include/qemu/osdep.h

   1 /*
   2  * OS includes and handling of OS dependencies
   3  *
   4  * This header exists to pull in some common system headers that
   5  * most code in QEMU will want, and to fix up some possible issues with
   6  * it (missing defines, Windows weirdness, and so on).
   7  *
   8  * To avoid getting into possible circular include dependencies, this
   9  * file should not include any other QEMU headers, with the exceptions
  10  * of config-host.h, config-target.h, qemu/compiler.h,
  11  * sysemu/os-posix.h, sysemu/os-win32.h, glib-compat.h and
  12  * qemu/typedefs.h, all of which are doing a similar job to this file
  13  * and are under similar constraints.
  14  *
  15  * This header also contains prototypes for functions defined in
  16  * os-*.c and util/oslib-*.c; those would probably be better split
  17  * out into separate header files.
  18  *
  19  * In an ideal world this header would contain only:
  20  *  (1) things which everybody needs
  21  *  (2) things without which code would work on most platforms but
  22  *      fail to compile or misbehave on a minority of host OSes
  23  *
  24  * This work is licensed under the terms of the GNU GPL, version 2 or later.
  25  * See the COPYING file in the top-level directory.
  26  */
  27 #ifndef QEMU_OSDEP_H
  28 #define QEMU_OSDEP_H
  29
  30 #include "config-host.h"
  31 #ifdef NEED_CPU_H
  32 #include CONFIG_TARGET
  33 #else
  34 #include "exec/poison.h"
  35 #endif
  36
  37 /*
  38  * HOST_WORDS_BIGENDIAN was replaced with HOST_BIG_ENDIAN. Prevent it from
  39  * creeping back in.
  40  */
  41 #pragma GCC poison HOST_WORDS_BIGENDIAN
  42
  43 /*
  44  * TARGET_WORDS_BIGENDIAN was replaced with TARGET_BIG_ENDIAN. Prevent it from
  45  * creeping back in.
  46  */
  47 #pragma GCC poison TARGET_WORDS_BIGENDIAN
  48
  49 #include "qemu/compiler.h"
  50
  51 /* Older versions of C++ don't get definitions of various macros from
  52  * stdlib.h unless we define these macros before first inclusion of
  53  * that system header.
  54  */
  55 #ifndef __STDC_CONSTANT_MACROS
  56 #define __STDC_CONSTANT_MACROS
  57 #endif
  58 #ifndef __STDC_LIMIT_MACROS
  59 #define __STDC_LIMIT_MACROS
  60 #endif
  61 #ifndef __STDC_FORMAT_MACROS
  62 #define __STDC_FORMAT_MACROS
  63 #endif
  64
  65 /* The following block of code temporarily renames the daemon() function so the
  66  * compiler does not see the warning associated with it in stdlib.h on OSX
  67  */
  68 #ifdef __APPLE__
  69 #define daemon qemu_fake_daemon_function
  70 #include <stdlib.h>
  71 #undef daemon
  72 QEMU_EXTERN_C int daemon(int, int);
  73 #endif
  74
  75 #ifdef _WIN32
  76 /* as defined in sdkddkver.h */
  77 #ifndef _WIN32_WINNT
  78 #define _WIN32_WINNT 0x0601 /* Windows 7 API (should be in sync with glib) */
  79 #endif
  80 /* reduces the number of implicitly included headers */
  81 #ifndef WIN32_LEAN_AND_MEAN
  82 #define WIN32_LEAN_AND_MEAN
  83 #endif
  84 #endif
  85
  86 /* enable C99/POSIX format strings (needs mingw32-runtime 3.15 or later) */
  87 #ifdef __MINGW32__
  88 #define __USE_MINGW_ANSI_STDIO 1
  89 #endif
  90
  91 #include <stdarg.h>
  92 #include <stddef.h>
  93 #include <stdbool.h>
  94 #include <stdint.h>
  95 #include <sys/types.h>
  96 #include <stdlib.h>
  97 #include <stdio.h>
  98
  99 #include <string.h>
 100 #include <strings.h>
 101 #include <inttypes.h>
 102 #include <limits.h>
 103 /* Put unistd.h before time.h as that triggers localtime_r/gmtime_r
 104  * function availability on recentish Mingw-w64 platforms. */
