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putty-source/unix/pty.c
Ben Harris 09095a7d92 Avoid treating non-X GDK display names as X ones 
When running on Wayland, gdk_display_get_name() can return things like
"wayland-0" rather than valid X display names.  PuTTY nonetheless
treated them as X display names, meaning that when running under
Wayland, pterm would set DISPLAY to "wayland-0" in subprocesses, and
PuTTY's X forwarding wouldn't work properly.

To fix this, places that call gdk_display_get_name() now only do so on
displays for which GDK_IS_X_DISPLAY() is true.  As with
GDK_IS_X_WINDOW(), this requires some backward-compatibility for GDK
versions where everything is implicitly running on X.

To make this work usefully, pterm now also won't unset DISPLAY if it
can't get an X display name and instead will pass through whatever value
of DISPLAY it received.  I think that's better behaviour anyway.

There are two separate parts of PuTTY that call gdk_display_get_name().
platform_get_x_display() in unix/putty.c is used for X forwarding, while
gtk_seat_get_x_display() in unix/window.c is used used for setting DISPLAY
and recording in utmp.  I've updated both of them.
2024-12-15 00:07:21 +00:00

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/*
* Pseudo-tty backend for pterm.
*/
#define _GNU_SOURCE
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <signal.h>
#include <assert.h>
#include <fcntl.h>
#include <termios.h>
#include <grp.h>
#if HAVE_UTMP_H
#include <utmp.h>
#endif
#include <pwd.h>
#include <time.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <sys/wait.h>
#include <sys/ioctl.h>
#include <errno.h>
#include <termios.h>
#include "putty.h"
#include "ssh.h"
#include "ssh/server.h" /* to check the prototypes of server-needed things */
#include "tree234.h"
#ifndef OMIT_UTMP
#include <utmpx.h>
#endif
/* updwtmpx() needs the name of the wtmp file. Try to find it. */
#ifndef WTMPX_FILE
#ifdef _PATH_WTMPX
#define WTMPX_FILE _PATH_WTMPX
#else
#define WTMPX_FILE "/var/log/wtmpx"
#endif
#endif
#ifndef LASTLOG_FILE
#ifdef _PATH_LASTLOG
#define LASTLOG_FILE _PATH_LASTLOG
#else
#define LASTLOG_FILE "/var/log/lastlog"
#endif
#endif
typedef struct Pty Pty;
/*
* The pty_signal_pipe, along with the SIGCHLD handler, must be
* process-global rather than session-specific.
*/
static int pty_signal_pipe[2] = { -1, -1 }; /* obviously bogus initial val */
typedef struct PtyFd {
int fd;
Pty *pty;
} PtyFd;
struct Pty {
Conf *conf;
int master_fd, slave_fd;
int pipefds[6];
PtyFd fds[3];
int master_i, master_o, master_e;
Seat *seat;
size_t output_backlog;
char name[FILENAME_MAX];
pid_t child_pid;
int term_width, term_height;
bool child_dead, finished;
int exit_code;
bufchain output_data;
bool pending_eof;
Backend backend;
};
#define PTY_MAX_BACKLOG 32768
/*
* We store all the (active) PtyFd structures in a tree sorted by fd,
* so that when we get an uxsel notification we know which backend
* instance is the owner of the pty that caused it, and then we can
* find out which fd is the relevant one too.
*/
static int ptyfd_compare(void *av, void *bv)
{
PtyFd *a = (PtyFd *)av;
PtyFd *b = (PtyFd *)bv;
if (a->fd < b->fd)
return -1;
else if (a->fd > b->fd)
return +1;
return 0;
}
static int ptyfd_find(void *av, void *bv)
{
int a = *(int *)av;
PtyFd *b = (PtyFd *)bv;
if (a < b->fd)
return -1;
else if (a > b->fd)
return +1;
return 0;
}
static tree234 *ptyfds = NULL;
/*
* We also have a tree of Pty structures themselves, sorted by child
* pid, so that when we wait() in response to the signal we know which
* backend instance is the owner of the process that caused the
* signal.
*/
static int pty_compare_by_pid(void *av, void *bv)
{
Pty *a = (Pty *)av;
Pty *b = (Pty *)bv;
if (a->child_pid < b->child_pid)
return -1;
else if (a->child_pid > b->child_pid)
return +1;
return 0;
}
static int pty_find_by_pid(void *av, void *bv)
{
pid_t a = *(pid_t *)av;
Pty *b = (Pty *)bv;
if (a < b->child_pid)
return -1;
else if (a > b->child_pid)
return +1;
return 0;
}
static tree234 *ptys_by_pid = NULL;
/*
* If we are using pty_pre_init(), it will need to have already
* allocated a pty structure, which we must then return from
* pty_init() rather than allocating a new one. Here we store that
* structure between allocation and use.
*
* Note that although most of this module is entirely capable of
* handling multiple ptys in a single process, pty_pre_init() is
* fundamentally _dependent_ on there being at most one pty per
* process, so the normal static-data constraints don't apply.
*
* Likewise, since utmp is only used via pty_pre_init, it too must
* be single-instance, so we can declare utmp-related variables
* here.
*/
static Pty *single_pty = NULL;
#ifndef OMIT_UTMP
static pid_t pty_utmp_helper_pid = -1;
static int pty_utmp_helper_pipe = -1;
static bool pty_stamped_utmp;
static struct utmpx utmp_entry;
#endif
/*
* pty_argv is a grievous hack to allow a proper argv to be passed
* through from the Unix command line. Again, it doesn't really
* make sense outside a one-pty-per-process setup.
