diff options
Diffstat (limited to 'src/shared')
| -rw-r--r-- | src/shared/pty.c | 633 | ||||
| -rw-r--r-- | src/shared/pty.h | 72 |
2 files changed, 0 insertions, 705 deletions
diff --git a/src/shared/pty.c b/src/shared/pty.c deleted file mode 100644 index 35d9ff5f4d..0000000000 --- a/src/shared/pty.c +++ /dev/null @@ -1,633 +0,0 @@ -/*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/ - -/*** - This file is part of systemd. - - Copyright 2014 David Herrmann <dh.herrmann@gmail.com> - - 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/>. -***/ - -/* - * PTY - * A PTY object represents a single PTY connection between a master and a - * child. The child process is fork()ed so the caller controls what program - * will be run. - * - * Programs like /bin/login tend to perform a vhangup() on their TTY - * before running the login procedure. This also causes the pty master - * to get a EPOLLHUP event as long as no client has the TTY opened. - * This means, we cannot use the TTY connection as reliable way to track - * the client. Instead, we _must_ rely on the PID of the client to track - * them. - * However, this has the side effect that if the client forks and the - * parent exits, we loose them and restart the client. But this seems to - * be the expected behavior so we implement it here. - * - * Unfortunately, epoll always polls for EPOLLHUP so as long as the - * vhangup() is ongoing, we will _always_ get EPOLLHUP and cannot sleep. - * This gets worse if the client closes the TTY but doesn't exit. - * Therefore, the fd must be edge-triggered in the epoll-set so we - * only get the events once they change. - */ - -#include <errno.h> -#include <fcntl.h> -#include <signal.h> -#include <stdbool.h> -#include <stdint.h> -#include <stdlib.h> -#include <sys/epoll.h> -#include <sys/ioctl.h> -#include <sys/uio.h> -#include <sys/wait.h> -#include <termios.h> -#include <unistd.h> - -#include "barrier.h" -#include "macro.h" -#include "ring.h" -#include "util.h" -#include "signal-util.h" -#include "pty.h" - -#define PTY_BUFSIZE 4096 - -enum { - PTY_ROLE_UNKNOWN, - PTY_ROLE_PARENT, - PTY_ROLE_CHILD, -}; - -struct Pty { - unsigned long ref; - Barrier barrier; - int fd; - pid_t child; - sd_event_source *fd_source; - sd_event_source *child_source; - - char in_buf[PTY_BUFSIZE]; - Ring out_buf; - - pty_event_t event_fn; - void *event_fn_userdata; - - bool needs_requeue : 1; - unsigned int role : 2; -}; - -int pty_new(Pty **out) { - _pty_unref_ Pty *pty = NULL; - int r; - - assert_return(out, -EINVAL); - - pty = new0(Pty, 1); - if (!pty) - return -ENOMEM; - - pty->ref = 1; - pty->fd = -1; - pty->barrier = (Barrier) BARRIER_NULL; - - pty->fd = posix_openpt(O_RDWR | O_NOCTTY | O_CLOEXEC | O_NONBLOCK); - if (pty->fd < 0) - return -errno; - - /* - * The slave-node is initialized to uid/gid of the caller of - * posix_openpt(). Only if devpts is mounted with fixed uid/gid this is - * skipped. In that case, grantpt() can overwrite these, but then you - * have to be root to use chown() (or a pt_chown helper has to be - * present). In those cases grantpt() really does something, - * otherwise it's a no-op. We call grantpt() here to try supporting - * those cases, even though no-one uses that, I guess. If you need other - * access-rights, set them yourself after this call returns (no, this is - * not racy, it looks racy, but races regarding your own UID are never - * important