458 lines
16 KiB
C
458 lines
16 KiB
C
/*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/
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/***
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This file is part of systemd.
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Copyright 2010-2013 Lennart Poettering
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systemd is free software; you can redistribute it and/or modify it
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under the terms of the GNU Lesser General Public License as published by
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the Free Software Foundation; either version 2.1 of the License, or
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(at your option) any later version.
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systemd is distributed in the hope that it will be useful, but
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WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public License
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along with systemd; If not, see <http://www.gnu.org/licenses/>.
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***/
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#include <sys/epoll.h>
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#include <sys/signalfd.h>
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#include <sys/ioctl.h>
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#include <limits.h>
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#include <termios.h>
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#include "util.h"
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#include "ptyfwd.h"
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struct PTYForward {
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sd_event *event;
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int master;
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sd_event_source *stdin_event_source;
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sd_event_source *stdout_event_source;
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sd_event_source *master_event_source;
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sd_event_source *sigwinch_event_source;
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struct termios saved_stdin_attr;
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struct termios saved_stdout_attr;
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bool saved_stdin:1;
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bool saved_stdout:1;
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bool stdin_readable:1;
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bool stdin_hangup:1;
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bool stdout_writable:1;
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bool stdout_hangup:1;
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bool master_readable:1;
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bool master_writable:1;
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bool master_hangup:1;
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bool master_suppressed_hangup:1;
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bool repeat:1;
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bool last_char_set:1;
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char last_char;
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char in_buffer[LINE_MAX], out_buffer[LINE_MAX];
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size_t in_buffer_full, out_buffer_full;
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usec_t escape_timestamp;
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unsigned escape_counter;
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};
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#define ESCAPE_USEC (1*USEC_PER_SEC)
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static bool look_for_escape(PTYForward *f, const char *buffer, size_t n) {
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const char *p;
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assert(f);
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assert(buffer);
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assert(n > 0);
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for (p = buffer; p < buffer + n; p++) {
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/* Check for ^] */
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if (*p == 0x1D) {
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usec_t nw = now(CLOCK_MONOTONIC);
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if (f->escape_counter == 0 || nw > f->escape_timestamp + ESCAPE_USEC) {
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f->escape_timestamp = nw;
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f->escape_counter = 1;
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} else {
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(f->escape_counter)++;
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if (f->escape_counter >= 3)
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return true;
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}
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} else {
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f->escape_timestamp = 0;
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f->escape_counter = 0;
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}
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}
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return false;
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}
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static int shovel(PTYForward *f) {
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ssize_t k;
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assert(f);
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while ((f->stdin_readable && f->in_buffer_full <= 0) ||
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(f->master_writable && f->in_buffer_full > 0) ||
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(f->master_readable && f->out_buffer_full <= 0) ||
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(f->stdout_writable && f->out_buffer_full > 0)) {
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if (f->stdin_readable && f->in_buffer_full < LINE_MAX) {
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k = read(STDIN_FILENO, f->in_buffer + f->in_buffer_full, LINE_MAX - f->in_buffer_full);
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if (k < 0) {
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if (errno == EAGAIN)
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f->stdin_readable = false;
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else if (errno == EIO || errno == EPIPE || errno == ECONNRESET) {
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f->stdin_readable = false;
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f->stdin_hangup = true;
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f->stdin_event_source = sd_event_source_unref(f->stdin_event_source);
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} else {
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log_error_errno(errno, "read(): %m");
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return sd_event_exit(f->event, EXIT_FAILURE);
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}
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} else if (k == 0) {
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/* EOF on stdin */
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f->stdin_readable = false;
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f->stdin_hangup = true;
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f->stdin_event_source = sd_event_source_unref(f->stdin_event_source);
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} else {
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/* Check if ^] has been
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* pressed three times within
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* one second. If we get this
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* we quite immediately. */
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if (look_for_escape(f, f->in_buffer + f->in_buffer_full, k))
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return sd_event_exit(f->event, EXIT_FAILURE);
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f->in_buffer_full += (size_t) k;
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}
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}
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if (f->master_writable && f->in_buffer_full > 0) {
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k = write(f->master, f->in_buffer, f->in_buffer_full);
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if (k < 0) {
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if (errno == EAGAIN || errno == EIO)
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f->master_writable = false;
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else if (errno == EPIPE || errno == ECONNRESET) {
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f->master_writable = f->master_readable = false;