*/
char **pty_argv;
char *pty_osx_envrestore_prefix;
static void pty_close(Pty *pty);
static void pty_try_write(Pty *pty);
#ifndef OMIT_UTMP
static void setup_utmp(char *ttyname, char *location)
{
#if HAVE_LASTLOG
struct lastlog lastlog_entry;
FILE *lastlog;
#endif
struct passwd *pw;
struct timeval tv;
pw = getpwuid(getuid());
if (!pw)
return; /* can't stamp utmp if we don't have a username */
memset(&utmp_entry, 0, sizeof(utmp_entry));
utmp_entry.ut_type = USER_PROCESS;
utmp_entry.ut_pid = getpid();
#if __GNUC__ >= 8
# pragma GCC diagnostic push
# pragma GCC diagnostic ignored "-Wstringop-truncation"
#endif // __GNUC__ >= 8
strncpy(utmp_entry.ut_line, ttyname+5, lenof(utmp_entry.ut_line));
strncpy(utmp_entry.ut_id, ttyname+8, lenof(utmp_entry.ut_id));
strncpy(utmp_entry.ut_user, pw->pw_name, lenof(utmp_entry.ut_user));
strncpy(utmp_entry.ut_host, location, lenof(utmp_entry.ut_host));
#if __GNUC__ >= 8
# pragma GCC diagnostic pop
#endif // __GNUC__ >= 8
/*
* Apparently there are some architectures where (struct
* utmpx).ut_tv is not essentially struct timeval (e.g. Linux
* amd64). Hence the temporary.
*/
gettimeofday(&tv, NULL);
utmp_entry.ut_tv.tv_sec = tv.tv_sec;
utmp_entry.ut_tv.tv_usec = tv.tv_usec;
setutxent();
pututxline(&utmp_entry);
endutxent();
#if HAVE_UPDWTMPX
/* Reportedly, AIX 5.1 has <utmpx.h> and pututxline(), but no
* updwtmpx(). */
updwtmpx(WTMPX_FILE, &utmp_entry);
#endif
#if HAVE_LASTLOG
memset(&lastlog_entry, 0, sizeof(lastlog_entry));
strncpy(lastlog_entry.ll_line, ttyname+5, lenof(lastlog_entry.ll_line));
strncpy(lastlog_entry.ll_host, location, lenof(lastlog_entry.ll_host));
time(&lastlog_entry.ll_time);
if ((lastlog = fopen(LASTLOG_FILE, "r+")) != NULL) {
fseek(lastlog, sizeof(lastlog_entry) * getuid(), SEEK_SET);
fwrite(&lastlog_entry, 1, sizeof(lastlog_entry), lastlog);
fclose(lastlog);
}
#endif
pty_stamped_utmp = true;
}
static void cleanup_utmp(void)
{
struct timeval tv;
if (!pty_stamped_utmp)
return;
utmp_entry.ut_type = DEAD_PROCESS;
memset(utmp_entry.ut_user, 0, lenof(utmp_entry.ut_user));
gettimeofday(&tv, NULL);
utmp_entry.ut_tv.tv_sec = tv.tv_sec;
utmp_entry.ut_tv.tv_usec = tv.tv_usec;
#if HAVE_UPDWTMPX
updwtmpx(WTMPX_FILE, &utmp_entry);
#endif
memset(utmp_entry.ut_line, 0, lenof(utmp_entry.ut_line));
utmp_entry.ut_tv.tv_sec = 0;
utmp_entry.ut_tv.tv_usec = 0;
setutxent();
pututxline(&utmp_entry);
endutxent();
pty_stamped_utmp = false; /* ensure we never double-cleanup */
}
#endif
static void sigchld_handler(int signum)
{
if (write(pty_signal_pipe[1], "x", 1) <= 0)
/* not much we can do about it */;
}
static void pty_setup_sigchld_handler(void)
{
static bool setup = false;
if (!setup) {
putty_signal(SIGCHLD, sigchld_handler);
setup = true;
}
}
#ifndef OMIT_UTMP
static void fatal_sig_handler(int signum)
{
putty_signal(signum, SIG_DFL);
cleanup_utmp();
raise(signum);
}
#endif
static int pty_open_slave(Pty *pty)
{
if (pty->slave_fd < 0) {
pty->slave_fd = open(pty->name, O_RDWR);
cloexec(pty->slave_fd);
}
return pty->slave_fd;
}
static void pty_open_master(Pty *pty)
{
#ifdef BSD_PTYS
const char chars1[] = "pqrstuvwxyz";
const char chars2[] = "0123456789abcdef";
const char *p1, *p2;
char master_name[20];
struct group *gp;
for (p1 = chars1; *p1; p1++)
for (p2 = chars2; *p2; p2++) {
sprintf(master_name, "/dev/pty%c%c", *p1, *p2);
pty->master_fd = open(master_name, O_RDWR);
if (pty->master_fd >= 0) {
if (geteuid() == 0 ||
access(master_name, R_OK | W_OK) == 0) {
/*
* We must also check at this point that we are
* able to open the slave side of the pty. We
* wouldn't want to allocate the wrong master,
* get all the way down to forking, and _then_
* find we're unable to open the slave.
*/
strcpy(pty->name, master_name);
pty->name[5] = 't'; /* /dev/ptyXX -> /dev/ttyXX */
cloexec(pty->master_fd);
if (pty_open_slave(pty) >= 0 &&
access(pty->name, R_OK | W_OK) == 0)
goto got_one;
if (pty->slave_fd > 0)
close(pty->slave_fd);
pty->slave_fd = -1;
}
close(pty->master_fd);
}
}
/* If we get here, we couldn't get a tty at all. */
fprintf(stderr, "pterm: unable to open a pseudo-terminal device\n");
exit(1);
got_one:
/* We need to chown/chmod the /dev/ttyXX device. */
gp = getgrnam("tty");
chown(pty->name, getuid(), gp ? gp->gr_gid : -1);
chmod(pty->name, 0600);
#else
const int flags = O_RDWR
#ifdef O_NOCTTY
| O_NOCTTY
#endif
;
#if HAVE_POSIX_OPENPT
#ifdef SET_NONBLOCK_VIA_OPENPT
/*
* OS X, as of 10.10 at least, doesn't permit me to set O_NONBLOCK
* on pty master fds via the usual fcntl mechanism. Fortunately,
* it does let me work around this by adding O_NONBLOCK to the
* posix_openpt flags parameter, which isn't a documented use of
* the API but seems to work. So we'll do that for now.
