xref: /qemu/util/oslib-posix.c (revision 3d100d0f) 
1 /*
2  * os-posix-lib.c
3  *
4  * Copyright (c) 2003-2008 Fabrice Bellard
5  * Copyright (c) 2010 Red Hat, Inc.
6  *
7  * QEMU library functions on POSIX which are shared between QEMU and
8  * the QEMU tools.
9  *
10  * Permission is hereby granted, free of charge, to any person obtaining a copy
11  * of this software and associated documentation files (the "Software"), to deal
12  * in the Software without restriction, including without limitation the rights
13  * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
14  * copies of the Software, and to permit persons to whom the Software is
15  * furnished to do so, subject to the following conditions:
16  *
17  * The above copyright notice and this permission notice shall be included in
18  * all copies or substantial portions of the Software.
19  *
20  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
21  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
22  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
23  * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
24  * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
25  * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
26  * THE SOFTWARE.
27  */
28 
29 #if defined(__linux__) && (defined(__x86_64__) || defined(__arm__))
30    /* Use 2 MiB alignment so transparent hugepages can be used by KVM.
31       Valgrind does not support alignments larger than 1 MiB,
32       therefore we need special code which handles running on Valgrind. */
33 #  define QEMU_VMALLOC_ALIGN (512 * 4096)
34 #elif defined(__linux__) && defined(__s390x__)
35    /* Use 1 MiB (segment size) alignment so gmap can be used by KVM. */
36 #  define QEMU_VMALLOC_ALIGN (256 * 4096)
37 #else
38 #  define QEMU_VMALLOC_ALIGN getpagesize()
39 #endif
40 
41 #include "qemu/osdep.h"
42 #include <termios.h>
43 #include <termios.h>
44 
45 #include <glib/gprintf.h>
46 
47 #include "sysemu/sysemu.h"
48 #include "trace.h"
49 #include "qapi/error.h"
50 #include "qemu/sockets.h"
51 #include <sys/mman.h>
52 #include <libgen.h>
53 #include <sys/signal.h>
54 #include "qemu/cutils.h"
55 
56 #ifdef CONFIG_LINUX
57 #include <sys/syscall.h>
58 #endif
59 
60 #ifdef __FreeBSD__
61 #include <sys/sysctl.h>
62 #endif
63 
64 #include <qemu/mmap-alloc.h>
65 
66 int qemu_get_thread_id(void)
67 {
68 #if defined(__linux__)
69     return syscall(SYS_gettid);
70 #else
71     return getpid();
72 #endif
73 }
74 
75 int qemu_daemon(int nochdir, int noclose)
76 {
77     return daemon(nochdir, noclose);
78 }
79 
80 void *qemu_oom_check(void *ptr)
81 {
82     if (ptr == NULL) {
83         fprintf(stderr, "Failed to allocate memory: %s\n", strerror(errno));
84         abort();
85     }
86     return ptr;
87 }
88 
89 void *qemu_try_memalign(size_t alignment, size_t size)
90 {
91     void *ptr;
92 
93     if (alignment < sizeof(void*)) {
94         alignment = sizeof(void*);
95     }
96 
97 #if defined(_POSIX_C_SOURCE) && !defined(__sun__)
98     int ret;
99     ret = posix_memalign(&ptr, alignment, size);
100     if (ret != 0) {
101         errno = ret;
102         ptr = NULL;
103     }
104 #elif defined(CONFIG_BSD)
105     ptr = valloc(size);
106 #else
107     ptr = memalign(alignment, size);
108 #endif
109     trace_qemu_memalign(alignment, size, ptr);
110     return ptr;
111 }
112 
113 void *qemu_memalign(size_t alignment, size_t size)
114 {
115     return qemu_oom_check(qemu_try_memalign(alignment, size));
116 }
117 
118 /* alloc shared memory pages */
119 void *qemu_anon_ram_alloc(size_t size, uint64_t *alignment)
120 {
121     size_t align = QEMU_VMALLOC_ALIGN;