 105 #include <unistd.h>
 106 #include <time.h>
 107 #include <ctype.h>
 108 #include <errno.h>
 109 #include <fcntl.h>
 110 #include <getopt.h>
 111 #include <sys/stat.h>
 112 #include <sys/time.h>
 113 #include <assert.h>
 114 /* setjmp must be declared before sysemu/os-win32.h
 115  * because it is redefined there. */
 116 #include <setjmp.h>
 117 #include <signal.h>
 118
 119 #ifdef CONFIG_IOVEC
 120 #include <sys/uio.h>
 121 #endif
 122
 123 #if defined(__linux__) && defined(__sparc__)
 124 /* The SPARC definition of QEMU_VMALLOC_ALIGN needs SHMLBA */
 125 #include <sys/shm.h>
 126 #endif
 127
 128 #ifndef _WIN32
 129 #include <sys/wait.h>
 130 #else
 131 #define WIFEXITED(x)   1
 132 #define WEXITSTATUS(x) (x)
 133 #endif
 134
 135 #ifdef __APPLE__
 136 #include <AvailabilityMacros.h>
 137 #endif
 138
 139 /*
 140  * This is somewhat like a system header; it must be outside any extern "C"
 141  * block because it includes system headers itself, including glib.h,
 142  * which will not compile if inside an extern "C" block.
 143  */
 144 #include "glib-compat.h"
 145
 146 #ifdef _WIN32
 147 #include "sysemu/os-win32.h"
 148 #endif
 149
 150 #ifdef CONFIG_POSIX
 151 #include "sysemu/os-posix.h"
 152 #endif
 153
 154 #ifdef __cplusplus
 155 extern "C" {
 156 #endif
 157
 158 #include "qemu/typedefs.h"
 159
 160 /**
 161  * Mark a function that executes in coroutine context
 162  *
 163  * Functions that execute in coroutine context cannot be called directly from
 164  * normal functions.  In the future it would be nice to enable compiler or
 165  * static checker support for catching such errors.  This annotation might make
 166  * it possible and in the meantime it serves as documentation.
 167  *
 168  * For example:
 169  *
 170  *   static void coroutine_fn foo(void) {
 171  *       ....
 172  *   }
 173  */
 174 #define coroutine_fn
 175
 176 /*
 177  * For mingw, as of v6.0.0, the function implementing the assert macro is
 178  * not marked as noreturn, so the compiler cannot delete code following an
 179  * assert(false) as unused.  We rely on this within the code base to delete
 180  * code that is unreachable when features are disabled.
 181  * All supported versions of Glib's g_assert() satisfy this requirement.
 182  */
 183 #ifdef __MINGW32__
 184 #undef assert
 185 #define assert(x)  g_assert(x)
 186 #endif
 187
 188 /**
 189  * qemu_build_not_reached()
 190  *
 191  * The compiler, during optimization, is expected to prove that a call
 192  * to this function cannot be reached and remove it.  If the compiler
 193  * supports QEMU_ERROR, this will be reported at compile time; otherwise
 194  * this will be reported at link time due to the missing symbol.
 195  */
 196 extern G_NORETURN
 197 void QEMU_ERROR("code path is reachable")
 198     qemu_build_not_reached_always(void);
 199 #if defined(__OPTIMIZE__) && !defined(__NO_INLINE__)
 200 #define qemu_build_not_reached()  qemu_build_not_reached_always()
 201 #else
 202 #define qemu_build_not_reached()  g_assert_not_reached()
 203 #endif
 204
 205 /**
 206  * qemu_build_assert()
 207  *
 208  * The compiler, during optimization, is expected to prove that the
 209  * assertion is true.
 210  */
 211 #define qemu_build_assert(test)  while (!(test)) qemu_build_not_reached()
 212
 213 /*
 214  * According to waitpid man page:
 215  * WCOREDUMP
 216  *  This  macro  is  not  specified  in POSIX.1-2001 and is not
 217  *  available on some UNIX implementations (e.g., AIX, SunOS).
 218  *  Therefore, enclose its use inside #ifdef WCOREDUMP ... #endif.
