source: trunk/software/tty/readtty_command.c @ 19

#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <string.h>
#include <errno.h>
#include <err.h>
#include <fcntl.h>
#include <signal.h>
#include <termios.h>
#include <sys/ioctl.h>
#include <sys/select.h>
#include <pwd.h>
#include <grp.h>

volatile int quit;
const char *prog;

static void
set_quit(int s)
{
        quit = 1;
}

static void
usage()
{
        errx(1, "usage: %s <device> <cmd>", prog);
}

static void
readline(int d, char *buf, int l)
{
        int i;
        int bytes;
        do {
                for (i = 0; i < l; i++) {
                        do {
                                bytes = read(d, &buf[i], 1);
                                if (quit)
                                        return;
                        } while ((bytes < 0 && errno == EAGAIN) || buf[i] == '\r');
                        if (bytes != 1) {
                                fprintf(stderr, "readline: read %d\n", bytes);
                                err(1, "read line");
                        }
                        if (buf[i] == '\n')
                                break;
                }
        } while (i == 0);
        if (buf[i] != '\n') {
                warnx("realine: end of line not found");
        }
        buf[i] = '\0';
}

int
main(int argc, char * const argv[])
{
        int d;
        char buf[256];
        int i;

        struct termios t, ot;

        prog = argv[0];
        argc -= 1;
        argv += 1;

        if (argc != 2)
                usage();
        if (*argv[1] == 'P' || *argv[1] == 'E') {
                /* check if user is in group wheel or sudo */
                gid_t mygroups[64];
                int ngroups = 64;
                struct passwd *pwp = getpwuid(getuid());
                if (pwp == NULL) {
                        err(1, "getpwuid(%d)", getuid());
                }
                if ((i = getgrouplist(pwp->pw_name, pwp->pw_gid, mygroups, &ngroups)) < 0) {
                        fprintf(stderr, "getgrouplist(%s,%d) fail: %d %d\n",
                            pwp->pw_name, pwp->pw_gid, i, ngroups);
                        exit(1);
                }
                for (i = 0; i < ngroups; i++) {
                        struct group *grpp = getgrgid(mygroups[i]);
                        if (grpp == NULL) {
                                err(1, "getgrgid(%d)", mygroups[i]);
                        }
                        if (strcmp(grpp->gr_name, "wheel") == 0 ||
                            strcmp(grpp->gr_name, "sudo") == 0) {
                                break;
                        }
                }
                if (i == ngroups) {
                        errx(1, "command %s: permission denied", argv[1]);
                }
        }

        d = open(argv[0], O_RDWR | O_NOCTTY | O_NONBLOCK, 0);
        if (d < 0) {
                err(1, "open %s", argv[0]);
        }

        if (tcgetattr(d, &ot) < 0) {
                err(1, "tcgetattr");
        }

        quit = 0;

        if (signal(SIGINT, set_quit) == SIG_ERR) {
                err(1, "signal(SIGINT)");
        }
        if (signal(SIGQUIT, set_quit) == SIG_ERR) {
                err(1, "signal(SIGQUIT)");
        }
        if (signal(SIGPIPE, set_quit) == SIG_ERR) {
                err(1, "signal(SIGPIPE)");
        }
        if (signal(SIGTERM, set_quit) == SIG_ERR) {
                err(1, "signal(SIGTERM)");
        }

        t = ot;
        cfmakeraw(&t);
        t.c_cflag |= CLOCAL;
        t.c_cflag &= ~CRTSCTS;
        cfsetspeed(&t, B921600);

        if (tcsetattr(d, TCSANOW | TCSAFLUSH, &t) < 0) {
                err(1, "tcsetattr");
        }
        do {
                write(d, "M0\n", 3);
                readline(d, buf, sizeof(buf));
                if (quit)
                        goto quit;
        } while (memcmp(buf, "OK", 2) != 0);

        snprintf(buf, sizeof(buf) - 1, "%s\n", argv[1]);
        write(d, buf, strlen(buf));
        readline(d, buf, sizeof(buf));
        if (quit)
                goto quit;
        printf("%s\n", buf);
quit:
        if (fflush(stdout) == EOF) {
                warn("fflush");
        }
        if (tcsetattr(d, TCSANOW, &ot) < 0) {
                err(1, "restore tcsetattr");
        }
        exit(0);
}