122     void *ptr = qemu_ram_mmap(-1, size, align, false);
123 
124     if (ptr == MAP_FAILED) {
125         return NULL;
126     }
127 
128     if (alignment) {
129         *alignment = align;
130     }
131 
132     trace_qemu_anon_ram_alloc(size, ptr);
133     return ptr;
134 }
135 
136 void qemu_vfree(void *ptr)
137 {
138     trace_qemu_vfree(ptr);
139     free(ptr);
140 }
141 
142 void qemu_anon_ram_free(void *ptr, size_t size)
143 {
144     trace_qemu_anon_ram_free(ptr, size);
145     qemu_ram_munmap(ptr, size);
146 }
147 
148 void qemu_set_block(int fd)
149 {
150     int f;
151     f = fcntl(fd, F_GETFL);
152     fcntl(fd, F_SETFL, f & ~O_NONBLOCK);
153 }
154 
155 void qemu_set_nonblock(int fd)
156 {
157     int f;
158     f = fcntl(fd, F_GETFL);
159     fcntl(fd, F_SETFL, f | O_NONBLOCK);
160 }
161 
162 int socket_set_fast_reuse(int fd)
163 {
164     int val = 1, ret;
165 
166     ret = setsockopt(fd, SOL_SOCKET, SO_REUSEADDR,
167                      (const char *)&val, sizeof(val));
168 
169     assert(ret == 0);
170 
171     return ret;
172 }
173 
174 void qemu_set_cloexec(int fd)
175 {
176     int f;
177     f = fcntl(fd, F_GETFD);
178     fcntl(fd, F_SETFD, f | FD_CLOEXEC);
179 }
180 
181 /*
182  * Creates a pipe with FD_CLOEXEC set on both file descriptors
183  */
184 int qemu_pipe(int pipefd[2])
185 {
186     int ret;
187 
188 #ifdef CONFIG_PIPE2
189     ret = pipe2(pipefd, O_CLOEXEC);
190     if (ret != -1 || errno != ENOSYS) {
191         return ret;
192     }
193 #endif
194     ret = pipe(pipefd);
195     if (ret == 0) {
196         qemu_set_cloexec(pipefd[0]);
197         qemu_set_cloexec(pipefd[1]);
198     }
199 
200     return ret;
201 }
202 
203 int qemu_utimens(const char *path, const struct timespec *times)
204 {
205     struct timeval tv[2], tv_now;
206     struct stat st;
207     int i;
208 #ifdef CONFIG_UTIMENSAT
209     int ret;
210 
211     ret = utimensat(AT_FDCWD, path, times, AT_SYMLINK_NOFOLLOW);
212     if (ret != -1 || errno != ENOSYS) {
213         return ret;
214     }
215 #endif
216     /* Fallback: use utimes() instead of utimensat() */
217 
218     /* happy if special cases */
219     if (times[0].tv_nsec == UTIME_OMIT && times[1].tv_nsec == UTIME_OMIT) {
220         return 0;
221     }
222     if (times[0].tv_nsec == UTIME_NOW && times[1].tv_nsec == UTIME_NOW) {
223         return utimes(path, NULL);
224     }
225 
226     /* prepare for hard cases */
227     if (times[0].tv_nsec == UTIME_NOW || times[1].tv_nsec == UTIME_NOW) {
228         gettimeofday(&tv_now, NULL);
229     }
230     if (times[0].tv_nsec == UTIME_OMIT || times[1].tv_nsec == UTIME_OMIT) {
231         stat(path, &st);
232     }
233 
234     for (i = 0; i < 2; i++) {
235         if (times[i].tv_nsec == UTIME_NOW) {
236             tv[i].tv_sec = tv_now.tv_sec;
237             tv[i].tv_usec = tv_now.tv_usec;
238         } else if (times[i].tv_nsec == UTIME_OMIT) {
239             tv[i].tv_sec = (i == 0) ? st.st_atime : st.st_mtime;
240             tv[i].tv_usec = 0;
241         } else {
242             tv[i].tv_sec = times[i].tv_sec;
243             tv[i].tv_usec = times[i].tv_nsec / 1000;
244         }
245     }
246 
247     return utimes(path, &tv[0]);
248 }
249 
250 char *
251 qemu_get_local_state_pathname(const char *relative_pathname)
252 {
253     return g_strdup_printf("%s/%s", CONFIG_QEMU_LOCALSTATEDIR,
254                            relative_pathname);
255 }
256 
257 void qemu_set_tty_echo(int fd, bool echo)
258 {
259     struct termios tty;
260 
261     tcgetattr(fd, &tty);
262 
263     if (echo) {
