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Fix "not a tty" bug on Solaris 10

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* configure.ac (PTY_OPEN): Define to plain 'open'
on SVR4-derived hosts, so that the O_CLOEXEC flag isn't set.
* src/process.c (allocate_pty): Set the O_CLOEXEC flag after
calling PTY_TTY_NAME_SPRINTF, for the benefit of SVR4-derived
hosts that call grantpt which does its work via a setuid subcommand
(Bug#19191, Bug#19927, Bug#20555, Bug#20686).
Also, set O_CLOEXEC even if PTY_OPEN is not defined, since it
seems relevant in that case too.
This commit is contained in:
Paul Eggert 2015-06-11 16:41:36 -07:00
parent 8d0efee90c
commit 32e53667a9
2 changed files with 17 additions and 12 deletions
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5
configure.ac
View file

@ -4397,14 +4397,17 @@ case $opsys in
;;
sol2* )
dnl On SysVr4, grantpt(3) forks a subprocess, so keep sigchld_handler()
dnl On SysVr4, grantpt(3) forks a subprocess, so do not use
dnl O_CLOEXEC when opening the pty, and keep the SIGCHLD handler
dnl from intercepting that death. If any child but grantpt's should die
dnl within, it should be caught after sigrelse(2).
AC_DEFINE(PTY_OPEN, [fd = open (pty_name, O_RDWR | O_NONBLOCK)])
AC_DEFINE(PTY_TTY_NAME_SPRINTF, [{ char *ptsname (int), *ptyname; int grantpt_result; sigset_t blocked; sigemptyset (&blocked); sigaddset (&blocked, SIGCHLD); pthread_sigmask (SIG_BLOCK, &blocked, 0); grantpt_result = grantpt (fd); pthread_sigmask (SIG_UNBLOCK, &blocked, 0); if (grantpt_result == -1 || unlockpt (fd) == -1 || !(ptyname = ptsname (fd))) { emacs_close (fd); return -1; } snprintf (pty_name, PTY_NAME_SIZE, "%s", ptyname); }])
;;
unixware )
dnl Comments are as per sol2*.
AC_DEFINE(PTY_OPEN, [fd = open (pty_name, O_RDWR | O_NONBLOCK)])
AC_DEFINE(PTY_TTY_NAME_SPRINTF, [{ char *ptsname (int), *ptyname; int grantpt_result; sigset_t blocked; sigemptyset (&blocked); sigaddset (&blocked, SIGCHLD); pthread_sigmask (SIG_BLOCK, &blocked, 0); grantpt_result = grantpt (fd); pthread_sigmask (SIG_UNBLOCK, &blocked, 0); if (grantpt_result == -1) fatal("could not grant slave pty"); if (unlockpt(fd) == -1) fatal("could not unlock slave pty"); if (!(ptyname = ptsname(fd))) fatal ("could not enable slave pty"); snprintf (pty_name, PTY_NAME_SIZE, "%s", ptyname); }])
;;
esac

24
src/process.c
View file

@ -658,22 +658,24 @@ allocate_pty (char pty_name[PTY_NAME_SIZE])
if (fd >= 0)
{
#ifdef PTY_OPEN
/* Set FD's close-on-exec flag. This is needed even if
PT_OPEN calls posix_openpt with O_CLOEXEC, since POSIX
doesn't require support for that combination.
Multithreaded platforms where posix_openpt ignores
O_CLOEXEC (or where PTY_OPEN doesn't call posix_openpt)
have a race condition between the PTY_OPEN and here. */
fcntl (fd, F_SETFD, FD_CLOEXEC);
#endif
/* Check to make certain that both sides are available
this avoids a nasty yet stupid bug in rlogins. */
#ifdef PTY_TTY_NAME_SPRINTF
PTY_TTY_NAME_SPRINTF
#else
sprintf (pty_name, "/dev/tty%c%x", c, i);
#endif /* no PTY_TTY_NAME_SPRINTF */
/* Set FD's close-on-exec flag. This is needed even if
PT_OPEN calls posix_openpt with O_CLOEXEC, since POSIX
doesn't require support for that combination.
Do this after PTY_TTY_NAME_SPRINTF, which on some platforms
doesn't work if the close-on-exec flag is set (Bug#20555).
Multithreaded platforms where posix_openpt ignores
O_CLOEXEC (or where PTY_OPEN doesn't call posix_openpt)
have a race condition between the PTY_OPEN and here. */
fcntl (fd, F_SETFD, FD_CLOEXEC);
/* Check to make certain that both sides are available.
This avoids a nasty yet stupid bug in rlogins. */
if (faccessat (AT_FDCWD, pty_name, R_OK | W_OK, AT_EACCESS) != 0)
{
emacs_close (fd);