util/oslib-posix.c

   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 /* The following block of code temporarily renames the daemon() function so the
  30    compiler does not see the warning associated with it in stdlib.h on OSX */
  31 #ifdef __APPLE__
  32 #define daemon qemu_fake_daemon_function
  33 #include <stdlib.h>
  34 #undef daemon
  35 extern int daemon(int, int);
  36 #endif
  37
  38 #if defined(__linux__) && (defined(__x86_64__) || defined(__arm__))
  39    /* Use 2 MiB alignment so transparent hugepages can be used by KVM.
  40       Valgrind does not support alignments larger than 1 MiB,
  41       therefore we need special code which handles running on Valgrind. */
  42 #  define QEMU_VMALLOC_ALIGN (512 * 4096)
  43 #elif defined(__linux__) && defined(__s390x__)
  44    /* Use 1 MiB (segment size) alignment so gmap can be used by KVM. */
  45 #  define QEMU_VMALLOC_ALIGN (256 * 4096)
  46 #else
  47 #  define QEMU_VMALLOC_ALIGN getpagesize()
  48 #endif
  49 #define HUGETLBFS_MAGIC       0x958458f6
  50
  51 #include <termios.h>
  52 #include <unistd.h>
  53
  54 #include <glib/gprintf.h>
  55
  56 #include "config-host.h"
  57 #include "sysemu/sysemu.h"
  58 #include "trace.h"
  59 #include "qemu/sockets.h"
  60 #include <sys/mman.h>
  61 #include <libgen.h>
  62 #include <setjmp.h>
  63 #include <sys/signal.h>
  64
  65 #ifdef CONFIG_LINUX
  66 #include <sys/syscall.h>
  67 #include <sys/vfs.h>
  68 #endif
  69
  70 #ifdef __FreeBSD__
  71 #include <sys/sysctl.h>
  72 #endif
  73
  74 int qemu_get_thread_id(void)
  75 {
  76 #if defined(__linux__)
  77     return syscall(SYS_gettid);
  78 #else
  79     return getpid();
  80 #endif
  81 }
  82
  83 int qemu_daemon(int nochdir, int noclose)
  84 {
  85     return daemon(nochdir, noclose);
  86 }
  87
  88 void *qemu_oom_check(void *ptr)
  89 {
  90     if (ptr == NULL) {
  91         fprintf(stderr, "Failed to allocate memory: %s\n", strerror(errno));
  92         abort();
  93     }
  94     return ptr;
  95 }
  96
  97 void *qemu_memalign(size_t alignment, size_t size)
  98 {
  99     void *ptr;
 100
 101     if (alignment < sizeof(void*)) {
 102         alignment = sizeof(void*);
 103     }
 104
 105 #if defined(_POSIX_C_SOURCE) && !defined(__sun__)
 106     int ret;
 107     ret = posix_memalign(&ptr, alignment, size);
 108     if (ret != 0) {
 109         fprintf(stderr, "Failed to allocate %zu B: %s\n",
 110                 size, strerror(ret));
 111         abort();
 112     }
 113 #elif defined(CONFIG_BSD)
 114     ptr = qemu_oom_check(valloc(size));
 115 #else
 116     ptr = qemu_oom_check(memalign(alignment, size));
 117 #endif
 118     trace_qemu_memalign(alignment, size, ptr);
 119     return ptr;
 120 }
 121
 122 /* alloc shared memory pages */
 123 void *qemu_anon_ram_alloc(size_t size)
 124 {
 125     size_t align = QEMU_VMALLOC_ALIGN;
 126     size_t total = size + align - getpagesize();
 127     void *ptr = mmap(0, total, PROT_READ | PROT_WRITE,
 128                      MAP_ANONYMOUS | MAP_PRIVATE, -1, 0);
 129     size_t offset = QEMU_ALIGN_UP((uintptr_t)ptr, align) - (uintptr_t)ptr;
 130
 131     if (ptr == MAP_FAILED) {
 132         return NULL;
 133     }
 134
 135     ptr += offset;
 136     total -= offset;
 137
 138     if (offset > 0) {
 139         munmap(ptr - offset, offset);
 140     }
 141     if (total > size) {
 142         munmap(ptr + size, total - size);
 143     }
 144
 145     trace_qemu_anon_ram_alloc(size, ptr);
