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-rw-r--r--src/libshared/ptyfwd.c484
1 files changed, 484 insertions, 0 deletions
diff --git a/src/libshared/ptyfwd.c b/src/libshared/ptyfwd.c
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+++ b/src/libshared/ptyfwd.c
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+/***
+ This file is part of systemd.
+
+ Copyright 2010-2013 Lennart Poettering
+
+ systemd is free software; you can redistribute it and/or modify it
+ under the terms of the GNU Lesser General Public License as published by
+ the Free Software Foundation; either version 2.1 of the License, or
+ (at your option) any later version.
+
+ systemd is distributed in the hope that it will be useful, but
+ WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
+ Lesser General Public License for more details.
+
+ You should have received a copy of the GNU Lesser General Public License
+ along with systemd; If not, see <http://www.gnu.org/licenses/>.
+***/
+
+#include <errno.h>
+#include <limits.h>
+#include <signal.h>
+#include <stddef.h>
+#include <stdint.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/epoll.h>
+#include <sys/ioctl.h>
+#include <sys/time.h>
+#include <termios.h>
+#include <unistd.h>
+
+#include <systemd/sd-event.h>
+
+#include "alloc-util.h"
+#include "fd-util.h"
+#include "log.h"
+#include "macro.h"
+#include "ptyfwd.h"
+#include "time-util.h"
+
+struct PTYForward {
+ sd_event *event;
+
+ int master;
+
+ PTYForwardFlags flags;
+
+ sd_event_source *stdin_event_source;
+ sd_event_source *stdout_event_source;
+ sd_event_source *master_event_source;
+
+ sd_event_source *sigwinch_event_source;
+
+ struct termios saved_stdin_attr;
+ struct termios saved_stdout_attr;
+
+ bool saved_stdin:1;
+ bool saved_stdout:1;
+
+ bool stdin_readable:1;
+ bool stdin_hangup:1;
+ bool stdout_writable:1;
+ bool stdout_hangup:1;
+ bool master_readable:1;
+ bool master_writable:1;
+ bool master_hangup:1;
+
+ bool read_from_master:1;
+
+ bool last_char_set:1;
+ char last_char;
+
+ char in_buffer[LINE_MAX], out_buffer[LINE_MAX];
+ size_t in_buffer_full, out_buffer_full;
+
+ usec_t escape_timestamp;
+ unsigned escape_counter;
+};
+
+#define ESCAPE_USEC (1*USEC_PER_SEC)
+
+static bool look_for_escape(PTYForward *f, const char *buffer, size_t n) {
+ const char *p;
+
+ assert(f);
+ assert(buffer);
+ assert(n > 0);
+
+ for (p = buffer; p < buffer + n; p++) {
+
+ /* Check for ^] */
+ if (*p == 0x1D) {
+ usec_t nw = now(CLOCK_MONOTONIC);
+
+ if (f->escape_counter == 0 || nw > f->escape_timestamp + ESCAPE_USEC) {
+ f->escape_timestamp = nw;
+ f->escape_counter = 1;
+ } else {
+ (f->escape_counter)++;
+
+ if (f->escape_counter >= 3)
+ return true;
+ }
+ } else {
+ f->escape_timestamp = 0;
+ f->escape_counter = 0;
+ }
+ }
+
+ return false;
+}
+
+static bool ignore_vhangup(PTYForward *f) {
+ assert(f);
+
+ if (f->flags & PTY_FORWARD_IGNORE_VHANGUP)
+ return true;
+
+ if ((f->flags & PTY_FORWARD_IGNORE_INITIAL_VHANGUP) && !f->read_from_master)
