LXR busybox/libbb/getpty.c

   1/* vi: set sw=4 ts=4: */
   2/*
   3 * Mini getpty implementation for busybox
   4 * Bjorn Wesen, Axis Communications AB (bjornw@axis.com)
   5 *
   6 * Licensed under GPLv2 or later, see file LICENSE in this source tree.
   7 */
   8#include "libbb.h"
   9
  10#define DEBUG 0
  11
  12int FAST_FUNC xgetpty(char *line)
  13{
  14        int p;
  15
  16#if ENABLE_FEATURE_DEVPTS
  17        p = open("/dev/ptmx", O_RDWR);
  18        if (p >= 0) {
  19                grantpt(p); /* chmod+chown corresponding slave pty */
  20                unlockpt(p); /* (what does this do?) */
  21# ifndef HAVE_PTSNAME_R
  22                {
  23                        const char *name;
  24                        name = ptsname(p); /* find out the name of slave pty */
  25                        if (!name) {
  26                                bb_simple_perror_msg_and_die("ptsname error (is /dev/pts mounted?)");
  27                        }
  28                        safe_strncpy(line, name, GETPTY_BUFSIZE);
  29                }
  30# else
  31                /* find out the name of slave pty */
  32                if (ptsname_r(p, line, GETPTY_BUFSIZE-1) != 0) {
  33                        bb_simple_perror_msg_and_die("ptsname error (is /dev/pts mounted?)");
  34                }
  35                line[GETPTY_BUFSIZE-1] = '\0';
  36# endif
  37                return p;
  38        }
  39#else
  40        struct stat stb;
  41        int i;
  42        int j;
  43
  44        strcpy(line, "/dev/ptyXX");
  45
  46        for (i = 0; i < 16; i++) {
  47                line[8] = "pqrstuvwxyzabcde"[i];
  48                line[9] = '0';
  49                if (stat(line, &stb) < 0) {
  50                        continue;
  51                }
  52                for (j = 0; j < 16; j++) {
  53                        line[9] = j < 10 ? j + '0' : j - 10 + 'a';
  54                        if (DEBUG)
  55                                fprintf(stderr, "Trying to open device: %s\n", line);
  56                        p = open(line, O_RDWR | O_NOCTTY);
  57                        if (p >= 0) {
  58                                line[5] = 't';
  59                                return p;
  60                        }
  61                }
  62        }
  63#endif /* FEATURE_DEVPTS */
  64        bb_simple_error_msg_and_die("can't find free pty");
  65}
  66