 219  */
 220 #ifndef WCOREDUMP
 221 #define WCOREDUMP(status) 0
 222 #endif
 223 /*
 224  * We have a lot of unaudited code that may fail in strange ways, or
 225  * even be a security risk during migration, if you disable assertions
 226  * at compile-time.  You may comment out these safety checks if you
 227  * absolutely want to disable assertion overhead, but it is not
 228  * supported upstream so the risk is all yours.  Meanwhile, please
 229  * submit patches to remove any side-effects inside an assertion, or
 230  * fixing error handling that should use Error instead of assert.
 231  */
 232 #ifdef NDEBUG
 233 #error building with NDEBUG is not supported
 234 #endif
 235 #ifdef G_DISABLE_ASSERT
 236 #error building with G_DISABLE_ASSERT is not supported
 237 #endif
 238
 239 #ifndef O_LARGEFILE
 240 #define O_LARGEFILE 0
 241 #endif
 242 #ifndef O_BINARY
 243 #define O_BINARY 0
 244 #endif
 245 #ifndef MAP_ANONYMOUS
 246 #define MAP_ANONYMOUS MAP_ANON
 247 #endif
 248 #ifndef MAP_FIXED_NOREPLACE
 249 #define MAP_FIXED_NOREPLACE 0
 250 #endif
 251 #ifndef MAP_NORESERVE
 252 #define MAP_NORESERVE 0
 253 #endif
 254 #ifndef ENOMEDIUM
 255 #define ENOMEDIUM ENODEV
 256 #endif
 257 #if !defined(ENOTSUP)
 258 #define ENOTSUP 4096
 259 #endif
 260 #if !defined(ECANCELED)
 261 #define ECANCELED 4097
 262 #endif
 263 #if !defined(EMEDIUMTYPE)
 264 #define EMEDIUMTYPE 4098
 265 #endif
 266 #if !defined(ESHUTDOWN)
 267 #define ESHUTDOWN 4099
 268 #endif
 269
 270 #define RETRY_ON_EINTR(expr) \
 271     (__extension__                                          \
 272         ({ typeof(expr) __result;                               \
 273            do {                                             \
 274                 __result = (expr);         \
 275            } while (__result == -1 && errno == EINTR);     \
 276            __result; }))
 277
 278 /* time_t may be either 32 or 64 bits depending on the host OS, and
 279  * can be either signed or unsigned, so we can't just hardcode a
 280  * specific maximum value. This is not a C preprocessor constant,
 281  * so you can't use TIME_MAX in an #ifdef, but for our purposes
 282  * this isn't a problem.
 283  */
 284
 285 /* The macros TYPE_SIGNED, TYPE_WIDTH, and TYPE_MAXIMUM are from
 286  * Gnulib, and are under the LGPL v2.1 or (at your option) any
 287  * later version.
 288  */
 289
 290 /* True if the real type T is signed.  */
 291 #define TYPE_SIGNED(t) (!((t)0 < (t)-1))
 292
 293 /* The width in bits of the integer type or expression T.
 294  * Padding bits are not supported.
 295  */
 296 #define TYPE_WIDTH(t) (sizeof(t) * CHAR_BIT)
 297
 298 /* The maximum and minimum values for the integer type T.  */
 299 #define TYPE_MAXIMUM(t)                                                \
 300   ((t) (!TYPE_SIGNED(t)                                                \
 301         ? (t)-1                                                        \
 302         : ((((t)1 << (TYPE_WIDTH(t) - 2)) - 1) * 2 + 1)))
 303
 304 #ifndef TIME_MAX
 305 #define TIME_MAX TYPE_MAXIMUM(time_t)
 306 #endif
 307
 308 /* Mac OSX has a <stdint.h> bug that incorrectly defines SIZE_MAX with
 309  * the wrong type. Our replacement isn't usable in preprocessor
 310  * expressions, but it is sufficient for our needs. */
 311 #ifdef HAVE_BROKEN_SIZE_MAX
 312 #undef SIZE_MAX
 313 #define SIZE_MAX ((size_t)-1)
 314 #endif
 315
 316 /*
 317  * Two variations of MIN/MAX macros. The first is for runtime use, and
 318  * evaluates arguments only once (so it is safe even with side
 319  * effects), but will not work in constant contexts (such as array
 320  * size declarations) because of the '{}'.  The second is for constant
 321  * expression use, where evaluating arguments twice is safe because
 322  * the result is going to be constant anyway, but will not work in a
 323  * runtime context because of a void expression where a value is
 324  * expected.  Thus, both gcc and clang will fail to compile if you use
 325  * the wrong macro (even if the error may seem a bit cryptic).
