1: /*
2: * Copyright (c) 2011-2014 Todd C. Miller <Todd.Miller@courtesan.com>
3: *
4: * Permission to use, copy, modify, and distribute this software for any
5: * purpose with or without fee is hereby granted, provided that the above
6: * copyright notice and this permission notice appear in all copies.
7: *
8: * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
9: * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
10: * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
11: * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
12: * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
13: * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
14: * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
15: */
16:
17: #include <config.h>
18:
19: #include <sys/types.h>
20: #include <stdio.h>
21: #ifdef STDC_HEADERS
22: # include <stdlib.h>
23: # include <stddef.h>
24: #else
25: # ifdef HAVE_STDLIB_H
26: # include <stdlib.h>
27: # endif
28: #endif /* STDC_HEADERS */
29: #ifdef HAVE_STRING_H
30: # if defined(HAVE_MEMORY_H) && !defined(STDC_HEADERS)
31: # include <memory.h>
32: # endif
33: # include <string.h>
34: #endif /* HAVE_STRING_H */
35: #ifdef HAVE_STRINGS_H
36: # include <strings.h>
37: #endif /* HAVE_STRINGS_H */
38: #include <errno.h>
39: #include <signal.h>
40: #include <termios.h>
41: #include <unistd.h>
42:
43: #include "missing.h"
44: #include "sudo_debug.h"
45: #include "sudo_util.h"
46:
47: #ifndef TCSASOFT
48: # define TCSASOFT 0
49: #endif
50: #ifndef ECHONL
51: # define ECHONL 0
52: #endif
53: #ifndef IEXTEN
54: # define IEXTEN 0
55: #endif
56: #ifndef IUCLC
57: # define IUCLC 0
58: #endif
59:
60: #ifndef _POSIX_VDISABLE
61: # ifdef VDISABLE
62: # define _POSIX_VDISABLE VDISABLE
63: # else
64: # define _POSIX_VDISABLE 0
65: # endif
66: #endif
67:
68: static struct termios term, oterm;
69: static int changed;
70:
71: /* tgetpass() needs to know the erase and kill chars for cbreak mode. */
72: int term_erase;
73: int term_kill;
74:
75: static volatile sig_atomic_t got_sigttou;
76:
77: /*
78: * SIGTTOU signal handler for term_restore that just sets a flag.
79: */
80: static void sigttou(int signo)
81: {
82: got_sigttou = 1;
83: }
84:
85: /*
86: * Like tcsetattr() but restarts on EINTR _except_ for SIGTTOU.
87: * Returns 0 on success or -1 on failure, setting errno.
88: * Sets got_sigttou on failure if interrupted by SIGTTOU.
89: */
90: static int
91: tcsetattr_nobg(int fd, int flags, struct termios *tp)
92: {
93: sigaction_t sa, osa;
94: int rc;
95:
96: /*
97: * If we receive SIGTTOU from tcsetattr() it means we are
98: * not in the foreground process group.
99: * This should be less racy than using tcgetpgrp().
100: */
101: memset(&sa, 0, sizeof(sa));
102: sigemptyset(&sa.sa_mask);
103: sa.sa_handler = sigttou;
104: got_sigttou = 0;
105: sigaction(SIGTTOU, &sa, &osa);
106: do {
107: rc = tcsetattr(fd, flags, tp);
108: } while (rc != 0 && errno == EINTR && !got_sigttou);
109: sigaction(SIGTTOU, &osa, NULL);
110:
111: return rc;
112: }
113:
114: /*
115: * Restore saved terminal settings if we are in the foreground process group.
116: * Returns true on success or false on failure.
117: */
118: bool
119: term_restore(int fd, bool flush)
120: {
121: debug_decl(term_restore, SUDO_DEBUG_UTIL)
122:
123: if (changed) {
124: const int flags = flush ? (TCSASOFT|TCSAFLUSH) : (TCSASOFT|TCSADRAIN);
125: if (tcsetattr_nobg(fd, flags, &oterm) != 0)
126: debug_return_bool(false);
127: changed = 0;
128: }
129: debug_return_bool(true);
130: }
131:
132: /*
133: * Disable terminal echo.
134: * Returns true on success or false on failure.
