source: MondoRescue/branches/3.0/mindi-busybox/libbb/getpty.c@ 2899

/* vi: set sw=4 ts=4: */
/*
 * Mini getpty implementation for busybox
 * Bjorn Wesen, Axis Communications AB (bjornw@axis.com)
 *
 * Licensed under GPLv2 or later, see file LICENSE in this source tree.
 */

#include "libbb.h"

#define DEBUG 0

int FAST_FUNC xgetpty(char *line)
{
    int p;

#if ENABLE_FEATURE_DEVPTS
    p = open("/dev/ptmx", O_RDWR);
    if (p > 0) {
        grantpt(p); /* chmod+chown corresponding slave pty */
        unlockpt(p); /* (what does this do?) */
#if 0 /* if ptsname_r is not available... */
        const char *name;
        name = ptsname(p); /* find out the name of slave pty */
        if (!name) {
            bb_perror_msg_and_die("ptsname error (is /dev/pts mounted?)");
        }
        safe_strncpy(line, name, GETPTY_BUFSIZE);
#else
        /* find out the name of slave pty */
        if (ptsname_r(p, line, GETPTY_BUFSIZE-1) != 0) {
            bb_perror_msg_and_die("ptsname error (is /dev/pts mounted?)");
        }
        line[GETPTY_BUFSIZE-1] = '\0';
#endif
        return p;
    }
#else
    struct stat stb;
    int i;
    int j;

    strcpy(line, "/dev/ptyXX");

    for (i = 0; i < 16; i++) {
        line[8] = "pqrstuvwxyzabcde"[i];
        line[9] = '0';
        if (stat(line, &stb) < 0) {
            continue;
        }
        for (j = 0; j < 16; j++) {
            line[9] = j < 10 ? j + '0' : j - 10 + 'a';
            if (DEBUG)
                fprintf(stderr, "Trying to open device: %s\n", line);
            p = open(line, O_RDWR | O_NOCTTY);
            if (p >= 0) {
                line[5] = 't';
                return p;
            }
        }
    }
#endif /* FEATURE_DEVPTS */
    bb_error_msg_and_die("can't find free pty");
}