 326  *
 327  * Note that neither form is usable as an #if condition; if you truly
 328  * need to write conditional code that depends on a minimum or maximum
 329  * determined by the pre-processor instead of the compiler, you'll
 330  * have to open-code it.  Sadly, Coverity is severely confused by the
 331  * constant variants, so we have to dumb things down there.
 332  */
 333 #undef MIN
 334 #define MIN(a, b)                                       \
 335     ({                                                  \
 336         typeof(1 ? (a) : (b)) _a = (a), _b = (b);       \
 337         _a < _b ? _a : _b;                              \
 338     })
 339 #undef MAX
 340 #define MAX(a, b)                                       \
 341     ({                                                  \
 342         typeof(1 ? (a) : (b)) _a = (a), _b = (b);       \
 343         _a > _b ? _a : _b;                              \
 344     })
 345
 346 #ifdef __COVERITY__
 347 # define MIN_CONST(a, b) ((a) < (b) ? (a) : (b))
 348 # define MAX_CONST(a, b) ((a) > (b) ? (a) : (b))
 349 #else
 350 # define MIN_CONST(a, b)                                        \
 351     __builtin_choose_expr(                                      \
 352         __builtin_constant_p(a) && __builtin_constant_p(b),     \
 353         (a) < (b) ? (a) : (b),                                  \
 354         ((void)0))
 355 # define MAX_CONST(a, b)                                        \
 356     __builtin_choose_expr(                                      \
 357         __builtin_constant_p(a) && __builtin_constant_p(b),     \
 358         (a) > (b) ? (a) : (b),                                  \
 359         ((void)0))
 360 #endif
 361
 362 /*
 363  * Minimum function that returns zero only if both values are zero.
 364  * Intended for use with unsigned values only.
 365  */
 366 #ifndef MIN_NON_ZERO
 367 #define MIN_NON_ZERO(a, b)                              \
 368     ({                                                  \
 369         typeof(1 ? (a) : (b)) _a = (a), _b = (b);       \
 370         _a == 0 ? _b : (_b == 0 || _b > _a) ? _a : _b;  \
 371     })
 372 #endif
 373
 374 /*
 375  * Round number down to multiple. Safe when m is not a power of 2 (see
 376  * ROUND_DOWN for a faster version when a power of 2 is guaranteed).
 377  */
 378 #define QEMU_ALIGN_DOWN(n, m) ((n) / (m) * (m))
 379
 380 /*
 381  * Round number up to multiple. Safe when m is not a power of 2 (see
 382  * ROUND_UP for a faster version when a power of 2 is guaranteed).
 383  */
 384 #define QEMU_ALIGN_UP(n, m) QEMU_ALIGN_DOWN((n) + (m) - 1, (m))
 385
 386 /* Check if n is a multiple of m */
 387 #define QEMU_IS_ALIGNED(n, m) (((n) % (m)) == 0)
 388
 389 /* n-byte align pointer down */
 390 #define QEMU_ALIGN_PTR_DOWN(p, n) \
 391     ((typeof(p))QEMU_ALIGN_DOWN((uintptr_t)(p), (n)))
 392
 393 /* n-byte align pointer up */
 394 #define QEMU_ALIGN_PTR_UP(p, n) \
 395     ((typeof(p))QEMU_ALIGN_UP((uintptr_t)(p), (n)))
 396
 397 /* Check if pointer p is n-bytes aligned */
 398 #define QEMU_PTR_IS_ALIGNED(p, n) QEMU_IS_ALIGNED((uintptr_t)(p), (n))
 399
 400 /*
 401  * Round number down to multiple. Requires that d be a power of 2 (see
 402  * QEMU_ALIGN_UP for a safer but slower version on arbitrary
 403  * numbers); works even if d is a smaller type than n.