264         tty.c_lflag |= ECHO | ECHONL | ICANON | IEXTEN;
265     } else {
266         tty.c_lflag &= ~(ECHO | ECHONL | ICANON | IEXTEN);
267     }
268 
269     tcsetattr(fd, TCSANOW, &tty);
270 }
271 
272 static char exec_dir[PATH_MAX];
273 
274 void qemu_init_exec_dir(const char *argv0)
275 {
276     char *dir;
277     char *p = NULL;
278     char buf[PATH_MAX];
279 
280     assert(!exec_dir[0]);
281 
282 #if defined(__linux__)
283     {
284         int len;
285         len = readlink("/proc/self/exe", buf, sizeof(buf) - 1);
286         if (len > 0) {
287             buf[len] = 0;
288             p = buf;
289         }
290     }
291 #elif defined(__FreeBSD__)
292     {
293         static int mib[4] = {CTL_KERN, KERN_PROC, KERN_PROC_PATHNAME, -1};
294         size_t len = sizeof(buf) - 1;
295 
296         *buf = '\0';
297         if (!sysctl(mib, ARRAY_SIZE(mib), buf, &len, NULL, 0) &&
298             *buf) {
299             buf[sizeof(buf) - 1] = '\0';
300             p = buf;
301         }
302     }
303 #endif
304     /* If we don't have any way of figuring out the actual executable
305        location then try argv[0].  */
306     if (!p) {
307         if (!argv0) {
308             return;
309         }
310         p = realpath(argv0, buf);
311         if (!p) {
312             return;
313         }
314     }
315     dir = dirname(p);
316 
317     pstrcpy(exec_dir, sizeof(exec_dir), dir);
318 }
319 
320 char *qemu_get_exec_dir(void)
321 {
322     return g_strdup(exec_dir);
323 }
324 
325 static sigjmp_buf sigjump;
326 
327 static void sigbus_handler(int signal)
328 {
329     siglongjmp(sigjump, 1);
330 }
331 
332 void os_mem_prealloc(int fd, char *area, size_t memory)
333 {
334     int ret;
335     struct sigaction act, oldact;
336     sigset_t set, oldset;
337 
338     memset(&act, 0, sizeof(act));
339     act.sa_handler = &sigbus_handler;
340     act.sa_flags = 0;
341 
342     ret = sigaction(SIGBUS, &act, &oldact);
343     if (ret) {
344         perror("os_mem_prealloc: failed to install signal handler");
345         exit(1);
346     }
347 
348     /* unblock SIGBUS */
349     sigemptyset(&set);
350     sigaddset(&set, SIGBUS);
351     pthread_sigmask(SIG_UNBLOCK, &set, &oldset);
352 
353     if (sigsetjmp(sigjump, 1)) {
354         fprintf(stderr, "os_mem_prealloc: Insufficient free host memory "
355                         "pages available to allocate guest RAM\n");
356         exit(1);
357     } else {
358         int i;
359         size_t hpagesize = qemu_fd_getpagesize(fd);
360         size_t numpages = DIV_ROUND_UP(memory, hpagesize);
361 
362         /* MAP_POPULATE silently ignores failures */
363         for (i = 0; i < numpages; i++) {
364             memset(area + (hpagesize * i), 0, 1);
365         }
366 
367         ret = sigaction(SIGBUS, &oldact, NULL);
368         if (ret) {
369             perror("os_mem_prealloc: failed to reinstall signal handler");
370             exit(1);
371         }
372 
373         pthread_sigmask(SIG_SETMASK, &oldset, NULL);
374     }
375 }
376 
377 
378 static struct termios oldtty;
379 
380 static void term_exit(void)
381 {
382     tcsetattr(0, TCSANOW, &oldtty);
383 }
384 
385 static void term_init(void)
386 {
387     struct termios tty;
388 
389     tcgetattr(0, &tty);
390     oldtty = tty;
391 
392     tty.c_iflag &= ~(IGNBRK|BRKINT|PARMRK|ISTRIP
393                           |INLCR|IGNCR|ICRNL|IXON);
394     tty.c_oflag |= OPOST;
395     tty.c_lflag &= ~(ECHO|ECHONL|ICANON|IEXTEN);
396     tty.c_cflag &= ~(CSIZE|PARENB);
397     tty.c_cflag |= CS8;
398     tty.c_cc[VMIN] = 1;
399     tty.c_cc[VTIME] = 0;