*/
pty->master_fd = posix_openpt(flags | O_NONBLOCK);
#else
pty->master_fd = posix_openpt(flags);
#endif
if (pty->master_fd < 0) {
perror("posix_openpt");
exit(1);
}
#else
pty->master_fd = open("/dev/ptmx", flags);
if (pty->master_fd < 0) {
perror("/dev/ptmx: open");
exit(1);
}
#endif
if (grantpt(pty->master_fd) < 0) {
perror("grantpt");
exit(1);
}
if (unlockpt(pty->master_fd) < 0) {
perror("unlockpt");
exit(1);
}
cloexec(pty->master_fd);
pty->name[FILENAME_MAX-1] = '\0';
strncpy(pty->name, ptsname(pty->master_fd), FILENAME_MAX-1);
#endif
#ifndef SET_NONBLOCK_VIA_OPENPT
nonblock(pty->master_fd);
#endif
}
static Pty *new_pty_struct(void)
{
Pty *pty = snew(Pty);
memset(pty, 0, sizeof(Pty));
pty->conf = NULL;
pty->pending_eof = false;
bufchain_init(&pty->output_data);
return pty;
}
/*
* Pre-initialisation. This is here to get around the fact that GTK
* doesn't like being run in setuid/setgid programs (probably
* sensibly). So before we initialise GTK - and therefore before we
* even process the command line - we check to see if we're running
* set[ug]id. If so, we open our pty master _now_, chown it as
* necessary, and drop privileges. We can always close it again
* later. If we're potentially going to be doing utmp as well, we
* also fork off a utmp helper process and communicate with it by
* means of a pipe; the utmp helper will keep privileges in order
* to clean up utmp when we exit (i.e. when its end of our pipe
* closes).
*/
void pty_pre_init(void)
{
#ifndef NO_PTY_PRE_INIT
Pty *pty;
#ifndef OMIT_UTMP
pid_t pid;
int pipefd[2];
#endif
pty = single_pty = new_pty_struct();
/* set the child signal handler straight away; it needs to be set
* before we ever fork. */
pty_setup_sigchld_handler();
pty->master_fd = pty->slave_fd = -1;
#ifndef OMIT_UTMP
pty_stamped_utmp = false;
#endif
if (geteuid() != getuid() || getegid() != getgid()) {
pty_open_master(pty);
#ifndef OMIT_UTMP
/*
* Fork off the utmp helper.
*/
if (pipe(pipefd) < 0) {
perror("pterm: pipe");
exit(1);
}
cloexec(pipefd[0]);
cloexec(pipefd[1]);
pid = fork();
if (pid < 0) {
perror("pterm: fork");
exit(1);
} else if (pid == 0) {
char display[128], buffer[128];
int dlen, ret;
close(pipefd[1]);
/*
* Now sit here until we receive a display name from the
* other end of the pipe, and then stamp utmp. Unstamp utmp
* again, and exit, when the pipe closes.
*/
dlen = 0;
while (1) {
ret = read(pipefd[0], buffer, lenof(buffer));
if (ret <= 0) {
cleanup_utmp();
_exit(0);
} else if (!pty_stamped_utmp) {
if (dlen < lenof(display))
memcpy(display+dlen, buffer,
min(ret, lenof(display)-dlen));
if (buffer[ret-1] == '\0') {
/*
* Now we have a display name. NUL-terminate
* it, and stamp utmp.
*/
display[lenof(display)-1] = '\0';
/*
* Trap as many fatal signals as we can in the
* hope of having the best possible chance to
* clean up utmp before termination. We are
* unfortunately unprotected against SIGKILL,
* but that's life.
*/
putty_signal(SIGHUP, fatal_sig_handler);
putty_signal(SIGINT, fatal_sig_handler);
putty_signal(SIGQUIT, fatal_sig_handler);
putty_signal(SIGILL, fatal_sig_handler);
putty_signal(SIGABRT, fatal_sig_handler);
putty_signal(SIGFPE, fatal_sig_handler);
putty_signal(SIGPIPE, fatal_sig_handler);
putty_signal(SIGALRM, fatal_sig_handler);
putty_signal(SIGTERM, fatal_sig_handler);
putty_signal(SIGSEGV, fatal_sig_handler);
putty_signal(SIGUSR1, fatal_sig_handler);
putty_signal(SIGUSR2, fatal_sig_handler);
#ifdef SIGBUS
putty_signal(SIGBUS, fatal_sig_handler);
#endif
#ifdef SIGPOLL
putty_signal(SIGPOLL, fatal_sig_handler);
#endif
#ifdef SIGPROF
putty_signal(SIGPROF, fatal_sig_handler);
#endif
#ifdef SIGSYS
putty_signal(SIGSYS, fatal_sig_handler);
#endif
#ifdef SIGTRAP
putty_signal(SIGTRAP, fatal_sig_handler);
#endif
#ifdef SIGVTALRM
putty_signal(SIGVTALRM, fatal_sig_handler);
#endif
#ifdef SIGXCPU
putty_signal(SIGXCPU, fatal_sig_handler);
#endif
#ifdef SIGXFSZ
putty_signal(SIGXFSZ, fatal_sig_handler);
#endif
#ifdef SIGIO
putty_signal(SIGIO, fatal_sig_handler);
#endif
setup_utmp(pty->name, display);
}
}
}
} else {
close(pipefd[0]);
pty_utmp_helper_pid = pid;
pty_utmp_helper_pipe = pipefd[1];
}
#endif
}
/* Drop privs. */
{
#if HAVE_SETRESUID && HAVE_SETRESGID
int gid = getgid(), uid = getuid();
int setresgid(gid_t, gid_t, gid_t);
int setresuid(uid_t, uid_t, uid_t);
if (setresgid(gid, gid, gid) < 0) {
perror("setresgid");
exit(1);
}
if (setresuid(uid, uid, uid) < 0) {
perror("setresuid");
exit(1);
}
#else
if (setgid(getgid()) < 0) {
perror("setgid");
exit(1);
}
if (setuid(getuid()) < 0) {
perror("setuid");
exit(1);
}
#endif
}
#endif /* NO_PTY_PRE_INIT */
}
static void pty_try_wait(void);
static void pty_uxsel_setup(Pty *pty);
static void pty_real_select_result(Pty *pty, int fd, int event, int status)
{
char buf[4096];
int ret;
bool finished = false;
if (event < 0) {
/*
* We've been called because our child process did
* something. `status' tells us what.
