pty/script.c

This is pty/script.c (Listing 64-3, page 1392), an example from the book, The Linux Programming Interface.

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Function list (Bold in this list means a function is not static)

ttyReset()
main()

#include <sys/stat.h>
#include <fcntl.h>
#include <libgen.h>
#include <termios.h>
#include <sys/select.h>
#include "pty_fork.h"           /* Declaration of ptyFork() */
#include "tty_functions.h"      /* Declaration of ttySetRaw() */
#include "tlpi_hdr.h"

#define BUF_SIZE 256
#define MAX_SNAME 1000

struct termios ttyOrig;

static void             /* Reset terminal mode on program exit */
ttyReset(void)
{
    if (tcsetattr(STDIN_FILENO, TCSANOW, &ttyOrig) == -1)
        errExit("tcsetattr");
}

int
main(int argc, char *argv[])
{
    char slaveName[MAX_SNAME];
    char *shell;
    int masterFd, scriptFd;
    struct winsize ws;
    fd_set inFds;
    char buf[BUF_SIZE];
    ssize_t numRead;
    pid_t childPid;

    if (tcgetattr(STDIN_FILENO, &ttyOrig) == -1)
        errExit("tcgetattr");
    if (ioctl(STDIN_FILENO, TIOCGWINSZ, &ws) < 0)
        errExit("ioctl-TIOCGWINSZ");

    childPid = ptyFork(&masterFd, slaveName, MAX_SNAME, &ttyOrig, &ws);
    if (childPid == -1)
        errExit("ptyFork");

    if (childPid == 0) {        /* Child: execute a shell on pty slave */
        shell = getenv("SHELL");
        if (shell == NULL || *shell == '\0')
            shell = "/bin/sh";

        execlp(shell, shell, (char *) NULL);
        errExit("execlp");      /* If we get here, something went wrong */
    }

    /* Parent: relay data between terminal and pty master */

    scriptFd = open((argc > 1) ? argv[1] : "typescript",
                        O_WRONLY | O_CREAT | O_TRUNC,
                        S_IRUSR | S_IWUSR | S_IRGRP | S_IWGRP |
                                S_IROTH | S_IWOTH);
    if (scriptFd == -1)
        errExit("open typescript");

    ttySetRaw(STDIN_FILENO, &ttyOrig);

    if (atexit(ttyReset) != 0)
        errExit("atexit");

    for (;;) {
        FD_ZERO(&inFds);
        FD_SET(STDIN_FILENO, &inFds);
        FD_SET(masterFd, &inFds);

        if (select(masterFd + 1, &inFds, NULL, NULL, NULL) == -1)
            errExit("select");

        if (FD_ISSET(STDIN_FILENO, &inFds)) {   /* stdin --> pty */
            numRead = read(STDIN_FILENO, buf, BUF_SIZE);
            if (numRead <= 0)
                exit(EXIT_SUCCESS);

            if (write(masterFd, buf, numRead) != numRead)
                fatal("partial/failed write (masterFd)");
        }

        if (FD_ISSET(masterFd, &inFds)) {      /* pty --> stdout+file */
            numRead = read(masterFd, buf, BUF_SIZE);
            if (numRead <= 0)
                exit(EXIT_SUCCESS);

            if (write(STDOUT_FILENO, buf, numRead) != numRead)
                fatal("partial/failed write (STDOUT_FILENO)");
            if (write(scriptFd, buf, numRead) != numRead)
                fatal("partial/failed write (scriptFd)");
        }
    }
}

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