+ return true;
+
+ return false;
+}
+
+static int shovel(PTYForward *f) {
+ ssize_t k;
+
+ assert(f);
+
+ while ((f->stdin_readable && f->in_buffer_full <= 0) ||
+ (f->master_writable && f->in_buffer_full > 0) ||
+ (f->master_readable && f->out_buffer_full <= 0) ||
+ (f->stdout_writable && f->out_buffer_full > 0)) {
+
+ if (f->stdin_readable && f->in_buffer_full < LINE_MAX) {
+
+ k = read(STDIN_FILENO, f->in_buffer + f->in_buffer_full, LINE_MAX - f->in_buffer_full);
+ if (k < 0) {
+
+ if (errno == EAGAIN)
+ f->stdin_readable = false;
+ else if (errno == EIO || errno == EPIPE || errno == ECONNRESET) {
+ f->stdin_readable = false;
+ f->stdin_hangup = true;
+
+ f->stdin_event_source = sd_event_source_unref(f->stdin_event_source);
+ } else {
+ log_error_errno(errno, "read(): %m");
+ return sd_event_exit(f->event, EXIT_FAILURE);
+ }
+ } else if (k == 0) {
+ /* EOF on stdin */
+ f->stdin_readable = false;
+ f->stdin_hangup = true;
+
+ f->stdin_event_source = sd_event_source_unref(f->stdin_event_source);
+ } else {
+ /* Check if ^] has been
+ * pressed three times within
+ * one second. If we get this
+ * we quite immediately. */
+ if (look_for_escape(f, f->in_buffer + f->in_buffer_full, k))
+ return sd_event_exit(f->event, EXIT_FAILURE);
+
+ f->in_buffer_full += (size_t) k;
+ }
+ }
+
+ if (f->master_writable && f->in_buffer_full > 0) {
+
+ k = write(f->master, f->in_buffer, f->in_buffer_full);
+ if (k < 0) {
+
+ if (errno == EAGAIN || errno == EIO)
+ f->master_writable = false;
+ else if (errno == EPIPE || errno == ECONNRESET) {
+ f->master_writable = f->master_readable = false;
+ f->master_hangup = true;
+
+ f->master_event_source = sd_event_source_unref(f->master_event_source);
+ } else {
+ log_error_errno(errno, "write(): %m");
+ return sd_event_exit(f->event, EXIT_FAILURE);
+ }
+ } else {
+ assert(f->in_buffer_full >= (size_t) k);
+ memmove(f->in_buffer, f->in_buffer + k, f->in_buffer_full - k);
+ f->in_buffer_full -= k;
+ }
+ }
+
+ if (f->master_readable && f->out_buffer_full < LINE_MAX) {
+
+ k = read(f->master, f->out_buffer + f->out_buffer_full, LINE_MAX - f->out_buffer_full);
+ if (k < 0) {
+
+ /* Note that EIO on the master device
+ * might be caused by vhangup() or
+ * temporary closing of everything on
+ * the other side, we treat it like
+ * EAGAIN here and try again, unless
+ * ignore_vhangup is off. */
+
+ if (errno == EAGAIN || (errno == EIO && ignore_vhangup(f)))
+ f->master_readable = false;
+ else if (errno == EPIPE || errno == ECONNRESET || errno == EIO) {
+ f->master_readable = f->master_writable = false;
+ f->master_hangup = true;
+
+ f->master_event_source = sd_event_source_unref(f->master_event_source);
+ } else {
+ log_error_errno(errno, "read(): %m");
+ return sd_event_exit(f->event, EXIT_FAILURE);
+ }
+ } else {
+ f->read_from_master = true;
+ f->out_buffer_full += (size_t) k;
+ }
+ }
+
+ if (f->stdout_writable && f->out_buffer_full > 0) {
+
+ k = write(STDOUT_FILENO, f->out_buffer, f->out_buffer_full);