135: */
136: bool
137: term_noecho(int fd)
138: {
139: debug_decl(term_noecho, SUDO_DEBUG_UTIL)
140:
141: again:
142: if (!changed && tcgetattr(fd, &oterm) != 0)
143: debug_return_bool(false);
144: (void) memcpy(&term, &oterm, sizeof(term));
145: CLR(term.c_lflag, ECHO|ECHONL);
146: #ifdef VSTATUS
147: term.c_cc[VSTATUS] = _POSIX_VDISABLE;
148: #endif
149: if (tcsetattr_nobg(fd, TCSADRAIN|TCSASOFT, &term) == 0) {
150: changed = 1;
151: debug_return_bool(true);
152: }
153: if (got_sigttou) {
154: /* We were in the background, so oterm is probably bogus. */
155: kill(getpid(), SIGTTOU);
156: goto again;
157: }
158: debug_return_bool(false);
159: }
160:
161: /*
162: * Set terminal to raw mode.
163: * Returns true on success or false on failure.
164: */
165: bool
166: term_raw(int fd, int isig)
167: {
168: struct termios term;
169: debug_decl(term_raw, SUDO_DEBUG_UTIL)
170:
171: again:
172: if (!changed && tcgetattr(fd, &oterm) != 0)
173: return 0;
174: (void) memcpy(&term, &oterm, sizeof(term));
175: /* Set terminal to raw mode */
176: term.c_cc[VMIN] = 1;
177: term.c_cc[VTIME] = 0;
178: CLR(term.c_iflag, ICRNL | IGNCR | INLCR | IUCLC | IXON);
179: CLR(term.c_oflag, OPOST);
180: CLR(term.c_lflag, ECHO | ICANON | ISIG | IEXTEN);
181: if (isig)
182: SET(term.c_lflag, ISIG);
183: if (tcsetattr_nobg(fd, TCSADRAIN|TCSASOFT, &term) == 0) {
184: changed = 1;
185: debug_return_bool(true);
186: }
187: if (got_sigttou) {
188: /* We were in the background, so oterm is probably bogus. */
189: kill(getpid(), SIGTTOU);
190: goto again;
191: }
192: debug_return_bool(false);
193: }
194:
195: /*
196: * Set terminal to cbreak mode.
197: * Returns true on success or false on failure.
198: */
199: bool
200: term_cbreak(int fd)
201: {
202: debug_decl(term_cbreak, SUDO_DEBUG_UTIL)
203:
204: again:
205: if (!changed && tcgetattr(fd, &oterm) != 0)
206: return 0;
207: (void) memcpy(&term, &oterm, sizeof(term));
208: /* Set terminal to half-cooked mode */
209: term.c_cc[VMIN] = 1;
210: term.c_cc[VTIME] = 0;
211: /* cppcheck-suppress redundantAssignment */
212: CLR(term.c_lflag, ECHO | ECHONL | ICANON | IEXTEN);
213: /* cppcheck-suppress redundantAssignment */
214: SET(term.c_lflag, ISIG);
215: #ifdef VSTATUS
216: term.c_cc[VSTATUS] = _POSIX_VDISABLE;
217: #endif
218: if (tcsetattr_nobg(fd, TCSADRAIN|TCSASOFT, &term) == 0) {
219: term_erase = term.c_cc[VERASE];
220: term_kill = term.c_cc[VKILL];
221: changed = 1;
222: debug_return_bool(true);
223: }
224: if (got_sigttou) {
225: /* We were in the background, so oterm is probably bogus. */
226: kill(getpid(), SIGTTOU);
227: goto again;
228: }
229: debug_return_bool(false);
230: }
231:
232: /*
233: * Copy terminal settings from one descriptor to another.
234: * Returns true on success or false on failure.
235: */
236: bool
237: term_copy(int src, int dst)
238: {
239: struct termios tt;
240: debug_decl(term_copy, SUDO_DEBUG_UTIL)
241:
242: again:
243: if (tcgetattr(src, &tt) != 0)
244: debug_return_bool(false);
245: if (tcsetattr_nobg(dst, TCSANOW|TCSASOFT, &tt) == 0)
246: debug_return_bool(true);
247: if (got_sigttou) {
248: /* We were in the background, so oterm is probably bogus. */
249: kill(getpid(), SIGTTOU);
250: goto again;
251: }
252: debug_return_bool(false);
253: }
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