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fix a problem that the standard streams are unexpectedly closed

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In the current implementation, the slave PTY (assigned to the variable
`s') is always closed after duplicating it to file descriptors of
standard streams (0, 1, and 2).  However, when the allocated slave PTY
`s' is already one of 0, 1, or 2, this causes unexpected closing of a
standard stream.  The same problem occurs when the file descriptor of
the master PTY (the variable `m') is one of 0, 1, or 2.

In this patch, the original master PTY (m) is closed before it would
be overwritten by duplicated slave PTYs.  The original slave PTY (s)
is closed only when it is not one of the stanrad streams.
This commit is contained in:
Koichi Murase 2021-08-24 06:25:05 +09:00 • committed by Sergey Silaev
parent 302f26f48c
commit 85d4f7e7cd
1 changed files with 3 additions and 2 deletions
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5
st.c
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@ -804,14 +804,15 @@ ttynew(char *line, char *cmd, char *out, char **args)
break;
case 0:
close(iofd);
close(m);
setsid(); /* create a new process group */
dup2(s, 0);
dup2(s, 1);
dup2(s, 2);
if (ioctl(s, TIOCSCTTY, NULL) < 0)
die("ioctl TIOCSCTTY failed: %s\n", strerror(errno));
close(s);
close(m);
if (s > 2)
close(s);
#ifdef __OpenBSD__
if (pledge("stdio getpw proc exec", NULL) == -1)
die("pledge\n");