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f->master_hangup = true;
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f->master_event_source = sd_event_source_unref(f->master_event_source);
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} else {
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log_error_errno(errno, "write(): %m");
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return sd_event_exit(f->event, EXIT_FAILURE);
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}
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} else {
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assert(f->in_buffer_full >= (size_t) k);
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memmove(f->in_buffer, f->in_buffer + k, f->in_buffer_full - k);
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f->in_buffer_full -= k;
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}
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}
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if (f->master_readable && f->out_buffer_full < LINE_MAX) {
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k = read(f->master, f->out_buffer + f->out_buffer_full, LINE_MAX - f->out_buffer_full);
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if (k < 0) {
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if (errno == EAGAIN)
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f->master_readable = false;
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else if (errno == EIO && f->repeat) {
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/* Note that EIO on the master device
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* might be cause by vhangup() or
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* temporary closing of everything on
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* the other side, we treat it like
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* EAGAIN here and try again, unless
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* repeat is off. */
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f->master_readable = false;
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f->master_suppressed_hangup = true;
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} else if (errno == EPIPE || errno == ECONNRESET || errno == EIO) {
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f->master_readable = f->master_writable = false;
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f->master_hangup = true;
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f->master_event_source = sd_event_source_unref(f->master_event_source);
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} else {
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log_error_errno(errno, "read(): %m");
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return sd_event_exit(f->event, EXIT_FAILURE);
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}
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} else
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f->out_buffer_full += (size_t) k;
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}
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if (f->stdout_writable && f->out_buffer_full > 0) {
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k = write(STDOUT_FILENO, f->out_buffer, f->out_buffer_full);
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if (k < 0) {
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if (errno == EAGAIN)
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f->stdout_writable = false;
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else if (errno == EIO || errno == EPIPE || errno == ECONNRESET) {
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f->stdout_writable = false;
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f->stdout_hangup = true;
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f->stdout_event_source = sd_event_source_unref(f->stdout_event_source);
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} else {
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log_error_errno(errno, "write(): %m");
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return sd_event_exit(f->event, EXIT_FAILURE);
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}
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} else {
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if (k > 0) {
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f->last_char = f->out_buffer[k-1];
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f->last_char_set = true;
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}
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assert(f->out_buffer_full >= (size_t) k);
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memmove(f->out_buffer, f->out_buffer + k, f->out_buffer_full - k);
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f->out_buffer_full -= k;
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}
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}
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}
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if (f->stdin_hangup || f->stdout_hangup || f->master_hangup) {
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/* Exit the loop if any side hung up and if there's
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* nothing more to write or nothing we could write. */
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if ((f->out_buffer_full <= 0 || f->stdout_hangup) &&
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(f->in_buffer_full <= 0 || f->master_hangup))
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return sd_event_exit(f->event, EXIT_SUCCESS);
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}
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return 0;
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}
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static int on_master_event(sd_event_source *e, int fd, uint32_t revents, void *userdata) {
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PTYForward *f = userdata;
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assert(f);
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assert(e);
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assert(e == f->master_event_source);
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assert(fd >= 0);
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assert(fd == f->master);
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f->master_suppressed_hangup = false;
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if (revents & (EPOLLIN|EPOLLHUP))
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f->master_readable = true;
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if (revents & (EPOLLOUT|EPOLLHUP))
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f->master_writable = true;
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return shovel(f);
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}
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static int on_stdin_event(sd_event_source *e, int fd, uint32_t revents, void *userdata) {
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PTYForward *f = userdata;
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assert(f);
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assert(e);
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assert(e == f->stdin_event_source);
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assert(fd >= 0);
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assert(fd == STDIN_FILENO);
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if (revents & (EPOLLIN|EPOLLHUP))
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f->stdin_readable = true;
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return shovel(f);
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}
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static int on_stdout_event(sd_event_source *e, int fd, uint32_t revents, void *userdata) {
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PTYForward *f = userdata;
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assert(f);
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assert(e);
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assert(e == f->stdout_event_source);
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assert(fd >= 0);
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assert(fd == STDOUT_FILENO);
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if (revents & (EPOLLOUT|EPOLLHUP))
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f->stdout_writable = true;
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return shovel(f);
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}
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static int on_sigwinch_event(sd_event_source *e, const struct signalfd_siginfo *si, void *userdata) {
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PTYForward *f = userdata;
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struct winsize ws;
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assert(f);
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assert(e);
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assert(e == f->sigwinch_event_source);
