1/* Copyright (C) 1998-2024 Free Software Foundation, Inc.
2 This file is part of the GNU C Library.
3
4 The GNU C Library is free software; you can redistribute it and/or
5 modify it under the terms of the GNU Lesser General Public
6 License as published by the Free Software Foundation; either
7 version 2.1 of the License, or (at your option) any later version.
8
9 The GNU C Library is distributed in the hope that it will be useful,
10 but WITHOUT ANY WARRANTY; without even the implied warranty of
11 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
12 Lesser General Public License for more details.
13
14 You should have received a copy of the GNU Lesser General Public
15 License along with the GNU C Library; if not, see
16 <https://www.gnu.org/licenses/>. */
17
18#include <errno.h>
19#include <fcntl.h>
20#include <string.h>
21#include <unistd.h>
22#include <stdlib.h>
23
24/* Prefix for master pseudo terminal nodes. */
25#define _PATH_PTY "/dev/pty"
26
27
28/* Letters indicating a series of pseudo terminals. */
29#ifndef PTYNAME1
30#define PTYNAME1 "pqrsPQRS"
31#endif
32const char __libc_ptyname1[] attribute_hidden = PTYNAME1;
33
34/* Letters indicating the position within a series. */
35#ifndef PTYNAME2
36#define PTYNAME2 "0123456789abcdefghijklmnopqrstuv";
37#endif
38const char __libc_ptyname2[] attribute_hidden = PTYNAME2;
39
40
41/* Open a master pseudo terminal and return its file descriptor. */
42int
43__bsd_openpt (int oflag)
44{
45 char buf[sizeof (_PATH_PTY) + 2];
46 const char *p, *q;
47 char *s;
48
49 s = __mempcpy (buf, _PATH_PTY, sizeof (_PATH_PTY) - 1);
50 /* s[0] and s[1] will be filled in the loop. */
51 s[2] = '\0';
52
53 for (p = __libc_ptyname1; *p != '\0'; ++p)
54 {
55 s[0] = *p;
56
57 for (q = __libc_ptyname2; *q != '\0'; ++q)
58 {
59 int fd;
60
61 s[1] = *q;
62
63 fd = __open (buf, oflag);
64 if (fd != -1)
65 return fd;
66
67 if (errno == ENOENT)
68 return -1;
69 }
70 }
71
72 __set_errno (ENOENT);
73 return -1;
74}
75
76int
77__getpt (void)
78{
79 return __bsd_openpt (O_RDWR);
80}
81libc_hidden_def (__getpt)
82weak_alias (__getpt, getpt)
83
84int
85__posix_openpt (int oflag)
86{
87 return __bsd_openpt (oflag);
88}
89weak_alias (__posix_openpt, posix_openpt)
90

source code of glibc/sysdeps/unix/bsd/getpt.c