diff options
Diffstat (limited to 'libc/stdlib/unix_grantpt.c')
| -rw-r--r-- | libc/stdlib/unix_grantpt.c | 197 |
1 files changed, 197 insertions, 0 deletions
diff --git a/libc/stdlib/unix_grantpt.c b/libc/stdlib/unix_grantpt.c new file mode 100644 index 000000000..eb6ce0b35 --- /dev/null +++ b/libc/stdlib/unix_grantpt.c @@ -0,0 +1,197 @@ +/* Copyright (C) 1998 Free Software Foundation, Inc. + This file is part of the GNU C Library. + Contributed by Zack Weinberg <zack@rabi.phys.columbia.edu>, 1998. + + The GNU C Library is free software; you can redistribute it and/or + modify it under the terms of the GNU Library General Public License as + published by the Free Software Foundation; either version 2 of the + License, or (at your option) any later version. + + The GNU C Library is distributed in the hope that it will be useful, + but WITHOUT ANY WARRANTY; without even the implied warranty of + MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU + Library General Public License for more details. + + You should have received a copy of the GNU Library General Public + License along with the GNU C Library; see the file COPYING.LIB. If not, + write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330, + Boston, MA 02111-1307, USA. */ + +#include <assert.h> +#include <errno.h> +#include <grp.h> +#include <limits.h> +#include <stdlib.h> +#include <string.h> +#include <sys/resource.h> +#include <sys/stat.h> +#include <sys/types.h> +#include <sys/wait.h> +#include <unistd.h> + +#include "pty-private.h" + +extern int ptsname_r (int fd, char *buf, size_t buflen); + +/* Return the result of ptsname_r in the buffer pointed to by PTS, + which should be of length BUF_LEN. If it is too long to fit in + this buffer, a sufficiently long buffer is allocated using malloc, + and returned in PTS. 0 is returned upon success, -1 otherwise. */ +static int +pts_name (int fd, char **pts, size_t buf_len) +{ + int rv; + char *buf = *pts; + + for (;;) + { + char *new_buf; + + if (buf_len) + { + rv = ptsname_r (fd, buf, buf_len); + + if (rv != 0 || memchr (buf, '\0', buf_len)) + /* We either got an error, or we succeeded and the + returned name fit in the buffer. */ + break; + + /* Try again with a longer buffer. */ + buf_len += buf_len; /* Double it */ + } + else + /* No initial buffer; start out by mallocing one. */ + buf_len = 128; /* First time guess. */ + + if (buf != *pts) + /* We've already malloced another buffer at least once. */ + new_buf = realloc (buf, buf_len); + else + new_buf = malloc (buf_len); + if (! new_buf) + { + rv = -1; + errno = ENOMEM; + break; + } + buf = new_buf; + } + + if (rv == 0) + *pts = buf; /* Return buffer to the user. */ + else if (buf != *pts) + free (buf); /* Free what we malloced when returning an error. */ + + return rv; +} + +/* Change the ownership and access permission of the slave pseudo + terminal associated with the master pseudo terminal specified + by FD. */ +int +grantpt (int fd) +{ + int retval = -1; +#ifdef PATH_MAX + char _buf[PATH_MAX]; +#else + char _buf[512]; +#endif + char *buf = _buf; + struct stat st; + uid_t uid; + gid_t gid; + pid_t pid; + + if (pts_name (fd, &buf, sizeof (_buf))) + return -1; + + if (_xstat (_STAT_VER, buf, &st) < 0) + goto cleanup; + + /* Make sure that we own the device. */ + uid = getuid (); + if (st.st_uid != uid) + { + if (chown (buf, uid, st.st_gid) < 0) + goto helper; + } + + gid = getgid (); + + /* Make sure the group of the device is that special group. */ + if (st.st_gid != gid) + { + if (chown (buf, uid, gid) < 0) + goto helper; + } + + /* Make sure the permission mode is set to readable and writable by + the owner, and writable by the group. */ + if ((st.st_mode & ACCESSPERMS) != (S_IRUSR|S_IWUSR|S_IWGRP)) + { + if (chmod (buf, S_IRUSR|S_IWUSR|S_IWGRP) < 0) + goto helper; + } + + retval = 0; + goto cleanup; + + /* We have to use the helper program. */ + helper: + + pid = fork (); + if (pid == -1) + goto cleanup; + else if (pid == 0) + { + /* Disable core dumps. */ + struct rlimit rl = { 0, 0 }; + setrlimit (RLIMIT_CORE, &rl); + + /* We pase the master pseudo terminal as file descriptor PTY_FILENO. */ + if (fd != PTY_FILENO) + if (dup2 (fd, PTY_FILENO) < 0) + exit (FAIL_EBADF); + + execle (_PATH_PT_CHOWN, _PATH_PT_CHOWN, NULL, NULL); + exit (FAIL_EXEC); + } + else + { + int w; + + if (waitpid (pid, &w, 0) == -1) + goto cleanup; + if (!WIFEXITED (w)) + errno = ENOEXEC; + else + switch (WEXITSTATUS(w)) + { + case 0: + retval = 0; + break; + case FAIL_EBADF: + errno = EBADF; + break; + case FAIL_EINVAL: + errno = EINVAL; + break; + case FAIL_EACCES: + errno = EACCES; + break; + case FAIL_EXEC: + errno = ENOEXEC; + break; + + default: + assert(! "getpt: internal error: invalid exit code from pt_chown"); + } + } + + cleanup: + if (buf != _buf) + free (buf); + + return retval; +} |