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Re: Bash uses lseek while reading from serial device
- From: "Ross Ridge" <rridge at csclub dot uwaterloo dot ca>
- To: cygwin at cygwin dot com
- Date: Mon, 18 Aug 2014 22:39:53 -0400
- Subject: Re: Bash uses lseek while reading from serial device
- Authentication-results: sourceware.org; auth=none
Corinna Vinschen writes:
> On Linux isatty on a descriptor connected to serial line returns 0,
> on Cygwin it returned 1 so far. I fixed both problems here, isatty
> on a serial line returns 0 now, and lseek on serial (and, FWIW,
> sockets) don't simply return 0 anymore, but rather -1 with errno set
> to ESPIPE, as on Linux.
I'm not sure if Chet Ramey's suggestion that if isatty() returns 1
then bash is allowed to assume reads are newline-delimited is correct.
On Unix this would only be true if cannonical mode input processing was
enabled (icanon), and Cygwin stty reports that this mode is disabled
(-icanon) on serial devices. Or at least it used to, with the snapshot
DLL it now complains "/dev/ttyS0: Inappropriate ioctl for device".
For what its worth my tests on Linux shows that isatty() returns 1 on
a serial device, namely /dev/ttyS0. Which is what I would expect given
that serial devices have traditionally been synonymous with ttys on Unix.
> Ross, please give it a try.
The snapshot DLL solves the bug and the script runs without any data
being lost. Thanks for looking into this.
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