Fix pathconf statvfs namespace (bug 18507).
[glibc.git] / sysdeps / unix / grantpt.c
blobc04c85d450f9296efa506121bcee022afda3e2dd
1 /* Copyright (C) 1998-2015 Free Software Foundation, Inc.
2 This file is part of the GNU C Library.
3 Contributed by Zack Weinberg <zack@rabi.phys.columbia.edu>, 1998.
5 The GNU C Library is free software; you can redistribute it and/or
6 modify it under the terms of the GNU Lesser General Public
7 License as published by the Free Software Foundation; either
8 version 2.1 of the License, or (at your option) any later version.
10 The GNU C Library is distributed in the hope that it will be useful,
11 but WITHOUT ANY WARRANTY; without even the implied warranty of
12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
13 Lesser General Public License for more details.
15 You should have received a copy of the GNU Lesser General Public
16 License along with the GNU C Library; if not, see
17 <http://www.gnu.org/licenses/>. */
19 #include <assert.h>
20 #include <errno.h>
21 #include <fcntl.h>
22 #include <grp.h>
23 #include <limits.h>
24 #include <stdlib.h>
25 #include <string.h>
26 #include <sys/resource.h>
27 #include <sys/stat.h>
28 #include <sys/types.h>
29 #include <sys/wait.h>
30 #include <unistd.h>
32 #include "pty-private.h"
35 /* Return the result of ptsname_r in the buffer pointed to by PTS,
36 which should be of length BUF_LEN. If it is too long to fit in
37 this buffer, a sufficiently long buffer is allocated using malloc,
38 and returned in PTS. 0 is returned upon success, -1 otherwise. */
39 static int
40 pts_name (int fd, char **pts, size_t buf_len, struct stat64 *stp)
42 int rv;
43 char *buf = *pts;
45 for (;;)
47 char *new_buf;
49 if (buf_len)
51 rv = __ptsname_internal (fd, buf, buf_len, stp);
52 if (rv != 0)
54 if (rv == ENOTTY)
55 /* ptsname_r returns with ENOTTY to indicate
56 a descriptor not referring to a pty master.
57 For this condition, grantpt must return EINVAL. */
58 rv = EINVAL;
59 errno = rv; /* Not necessarily set by __ptsname_r. */
60 break;
63 if (memchr (buf, '\0', buf_len))
64 /* We succeeded and the returned name fit in the buffer. */
65 break;
67 /* Try again with a longer buffer. */
68 buf_len += buf_len; /* Double it */
70 else
71 /* No initial buffer; start out by mallocing one. */
72 buf_len = 128; /* First time guess. */
74 if (buf != *pts)
75 /* We've already malloced another buffer at least once. */
76 new_buf = (char *) realloc (buf, buf_len);
77 else
78 new_buf = (char *) malloc (buf_len);
79 if (! new_buf)
81 rv = -1;
82 __set_errno (ENOMEM);
83 break;
85 buf = new_buf;
88 if (rv == 0)
89 *pts = buf; /* Return buffer to the user. */
90 else if (buf != *pts)
91 free (buf); /* Free what we malloced when returning an error. */
93 return rv;
96 /* Change the ownership and access permission of the slave pseudo
97 terminal associated with the master pseudo terminal specified
98 by FD. */
99 int
100 grantpt (int fd)
102 int retval = -1;
103 #ifdef PATH_MAX
104 char _buf[PATH_MAX];
105 #else
106 char _buf[512];
107 #endif
108 char *buf = _buf;
109 struct stat64 st;
111 if (__glibc_unlikely (pts_name (fd, &buf, sizeof (_buf), &st)))
113 int save_errno = errno;
115 /* Check, if the file descriptor is valid. pts_name returns the
116 wrong errno number, so we cannot use that. */
117 if (__libc_fcntl (fd, F_GETFD) == -1 && errno == EBADF)
118 return -1;
120 /* If the filedescriptor is no TTY, grantpt has to set errno
121 to EINVAL. */
122 if (save_errno == ENOTTY)
123 __set_errno (EINVAL);
124 else
125 __set_errno (save_errno);
127 return -1;
130 /* Make sure that we own the device. */
131 uid_t uid = __getuid ();
132 if (st.st_uid != uid)
134 if (__chown (buf, uid, st.st_gid) < 0)
135 goto helper;
138 static int tty_gid = -1;
139 if (__glibc_unlikely (tty_gid == -1))
141 char *grtmpbuf;
142 struct group grbuf;
143 size_t grbuflen = __sysconf (_SC_GETGR_R_SIZE_MAX);
144 struct group *p;
146 /* Get the group ID of the special `tty' group. */
147 if (grbuflen == (size_t) -1L)
148 /* `sysconf' does not support _SC_GETGR_R_SIZE_MAX.
149 Try a moderate value. */
150 grbuflen = 1024;
151 grtmpbuf = (char *) __alloca (grbuflen);
152 __getgrnam_r (TTY_GROUP, &grbuf, grtmpbuf, grbuflen, &p);
153 if (p != NULL)
154 tty_gid = p->gr_gid;
156 gid_t gid = tty_gid == -1 ? __getgid () : tty_gid;
158 /* Make sure the group of the device is that special group. */
159 if (st.st_gid != gid)
161 if (__chown (buf, uid, gid) < 0)
162 goto helper;
165 /* Make sure the permission mode is set to readable and writable by
166 the owner, and writable by the group. */
167 if ((st.st_mode & ACCESSPERMS) != (S_IRUSR|S_IWUSR|S_IWGRP))
169 if (__chmod (buf, S_IRUSR|S_IWUSR|S_IWGRP) < 0)
170 goto helper;
173 retval = 0;
174 goto cleanup;
176 /* We have to use the helper program if it is available. */
177 helper:;
179 #if HAVE_PT_CHOWN
180 pid_t pid = __fork ();
181 if (pid == -1)
182 goto cleanup;
183 else if (pid == 0)
185 /* Disable core dumps. */
186 struct rlimit rl = { 0, 0 };
187 __setrlimit (RLIMIT_CORE, &rl);
189 /* We pass the master pseudo terminal as file descriptor PTY_FILENO. */
190 if (fd != PTY_FILENO)
191 if (__dup2 (fd, PTY_FILENO) < 0)
192 _exit (FAIL_EBADF);
194 # ifdef CLOSE_ALL_FDS
195 CLOSE_ALL_FDS ();
196 # endif
198 execle (_PATH_PT_CHOWN, basename (_PATH_PT_CHOWN), NULL, NULL);
199 _exit (FAIL_EXEC);
201 else
203 int w;
205 if (__waitpid (pid, &w, 0) == -1)
206 goto cleanup;
207 if (!WIFEXITED (w))
208 __set_errno (ENOEXEC);
209 else
210 switch (WEXITSTATUS (w))
212 case 0:
213 retval = 0;
214 break;
215 case FAIL_EBADF:
216 __set_errno (EBADF);
217 break;
218 case FAIL_EINVAL:
219 __set_errno (EINVAL);
220 break;
221 case FAIL_EACCES:
222 __set_errno (EACCES);
223 break;
224 case FAIL_EXEC:
225 __set_errno (ENOEXEC);
226 break;
227 case FAIL_ENOMEM:
228 __set_errno (ENOMEM);
229 break;
231 default:
232 assert(! "grantpt: internal error: invalid exit code from pt_chown");
235 #endif
237 cleanup:
238 if (buf != _buf)
239 free (buf);
241 return retval;