*/
if ((WIFEXITED(status) || WIFSIGNALED(status))) {
/*
* The primary child process died.
*/
pty->child_dead = true;
del234(ptys_by_pid, pty);
pty->exit_code = status;
/*
* If this is an ordinary pty session, this is also the
* moment to terminate the whole backend.
*
* We _could_ instead keep the terminal open for remaining
* subprocesses to output to, but conventional wisdom
* seems to feel that that's the Wrong Thing for an
* xterm-alike, so we bail out now (though we don't
* necessarily _close_ the window, depending on the state
* of Close On Exit). This would be easy enough to change
* or make configurable if necessary.
*/
if (pty->master_fd >= 0)
finished = true;
}
} else {
if (event == SELECT_R) {
bool is_stdout = (fd == pty->master_o);
ret = read(fd, buf, sizeof(buf));
/*
* Treat EIO on a pty master as equivalent to EOF (because
* that's how the kernel seems to report the event where
* the last process connected to the other end of the pty
* went away).
*/
if (fd == pty->master_fd && ret < 0 && errno == EIO)
ret = 0;
if (ret == 0) {
/*
* EOF on this input fd, so to begin with, we may as
* well close it, and remove all references to it in
* the pty's fd fields.
*/
uxsel_del(fd);
close(fd);
if (pty->master_fd == fd)
pty->master_fd = -1;
if (pty->master_o == fd)
pty->master_o = -1;
if (pty->master_e == fd)
pty->master_e = -1;
if (is_stdout) {
/*
* We assume a clean exit if the pty (or stdout
* pipe) has closed, but the actual child process
* hasn't. The only way I can imagine this
* happening is if it detaches itself from the pty
* and goes daemonic - in which case the expected
* usage model would precisely _not_ be for the
* pterm window to hang around!
*/
finished = true;
pty_try_wait(); /* one last effort to collect exit code */
if (!pty->child_dead)
pty->exit_code = 0;
}
} else if (ret < 0) {
perror("read pty master");
exit(1);
} else if (ret > 0) {
pty->output_backlog = seat_output(
pty->seat, !is_stdout, buf, ret);
pty_uxsel_setup(pty);
}
} else if (event == SELECT_W) {
/*
* Attempt to send data down the pty.
*/
pty_try_write(pty);
}
}
if (finished && !pty->finished) {
int close_on_exit;
int i;
for (i = 0; i < 3; i++)
if (pty->fds[i].fd >= 0)
uxsel_del(pty->fds[i].fd);
pty_close(pty);
pty->finished = true;
/*
* This is a slight layering-violation sort of hack: only
* if we're not closing on exit (COE is set to Never, or to
* Only On Clean and it wasn't a clean exit) do we output a
* `terminated' message.
*/
close_on_exit = conf_get_int(pty->conf, CONF_close_on_exit);
if (close_on_exit == FORCE_OFF ||
(close_on_exit == AUTO && pty->exit_code != 0)) {
char *message;
if (WIFEXITED(pty->exit_code)) {
message = dupprintf(
"\r\n[pterm: process terminated with exit code %d]\r\n",
WEXITSTATUS(pty->exit_code));
} else if (WIFSIGNALED(pty->exit_code)) {
#if !HAVE_STRSIGNAL
message = dupprintf(
"\r\n[pterm: process terminated on signal %d]\r\n",
WTERMSIG(pty->exit_code));
#else
message = dupprintf(
"\r\n[pterm: process terminated on signal %d (%s)]\r\n",
WTERMSIG(pty->exit_code),
strsignal(WTERMSIG(pty->exit_code)));
#endif
} else {
/* _Shouldn't_ happen, but if it does, a vague message
* is better than no message at all */
message = dupprintf("\r\n[pterm: process terminated]\r\n");
}
seat_stdout_pl(pty->seat, ptrlen_from_asciz(message));
sfree(message);
}
seat_eof(pty->seat);
seat_notify_remote_exit(pty->seat);
}
}
static void pty_try_wait(void)
{
Pty *pty;
pid_t pid;
int status;
do {
pid = waitpid(-1, &status, WNOHANG);
pty = find234(ptys_by_pid, &pid, pty_find_by_pid);
if (pty)
pty_real_select_result(pty, -1, -1, status);
} while (pid > 0);
}
void pty_select_result(int fd, int event)
{
if (fd == pty_signal_pipe[0]) {
char c[1];
if (read(pty_signal_pipe[0], c, 1) <= 0)
/* ignore error */;
/* ignore its value; it'll be `x' */
pty_try_wait();
} else {
PtyFd *ptyfd = find234(ptyfds, &fd, ptyfd_find);
if (ptyfd)
pty_real_select_result(ptyfd->pty, fd, event, 0);
}
}
static void pty_uxsel_setup_fd(Pty *pty, int fd)
{
int rwx = 0;
if (fd < 0)
return;
/* read from standard output and standard error pipes, assuming
* we're not too backlogged */
if ((pty->master_o == fd || pty->master_e == fd) &&
pty->output_backlog < PTY_MAX_BACKLOG)
rwx |= SELECT_R;
/* write to standard input pipe if we have any data */
if (pty->master_i == fd && bufchain_size(&pty->output_data))
rwx |= SELECT_W;
uxsel_set(fd, rwx, pty_select_result);
}
static void pty_uxsel_setup(Pty *pty)
{
/*
* We potentially have three separate fds here, but on the other
* hand, some of them might be the same (if they're a pty master).
