trap signals for "-serial mon:stdio"
[qemu.git] / os-posix.c
1 /*
2 * os-posix.c
3 *
4 * Copyright (c) 2003-2008 Fabrice Bellard
5 * Copyright (c) 2010 Red Hat, Inc.
6 *
7 * Permission is hereby granted, free of charge, to any person obtaining a copy
8 * of this software and associated documentation files (the "Software"), to deal
9 * in the Software without restriction, including without limitation the rights
10 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
11 * copies of the Software, and to permit persons to whom the Software is
12 * furnished to do so, subject to the following conditions:
13 *
14 * The above copyright notice and this permission notice shall be included in
15 * all copies or substantial portions of the Software.
16 *
17 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
18 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
19 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
20 * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
21 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
22 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
23 * THE SOFTWARE.
24 */
25
26 #include <unistd.h>
27 #include <fcntl.h>
28 #include <signal.h>
29 #include <sys/types.h>
30 #include <sys/wait.h>
31 /*needed for MAP_POPULATE before including qemu-options.h */
32 #include <sys/mman.h>
33 #include <pwd.h>
34 #include <grp.h>
35 #include <libgen.h>
36
37 /* Needed early for CONFIG_BSD etc. */
38 #include "config-host.h"
39 #include "sysemu/sysemu.h"
40 #include "net/slirp.h"
41 #include "qemu-options.h"
42
43 #ifdef CONFIG_LINUX
44 #include <sys/prctl.h>
45 #endif
46
47 #ifdef __FreeBSD__
48 #include <sys/sysctl.h>
49 #endif
50
51 static struct passwd *user_pwd;
52 static const char *chroot_dir;
53 static int daemonize;
54 static int fds[2];
55
56 void os_setup_early_signal_handling(void)
57 {
58 struct sigaction act;
59 sigfillset(&act.sa_mask);
60 act.sa_flags = 0;
61 act.sa_handler = SIG_IGN;
62 sigaction(SIGPIPE, &act, NULL);
63 }
64
65 static void termsig_handler(int signal, siginfo_t *info, void *c)
66 {
67 qemu_system_killed(info->si_signo, info->si_pid);
68 }
69
70 void os_setup_signal_handling(void)
71 {
72 struct sigaction act;
73
74 memset(&act, 0, sizeof(act));
75 act.sa_sigaction = termsig_handler;
76 act.sa_flags = SA_SIGINFO;
77 sigaction(SIGINT, &act, NULL);
78 sigaction(SIGHUP, &act, NULL);
79 sigaction(SIGTERM, &act, NULL);
80 }
81
82 /* Find a likely location for support files using the location of the binary.
83 For installed binaries this will be "$bindir/../share/qemu". When
84 running from the build tree this will be "$bindir/../pc-bios". */
85 #define SHARE_SUFFIX "/share/qemu"
86 #define BUILD_SUFFIX "/pc-bios"
87 char *os_find_datadir(const char *argv0)
88 {
89 char *dir;
90 char *p = NULL;
91 char *res;
92 char buf[PATH_MAX];
93 size_t max_len;
94
95 #if defined(__linux__)
96 {
97 int len;
98 len = readlink("/proc/self/exe", buf, sizeof(buf) - 1);
99 if (len > 0) {
100 buf[len] = 0;
101 p = buf;
102 }
103 }
104 #elif defined(__FreeBSD__)
105 {
106 static int mib[4] = {CTL_KERN, KERN_PROC, KERN_PROC_PATHNAME, -1};
107 size_t len = sizeof(buf) - 1;
108
109 *buf = '\0';
110 if (!sysctl(mib, ARRAY_SIZE(mib), buf, &len, NULL, 0) &&
111 *buf) {
112 buf[sizeof(buf) - 1] = '\0';
113 p = buf;
114 }
115 }
116 #endif
117 /* If we don't have any way of figuring out the actual executable
118 location then try argv[0]. */
119 if (!p) {
120 p = realpath(argv0, buf);
121 if (!p) {
122 return NULL;
123 }
124 }
125 dir = dirname(p);
126 dir = dirname(dir);
127
128 max_len = strlen(dir) +
129 MAX(strlen(SHARE_SUFFIX), strlen(BUILD_SUFFIX)) + 1;
130 res = g_malloc0(max_len);
131 snprintf(res, max_len, "%s%s", dir, SHARE_SUFFIX);
132 if (access(res, R_OK)) {
133 snprintf(res, max_len, "%s%s", dir, BUILD_SUFFIX);
134 if (access(res, R_OK)) {
135 g_free(res);
136 res = NULL;
137 }
138 }
139
140 return res;
141 }
142 #undef SHARE_SUFFIX
143 #undef BUILD_SUFFIX
144
145 void os_set_proc_name(const char *s)
146 {
147 #if defined(PR_SET_NAME)
148 char name[16];
149 if (!s)
150 return;
151 pstrcpy(name, sizeof(name), s);
152 /* Could rewrite argv[0] too, but that's a bit more complicated.
153 This simple way is enough for `top'. */
154 if (prctl(PR_SET_NAME, name)) {
155 perror("unable to change process name");
156 exit(1);
157 }
158 #else
159 fprintf(stderr, "Change of process name not supported by your OS\n");
160 exit(1);
161 #endif
162 }
163
164 /*
165 * Parse OS specific command line options.