400 
401     tcsetattr(0, TCSANOW, &tty);
402 
403     atexit(term_exit);
404 }
405 
406 int qemu_read_password(char *buf, int buf_size)
407 {
408     uint8_t ch;
409     int i, ret;
410 
411     printf("password: ");
412     fflush(stdout);
413     term_init();
414     i = 0;
415     for (;;) {
416         ret = read(0, &ch, 1);
417         if (ret == -1) {
418             if (errno == EAGAIN || errno == EINTR) {
419                 continue;
420             } else {
421                 break;
422             }
423         } else if (ret == 0) {
424             ret = -1;
425             break;
426         } else {
427             if (ch == '\r' ||
428                 ch == '\n') {
429                 ret = 0;
430                 break;
431             }
432             if (i < (buf_size - 1)) {
433                 buf[i++] = ch;
434             }
435         }
436     }
437     term_exit();
438     buf[i] = '\0';
439     printf("\n");
440     return ret;
441 }
442 
443 
444 pid_t qemu_fork(Error **errp)
445 {
446     sigset_t oldmask, newmask;
447     struct sigaction sig_action;
448     int saved_errno;
449     pid_t pid;
450 
451     /*
452      * Need to block signals now, so that child process can safely
453      * kill off caller's signal handlers without a race.
454      */
455     sigfillset(&newmask);
456     if (pthread_sigmask(SIG_SETMASK, &newmask, &oldmask) != 0) {
457         error_setg_errno(errp, errno,
458                          "cannot block signals");
459         return -1;
460     }
461 
462     pid = fork();
463     saved_errno = errno;
464 
465     if (pid < 0) {
466         /* attempt to restore signal mask, but ignore failure, to
467          * avoid obscuring the fork failure */
468         (void)pthread_sigmask(SIG_SETMASK, &oldmask, NULL);
469         error_setg_errno(errp, saved_errno,
470                          "cannot fork child process");
471         errno = saved_errno;
472         return -1;
473     } else if (pid) {
474         /* parent process */
475 
476         /* Restore our original signal mask now that the child is
477          * safely running. Only documented failures are EFAULT (not
478          * possible, since we are using just-grabbed mask) or EINVAL
479          * (not possible, since we are using correct arguments).  */
480         (void)pthread_sigmask(SIG_SETMASK, &oldmask, NULL);
481     } else {
482         /* child process */
483         size_t i;
484 
485         /* Clear out all signal handlers from parent so nothing
486          * unexpected can happen in our child once we unblock
487          * signals */
488         sig_action.sa_handler = SIG_DFL;
489         sig_action.sa_flags = 0;
490         sigemptyset(&sig_action.sa_mask);
491 
492         for (i = 1; i < NSIG; i++) {
493             /* Only possible errors are EFAULT or EINVAL The former
494              * won't happen, the latter we expect, so no need to check
495              * return value */
496             (void)sigaction(i, &sig_action, NULL);
497         }
498 
499         /* Unmask all signals in child, since we've no idea what the
500          * caller's done with their signal mask and don't want to
501          * propagate that to children */
502         sigemptyset(&newmask);
503         if (pthread_sigmask(SIG_SETMASK, &newmask, NULL) != 0) {
504             Error *local_err = NULL;
505             error_setg_errno(&local_err, errno,
506                              "cannot unblock signals");
507             error_report_err(local_err);
508             _exit(1);
509         }
510     }
511     return pid;
512 }
513