* So we can't just call uxsel_set(master_o, SELECT_R) and then
* uxsel_set(master_i, SELECT_W), without the latter potentially
* undoing the work of the former if master_o == master_i.
*
* Instead, here we call a single uxsel on each one of these fds
* (if it exists at all), and for each one, check it against all
* three to see which bits to set.
*/
pty_uxsel_setup_fd(pty, pty->master_o);
pty_uxsel_setup_fd(pty, pty->master_e);
pty_uxsel_setup_fd(pty, pty->master_i);
/*
* In principle this only needs calling once for all pty
* backend instances, but it's simplest just to call it every
* time; uxsel won't mind.
*/
uxsel_set(pty_signal_pipe[0], SELECT_R, pty_select_result);
}
static void copy_ttymodes_into_termios(
struct termios *attrs, struct ssh_ttymodes modes)
{
#define TTYMODE_CHAR(name, ssh_opcode, cc_index) { \
if (modes.have_mode[ssh_opcode]) { \
unsigned value = modes.mode_val[ssh_opcode]; \
/* normalise wire value of 255 to local _POSIX_VDISABLE */ \
attrs->c_cc[cc_index] = (value == 255 ? \
_POSIX_VDISABLE : value); \
} \
}
#define TTYMODE_FLAG(flagval, ssh_opcode, field, flagmask) { \
if (modes.have_mode[ssh_opcode]) { \
attrs->c_##field##flag &= ~flagmask; \
if (modes.mode_val[ssh_opcode]) \
attrs->c_##field##flag |= flagval; \
} \
}
#define TTYMODES_LOCAL_ONLY /* omit any that this platform doesn't know */
#include "ssh/ttymode-list.h"
#undef TTYMODES_LOCAL_ONLY
#undef TTYMODE_CHAR
#undef TTYMODE_FLAG
if (modes.have_mode[TTYMODE_ISPEED])
cfsetispeed(attrs, modes.mode_val[TTYMODE_ISPEED]);
if (modes.have_mode[TTYMODE_OSPEED])
cfsetospeed(attrs, modes.mode_val[TTYMODE_OSPEED]);
}
/*
* The main setup function for the pty back end. This doesn't match
* the signature of backend_init(), partly because it has to be able
* to take extra arguments such as an argv array, and also because
* once we're changing the type signature _anyway_ we can discard the
* stuff that's not really applicable to this backend like host names
* and port numbers.
*/
Backend *pty_backend_create(
Seat *seat, LogContext *logctx, Conf *conf, char **argv, const char *cmd,
struct ssh_ttymodes ttymodes, bool pipes_instead, const char *dir,
const char *const *env_vars_to_unset)
{
int slavefd;
pid_t pid, pgrp;
#ifndef NOT_X_WINDOWS /* for Mac OS X native compilation */
bool got_windowid;
long windowid;
#endif
Pty *pty;
int i;
/* No local authentication phase in this protocol */
seat_set_trust_status(seat, false);
if (single_pty) {
pty = single_pty;
assert(pty->conf == NULL);
} else {
pty = new_pty_struct();
pty->master_fd = pty->slave_fd = -1;
#ifndef OMIT_UTMP
pty_stamped_utmp = false;
#endif
}
for (i = 0; i < 6; i++)
pty->pipefds[i] = -1;
for (i = 0; i < 3; i++) {
pty->fds[i].fd = -1;
pty->fds[i].pty = pty;
}
if (pty_signal_pipe[0] < 0) {
if (pipe(pty_signal_pipe) < 0) {
perror("pipe");
exit(1);
}
cloexec(pty_signal_pipe[0]);
cloexec(pty_signal_pipe[1]);
}
pty->seat = seat;
pty->backend.vt = &pty_backend;
pty->conf = conf_copy(conf);
pty->term_width = conf_get_int(conf, CONF_width);
pty->term_height = conf_get_int(conf, CONF_height);
if (!ptyfds)
ptyfds = newtree234(ptyfd_compare);
if (pipes_instead) {
if (pty->master_fd >= 0) {
/* If somehow we've got a pty master already and don't
* need it, throw it away! */
close(pty->master_fd);
#ifndef OMIT_UTMP
if (pty_utmp_helper_pipe >= 0) {
close(pty_utmp_helper_pipe); /* don't need this either */
pty_utmp_helper_pipe = -1;
}
#endif
}
for (i = 0; i < 6; i += 2) {
if (pipe(pty->pipefds + i) < 0) {
backend_free(&pty->backend);
return NULL;
}
}
pty->fds[0].fd = pty->master_i = pty->pipefds[1];
pty->fds[1].fd = pty->master_o = pty->pipefds[2];
pty->fds[2].fd = pty->master_e = pty->pipefds[4];
add234(ptyfds, &pty->fds[0]);
add234(ptyfds, &pty->fds[1]);
add234(ptyfds, &pty->fds[2]);
} else {
if (pty->master_fd < 0)
pty_open_master(pty);
#ifndef OMIT_UTMP
/*
* Stamp utmp (that is, tell the utmp helper process to do so),
* or not.
