Commit 0eb4bba1 authored by simonmar's avatar simonmar
Browse files

[project @ 2000-05-11 13:15:38 by simonmar]

Don't open with O_NONBLOCK, instead open in blocking mode and set
O_NONBLOCK subsequently with fcntl().  This appears to fix the
problems with FIFOs.

Pick one of the following:

	- the semantics as implemented by Linux & Solaris is broken
	- the POSIX semantics is broken
	- our expectation that things should behave sensibly is unreasonable
parent 3baf7555
/*
* (c) The GRASP/AQUA Project, Glasgow University, 1994-1998
*
* $Id: openFile.c,v 1.16 2000/04/12 17:33:16 simonmar Exp $
* $Id: openFile.c,v 1.17 2000/05/11 13:15:38 simonmar Exp $
*
* openFile Runtime Support
*/
......@@ -94,22 +94,22 @@ openFile(StgByteArray file, StgInt how, StgInt binary)
switch (how) {
case OPENFILE_APPEND:
oflags = O_NONBLOCK | O_WRONLY | O_NOCTTY | O_APPEND;
oflags = O_WRONLY | O_NOCTTY | O_APPEND;
for_writing = 1;
flags |= FILEOBJ_WRITE;
break;
case OPENFILE_WRITE:
oflags = O_NONBLOCK | O_WRONLY | O_NOCTTY;
oflags = O_WRONLY | O_NOCTTY;
flags |= FILEOBJ_WRITE;
for_writing = 1;
break;
case OPENFILE_READ_ONLY:
oflags = O_NONBLOCK | O_RDONLY | O_NOCTTY;
oflags = O_RDONLY | O_NOCTTY;
flags |= FILEOBJ_READ;
for_writing = 0;
break;
case OPENFILE_READ_WRITE:
oflags = O_NONBLOCK | O_RDWR | O_NOCTTY;
oflags = O_RDWR | O_NOCTTY;
flags |= FILEOBJ_READ | FILEOBJ_WRITE;
for_writing = 1;
break;
......@@ -191,8 +191,17 @@ openFile(StgByteArray file, StgInt how, StgInt binary)
}
}
/* Make sure that we aren't looking at a directory */
/* Set non-blocking mode *after* the open. The reason is that
* when reading from a FIFO, if we open in non-blocking mode
* then any reads from the FIFO will return EOF straight away
* without waiting for a writing process. If we set O_NONBLOCK
* after doing the open, then we apparently get to wait for a
* writer. This broken behaviour has been observed on both Linux
* & Solaris. --SDM
*/
fcntl(fd, F_SETFL, oflags | O_NONBLOCK);
/* Make sure that we aren't looking at a directory */
while (fstat(fd, &sb) < 0) {
/* highly unlikely */
if (errno != EINTR) {
......
Markdown is supported
0% or .
You are about to add 0 people to the discussion. Proceed with caution.
Finish editing this message first!
Please register or to comment