 146     return ptr;
 147 }
 148
 149 void qemu_vfree(void *ptr)
 150 {
 151     trace_qemu_vfree(ptr);
 152     free(ptr);
 153 }
 154
 155 void qemu_anon_ram_free(void *ptr, size_t size)
 156 {
 157     trace_qemu_anon_ram_free(ptr, size);
 158     if (ptr) {
 159         munmap(ptr, size);
 160     }
 161 }
 162
 163 void qemu_set_block(int fd)
 164 {
 165     int f;
 166     f = fcntl(fd, F_GETFL);
 167     fcntl(fd, F_SETFL, f & ~O_NONBLOCK);
 168 }
 169
 170 void qemu_set_nonblock(int fd)
 171 {
 172     int f;
 173     f = fcntl(fd, F_GETFL);
 174     fcntl(fd, F_SETFL, f | O_NONBLOCK);
 175 }
 176
 177 int socket_set_fast_reuse(int fd)
 178 {
 179     int val = 1, ret;
 180
 181     ret = setsockopt(fd, SOL_SOCKET, SO_REUSEADDR,
 182                      (const char *)&val, sizeof(val));
 183
 184     assert(ret == 0);
 185
 186     return ret;
 187 }
 188
 189 void qemu_set_cloexec(int fd)
 190 {
 191     int f;
 192     f = fcntl(fd, F_GETFD);
 193     fcntl(fd, F_SETFD, f | FD_CLOEXEC);
 194 }
 195
 196 /*
 197  * Creates a pipe with FD_CLOEXEC set on both file descriptors
 198  */
 199 int qemu_pipe(int pipefd[2])
 200 {
 201     int ret;
 202
 203 #ifdef CONFIG_PIPE2
 204     ret = pipe2(pipefd, O_CLOEXEC);
 205     if (ret != -1 || errno != ENOSYS) {
 206         return ret;
 207     }
 208 #endif
 209     ret = pipe(pipefd);
 210     if (ret == 0) {
 211         qemu_set_cloexec(pipefd[0]);
 212         qemu_set_cloexec(pipefd[1]);
 213     }
 214
 215     return ret;
 216 }
 217
 218 int qemu_utimens(const char *path, const struct timespec *times)
 219 {
 220     struct timeval tv[2], tv_now;
 221     struct stat st;
 222     int i;
 223 #ifdef CONFIG_UTIMENSAT
 224     int ret;
 225
 226     ret = utimensat(AT_FDCWD, path, times, AT_SYMLINK_NOFOLLOW);
 227     if (ret != -1 || errno != ENOSYS) {
 228         return ret;
 229     }
 230 #endif
 231     /* Fallback: use utimes() instead of utimensat() */
 232
 233     /* happy if special cases */
 234     if (times[0].tv_nsec == UTIME_OMIT && times[1].tv_nsec == UTIME_OMIT) {
 235         return 0;
 236     }
 237     if (times[0].tv_nsec == UTIME_NOW && times[1].tv_nsec == UTIME_NOW) {
 238         return utimes(path, NULL);
 239     }
 240
 241     /* prepare for hard cases */
 242     if (times[0].tv_nsec == UTIME_NOW || times[1].tv_nsec == UTIME_NOW) {
 243         gettimeofday(&tv_now, NULL);
 244     }
 245     if (times[0].tv_nsec == UTIME_OMIT || times[1].tv_nsec == UTIME_OMIT) {
 246         stat(path, &st);
 247     }
 248
 249     for (i = 0; i < 2; i++) {
 250         if (times[i].tv_nsec == UTIME_NOW) {
 251             tv[i].tv_sec = tv_now.tv_sec;
 252             tv[i].tv_usec = tv_now.tv_usec;
 253         } else if (times[i].tv_nsec == UTIME_OMIT) {
 254             tv[i].tv_sec = (i == 0) ? st.st_atime : st.st_mtime;
 255             tv[i].tv_usec = 0;
 256         } else {
 257             tv[i].tv_sec = times[i].tv_sec;
 258             tv[i].tv_usec = times[i].tv_nsec / 1000;
 259         }
 260     }
 261
 262     return utimes(path, &tv[0]);
 263 }
 264
 265 char *
 266 qemu_get_local_state_pathname(const char *relative_pathname)
 267 {
 268     return g_strdup_printf("%s/%s", CONFIG_QEMU_LOCALSTATEDIR,
 269                            relative_pathname);
 270 }
 271
 272 void qemu_set_tty_echo(int fd, bool echo)
 273 {
 274     struct termios tty;
 275
 276     tcgetattr(fd, &tty);
 277
 278     if (echo) {