*/
if (pty_utmp_helper_pipe >= 0) { /* if it's < 0, we can't anyway */
if (!conf_get_bool(conf, CONF_stamp_utmp)) {
/* We're not stamping utmp, so just let the child
* process die that was waiting to unstamp it later. */
close(pty_utmp_helper_pipe);
pty_utmp_helper_pipe = -1;
} else {
const char *location = seat_get_x_display(pty->seat);
int len = strlen(location)+1, pos = 0; /* +1 to include NUL */
while (pos < len) {
int ret = write(pty_utmp_helper_pipe,
location + pos, len - pos);
if (ret < 0) {
perror("pterm: writing to utmp helper process");
close(pty_utmp_helper_pipe); /* arrgh, just give up */
pty_utmp_helper_pipe = -1;
break;
}
pos += ret;
}
}
}
#endif
pty->master_i = pty->master_fd;
pty->master_o = pty->master_fd;
pty->master_e = -1;
pty->fds[0].fd = pty->master_fd;
add234(ptyfds, &pty->fds[0]);
}
#ifndef NOT_X_WINDOWS /* for Mac OS X native compilation */
got_windowid = seat_get_windowid(pty->seat, &windowid);
#endif
/*
* Set up the signal handler to catch SIGCHLD, if pty_pre_init
* didn't already do it.
*/
pty_setup_sigchld_handler();
/*
* Fork and execute the command.
*/
pid = fork();
if (pid < 0) {
perror("fork");
exit(1);
}
if (pid == 0) {
struct termios attrs;
/*
* We are the child.
*/
if (pty_osx_envrestore_prefix) {
int plen = strlen(pty_osx_envrestore_prefix);
extern char **environ;
char **ep;
restart_osx_env_restore:
for (ep = environ; *ep; ep++) {
char *e = *ep;
if (!strncmp(e, pty_osx_envrestore_prefix, plen)) {
bool unset = (e[plen] == 'u');
char *pname = dupprintf("%.*s", (int)strcspn(e, "="), e);
char *name = pname + plen + 1;
char *value = e + strcspn(e, "=");
if (*value) value++;
value = dupstr(value);
if (unset)
unsetenv(name);
else
setenv(name, value, 1);
unsetenv(pname);
sfree(pname);
sfree(value);
goto restart_osx_env_restore;
}
}
}
pgrp = getpid();
if (pipes_instead) {
int i;
dup2(pty->pipefds[0], 0);
dup2(pty->pipefds[3], 1);
dup2(pty->pipefds[5], 2);
for (i = 0; i < 6; i++)
close(pty->pipefds[i]);
setsid();
} else {
slavefd = pty_open_slave(pty);
if (slavefd < 0) {
perror("slave pty: open");
_exit(1);
}
close(pty->master_fd);
noncloexec(slavefd);
dup2(slavefd, 0);
dup2(slavefd, 1);
dup2(slavefd, 2);
close(slavefd);
setsid();
#ifdef TIOCSCTTY
ioctl(0, TIOCSCTTY, 1);
#endif
tcsetpgrp(0, pgrp);
/*
* Set up configuration-dependent termios settings on the new
* pty. Linux would have let us do this on the pty master
* before we forked, but that fails on OS X, so we do it here
* instead.
*/
if (tcgetattr(0, &attrs) == 0) {
/*
* Set the backspace character to be whichever of ^H and
* ^? is specified by bksp_is_delete.
*/
attrs.c_cc[VERASE] = conf_get_bool(conf, CONF_bksp_is_delete)
? '\177' : '\010';
/*
* Set the IUTF8 bit iff the character set is UTF-8.
*/
#ifdef IUTF8
if (seat_is_utf8(seat))
attrs.c_iflag |= IUTF8;
else
attrs.c_iflag &= ~IUTF8;
#endif
copy_ttymodes_into_termios(&attrs, ttymodes);
tcsetattr(0, TCSANOW, &attrs);
}
}
setpgid(pgrp, pgrp);
if (!pipes_instead) {
int ptyfd = open(pty->name, O_WRONLY, 0);
if (ptyfd >= 0)
close(ptyfd);
}
setpgid(pgrp, pgrp);
if (env_vars_to_unset)
for (const char *const *p = env_vars_to_unset; *p; p++)
unsetenv(*p);
if (!pipes_instead) {
char *term_env_var = dupprintf("TERM=%s",
conf_get_str(conf, CONF_termtype));
putenv(term_env_var);
/* We mustn't free term_env_var, as putenv links it into the
* environment in place.
*/
}
#ifndef NOT_X_WINDOWS /* for Mac OS X native compilation */
if (got_windowid) {
char *windowid_env_var = dupprintf("WINDOWID=%ld", windowid);
putenv(windowid_env_var);
/* We mustn't free windowid_env_var, as putenv links it into the
* environment in place.
*/
}
{
/*
* In case we were invoked with a --display argument that
* doesn't match DISPLAY in our actual environment, we
* should set DISPLAY for processes running inside the
* terminal to match the display the terminal itself is
* on.
*/
const char *x_display = seat_get_x_display(pty->seat);
if (x_display) {
char *x_display_env_var = dupprintf("DISPLAY=%s", x_display);
putenv(x_display_env_var);
/* As above, we don't free this. */
}
}
#endif
{
char *key, *val;
for (val = conf_get_str_strs(conf, CONF_environmt, NULL, &key);
val != NULL;
val = conf_get_str_strs(conf, CONF_environmt, key, &key)) {
char *varval = dupcat(key, "=", val);
putenv(varval);
/*
* We must not free varval, since putenv links it
* into the environment _in place_. Weird, but
* there we go. Memory usage will be rationalised
* as soon as we exec anyway.
*/
}
}
if (dir) {
if (chdir(dir) < 0) {
/* Ignore the error - nothing we can sensibly do about it,
* and our existing cwd is as good a fallback as any. */
}
}
/*
* SIGINT, SIGQUIT and SIGPIPE may have been set to ignored by
* our parent, particularly by things like sh -c 'pterm &' and
* some window or session managers. SIGPIPE was also
* (potentially) blocked by us during startup. Reverse all
* this for our child process.
*/
putty_signal(SIGINT, SIG_DFL);
putty_signal(SIGQUIT, SIG_DFL);
putty_signal(SIGPIPE, SIG_DFL);
block_signal(SIGPIPE, false);
if (argv || cmd) {
/*
* If we were given a separated argument list, try to exec
* it.
