Adding upstream version 255.4.upstream/255.4

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 677 insertions, 0 deletions

diff --git a/src/shared/ptyfwd.c b/src/shared/ptyfwd.c
new file mode 100644
index 0000000..195e603
--- /dev/null
+++ b/src/shared/ptyfwd.c
@@ -0,0 +1,677 @@
+/* SPDX-License-Identifier: LGPL-2.1-or-later */
+
+#include <errno.h>
+#include <fcntl.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 "sd-event.h"
+
+#include "alloc-util.h"
+#include "errno-util.h"
+#include "fd-util.h"
+#include "log.h"
+#include "macro.h"
+#include "ptyfwd.h"
+#include "terminal-util.h"
+#include "time-util.h"
+
+struct PTYForward {
+        sd_event *event;
+
+        int input_fd;
+        int output_fd;
+        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 close_input_fd:1;
+        bool close_output_fd:1;
+
+        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 done:1;
+        bool drain: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;
+
+        PTYForwardHandler handler;
+        void *userdata;
+};
+
+#define ESCAPE_USEC (1*USEC_PER_SEC)
+
+static void pty_forward_disconnect(PTYForward *f) {
+
+        if (!f)
+                return;
+
+        f->stdin_event_source = sd_event_source_unref(f->stdin_event_source);
+        f->stdout_event_source = sd_event_source_unref(f->stdout_event_source);
+
+        f->master_event_source = sd_event_source_unref(f->master_event_source);
+        f->sigwinch_event_source = sd_event_source_unref(f->sigwinch_event_source);
+        f->event = sd_event_unref(f->event);
+
+        if (f->output_fd >= 0) {
+                if (f->saved_stdout)
+                        (void) tcsetattr(f->output_fd, TCSANOW, &f->saved_stdout_attr);
+
+                /* STDIN/STDOUT should not be non-blocking normally, so let's reset it */
+                (void) fd_nonblock(f->output_fd, false);
+                if (f->close_output_fd)
+                        f->output_fd = safe_close(f->output_fd);
+        }
+
+        if (f->input_fd >= 0) {
+                if (f->saved_stdin)
+                        (void) tcsetattr(f->input_fd, TCSANOW, &f->saved_stdin_attr);
+
+                (void) fd_nonblock(f->input_fd, false);
+                if (f->close_input_fd)
+                        f->input_fd = safe_close(f->input_fd);
+        }
+
+        f->saved_stdout = f->saved_stdin = false;
+}
+
+static int pty_forward_done(PTYForward *f, int rcode) {
+        _cleanup_(sd_event_unrefp) sd_event *e = NULL;
+        assert(f);
+
+        if (f->done)
+                return 0;
+
+        e = sd_event_ref(f->event);
+
+        f->done = true;
+        pty_forward_disconnect(f);
+
+        if (f->handler)
+                return f->handler(f, rcode, f->userdata);
+        else
+                return sd_event_exit(e, rcode < 0 ? EXIT_FAILURE : rcode);
+}
+
+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 bool drained(PTYForward *f) {
+        int q = 0;
+
+        assert(f);
+
+        if (f->out_buffer_full > 0)
+                return false;
+
+        if (f->master_readable)
+                return false;
+
+        if (ioctl(f->master, TIOCINQ, &q) < 0)
+                log_debug_errno(errno, "TIOCINQ failed on master: %m");
+        else if (q > 0)
+                return false;
+
+        if (ioctl(f->master, TIOCOUTQ, &q) < 0)
+                log_debug_errno(errno, "TIOCOUTQ failed on master: %m");
+        else if (q > 0)
+                return false;
+
+        return true;
+}
+
+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(f->input_fd, 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_IS_DISCONNECT(errno)) {
+                                        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 pty_forward_done(f, -errno);
+                                }
+                        } 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 pty_forward_done(f, -ECANCELED);
+
+                                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 (IN_SET(errno, EAGAIN, EIO))
+                                        f->master_writable = false;
+                                else if (IN_SET(errno, EPIPE, 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 pty_forward_done(f, -errno);
+                                }
+                        } 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 (IN_SET(errno, EPIPE, ECONNRESET, 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 pty_forward_done(f, -errno);
+                                }
+                        }  else {
+                                f->read_from_master = true;
+                                f->out_buffer_full += (size_t) k;
+                        }
