/* vi: set sw=4 ts=4: */
/*
 * script implementation for busybox
 *
 * pascal.bellard@ads-lu.com
 *
 * Based on code from util-linux v 2.12r
 * Copyright (c) 1980
 * The Regents of the University of California.  All rights reserved.
 *
 * Licensed under GPLv2 or later, see file LICENSE in this source tree.
 */
//config:config SCRIPT
//config:       bool "script (8 kb)"
//config:       default y
//config:       help
//config:       The script makes typescript of terminal session.

//applet:IF_SCRIPT(APPLET(script, BB_DIR_USR_BIN, BB_SUID_DROP))

//kbuild:lib-$(CONFIG_SCRIPT) += script.o

//usage:#define script_trivial_usage
//usage:       "[-afq] [-t[FILE]] [-c PROG] [OUTFILE]"
//usage:#define script_full_usage "\n\n"
//usage:       "Default OUTFILE is 'typescript'"
//usage:     "\n"
//usage:     "\n        -a      Append output"
//usage:     "\n        -c PROG Run PROG, not shell"
/* Accepted but has no effect (we never buffer output) */
/*//usage:     "\n      -f      Flush output after each write"*/
//usage:     "\n        -q      Quiet"
//usage:     "\n        -t[FILE] Send timing to stderr or FILE"

//util-linux-2.28:
//-e: return exit code of the child

//FYI (reported as bbox bug #2749):
// > script -q -c 'echo -e -n "1\n2\n3\n"' /dev/null </dev/null >123.txt
// > The output file on full-blown ubuntu system contains 6 bytes.
// > Output on Busybox system (arm-linux) contains extra '\r' byte in each line.
//however, in my test, "script" from util-linux-2.28 seems to also add '\r' bytes.

#include "libbb.h"
#include "common_bufsiz.h"

int script_main(int argc, char **argv) MAIN_EXTERNALLY_VISIBLE;
int script_main(int argc UNUSED_PARAM, char **argv)
{
        int opt;
        int mode;
        int child_pid;
        int attr_ok; /* NB: 0: ok */
        int winsz_ok;
        int pty;
        char pty_line[GETPTY_BUFSIZE];
        struct termios tt, rtt;
        struct winsize win;
        FILE *timing_fp;
        const char *str_t = NULL;
        const char *fname = "typescript";
        const char *shell;
        char shell_opt[] = "-i";
        char *shell_arg = NULL;
        enum {
                OPT_a = (1 << 0),
                OPT_c = (1 << 1),
                OPT_f = (1 << 2),
                OPT_q = (1 << 3),
                OPT_t = (1 << 4),
        };

#if ENABLE_LONG_OPTS
        static const char script_longopts[] ALIGN1 =
                "append\0"  No_argument       "a"
                "command\0" Required_argument "c"
                "flush\0"   No_argument       "f"
                "quiet\0"   No_argument       "q"
                "timing\0"  Optional_argument "t"
                ;
#endif

        opt = getopt32long(argv, "^" "ac:fqt::" "\0" "?1"/* max one arg */,
                                script_longopts,
                                &shell_arg, &str_t
        );
        //argc -= optind;
        argv += optind;
        if (argv[0]) {
                fname = argv[0];
        }
        mode = O_CREAT|O_TRUNC|O_WRONLY;
        if (opt & OPT_a) {
                mode = O_CREAT|O_APPEND|O_WRONLY;
        }
        if (opt & OPT_c) {
                shell_opt[1] = 'c';
        }
        if (!(opt & OPT_q)) {
                printf("Script started, file is %s\n", fname);
        }
        timing_fp = stderr;
        if (str_t) {
                timing_fp = xfopen_for_write(str_t);
        }

        shell = get_shell_name();

        /* Some people run "script ... 0>&-".
         * Our code assumes that STDIN_FILENO != pty.
         * Ensure STDIN_FILENO is not closed:
         */
        bb_sanitize_stdio();

        pty = xgetpty(pty_line);

        /* get current stdin's tty params */
        attr_ok = tcgetattr(0, &tt);
        winsz_ok = ioctl(0, TIOCGWINSZ, (char *)&win);

        rtt = tt;
        cfmakeraw(&rtt);
        rtt.c_lflag &= ~ECHO;
        tcsetattr(0, TCSAFLUSH, &rtt);

        /* "script" from util-linux exits when child exits,
         * we wouldn't wait for EOF from slave pty
         * (output may be produced by grandchildren of child) */
        signal(SIGCHLD, record_signo);