*/
if (argv) {
execvp(argv[0], argv);
}
/*
* Otherwise, if we were given a single command string,
* try passing that to $SHELL -c.
*
* In the case of pterm, this system of fallbacks arranges
* that we can _either_ follow 'pterm -e' with a list of
* argv elements to be fed directly to exec, _or_ with a
* single argument containing a command to be parsed by a
* shell (but, in cases of doubt, the former is more
* reliable). We arrange this by setting argv to the full
* argument list, and also setting cmd to the single
* element of argv if it's a length-1 list.
*
* A quick survey of other terminal emulators' -e options
* (as of Debian squeeze) suggests that:
*
* - xterm supports both modes, more or less like this
* - gnome-terminal will only accept a one-string shell command
* - Eterm, kterm and rxvt will only accept a list of
* argv elements (as did older versions of pterm).
*
* It therefore seems important to support both usage
* modes in order to be a drop-in replacement for either
* xterm or gnome-terminal, and hence for anyone's
* plausible uses of the Debian-style alias
* 'x-terminal-emulator'.
*
* In other use cases, a caller can set only one of argv
* and cmd to get a fixed handling of the input.
*/
if (cmd) {
char *shell = getenv("SHELL");
if (shell)
execl(shell, shell, "-c", cmd, (void *)NULL);
}
} else {
const char *shell = getenv("SHELL");
if (!shell)
shell = "/bin/sh";
char *shellname;
if (conf_get_bool(conf, CONF_login_shell)) {
const char *p = strrchr(shell, '/');
p = p ? p+1 : shell;
shellname = dupprintf("-%s", p);
} else
shellname = (char *)shell;
execl(shell, shellname, (void *)NULL);
}
/*
* If we're here, exec has gone badly foom.
*/
perror("exec");
_exit(127);
} else {
pty->child_pid = pid;
pty->child_dead = false;
pty->finished = false;
if (pty->slave_fd > 0)
close(pty->slave_fd);
if (!ptys_by_pid)
ptys_by_pid = newtree234(pty_compare_by_pid);
if (pty->pipefds[0] >= 0) {
close(pty->pipefds[0]);
pty->pipefds[0] = -1;
}
if (pty->pipefds[3] >= 0) {
close(pty->pipefds[3]);
pty->pipefds[3] = -1;
}
if (pty->pipefds[5] >= 0) {
close(pty->pipefds[5]);
pty->pipefds[5] = -1;
}
add234(ptys_by_pid, pty);
}
pty_uxsel_setup(pty);
return &pty->backend;
}
/*
* This is the pty backend's _official_ init method, for BackendVtable
* purposes. Its job is just to be an API converter, ignoring the
* irrelevant input parameters and making up auxiliary outputs. Also
* it gets the argv array from the global variable pty_argv, expecting
* that it will have been invoked by pterm.
*/
static char *pty_init(const BackendVtable *vt, Seat *seat,
Backend **backend_handle, LogContext *logctx,
Conf *conf, const char *host, int port,
char **realhost, bool nodelay, bool keepalive)
{
const char *cmd = NULL;
struct ssh_ttymodes modes;
memset(&modes, 0, sizeof(modes));
if (pty_argv && pty_argv[0] && !pty_argv[1])
cmd = pty_argv[0];
assert(vt == &pty_backend);
*backend_handle = pty_backend_create(
seat, logctx, conf, pty_argv, cmd, modes, false, NULL, NULL);
*realhost = dupstr("");
return NULL;
}
static void pty_reconfig(Backend *be, Conf *conf)
{
Pty *pty = container_of(be, Pty, backend);
/*
* We don't have much need to reconfigure this backend, but
* unfortunately we do need to pick up the setting of Close On
* Exit so we know whether to give a `terminated' message.
*/
conf_copy_into(pty->conf, conf);
}
/*
* Stub routine (never called in pterm).
*/
static void pty_free(Backend *be)
{
Pty *pty = container_of(be, Pty, backend);
int i;
pty_close(pty);
/* Either of these may fail `not found'. That's fine with us. */
del234(ptys_by_pid, pty);
for (i = 0; i < 3; i++)
if (pty->fds[i].fd >= 0)
del234(ptyfds, &pty->fds[i]);
bufchain_clear(&pty->output_data);
conf_free(pty->conf);
pty->conf = NULL;
if (pty == single_pty) {
/*
* Leave this structure around in case we need to Restart
* Session.
*/
} else {
sfree(pty);
}
}
static void pty_try_write(Pty *pty)
{
ssize_t ret;
assert(pty->master_i >= 0);
while (bufchain_size(&pty->output_data) > 0) {
ptrlen data = bufchain_prefix(&pty->output_data);
ret = write(pty->master_i, data.ptr, data.len);
if (ret < 0 && (errno == EWOULDBLOCK)) {
/*
* We've sent all we can for the moment.
*/
break;
}
if (ret < 0) {
perror("write pty master");
exit(1);
}
bufchain_consume(&pty->output_data, ret);
}
if (pty->pending_eof && bufchain_size(&pty->output_data) == 0) {
/* This should only happen if pty->master_i is a pipe that
* doesn't alias either output fd */
assert(pty->master_i != pty->master_o);
assert(pty->master_i != pty->master_e);
uxsel_del(pty->master_i);
close(pty->master_i);
pty->master_i = -1;
pty->pending_eof = false;
}
pty_uxsel_setup(pty);
}
/*
* Called to send data down the pty.