 279         tty.c_lflag |= ECHO | ECHONL | ICANON | IEXTEN;
 280     } else {
 281         tty.c_lflag &= ~(ECHO | ECHONL | ICANON | IEXTEN);
 282     }
 283
 284     tcsetattr(fd, TCSANOW, &tty);
 285 }
 286
 287 static char exec_dir[PATH_MAX];
 288
 289 void qemu_init_exec_dir(const char *argv0)
 290 {
 291     char *dir;
 292     char *p = NULL;
 293     char buf[PATH_MAX];
 294
 295     assert(!exec_dir[0]);
 296
 297 #if defined(__linux__)
 298     {
 299         int len;
 300         len = readlink("/proc/self/exe", buf, sizeof(buf) - 1);
 301         if (len > 0) {
 302             buf[len] = 0;
 303             p = buf;
 304         }
 305     }
 306 #elif defined(__FreeBSD__)
 307     {
 308         static int mib[4] = {CTL_KERN, KERN_PROC, KERN_PROC_PATHNAME, -1};
 309         size_t len = sizeof(buf) - 1;
 310
 311         *buf = '\0';
 312         if (!sysctl(mib, ARRAY_SIZE(mib), buf, &len, NULL, 0) &&
 313             *buf) {
 314             buf[sizeof(buf) - 1] = '\0';
 315             p = buf;
 316         }
 317     }
 318 #endif
 319     /* If we don't have any way of figuring out the actual executable
 320        location then try argv[0].  */
 321     if (!p) {
 322         if (!argv0) {
 323             return;
 324         }
 325         p = realpath(argv0, buf);
 326         if (!p) {
 327             return;
 328         }
 329     }
 330     dir = dirname(p);
 331
 332     pstrcpy(exec_dir, sizeof(exec_dir), dir);
 333 }
 334
 335 char *qemu_get_exec_dir(void)
 336 {
 337     return g_strdup(exec_dir);
 338 }
 339
 340 static sigjmp_buf sigjump;
 341
 342 static void sigbus_handler(int signal)
 343 {
 344     siglongjmp(sigjump, 1);
 345 }
 346
 347 static size_t fd_getpagesize(int fd)
 348 {
 349 #ifdef CONFIG_LINUX
 350     struct statfs fs;
 351     int ret;
 352
 353     if (fd != -1) {
 354         do {
 355             ret = fstatfs(fd, &fs);
 356         } while (ret != 0 && errno == EINTR);
 357
 358         if (ret == 0 && fs.f_type == HUGETLBFS_MAGIC) {
 359             return fs.f_bsize;
 360         }
 361     }
 362 #endif
 363
 364     return getpagesize();
 365 }
 366
 367 void os_mem_prealloc(int fd, char *area, size_t memory)
 368 {
 369     int ret;
 370     struct sigaction act, oldact;
 371     sigset_t set, oldset;
 372
 373     memset(&act, 0, sizeof(act));
 374     act.sa_handler = &sigbus_handler;
 375     act.sa_flags = 0;
 376
 377     ret = sigaction(SIGBUS, &act, &oldact);
 378     if (ret) {
 379         perror("os_mem_prealloc: failed to install signal handler");
 380         exit(1);
 381     }
 382
 383     /* unblock SIGBUS */
 384     sigemptyset(&set);
 385     sigaddset(&set, SIGBUS);
 386     pthread_sigmask(SIG_UNBLOCK, &set, &oldset);
 387
 388     if (sigsetjmp(sigjump, 1)) {
 389         fprintf(stderr, "os_mem_prealloc: failed to preallocate pages\n");
 390         exit(1);
 391     } else {
 392         int i;
 393         size_t hpagesize = fd_getpagesize(fd);
 394
 395         /* MAP_POPULATE silently ignores failures */
 396         memory = (memory + hpagesize - 1) & -hpagesize;
 397         for (i = 0; i < (memory / hpagesize); i++) {
 398             memset(area + (hpagesize * i), 0, 1);
 399         }
 400
 401         ret = sigaction(SIGBUS, &oldact, NULL);
 402         if (ret) {
 403             perror("os_mem_prealloc: failed to reinstall signal handler");
 404             exit(1);
 405         }
 406
 407         pthread_sigmask(SIG_SETMASK, &oldset, NULL);
 408     }
 409 }