as an attacker could ptrace you; and the slave-pty is also - * still locked). - */ - r = grantpt(pty->fd); - if (r < 0) - return -errno; - - r = barrier_create(&pty->barrier); - if (r < 0) - return r; - - *out = pty; - pty = NULL; - return 0; -} - -Pty *pty_ref(Pty *pty) { - if (!pty || pty->ref < 1) - return NULL; - - ++pty->ref; - return pty; -} - -Pty *pty_unref(Pty *pty) { - if (!pty || pty->ref < 1 || --pty->ref > 0) - return NULL; - - pty_close(pty); - pty->child_source = sd_event_source_unref(pty->child_source); - barrier_destroy(&pty->barrier); - ring_clear(&pty->out_buf); - free(pty); - - return NULL; -} - -Barrier *pty_get_barrier(Pty *pty) { - assert(pty); - return &pty->barrier; -} - -bool pty_is_unknown(Pty *pty) { - return pty && pty->role == PTY_ROLE_UNKNOWN; -} - -bool pty_is_parent(Pty *pty) { - return pty && pty->role == PTY_ROLE_PARENT; -} - -bool pty_is_child(Pty *pty) { - return pty && pty->role == PTY_ROLE_CHILD; -} - -bool pty_has_child(Pty *pty) { - return pty_is_parent(pty) && pty->child > 0; -} - -pid_t pty_get_child(Pty *pty) { - return pty_has_child(pty) ? pty->child : -ECHILD; -} - -bool pty_is_open(Pty *pty) { - return pty && pty->fd >= 0; -} - -int pty_get_fd(Pty *pty) { - assert_return(pty, -EINVAL); - - return pty_is_open(pty) ? pty->fd : -EPIPE; -} - -int pty_make_child(Pty *pty) { - _cleanup_free_ char *slave_name = NULL; - int r, fd; - - assert_return(pty, -EINVAL); - assert_return(pty_is_unknown(pty), -EALREADY); - - r = ptsname_malloc(pty->fd, &slave_name); - if (r < 0) - return -errno; - - fd = open(slave_name, O_RDWR | O_CLOEXEC | O_NOCTTY); - if (fd < 0) - return -errno; - - safe_close(pty->fd); - pty->fd = fd; - pty->child = getpid(); - pty->role = PTY_ROLE_CHILD; - barrier_set_role(&pty->barrier, BARRIER_CHILD); - - return 0; -} - -int pty_make_parent(Pty *pty, pid_t child) { - assert_return(pty, -EINVAL); - assert_return(pty_is_unknown(pty), -EALREADY); - - pty->child = child; - pty->role = PTY_ROLE_PARENT; - - return 0; -} - -int pty_unlock(Pty *pty) { - assert_return(pty, -EINVAL); - assert_return(pty_is_unknown(pty) || pty_is_parent(pty), -EINVAL); - assert_return(pty_is_open(pty), -ENODEV); - - return unlockpt(pty->fd) < 0 ? -errno : 0; -} - -int pty_setup_child(Pty *pty) { - struct termios attr; - pid_t pid; - int r; - - assert_return(pty, -EINVAL); - assert_return(pty_is_child(pty), -EINVAL); - assert_return(pty_is_open(pty), -EALREADY); - - r = reset_signal_mask(); - if (r < 0) - return r; - - r = reset_all_signal_handlers(); - if (r < 0) - return r; - - pid = setsid(); - if (pid < 0 && errno != EPERM) - return -errno; - - r = ioctl(pty->fd, TIOCSCTTY, 0); - if (r < 0) - return -errno; - - r = tcgetattr(pty->fd, &attr); - if (r < 0) - return -errno; - - /* erase character should be normal backspace, PLEASEEE! */ - attr.c_cc[VERASE] = 010; - /* always set UTF8 flag */ - attr.c_iflag |= IUTF8; - - r = tcsetattr(pty->fd, TCSANOW, &attr); - if (r < 0) - return -errno; - - if (dup2(pty->fd, STDIN_FILENO) != STDIN_FILENO || - dup2(pty->fd, STDOUT_FILENO) != STDOUT_FILENO || - dup2(pty->fd, STDERR_FILENO) != STDERR_FILENO) - return -errno; - - /* only close FD if it's not a std-fd */ - pty->fd = (pty->fd > 2) ? safe_close(pty->fd) : -1; - - return 0; -} - -void pty_close(Pty *pty) { - if (!pty_is_open(pty)) - return; - - pty->fd_source = sd_event_source_unref(pty->fd_source); - pty->fd = safe_close(pty->fd); -} - -/* - * Drain