*/
static void pty_send(Backend *be, const char *buf, size_t len)
{
Pty *pty = container_of(be, Pty, backend);
if (pty->master_i < 0 || pty->pending_eof)
return; /* ignore all writes if fd closed */
bufchain_add(&pty->output_data, buf, len);
pty_try_write(pty);
}
static void pty_close(Pty *pty)
{
int i;
if (pty->master_o >= 0)
uxsel_del(pty->master_o);
if (pty->master_e >= 0)
uxsel_del(pty->master_e);
if (pty->master_i >= 0)
uxsel_del(pty->master_i);
if (pty->master_fd >= 0) {
close(pty->master_fd);
pty->master_fd = -1;
}
for (i = 0; i < 6; i++) {
if (pty->pipefds[i] >= 0)
close(pty->pipefds[i]);
pty->pipefds[i] = -1;
}
pty->master_i = pty->master_o = pty->master_e = -1;
#ifndef OMIT_UTMP
if (pty_utmp_helper_pipe >= 0) {
close(pty_utmp_helper_pipe); /* this causes utmp to be cleaned up */
pty_utmp_helper_pipe = -1;
}
#endif
}
/*
* Called to query the current socket sendability status.
*/
static size_t pty_sendbuffer(Backend *be)
{
Pty *pty = container_of(be, Pty, backend);
return bufchain_size(&pty->output_data);
}
/*
* Called to set the size of the window
*/
static void pty_size(Backend *be, int width, int height)
{
Pty *pty = container_of(be, Pty, backend);
struct winsize size;
int xpixel = 0, ypixel = 0;
pty->term_width = width;
pty->term_height = height;
if (pty->master_fd < 0)
return;
seat_get_window_pixel_size(pty->seat, &xpixel, &ypixel);
size.ws_row = (unsigned short)pty->term_height;
size.ws_col = (unsigned short)pty->term_width;
size.ws_xpixel = (unsigned short)xpixel;
size.ws_ypixel = (unsigned short)ypixel;
ioctl(pty->master_fd, TIOCSWINSZ, (void *)&size);
return;
}
/*
* Send special codes.
*/
static void pty_special(Backend *be, SessionSpecialCode code, int arg)
{
Pty *pty = container_of(be, Pty, backend);
if (code == SS_BRK) {
if (pty->master_fd >= 0)
tcsendbreak(pty->master_fd, 0);
return;
}
if (code == SS_EOF) {
if (pty->master_i >= 0 && pty->master_i != pty->master_fd) {
pty->pending_eof = true;
pty_try_write(pty);
}
return;
}
{
int sig = -1;
#define SIGNAL_SUB(name) if (code == SS_SIG ## name) sig = SIG ## name;
#define SIGNAL_MAIN(name, text) SIGNAL_SUB(name)
#define SIGNALS_LOCAL_ONLY
#include "ssh/signal-list.h"
#undef SIGNAL_SUB
#undef SIGNAL_MAIN
#undef SIGNALS_LOCAL_ONLY
if (sig != -1) {
if (!pty->child_dead)
kill(pty->child_pid, sig);
return;
}
}
return;
}
/*
* Return a list of the special codes that make sense in this
* protocol.
*/
static const SessionSpecial *pty_get_specials(Backend *be)
{
/* Pty *pty = container_of(be, Pty, backend); */
/*
* Hmm. When I get round to having this actually usable, it
* might be quite nice to have the ability to deliver a few
* well chosen signals to the child process - SIGINT, SIGTERM,
* SIGKILL at least.
*/
return NULL;
}
static bool pty_connected(Backend *be)
{
/* Pty *pty = container_of(be, Pty, backend); */
return true;
}
static bool pty_sendok(Backend *be)
{
/* Pty *pty = container_of(be, Pty, backend); */
return true;
}
static void pty_unthrottle(Backend *be, size_t backlog)
{
Pty *pty = container_of(be, Pty, backend);
pty->output_backlog = backlog;
pty_uxsel_setup(pty);
}
static bool pty_ldisc(Backend *be, int option)
{
/* Pty *pty = container_of(be, Pty, backend); */
return false; /* neither editing nor echoing */
}
static void pty_provide_ldisc(Backend *be, Ldisc *ldisc)
{
/* Pty *pty = container_of(be, Pty, backend); */
/* This is a stub. */
}
static int pty_exitcode(Backend *be)
{
Pty *pty = container_of(be, Pty, backend);
if (!pty->finished)
return -1; /* not dead yet */
else if (WIFSIGNALED(pty->exit_code))
return 128 + WTERMSIG(pty->exit_code);
else
return WEXITSTATUS(pty->exit_code);
}
int pty_backend_exit_signum(Backend *be)
{
Pty *pty = container_of(be, Pty, backend);
if (!pty->finished || !WIFSIGNALED(pty->exit_code))
return -1;
return WTERMSIG(pty->exit_code);
}
ptrlen pty_backend_exit_signame(Backend *be, char **aux_msg)
{
*aux_msg = NULL;
int sig = pty_backend_exit_signum(be);
if (sig < 0)
return PTRLEN_LITERAL("");
#define SIGNAL_SUB(s) { \
if (sig == SIG ## s) \
return PTRLEN_LITERAL(#s); \
}
#define SIGNAL_MAIN(s, desc) SIGNAL_SUB(s)
#define SIGNALS_LOCAL_ONLY
#include "ssh/signal-list.h"
#undef SIGNAL_MAIN
#undef SIGNAL_SUB
#undef SIGNALS_LOCAL_ONLY
*aux_msg = dupprintf("untranslatable signal number %d: %s",
sig, strsignal(sig));
return PTRLEN_LITERAL("HUP"); /* need some kind of default */
}
static int pty_cfg_info(Backend *be)
{
/* Pty *pty = container_of(be, Pty, backend); */
return 0;
}
const BackendVtable pty_backend = {
.init = pty_init,
.free = pty_free,
.reconfig = pty_reconfig,
.send = pty_send,
.sendbuffer = pty_sendbuffer,
.size = pty_size,
.special = pty_special,
.get_specials = pty_get_specials,
.connected = pty_connected,
.exitcode = pty_exitcode,
.sendok = pty_sendok,
.ldisc_option_state = pty_ldisc,
.provide_ldisc = pty_provide_ldisc,
.unthrottle = pty_unthrottle,
.cfg_info = pty_cfg_info,
.id = "pty",
.displayname_tc = "pty",
.displayname_lc = "pty",
.protocol = -1,
};
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