On Thu, Dec 22, 2005 at 11:22:45PM +0100, Martin Costabel wrote:
> I am trying to understand why TeXmacs' shell plugin doesn't work on
> Tiger. This plugin is a simple binary executable compiled from the C++
> code I am attaching below. It is supposed to run /bin/sh as a child and
> run its stdin/out through the calling process. This works on OSX 10.3,
> but not on 10.4. What has changed on Tiger with respect to fork/pipes?
>
> If you compile the attached file tm_shell.cpp simply with
>
> g++ -o tm_shell tm_shell.cpp
>
> and then run ./tm_shell from the command line, it should just look like
> a new shell with a different prompt. This is also what happens on
> Panther. On Tiger, what happens is
>
> % ./tm_shell
> verbatim:Shell session inside TeXmacsverbatim:
> [1] + 21241 Suspended (tty input) ./tm_shell
>
> If I fg the process, it suspends itself immediately again. This is also
> what happens when one tries to run the shell plugin from within TeXmacs;
> the whole TeXmacs process gets suspended and has to be forcibly killed.
>
> It doesn't matter where the binary is compiled, on Panther or on Tiger,
> or with which version of g++. If the identical binary is run on Panther,
> it works; if it is run on Tiger, it doesn't.
>
> Does anyone see what is wrong with the code or why it wouldn't work on
> Tiger?
The bash in Tiger seems to stay in a loop ioctl'ing STDERR (duped to fd
255) and killing -21 (SIGTTIN) the processes it its group (including the
parent).
And killing the main process makes sh consume all cpu.
Using socketpair instead of two pipes makes it work.
Even with shell_output = for (;;); the main process still receives
SIGTTIN, so I guess it's a bug in bash.
--
lfr
0/0
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