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/* The window size changed, let's forward that. */
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if (ioctl(STDOUT_FILENO, TIOCGWINSZ, &ws) >= 0)
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(void)ioctl(f->master, TIOCSWINSZ, &ws);
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return 0;
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}
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int pty_forward_new(sd_event *event, int master, bool repeat, PTYForward **ret) {
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_cleanup_(pty_forward_freep) PTYForward *f = NULL;
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struct winsize ws;
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int r;
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f = new0(PTYForward, 1);
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if (!f)
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return -ENOMEM;
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f->repeat = repeat;
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if (event)
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f->event = sd_event_ref(event);
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else {
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r = sd_event_default(&f->event);
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if (r < 0)
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return r;
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}
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r = fd_nonblock(STDIN_FILENO, true);
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if (r < 0)
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return r;
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r = fd_nonblock(STDOUT_FILENO, true);
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if (r < 0)
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return r;
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r = fd_nonblock(master, true);
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if (r < 0)
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return r;
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f->master = master;
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if (ioctl(STDOUT_FILENO, TIOCGWINSZ, &ws) >= 0)
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(void)ioctl(master, TIOCSWINSZ, &ws);
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if (tcgetattr(STDIN_FILENO, &f->saved_stdin_attr) >= 0) {
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struct termios raw_stdin_attr;
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f->saved_stdin = true;
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raw_stdin_attr = f->saved_stdin_attr;
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cfmakeraw(&raw_stdin_attr);
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raw_stdin_attr.c_oflag = f->saved_stdin_attr.c_oflag;
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tcsetattr(STDIN_FILENO, TCSANOW, &raw_stdin_attr);
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}
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if (tcgetattr(STDOUT_FILENO, &f->saved_stdout_attr) >= 0) {
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struct termios raw_stdout_attr;
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f->saved_stdout = true;
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raw_stdout_attr = f->saved_stdout_attr;
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cfmakeraw(&raw_stdout_attr);
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raw_stdout_attr.c_iflag = f->saved_stdout_attr.c_iflag;
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raw_stdout_attr.c_lflag = f->saved_stdout_attr.c_lflag;
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tcsetattr(STDOUT_FILENO, TCSANOW, &raw_stdout_attr);
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}
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r = sd_event_add_io(f->event, &f->master_event_source, master, EPOLLIN|EPOLLOUT|EPOLLET, on_master_event, f);
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if (r < 0)
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return r;
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r = sd_event_add_io(f->event, &f->stdin_event_source, STDIN_FILENO, EPOLLIN|EPOLLET, on_stdin_event, f);
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if (r < 0 && r != -EPERM)
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return r;
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r = sd_event_add_io(f->event, &f->stdout_event_source, STDOUT_FILENO, EPOLLOUT|EPOLLET, on_stdout_event, f);
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if (r == -EPERM)
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/* stdout without epoll support. Likely redirected to regular file. */
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f->stdout_writable = true;
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else if (r < 0)
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return r;
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r = sd_event_add_signal(f->event, &f->sigwinch_event_source, SIGWINCH, on_sigwinch_event, f);
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*ret = f;
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f = NULL;
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return 0;
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}
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PTYForward *pty_forward_free(PTYForward *f) {
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if (f) {
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sd_event_source_unref(f->stdin_event_source);
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sd_event_source_unref(f->stdout_event_source);
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sd_event_source_unref(f->master_event_source);
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sd_event_unref(f->event);
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if (f->saved_stdout)
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tcsetattr(STDOUT_FILENO, TCSANOW, &f->saved_stdout_attr);
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if (f->saved_stdin)
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tcsetattr(STDIN_FILENO, TCSANOW, &f->saved_stdin_attr);
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free(f);
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}
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/* STDIN/STDOUT should not be nonblocking normally, so let's
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* unconditionally reset it */
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fd_nonblock(STDIN_FILENO, false);
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fd_nonblock(STDOUT_FILENO, false);
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return NULL;
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}
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int pty_forward_get_last_char(PTYForward *f, char *ch) {
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assert(f);
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assert(ch);
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if (!f->last_char_set)
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return -ENXIO;
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*ch = f->last_char;
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return 0;
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}
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int pty_forward_set_repeat(PTYForward *f, bool repeat) {
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int r;
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assert(f);
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if (f->repeat == repeat)
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return 0;
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f->repeat = repeat;
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/* Are we currently in a suppress hangup phase? If so, let's
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* immediately terminate things */
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if (!f->repeat && f->master_suppressed_hangup) {
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/* Let's try to read again from the master fd, and if
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* it is this will now cause termination of the
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* session. */
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f->master_readable = true;
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r = shovel(f);
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if (r < 0)
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return r;
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}
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return 0;
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}
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int pty_forward_get_repeat(PTYForward *f) {
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assert(f);
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return f->repeat;
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}
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