() call,
and it read all 255 bytes just fine.  What am I doing wrong with the
python code?


I am using Erlang to launch the Python program as a subprocess.  The
Erlang fragment that launches this and sends the data is:

    Port=open_port( {spawn_executable, "c:/Python31/pythonw.exe"},
		    [{args, ["c:/iotest/main.pyw"]}]),
    Port ! {self(),{command,lists:seq(1,255)}},


Thanks,
Dan.




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