input-queue and dispatch data via the event-handler. Returns <0 on - * error, 0 if queue is empty and 1 if we couldn't empty the input queue fast - * enough and there's still data left. - */ -static int pty_dispatch_read(Pty *pty) { - unsigned int i; - ssize_t len; - int r; - - /* - * We're edge-triggered, means we need to read the whole queue. This, - * however, might cause us to stall if the writer is faster than we - * are. Therefore, try reading as much as 8 times (32KiB) and only - * bail out then. - */ - - for (i = 0; i < 8; ++i) { - len = read(pty->fd, pty->in_buf, sizeof(pty->in_buf) - 1); - if (len < 0) { - if (errno == EINTR) - continue; - - return (errno == EAGAIN) ? 0 : -errno; - } else if (len == 0) - continue; - - /* set terminating zero for debugging safety */ - pty->in_buf[len] = 0; - r = pty->event_fn(pty, pty->event_fn_userdata, PTY_DATA, pty->in_buf, len); - if (r < 0) - return r; - } - - /* still data left, make sure we're queued again */ - pty->needs_requeue = true; - - return 1; -} - -/* - * Drain output-queue by writing data to the pty. Returns <0 on error, 0 if the - * output queue is empty now and 1 if we couldn't empty the output queue fast - * enough and there's still data left. - */ -static int pty_dispatch_write(Pty *pty) { - struct iovec vec[2]; - unsigned int i; - ssize_t len; - size_t num; - - /* - * Same as pty_dispatch_read(), we're edge-triggered so we need to call - * write() until either all data is written or it returns EAGAIN. We - * call it twice and if it still writes successfully, we reschedule. - */ - - for (i = 0; i < 2; ++i) { - num = ring_peek(&pty->out_buf, vec); - if (num < 1) - return 0; - - len = writev(pty->fd, vec, (int)num); - if (len < 0) { - if (errno == EINTR) - continue; - - return (errno == EAGAIN) ? 1 : -errno; - } else if (len == 0) - continue; - - ring_pull(&pty->out_buf, (size_t)len); - } - - /* still data left, make sure we're queued again */ - if (ring_get_size(&pty->out_buf) > 0) { - pty->needs_requeue = true; - return 1; - } - - return 0; -} - -static int pty_fd_fn(sd_event_source *source, int fd, uint32_t revents, void *userdata) { - Pty *pty = userdata; - int r_hup = 0, r_write = 0, r_read = 0, r; - - /* - * Whenever we encounter I/O errors, we have to make sure to drain the - * input queue first, before we handle any HUP. A child might send us - * a message and immediately close the queue. We must not handle the - * HUP first or we loose data. - * Therefore, if we read a message successfully, we always return - * success and wait for the next event-loop iteration. Furthermore, - * whenever there is a write-error, we must try reading from the input - * queue even if EPOLLIN is not set. The input might have arrived in - * between epoll_wait() and write(). Therefore, write-errors are only - * ever handled if the input-queue is empty. In all other cases they - * are ignored until either reading fails or the input queue is empty. - */ - - if (revents & (EPOLLHUP | EPOLLERR)) - r_hup = -EPIPE; - - if (revents & EPOLLOUT) - r_write = pty_dispatch_write(pty); - - /* Awesome! Kernel signals HUP without IN but queues are not empty.. */ - if ((revents & EPOLLIN) || r_hup < 0 || r_write < 0) { - r_read = pty_dispatch_read(pty); - if (r_read > 0) - return 0; /* still data left to fetch next round */ - } - - if (r_hup < 0 || r_write < 0 || r_read < 0) { - /* PTY closed and