+                }
+
+                if (f->stdout_writable && f->out_buffer_full > 0) {
+
+                        k = write(f->output_fd, f->out_buffer, f->out_buffer_full);
+                        if (k < 0) {
+
+                                if (errno == EAGAIN)
+                                        f->stdout_writable = false;
+                                else if (errno == EIO || ERRNO_IS_DISCONNECT(errno)) {
+                                        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 pty_forward_done(f, -errno);
+                                }
+
+                        } 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 pty_forward_done(f, 0);
+        }
+
+        /* If we were asked to drain, and there's nothing more to handle from the master, then call the callback
+         * too. */
+        if (f->drain && drained(f))
+                return pty_forward_done(f, 0);
+
+        return 0;
+}
+
+static int on_master_event(sd_event_source *e, int fd, uint32_t revents, void *userdata) {
+        PTYForward *f = ASSERT_PTR(userdata);
+
+        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 = ASSERT_PTR(userdata);
+
+        assert(e);
+        assert(e == f->stdin_event_source);
+        assert(fd >= 0);
+        assert(fd == f->input_fd);
+
+        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 = ASSERT_PTR(userdata);
+
+        assert(e);
+        assert(e == f->stdout_event_source);
+        assert(fd >= 0);
+        assert(fd == f->output_fd);
+
+        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 = ASSERT_PTR(userdata);
+        struct winsize ws;
+
+        assert(e);
+        assert(e == f->sigwinch_event_source);
+
+        /* The window size changed, let's forward that. */
+        if (ioctl(f->output_fd, 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 = new(PTYForward, 1);
+        if (!f)
+                return -ENOMEM;
+
+        *f = (struct PTYForward) {
+                .flags = flags,
+                .master = -EBADF,
+                .input_fd = -EBADF,
+                .output_fd = -EBADF,
+        };
+
+        if (event)
+                f->event = sd_event_ref(event);
+        else {
+                r = sd_event_default(&f->event);
+                if (r < 0)
+                        return r;
+        }
+
+        if (FLAGS_SET(flags, PTY_FORWARD_READ_ONLY))
+                f->output_fd = STDOUT_FILENO;
+        else {
+                /* If we shall be invoked in interactive mode, let's switch on non-blocking mode, so that we
+                 * never end up staving one direction while we block on the other. However, let's be careful
+                 * here and not turn on O_NONBLOCK for stdin/stdout directly, but of re-opened copies of
+                 * them. This has two advantages: when we are killed abruptly the stdin/stdout fds won't be
+                 * left in O_NONBLOCK state for the next process using them. In addition, if some process
+                 * running in the background wants to continue writing to our stdout it can do so without
+                 * being confused by O_NONBLOCK. */
+
+                f->input_fd = fd_reopen(STDIN_FILENO, O_RDONLY|O_CLOEXEC|O_NOCTTY|O_NONBLOCK);
+                if (f->input_fd < 0) {
+                        /* Handle failures gracefully, after all certain fd types cannot be reopened
+                         * (sockets, …) */
+                        log_debug_errno(f->input_fd, "Failed to reopen stdin, using original fd: %m");
+
+                        r = fd_nonblock(STDIN_FILENO, true);
+                        if (r < 0)
+                                return r;
+
+                        f->input_fd = STDIN_FILENO;
+                } else
+                        f->close_input_fd = true;
+
+                f->output_fd = fd_reopen(STDOUT_FILENO, O_WRONLY|O_CLOEXEC|O_NOCTTY|O_NONBLOCK);
+                if (f->output_fd < 0) {
+                        log_debug_errno(f->output_fd, "Failed to reopen stdout, using original fd: %m");
+
+                        r = fd_nonblock(STDOUT_FILENO, true);
+                        if (r < 0)
+                                return r;
+
+                        f->output_fd = STDOUT_FILENO;
+                } else
+                        f->close_output_fd = true;
+        }
+
+        r = fd_nonblock(master, true);
+        if (r < 0)
+                return r;
+
+        f->master = master;
+
+        if (ioctl(f->output_fd, TIOCGWINSZ, &ws) < 0)
+                /* If we can't get the resolution from the output fd, then use our internal, regular width/height,
+                 * i.e. something derived from $COLUMNS and $LINES if set. */
