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 tarball for details.
   7 */
   8
   9#include "libbb.h"
  10
  11#define DEBUG 0
  12
  13int FAST_FUNC xgetpty(char *line)
  14{
  15        int p;
  16
  17#if ENABLE_FEATURE_DEVPTS
  18        p = open("/dev/ptmx", O_RDWR);
  19        if (p > 0) {
  20                grantpt(p); /* chmod+chown corresponding slave pty */
  21                unlockpt(p); /* (what does this do?) */
  22#if 0 /* if ptsname_r is not available... */
  23                const char *name;
  24                name = ptsname(p); /* find out the name of slave pty */
  25                if (!name) {
  26                        bb_perror_msg_and_die("ptsname error (is /dev/pts mounted?)");
  27                }
  28                safe_strncpy(line, name, GETPTY_BUFSIZE);
  29#else
  30                /* find out the name of slave pty */
  31                if (ptsname_r(p, line, GETPTY_BUFSIZE-1) != 0) {
  32                        bb_perror_msg_and_die("ptsname error (is /dev/pts mounted?)");
  33                }
  34                line[GETPTY_BUFSIZE-1] = '\0';
  35#endif
  36                return p;
  37        }
  38#else
  39        struct stat stb;
  40        int i;
  41        int j;
  42
  43        strcpy(line, "/dev/ptyXX");
  44
  45        for (i = 0; i < 16; i++) {
  46                line[8] = "pqrstuvwxyzabcde"[i];
  47                line[9] = '0';
  48                if (stat(line, &stb) < 0) {
  49                        continue;
  50                }
  51                for (j = 0; j < 16; j++) {
  52                        line[9] = j < 10 ? j + '0' : j - 10 + 'a';
  53                        if (DEBUG)
  54                                fprintf(stderr, "Trying to open device: %s\n", line);
  55                        p = open(line, O_RDWR | O_NOCTTY);
  56                        if (p >= 0) {
  57                                line[5] = 't';
  58                                return p;
  59                        }
  60                }
  61        }
  62#endif /* FEATURE_DEVPTS */
  63        bb_error_msg_and_die("can't find free pty");
  64}
  65