diff options
Diffstat (limited to 'src/libshared/ptyfwd.c')
| -rw-r--r-- | src/libshared/ptyfwd.c | 484 |
1 files changed, 484 insertions, 0 deletions
diff --git a/src/libshared/ptyfwd.c b/src/libshared/ptyfwd.c new file mode 100644 index 0000000000..9629b50ed9 --- /dev/null +++ b/src/libshared/ptyfwd.c @@ -0,0 +1,484 @@ +/*** + 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); +} |