+                ws = (struct winsize) {
+                        .ws_row = lines(),
+                        .ws_col = columns(),
+                };
+
+        (void) ioctl(master, TIOCSWINSZ, &ws);
+
+        if (!(flags & PTY_FORWARD_READ_ONLY)) {
+                assert(f->input_fd >= 0);
+
+                if (tcgetattr(f->input_fd, &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(f->input_fd, TCSANOW, &raw_stdin_attr);
+                }
+
+                if (tcgetattr(f->output_fd, &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(f->output_fd, TCSANOW, &raw_stdout_attr);
+                }
+
+                r = sd_event_add_io(f->event, &f->stdin_event_source, f->input_fd, EPOLLIN|EPOLLET, on_stdin_event, f);
+                if (r < 0 && r != -EPERM)
+                        return r;
+
+                if (r >= 0)
+                        (void) sd_event_source_set_description(f->stdin_event_source, "ptyfwd-stdin");
+        }
+
+        r = sd_event_add_io(f->event, &f->stdout_event_source, f->output_fd, 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;
+        else
+                (void) sd_event_source_set_description(f->stdout_event_source, "ptyfwd-stdout");
+
+        r = sd_event_add_io(f->event, &f->master_event_source, master, EPOLLIN|EPOLLOUT|EPOLLET, on_master_event, f);
+        if (r < 0)
+                return r;
+
+        (void) sd_event_source_set_description(f->master_event_source, "ptyfwd-master");
+
+        r = sd_event_add_signal(f->event, &f->sigwinch_event_source, SIGWINCH, on_sigwinch_event, f);
+        if (r < 0)
+                return r;
+
+        (void) sd_event_source_set_description(f->sigwinch_event_source, "ptyfwd-sigwinch");
+
+        *ret = TAKE_PTR(f);
+
+        return 0;
+}
+
+PTYForward *pty_forward_free(PTYForward *f) {
+        pty_forward_disconnect(f);
+        return mfree(f);
+}
+
+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;
+}
+
+bool pty_forward_get_ignore_vhangup(PTYForward *f) {
+        assert(f);
+
+        return !!(f->flags & PTY_FORWARD_IGNORE_VHANGUP);
+}
+
+bool pty_forward_is_done(PTYForward *f) {
+        assert(f);
+
+        return f->done;
+}
+
+void pty_forward_set_handler(PTYForward *f, PTYForwardHandler cb, void *userdata) {
+        assert(f);
+
+        f->handler = cb;
+        f->userdata = userdata;
+}
+
+bool pty_forward_drain(PTYForward *f) {
+        assert(f);
+
+        /* Starts draining the forwarder. Specifically:
+         *
+         * - Returns true if there are no unprocessed bytes from the pty, false otherwise
+         *
+         * - Makes sure the handler function is called the next time the number of unprocessed bytes hits zero
+         */
+
+        f->drain = true;
+        return drained(f);
+}
+
+int pty_forward_set_priority(PTYForward *f, int64_t priority) {
+        int r;
+        assert(f);
+
+        if (f->stdin_event_source) {
+                r = sd_event_source_set_priority(f->stdin_event_source, priority);
+                if (r < 0)
+                        return r;
+        }
+
+        r = sd_event_source_set_priority(f->stdout_event_source, priority);
+        if (r < 0)
+                return r;
+
+        r = sd_event_source_set_priority(f->master_event_source, priority);
+        if (r < 0)
+                return r;
+
+        r = sd_event_source_set_priority(f->sigwinch_event_source, priority);
+        if (r < 0)
+                return r;
+
+        return 0;
+}
+
+int pty_forward_set_width_height(PTYForward *f, unsigned width, unsigned height) {
+        struct winsize ws;
+
+        assert(f);
+
+        if (width == UINT_MAX && height == UINT_MAX)
+                return 0; /* noop */
+
+        if (width != UINT_MAX &&
+            (width == 0 || width > USHRT_MAX))
+                return -ERANGE;
+
+        if (height != UINT_MAX &&
+            (height == 0 || height > USHRT_MAX))
+                return -ERANGE;
+
+        if (width == UINT_MAX || height == UINT_MAX) {
+                if (ioctl(f->master, TIOCGWINSZ, &ws) < 0)
+                        return -errno;
+
+                if (width != UINT_MAX)
+                        ws.ws_col = width;
+                if (height != UINT_MAX)
+                        ws.ws_row = height;
+        } else
+                ws = (struct winsize) {
+                        .ws_row = height,
+                        .ws_col = width,
+                };
+
+        if (ioctl(f->master, TIOCSWINSZ, &ws) < 0)
+                return -errno;
+
+        /* Make sure we ignore SIGWINCH window size events from now on */
+        f->sigwinch_event_source = sd_event_source_unref(f->sigwinch_event_source);
+
+        return 0;
+}