lib/pty-session: add generic PTY container code

The idea is to consolidate script(1), scriptlive(1) and su(1) --pty
and use the same code everywhere.

TODO: add callbacks for stdin/out logging (necessary for script(1)).

Signed-off-by: Karel Zak <kzak@redhat.com>

configure.ac

@@ -391,6 +391,7 @@ have_security_openpam_h=$ac_cv_header_security_openpam_h
 have_shadow_h=$ac_cv_header_shadow_h
 have_sys_signalfd_h=$ac_cv_header_sys_signalfd_h
 have_utmpx_h=$ac_cv_header_utmpx_h
+have_pty_h=$ac_cv_header_pty_h
 
 AS_CASE([$linux_os:$have_linux_version_h],
   [yes:no],
@@ -743,6 +744,12 @@ AS_IF([test "x$with_util" = xno], [
   UL_CHECK_LIB([util], [openpty])
 ])
 
+AS_IF([test "x$have_pty_h" = xyes -a "x$have_sys_signalfd_h" = xyes -a "x$have_util" = xyes], [
+   AM_CONDITIONAL([HAVE_PTY], [true])
+   AC_DEFINE([HAVE_PTY], [1], [have PTY support])
+], [
+   AM_CONDITIONAL([HAVE_PTY], [false])
+])
 
 AC_CHECK_TYPES([union semun], [], [], [[
 #include <sys/sem.h>

include/pty-session.h

@@ -0,0 +1,53 @@
+/*
+ * This code is in the public domain; do with it what you wish.
+ *
+ * Written by Karel Zak <kzak@redhat.com> in Jul 2019
+ */
+#ifndef UTIL_LINUX_PTY_SESSION_H
+#define UTIL_LINUX_PTY_SESSION_H
+
+#include <pty.h>
+#include <termios.h>
+#include <signal.h>
+
+struct ul_pty_callbacks {
+	void (*child_wait)(void *);
+	void (*child_sigstop)(void *);
+};
+
+struct ul_pty {
+	struct termios	stdin_attrs;	/* stdin and slave terminal runtime attributes */
+	int		master;		/* parent side */
+	int		slave;		/* child side */
+	int		sigfd;		/* signalfd() */
+	int		poll_timeout;
+	struct winsize	win;		/* terminal window size */
+	sigset_t	orgsig;		/* original signal mask */
+
+	int		delivered_signal;
+
+	struct ul_pty_callbacks	callbacks;
+	void			*callback_data;
+
+	pid_t		child;
+
+	unsigned int isterm:1;		/* is stdin terminal? */
+};
+
+void ul_pty_init_debug(int mask);
+struct ul_pty *ul_new_pty(int is_stdin_tty);
+
+sigset_t *ul_pty_get_orig_sigset(struct ul_pty *pty);
+int ul_pty_get_delivered_signal(struct ul_pty *pty);
+
+void ul_pty_set_callback_data(struct ul_pty *pty, void *data);
+void ul_pty_set_child(struct ul_pty *pty, pid_t child);
+
+struct ul_pty_callbacks *ul_pty_get_callbacks(struct ul_pty *pty);
+int ul_pty_is_running(struct ul_pty *pty);
+int ul_pty_setup(struct ul_pty *pty);
+void ul_pty_cleanup(struct ul_pty *pty);
+void ul_pty_init_slave(struct ul_pty *pty);
+int ul_pty_proxy_master(struct ul_pty *pty);
+
+#endif /* UTIL_LINUX_PTY_H */

lib/Makemodule.am

@@ -88,7 +88,6 @@ check_PROGRAMS += \
 	test_timeutils
 
 
-
 if LINUX
 if HAVE_CPU_SET_T
 check_PROGRAMS += test_cpuset
@@ -144,6 +143,14 @@ test_path_LDADD = $(LDADD)
 endif
 endif
 
+if HAVE_PTY
+check_PROGRAMS += test_pty
+test_pty_SOURCES = lib/pty-session.c \
+		   include/pty-session.h
+test_pty_CFLAGS = $(AM_CFLAGS) -DTEST_PROGRAM_PTY
+test_pty_LDADD = $(LDADD) libcommon.la -lutil
+endif
+
 if LINUX
 test_cpuset_SOURCES = lib/cpuset.c
 test_cpuset_CFLAGS = $(AM_CFLAGS) -DTEST_PROGRAM_CPUSET