        /* TODO: SIGWINCH? pass window size changes down to slave? */

        child_pid = xvfork();

        if (child_pid) {
                /* parent */
                struct pollfd pfd[2];
                int outfd, count, loop;
                double oldtime = time(NULL);
                smallint fd_count = 2;

#define buf bb_common_bufsiz1
                setup_common_bufsiz();

                outfd = xopen(fname, mode);
                pfd[0].fd = pty;
                pfd[0].events = POLLIN;
                pfd[1].fd = STDIN_FILENO;
                pfd[1].events = POLLIN;
                ndelay_on(pty); /* this descriptor is not shared, can do this */
                /* ndelay_on(STDIN_FILENO); - NO, stdin can be shared! Pity :( */

                /* copy stdin to pty master input,
                 * copy pty master output to stdout and file */
                /* TODO: don't use full_write's, use proper write buffering */
                while (fd_count && !bb_got_signal) {
                        /* not safe_poll! we want SIGCHLD to EINTR poll */
                        if (poll(pfd, fd_count, -1) < 0 && errno != EINTR) {
                                /* If child exits too quickly, we may get EIO:
                                 * for example, try "script -c true" */
                                break;
                        }
                        if (pfd[0].revents) {
                                errno = 0;
                                count = safe_read(pty, buf, COMMON_BUFSIZE);
                                if (count <= 0 && errno != EAGAIN) {
                                        /* err/eof from pty: exit */
                                        goto restore;
                                }
                                if (count > 0) {
                                        if (opt & OPT_t) {
                                                struct timeval tv;
                                                double newtime;

                                                gettimeofday(&tv, NULL);
                                                newtime = tv.tv_sec + (double) tv.tv_usec / 1000000;
                                                fprintf(timing_fp, "%f %u\n", newtime - oldtime, count);
                                                oldtime = newtime;
                                        }
                                        full_write(STDOUT_FILENO, buf, count);
                                        full_write(outfd, buf, count);
                                        // If we'd be using (buffered) FILE i/o, we'd need this:
                                        //if (opt & OPT_f) {
                                        //      fflush(outfd);
                                        //}
                                }
                        }
                        if (pfd[1].revents) {
                                count = safe_read(STDIN_FILENO, buf, COMMON_BUFSIZE);
                                if (count <= 0) {
                                        /* err/eof from stdin: don't read stdin anymore */
                                        pfd[1].revents = 0;
                                        fd_count--;
                                } else {
                                        full_write(pty, buf, count);
                                }
                        }
                }
                /* If loop was exited because SIGCHLD handler set bb_got_signal,
                 * there still can be some buffered output. But dont loop forever:
                 * we won't pump orphaned grandchildren's output indefinitely.
                 * Testcase: running this in script:
                 *      exec dd if=/dev/zero bs=1M count=1
                 * must have "1+0 records in, 1+0 records out" captured too.
                 * (util-linux's script doesn't do this. buggy :) */
                loop = 999;
                /* pty is in O_NONBLOCK mode, we exit as soon as buffer is empty */
                while (--loop && (count = safe_read(pty, buf, COMMON_BUFSIZE)) > 0) {
                        full_write(STDOUT_FILENO, buf, count);
                        full_write(outfd, buf, count);
                }
 restore:
                if (attr_ok == 0)
                        tcsetattr(0, TCSAFLUSH, &tt);
                if (!(opt & OPT_q))
                        printf("Script done, file is %s\n", fname);
                return EXIT_SUCCESS;
        }

        /* child: make pty slave to be input, output, error; run shell */
        close(pty); /* close pty master */
        /* open pty slave to fd 0,1,2 */
        close(0);
        xopen(pty_line, O_RDWR); /* uses fd 0 */
        xdup2(0, 1);
        xdup2(0, 2);
        /* copy our original stdin tty's parameters to pty */
        if (attr_ok == 0)
                tcsetattr(0, TCSAFLUSH, &tt);
        if (winsz_ok == 0)
                ioctl(0, TIOCSWINSZ, (char *)&win);
        /* set pty as a controlling tty */
        setsid();
        ioctl(0, TIOCSCTTY, 0 /* 0: don't forcibly steal */);

        /* Non-ignored signals revert to SIG_DFL on exec anyway */
        /*signal(SIGCHLD, SIG_DFL);*/
        execl(shell, shell, shell_opt, shell_arg, (char *) NULL);
        bb_simple_perror_msg_and_die(shell);
}