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Re: SIGHUP on pty closure


On 7/21/2011 11:43 PM, Marco atzeri wrote:
looking on the mc subshell issue, I found that mc
suppose that the subshell will receive a SIGHUP
when mc exit and close the master side of pty.

Is such assumption wrong or it is a missing piece of
cygwin pty implementation ?



------------- extract from subshell.c --------------
/* Attach all our standard file descriptors to the pty */

/* This is done just before the fork, because stderr must still */
/* be connected to the real tty during the above error messages; */
/* otherwise the user will never see them. */

dup2 (subshell_pty_slave, STDIN_FILENO);
dup2 (subshell_pty_slave, STDOUT_FILENO);
dup2 (subshell_pty_slave, STDERR_FILENO);

close (subshell_pipe[READ]);
close (subshell_pty_slave); /* These may be FD_CLOEXEC, but just in
case... */
/* Close master side of pty. This is important; apart from */
/* freeing up the descriptor for use in the subshell, it also */
/* means that when MC exits, the subshell will get a SIGHUP and */
/* exit too, because there will be no more descriptors pointing */
/* at the master side of the pty and so it will disappear. */
close (subshell_pty);

/* Execute the subshell at last */

switch (subshell_type)
{
case BASH:
execl (shell, "bash", "-rcfile", init_file, (char *) NULL);
break;
----------------------------------------------------------

It seems that mc is correct in the expectation.


http://pubs.opengroup.org/onlinepubs/9699919799/functions/close.html

"If fildes refers to the master side of a pseudo-terminal, and this is the last close, a SIGHUP signal shall be sent to the controlling process, if any, for which the slave side of the pseudo-terminal is the controlling terminal. It is unspecified whether closing the master side of the pseudo-terminal flushes all queued input and output."


I don't find such implementation on cygwin


fhandler_pty_master::close ()

Am I looking in the wrong place ?

Regards
Marco


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