+ if (k < 0) {
+
+ if (errno == EAGAIN)
+ f->stdout_writable = false;
+ else if (errno == EIO || errno == EPIPE || errno == ECONNRESET) {
+ f->stdout_writable = false;
+ f->stdout_hangup = true;
+ f->stdout_event_source = sd_event_source_unref(f->stdout_event_source);
+ } else {
+ log_error_errno(errno, "write(): %m");
+ return sd_event_exit(f->event, EXIT_FAILURE);
+ }
+
+ } else {
+
+ if (k > 0) {
+ f->last_char = f->out_buffer[k-1];
+ f->last_char_set = true;
+ }
+
+ assert(f->out_buffer_full >= (size_t) k);
+ memmove(f->out_buffer, f->out_buffer + k, f->out_buffer_full - k);
+ f->out_buffer_full -= k;
+ }
+ }
+ }
+
+ if (f->stdin_hangup || f->stdout_hangup || f->master_hangup) {
+ /* Exit the loop if any side hung up and if there's
+ * nothing more to write or nothing we could write. */
+
+ if ((f->out_buffer_full <= 0 || f->stdout_hangup) &&
+ (f->in_buffer_full <= 0 || f->master_hangup))
+ return sd_event_exit(f->event, EXIT_SUCCESS);
+ }
+
+ return 0;
+}
+
+static int on_master_event(sd_event_source *e, int fd, uint32_t revents, void *userdata) {
+ PTYForward *f = userdata;
+
+ assert(f);
+ assert(e);
+ assert(e == f->master_event_source);
+ assert(fd >= 0);
+ assert(fd == f->master);
+
+ if (revents & (EPOLLIN|EPOLLHUP))
+ f->master_readable = true;
+
+ if (revents & (EPOLLOUT|EPOLLHUP))
+ f->master_writable = true;
+
+ return shovel(f);
+}
+
+static int on_stdin_event(sd_event_source *e, int fd, uint32_t revents, void *userdata) {
+ PTYForward *f = userdata;
+
+ assert(f);
+ assert(e);
+ assert(e == f->stdin_event_source);
+ assert(fd >= 0);
+ assert(fd == STDIN_FILENO);
+
+ if (revents & (EPOLLIN|EPOLLHUP))
+ f->stdin_readable = true;
+
+ return shovel(f);
+}
+
+static int on_stdout_event(sd_event_source *e, int fd, uint32_t revents, void *userdata) {
+ PTYForward *f = userdata;
+
+ assert(f);
+ assert(e);
+ assert(e == f->stdout_event_source);
+ assert(fd >= 0);
+ assert(fd == STDOUT_FILENO);
+
+ if (revents & (EPOLLOUT|EPOLLHUP))
+ f->stdout_writable = true;
+
+ return shovel(f);
+}
+
+static int on_sigwinch_event(sd_event_source *e, const struct signalfd_siginfo *si, void *userdata) {
+ PTYForward *f = userdata;
+ struct winsize ws;
+
+ assert(f);
+ assert(e);
+ assert(e == f->sigwinch_event_source);
+
+ /* The window size changed, let's forward that. */
+ if (ioctl(STDOUT_FILENO, TIOCGWINSZ, &ws) >= 0)
+ (void) ioctl(f->master, TIOCSWINSZ, &ws);
+
+ return 0;
+}
+
+int pty_forward_new(
+ sd_event *event,
+ int master,
+ PTYForwardFlags flags,
+ PTYForward **ret) {
+
+ _cleanup_(pty_forward_freep) PTYForward *f = NULL;
+ struct winsize ws;
+ int r;
+
+ f = new0(PTYForward, 1);
+ if (!f)
+ return -ENOMEM;
+
+ f->flags = flags;
+
+ if (event)
+ f->event = sd_event_ref(event);
+ else {
+ r = sd_event_default(&f->event);
+ if (r < 0)
+ return r;
+ }
+
+ if (!(flags & PTY_FORWARD_READ_ONLY)) {
+ r = fd_nonblock(STDIN_FILENO, true);
+ if (r < 0)
+ return r;
+
+ r = fd_nonblock(STDOUT_FILENO, true);
+ if (r < 0)
+ return r;
+ }
+