166 * return 0 if option handled, -1 otherwise
167 */
168 void os_parse_cmd_args(int index, const char *optarg)
169 {
170 switch (index) {
171 #ifdef CONFIG_SLIRP
172 case QEMU_OPTION_smb:
173 if (net_slirp_smb(optarg) < 0)
174 exit(1);
175 break;
176 #endif
177 case QEMU_OPTION_runas:
178 user_pwd = getpwnam(optarg);
179 if (!user_pwd) {
180 fprintf(stderr, "User \"%s\" doesn't exist\n", optarg);
181 exit(1);
182 }
183 break;
184 case QEMU_OPTION_chroot:
185 chroot_dir = optarg;
186 break;
187 case QEMU_OPTION_daemonize:
188 daemonize = 1;
189 break;
190 #if defined(CONFIG_LINUX)
191 case QEMU_OPTION_enablefips:
192 fips_set_state(true);
193 break;
194 #endif
195 }
196 }
197
198 static void change_process_uid(void)
199 {
200 if (user_pwd) {
201 if (setgid(user_pwd->pw_gid) < 0) {
202 fprintf(stderr, "Failed to setgid(%d)\n", user_pwd->pw_gid);
203 exit(1);
204 }
205 if (initgroups(user_pwd->pw_name, user_pwd->pw_gid) < 0) {
206 fprintf(stderr, "Failed to initgroups(\"%s\", %d)\n",
207 user_pwd->pw_name, user_pwd->pw_gid);
208 exit(1);
209 }
210 if (setuid(user_pwd->pw_uid) < 0) {
211 fprintf(stderr, "Failed to setuid(%d)\n", user_pwd->pw_uid);
212 exit(1);
213 }
214 if (setuid(0) != -1) {
215 fprintf(stderr, "Dropping privileges failed\n");
216 exit(1);
217 }
218 }
219 }
220
221 static void change_root(void)
222 {
223 if (chroot_dir) {
224 if (chroot(chroot_dir) < 0) {
225 fprintf(stderr, "chroot failed\n");
226 exit(1);
227 }
228 if (chdir("/")) {
229 perror("not able to chdir to /");
230 exit(1);
231 }
232 }
233
234 }
235
236 void os_daemonize(void)
237 {
238 if (daemonize) {
239 pid_t pid;
240
241 if (pipe(fds) == -1)
242 exit(1);
243
244 pid = fork();
245 if (pid > 0) {
246 uint8_t status;
247 ssize_t len;
248
249 close(fds[1]);
250
251 again:
252 len = read(fds[0], &status, 1);
253 if (len == -1 && (errno == EINTR))
254 goto again;
255
256 if (len != 1)
257 exit(1);
258 else if (status == 1) {
259 fprintf(stderr, "Could not acquire pidfile: %s\n", strerror(errno));
260 exit(1);
261 } else
262 exit(0);
263 } else if (pid < 0)
264 exit(1);
265
266 close(fds[0]);
267 qemu_set_cloexec(fds[1]);
268
269 setsid();
270
271 pid = fork();
272 if (pid > 0)
273 exit(0);
274 else if (pid < 0)
275 exit(1);
276
277 umask(027);
278
279 signal(SIGTSTP, SIG_IGN);
280 signal(SIGTTOU, SIG_IGN);
281 signal(SIGTTIN, SIG_IGN);
282 }
283 }
284
285 void os_setup_post(void)
286 {
287 int fd = 0;
288
289 if (daemonize) {
290 uint8_t status = 0;
291 ssize_t len;
292
293 again1:
294 len = write(fds[1], &status, 1);
295 if (len == -1 && (errno == EINTR))
296 goto again1;
297
298 if (len != 1)
299 exit(1);
300
301 if (chdir("/")) {
302 perror("not able to chdir to /");
303 exit(1);
304 }
305 TFR(fd = qemu_open("/dev/null", O_RDWR));
306 if (fd == -1)
307 exit(1);
308 }
309
310 change_root();
311 change_process_uid();
312
313 if (daemonize) {
314 dup2(fd, 0);
315 dup2(fd, 1);
316 dup2(fd, 2);
317
318 close(fd);
319 }
320 }
321
322 void os_pidfile_error(void)
323 {
324 if (daemonize) {
325 uint8_t status = 1;
326 if (write(fds[1], &status, 1) != 1) {
327 perror("daemonize. Writing to pipe\n");
328 }
329 } else
330 fprintf(stderr, "Could not acquire pid file: %s\n", strerror(errno));
331 }
332
333 void os_set_line_buffering(void)
334 {
335 setvbuf(stdout, NULL, _IOLBF, 0);
336 }
337
338 int qemu_create_pidfile(const char *filename)
339 {
340 char buffer[128];
341 int len;
342 int fd;
343
344 fd = qemu_open(filename, O_RDWR | O_CREAT, 0600);
345 if (fd == -1) {
346 return -1;
347 }
348 if (lockf(fd, F_TLOCK, 0) == -1) {
349 close(fd);
350 return -1;
351 }
352 len = snprintf(buffer, sizeof(buffer), FMT_pid "\n", getpid());
353 if (write(fd, buffer, len) != len) {
354 close(fd);
355 return -1;
356 }
357
358 /* keep pidfile open & locked forever */
359 return 0;
360 }
361
362 bool is_daemonized(void)
363 {
364 return daemonize;
365 }
366
367 int os_mlock(void)
368 {
369 int ret = 0;
370
371 ret = mlockall(MCL_CURRENT | MCL_FUTURE);
372 if (ret < 0) {
373 perror("mlockall");
374 }
375
376 return ret;
377 }