Windows binary stdin goes EOF after \x1a character

[Dan]

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.

 

[Neil Cerutti]

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:

stdin is not in binary mode. Try invoking with -u option.

 

[Dan]

stdin is not in binary mode. Try invoking with -u option.

That worked, thanks!
Dan.