diff options
Diffstat (limited to '')
| -rwxr-xr-x | home/.bin/dtch.c | 256 |
1 files changed, 256 insertions, 0 deletions
diff --git a/home/.bin/dtch.c b/home/.bin/dtch.c new file mode 100755 index 00000000..375b13d2 --- /dev/null +++ b/home/.bin/dtch.c @@ -0,0 +1,256 @@ +#if 0 +set -e +bin=$(dirname $0) +cc -Wall -Wextra -pedantic $@ -o $bin/dtch $0 +ln -f $bin/dtch $bin/atch +exit +#endif + +#include <err.h> +#include <errno.h> +#include <fcntl.h> +#include <poll.h> +#include <stdlib.h> +#include <sys/ioctl.h> +#include <sys/socket.h> +#include <sys/stat.h> +#include <sys/un.h> +#include <sysexits.h> +#include <termios.h> +#include <unistd.h> +#include <util.h> + +static struct passwd *getUser(void) { + uid_t uid = getuid(); + struct passwd *user = getpwuid(uid); + if (!user) err(EX_OSFILE, "/etc/passwd"); + return user; +} + +static void createDir(const char *home) { + int fd = open(home, 0); + if (fd < 0) err(EX_IOERR, "%s", home); + + int error = mkdirat(fd, ".dtch", S_IRWXU); + if (error && errno != EEXIST) err(EX_IOERR, "%s/.dtch", home); + + error = close(fd); + if (error) err(EX_IOERR, "%s", home); +} + +static struct sockaddr_un sockAddr(const char *home, const char *name) { + struct sockaddr_un addr = { .sun_family = AF_LOCAL }; + snprintf(addr.sun_path, sizeof(addr.sun_path), "%s/.dtch/%s", home, name); + return addr; +} + +static char z; +static struct iovec iov = { + .iov_base = &z, + .iov_len = sizeof(z), +}; + +static ssize_t sendFd(int sock, int fd) { + size_t len = CMSG_LEN(sizeof(int)); + char buf[len]; + struct msghdr msg = { + .msg_iov = &iov, + .msg_iovlen = 1, + .msg_control = buf, + .msg_controllen = len, + }; + + struct cmsghdr *cmsg = CMSG_FIRSTHDR(&msg); + cmsg->cmsg_len = len; + cmsg->cmsg_level = SOL_SOCKET; + cmsg->cmsg_type = SCM_RIGHTS; + *(int *)CMSG_DATA(cmsg) = fd; + + return sendmsg(sock, &msg, 0); +} + +static int recvFd(int sock) { + size_t len = CMSG_LEN(sizeof(int)); + char buf[len]; + struct msghdr msg = { + .msg_iov = &iov, + .msg_iovlen = 1, + .msg_control = buf, + .msg_controllen = len, + }; + + ssize_t n = recvmsg(sock, &msg, 0); + if (n < 0) return -1; + + struct cmsghdr *cmsg = CMSG_FIRSTHDR(&msg); + if (!cmsg) { + errno = ENOMSG; + return -1; + } + if (cmsg->cmsg_level != SOL_SOCKET || cmsg->cmsg_type != SCM_RIGHTS) { + errno = EBADMSG; + return -1; + } + + return *(int *)CMSG_DATA(cmsg); +} + +static ssize_t writeAll(int fd, const char *buf, ssize_t len) { + ssize_t writeLen; + while (0 < (writeLen = write(fd, buf, len))) { + buf += writeLen; + len -= writeLen; + } + return writeLen; +} + +static struct sockaddr_un addr; + +static void unlinkAddr(void) { + unlink(addr.sun_path); +} + +static int dtch(int argc, char *argv[]) { + int error; + + const struct passwd *user = getUser(); + const char *name = user->pw_name; + const char *cmd = user->pw_shell; + + if (argc > 2) { + name = argv[1]; + cmd = argv[2]; + argv += 2; + } else if (argc > 1) { + name = argv[1]; + argv++; + } + + int server = socket(PF_LOCAL, SOCK_STREAM, 0); + if (server < 0) err(EX_IOERR, "socket"); + + createDir(user->pw_dir); + addr = sockAddr(user->pw_dir, name); + + error = bind(server, (struct sockaddr *)&addr, sizeof(addr)); + if (error) err(EX_IOERR, "%s", addr.sun_path); + atexit(unlinkAddr); + + error = chmod(addr.sun_path, S_IRWXU); + if (error) err(EX_IOERR, "%s", addr.sun_path); + + int master; + pid_t pid = forkpty(&master, NULL, NULL, NULL); + if (pid < 0) err(EX_OSERR, "forkpty"); + + if (!pid) { + error = close(server); + if (error) warn("close(%d)", server); + execvp(cmd, argv); + err(EX_OSERR, "%s", cmd); + } + + // TODO: Kill child on error after this point? + + error = listen(server, 1); + if (error) err(EX_IOERR, "listen"); + + for (;;) { + int client = accept(server, NULL, NULL); + if (client < 0) err(EX_IOERR, "accept"); + + ssize_t len = sendFd(client, master); + if (len < 0) warn("sendmsg(%d)", client); + + // TODO: Send SIGWINCH? + + len = recv(client, &z, sizeof(z), 0); + if (len < 0) warn("recv(%d)", client); + + error = close(client); + if (error) warn("close(%d)", client); + + // TODO: Detect death of child. + } +} + +static struct termios saveTerm; + +static void restoreTerm(void) { + tcsetattr(STDERR_FILENO, TCSADRAIN, &saveTerm); +} + +static int atch(int argc, char *argv[]) { + int error; + + const struct passwd *user = getUser(); + + const char *name = user->pw_name; + if (argc > 1) name = argv[1]; + + int client = socket(PF_LOCAL, SOCK_STREAM, 0); + if (client < 0) err(EX_IOERR, "socket"); + + addr = sockAddr(user->pw_dir, name); + error = connect(client, (struct sockaddr *)&addr, sizeof(addr)); + if (error) err(EX_IOERR, "%s", addr.sun_path); + + int master = recvFd(client); + if (master < 0) err(EX_IOERR, "recvmsg(%d)", client); + + error = tcgetattr(STDERR_FILENO, &saveTerm); + if (error) err(EX_USAGE, "tcgetattr(%d)", STDERR_FILENO); + atexit(restoreTerm); + + struct termios raw; + cfmakeraw(&raw); + error = tcsetattr(STDERR_FILENO, TCSADRAIN, &raw); + if (error) err(EX_IOERR, "tcsetattr(%d)", STDERR_FILENO); + + struct winsize window; + error = ioctl(STDERR_FILENO, TIOCGWINSZ, &window); + if (error) warn("ioctl(%d, TIOCGWINSZ)", STDERR_FILENO); + error = ioctl(master, TIOCSWINSZ, &window); + if (error) warn("ioctl(%d, TIOCSWINSZ)", master); + + // TODO: Handle SIGWINCH? + + struct pollfd fds[2]; + fds[0].fd = STDIN_FILENO; + fds[0].events = POLLIN; + fds[1].fd = master; + fds[1].events = POLLIN; + + char buf[4096]; + while (0 < poll(fds, 2, -1)) { + if (fds[0].revents) { + ssize_t len = read(STDIN_FILENO, buf, sizeof(buf)); + if (len < 0) err(EX_IOERR, "read(%d)", STDIN_FILENO); + + if (len && buf[0] == ('Q' & ~0x40)) { + // TODO: Message? + exit(0); + } + + len = writeAll(master, buf, len); + if (len < 0) err(EX_IOERR, "write(%d)", master); + } + + if (fds[1].revents) { + ssize_t len = read(master, buf, sizeof(buf)); + if (len < 0) err(EX_IOERR, "read(%d)", master); + len = writeAll(STDOUT_FILENO, buf, len); + if (len < 0) err(EX_IOERR, "write(%d)", STDOUT_FILENO); + } + + } + err(EX_IOERR, "poll"); +} + +int main(int argc, char *argv[]) { + switch (argv[0][0]) { + case 'd': return dtch(argc, argv); + case 'a': return atch(argc, argv); + } + return EX_USAGE; +} |