input-queue drained */ - pty_close(pty); - r = pty->event_fn(pty, pty->event_fn_userdata, PTY_HUP, NULL, 0); - if (r < 0) - return r; - } - - return 0; -} - -static int pty_fd_prepare_fn(sd_event_source *source, void *userdata) { - Pty *pty = userdata; - int r; - - if (pty->needs_requeue) { - /* - * We're edge-triggered. In case we couldn't handle all events - * or in case new write-data is queued, we set needs_requeue. - * Before going asleep, we set the io-events *again*. sd-event - * notices that we're edge-triggered and forwards the call to - * the kernel even if the events didn't change. The kernel will - * check the events and re-queue us on the ready queue in case - * an event is pending. - */ - r = sd_event_source_set_io_events(source, EPOLLHUP | EPOLLERR | EPOLLIN | EPOLLOUT | EPOLLET); - if (r >= 0) - pty->needs_requeue = false; - } - - return 0; -} - -static int pty_child_fn(sd_event_source *source, const siginfo_t *si, void *userdata) { - Pty *pty = userdata; - int r; - - pty->child = 0; - - r = pty->event_fn(pty, pty->event_fn_userdata, PTY_CHILD, si, sizeof(*si)); - if (r < 0) - return r; - - return 0; -} - -int pty_attach_event(Pty *pty, sd_event *event, pty_event_t event_fn, void *event_fn_userdata) { - int r; - - assert_return(pty, -EINVAL); - assert_return(event, -EINVAL); - assert_return(event_fn, -EINVAL); - assert_return(pty_is_parent(pty), -EINVAL); - - pty_detach_event(pty); - - if (pty_is_open(pty)) { - r = sd_event_add_io(event, - &pty->fd_source, - pty->fd, - EPOLLHUP | EPOLLERR | EPOLLIN | EPOLLOUT | EPOLLET, - pty_fd_fn, - pty); - if (r < 0) - goto error; - - r = sd_event_source_set_prepare(pty->fd_source, pty_fd_prepare_fn); - if (r < 0) - goto error; - } - - if (pty_has_child(pty)) { - r = sd_event_add_child(event, - &pty->child_source, - pty->child, - WEXITED, - pty_child_fn, - pty); - if (r < 0) - goto error; - } - - pty->event_fn = event_fn; - pty->event_fn_userdata = event_fn_userdata; - - return 0; - -error: - pty_detach_event(pty); - return r; -} - -void pty_detach_event(Pty *pty) { - if (!pty) - return; - - pty->child_source = sd_event_source_unref(pty->child_source); - pty->fd_source = sd_event_source_unref(pty->fd_source); - pty->event_fn = NULL; - pty->event_fn_userdata = NULL; -} - -int pty_write(Pty *pty, const void *buf, size_t size) { - bool was_empty; - int r; - - assert_return(pty, -EINVAL); - assert_return(pty_is_open(pty), -ENODEV); - assert_return(pty_is_parent(pty), -ENODEV); - - if (size < 1) - return 0; - - /* - * Push @buf[0..@size] into the output ring-buffer. In case the - * ring-buffer wasn't empty beforehand, we're already waiting for - * EPOLLOUT and we're done. If it was empty, we have to re-queue the - * FD for EPOLLOUT as we're edge-triggered and wouldn't get any new - * EPOLLOUT event. - */ - - was_empty = ring_get_size(&pty->out_buf) < 1; - - r = ring_push(&pty->out_buf, buf, size); - if (r < 0) - return r; - - if (was_empty) - pty->needs_requeue = true; - - return 0; -} - -int pty_signal(Pty *pty, int sig) { - assert_return(pty, -EINVAL); - assert_return(pty_is_open(pty), -ENODEV); - assert_return(pty_is_parent(pty), -ENODEV); - - return ioctl(pty->fd, TIOCSIG, sig) < 0 ? -errno : 0; -} - -int pty_resize(Pty *pty, unsigned short term_width, unsigned short term_height) { - struct winsize ws = { - .ws_col = term_width, - .ws_row = term_height, - }; - - assert_return(pty, -EINVAL); - assert_return(pty_is_open(pty), -ENODEV); - assert_return(pty_is_parent(pty), -ENODEV); - - /* - * This will send SIGWINCH to the pty slave foreground process group. - * We will also get one, but we don't need it. - */ - return ioctl(pty->fd, TIOCSWINSZ, &ws) < 0 ? -errno : 0; -} - -pid_t pty_fork(Pty **out, sd_event *event, pty_event_t event_fn, void *event_fn_userdata, unsigned short initial_term_width, unsigned short initial_term_height) { - _pty_unref_ Pty *pty = NULL; - int r; - pid_t pid; - - assert_return(out, -EINVAL); - assert_return((event && event_fn) || (!event && !event_fn), -EINVAL); - - r = pty_new(&pty); - if (r < 0) - return r; - - r = pty_unlock(pty); - if (r < 0) - return r; - - pid = fork(); - if (pid < 0) - return -errno; - - if (pid == 0) { - /* child */ - - r = pty_make_child(pty); - if (r < 0) - _exit(-r); - - r = pty_setup_child(pty); - if (r < 0) - _exit(-r); - - /* sync with parent */ - if (!barrier_place_and_sync(&pty->barrier)) - _exit(1); - - /* fallthrough and return the child's PTY object */ - } else { - /* parent */ - - r = pty_make_parent(pty, pid); - if (r < 0) - goto parent_error; - - r = pty_resize(pty, initial_term_width, initial_term_height); - if (r < 0) - goto parent_error; - - if (event) { - r = pty_attach_event(pty, event, event_fn, event_fn_userdata); - if (r < 0) - goto parent_error; - } - - /* sync with child */ - if (!barrier_place_and_sync(&pty->barrier)) { - r = -ECHILD; - goto parent_error; - } - - /* fallthrough and return the parent's PTY object */ - } - - *out = pty; - pty = NULL; - return pid; - -parent_error: - barrier_abort(&pty->barrier); - waitpid(pty->child, NULL, 0); - pty->child = 0; - return r; -} diff --git a/src/shared/pty.h b/src/shared/pty.h deleted file mode 100644 index 63c7db2833..0000000000 --- a/src/shared/pty.h +++ /dev/null @@ -1,72 +0,0 @@ -/*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/ - -#pragma once - -/*** - This file is part of systemd. - - Copyright 2014 David Herrmann <dh.herrmann@gmail.com> - - 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 <stdbool.h> -#include <unistd.h> - -#include "barrier.h" -#include "macro.h" -#include "sd-event.h" - -typedef struct Pty Pty; - -enum { - PTY_CHILD, - PTY_HUP, - PTY_DATA, -}; - -typedef int (*pty_event_t) (Pty *pty, void *userdata, unsigned int event, const void *ptr, size_t size); - -int pty_new(Pty **out); -Pty *pty_ref(Pty *pty); -Pty *pty_unref(Pty *pty); - -#define _pty_unref_ _cleanup_(pty_unrefp) -DEFINE_TRIVIAL_CLEANUP_FUNC(Pty*, pty_unref); - -Barrier *pty_get_barrier(Pty *pty); - -bool pty_is_unknown(Pty *pty); -bool pty_is_parent(Pty *pty); -bool pty_is_child(Pty *pty); -bool pty_has_child(Pty *pty); -pid_t pty_get_child(Pty *pty); - -bool pty_is_open(Pty *pty); -int pty_get_fd(Pty *pty); - -int pty_make_child(Pty *pty); -int pty_make_parent(Pty *pty, pid_t child); -int pty_unlock(Pty *pty); -int pty_setup_child(Pty *pty); -void pty_close(Pty *pty); - -int pty_attach_event(Pty *pty, sd_event *event, pty_event_t event_fn, void *event_fn_userdata); -void pty_detach_event(Pty *pty); - -int pty_write(Pty *pty, const void *buf, size_t size); -int pty_signal(Pty *pty, int sig); -int pty_resize(Pty *pty, unsigned short term_width, unsigned short term_height); - -pid_t pty_fork(Pty **out, sd_event *event, pty_event_t event_fn, void *event_fn_userdata, unsigned short initial_term_width, unsigned short initial_term_height); |