+ r = fd_nonblock(master, true);
+ if (r < 0)
+ return r;
+
+ f->master = master;
+
+ if (ioctl(STDOUT_FILENO, TIOCGWINSZ, &ws) >= 0)
+ (void) ioctl(master, TIOCSWINSZ, &ws);
+
+ if (!(flags & PTY_FORWARD_READ_ONLY)) {
+ if (tcgetattr(STDIN_FILENO, &f->saved_stdin_attr) >= 0) {
+ struct termios raw_stdin_attr;
+
+ f->saved_stdin = true;
+
+ raw_stdin_attr = f->saved_stdin_attr;
+ cfmakeraw(&raw_stdin_attr);
+ raw_stdin_attr.c_oflag = f->saved_stdin_attr.c_oflag;
+ tcsetattr(STDIN_FILENO, TCSANOW, &raw_stdin_attr);
+ }
+
+ if (tcgetattr(STDOUT_FILENO, &f->saved_stdout_attr) >= 0) {
+ struct termios raw_stdout_attr;
+
+ f->saved_stdout = true;
+
+ raw_stdout_attr = f->saved_stdout_attr;
+ cfmakeraw(&raw_stdout_attr);
+ raw_stdout_attr.c_iflag = f->saved_stdout_attr.c_iflag;
+ raw_stdout_attr.c_lflag = f->saved_stdout_attr.c_lflag;
+ tcsetattr(STDOUT_FILENO, TCSANOW, &raw_stdout_attr);
+ }
+
+ r = sd_event_add_io(f->event, &f->stdin_event_source, STDIN_FILENO, EPOLLIN|EPOLLET, on_stdin_event, f);
+ if (r < 0 && r != -EPERM)
+ return r;
+ }
+
+ r = sd_event_add_io(f->event, &f->stdout_event_source, STDOUT_FILENO, EPOLLOUT|EPOLLET, on_stdout_event, f);
+ if (r == -EPERM)
+ /* stdout without epoll support. Likely redirected to regular file. */
+ f->stdout_writable = true;
+ else if (r < 0)
+ return r;
+
+ r = sd_event_add_io(f->event, &f->master_event_source, master, EPOLLIN|EPOLLOUT|EPOLLET, on_master_event, f);
+ if (r < 0)
+ return r;
+
+ r = sd_event_add_signal(f->event, &f->sigwinch_event_source, SIGWINCH, on_sigwinch_event, f);
+ if (r < 0)
+ return r;
+
+ *ret = f;
+ f = NULL;
+
+ return 0;
+}
+
+PTYForward *pty_forward_free(PTYForward *f) {
+
+ if (f) {
+ sd_event_source_unref(f->stdin_event_source);
+ sd_event_source_unref(f->stdout_event_source);
+ sd_event_source_unref(f->master_event_source);
+ sd_event_source_unref(f->sigwinch_event_source);
+ sd_event_unref(f->event);
+
+ if (f->saved_stdout)
+ tcsetattr(STDOUT_FILENO, TCSANOW, &f->saved_stdout_attr);
+ if (f->saved_stdin)
+ tcsetattr(STDIN_FILENO, TCSANOW, &f->saved_stdin_attr);
+
+ free(f);
+ }
+
+ /* STDIN/STDOUT should not be nonblocking normally, so let's
+ * unconditionally reset it */
+ fd_nonblock(STDIN_FILENO, false);
+ fd_nonblock(STDOUT_FILENO, false);
+
+ return NULL;
+}
+
+int pty_forward_get_last_char(PTYForward *f, char *ch) {
+ assert(f);
+ assert(ch);
+
+ if (!f->last_char_set)
+ return -ENXIO;
+
+ *ch = f->last_char;
+ return 0;
+}
+
+int pty_forward_set_ignore_vhangup(PTYForward *f, bool b) {
+ int r;
+
+ assert(f);
+
+ if (!!(f->flags & PTY_FORWARD_IGNORE_VHANGUP) == b)
+ return 0;
+
+ SET_FLAG(f->flags, PTY_FORWARD_IGNORE_VHANGUP, b);
+
+ if (!ignore_vhangup(f)) {
+
+ /* We shall now react to vhangup()s? Let's check
+ * immediately if we might be in one */
+
+ f->master_readable = true;
+ r = shovel(f);
+ if (r < 0)
+ return r;
+ }
+
+ return 0;
+}
+
+int pty_forward_get_ignore_vhangup(PTYForward *f) {
+ assert(f);
+
+ return !!(f->flags & PTY_FORWARD_IGNORE_VHANGUP);
+}