 404  */
 405 #ifndef ROUND_DOWN
 406 #define ROUND_DOWN(n, d) ((n) & -(0 ? (n) : (d)))
 407 #endif
 408
 409 /*
 410  * Round number up to multiple. Requires that d be a power of 2 (see
 411  * QEMU_ALIGN_UP for a safer but slower version on arbitrary
 412  * numbers); works even if d is a smaller type than n.
 413  */
 414 #ifndef ROUND_UP
 415 #define ROUND_UP(n, d) ROUND_DOWN((n) + (d) - 1, (d))
 416 #endif
 417
 418 #ifndef DIV_ROUND_UP
 419 #define DIV_ROUND_UP(n, d) (((n) + (d) - 1) / (d))
 420 #endif
 421
 422 /*
 423  * &(x)[0] is always a pointer - if it's same type as x then the argument is a
 424  * pointer, not an array.
 425  */
 426 #define QEMU_IS_ARRAY(x) (!__builtin_types_compatible_p(typeof(x), \
 427                                                         typeof(&(x)[0])))
 428 #ifndef ARRAY_SIZE
 429 #define ARRAY_SIZE(x) ((sizeof(x) / sizeof((x)[0])) + \
 430                        QEMU_BUILD_BUG_ON_ZERO(!QEMU_IS_ARRAY(x)))
 431 #endif
 432
 433 int qemu_daemon(int nochdir, int noclose);
 434 void *qemu_anon_ram_alloc(size_t size, uint64_t *align, bool shared,
 435                           bool noreserve);
 436 void qemu_anon_ram_free(void *ptr, size_t size);
 437
 438 #ifdef _WIN32
 439 #define HAVE_CHARDEV_SERIAL 1
 440 #elif defined(__linux__) || defined(__sun__) || defined(__FreeBSD__)    \
 441     || defined(__NetBSD__) || defined(__OpenBSD__) || defined(__DragonFly__) \
 442     || defined(__GLIBC__) || defined(__APPLE__)
 443 #define HAVE_CHARDEV_SERIAL 1
 444 #endif
 445
 446 #if defined(__HAIKU__)
 447 #define SIGIO SIGPOLL
 448 #endif
 449
 450 #ifdef HAVE_MADVISE_WITHOUT_PROTOTYPE
 451 /*
 452  * See MySQL bug #7156 (http://bugs.mysql.com/bug.php?id=7156) for discussion
 453  * about Solaris missing the madvise() prototype.
 454  */
 455 extern int madvise(char *, size_t, int);
 456 #endif
 457
 458 #if defined(CONFIG_LINUX)
 459 #ifndef BUS_MCEERR_AR
 460 #define BUS_MCEERR_AR 4
 461 #endif
 462 #ifndef BUS_MCEERR_AO
 463 #define BUS_MCEERR_AO 5
 464 #endif
 465 #endif
 466
 467 #if defined(__linux__) && \
 468     (defined(__x86_64__) || defined(__arm__) || defined(__aarch64__) \
 469      || defined(__powerpc64__))
 470    /* Use 2 MiB alignment so transparent hugepages can be used by KVM.
 471       Valgrind does not support alignments larger than 1 MiB,
 472       therefore we need special code which handles running on Valgrind. */
 473 #  define QEMU_VMALLOC_ALIGN (512 * 4096)
 474 #elif defined(__linux__) && defined(__s390x__)
 475    /* Use 1 MiB (segment size) alignment so gmap can be used by KVM. */
 476 #  define QEMU_VMALLOC_ALIGN (256 * 4096)
 477 #elif defined(__linux__) && defined(__sparc__)
 478 #  define QEMU_VMALLOC_ALIGN MAX(qemu_real_host_page_size(), SHMLBA)
 479 #else
 480 #  define QEMU_VMALLOC_ALIGN qemu_real_host_page_size()
 481 #endif
 482
 483 #ifdef CONFIG_POSIX
 484 struct qemu_signalfd_siginfo {
 485     uint32_t ssi_signo;   /* Signal number */
 486     int32_t  ssi_errno;   /* Error number (unused) */
 487     int32_t  ssi_code;    /* Signal code */
 488     uint32_t ssi_pid;     /* PID of sender */
 489     uint32_t ssi_uid;     /* Real UID of sender */
 490     int32_t  ssi_fd;      /* File descriptor (SIGIO) */
 491     uint32_t ssi_tid;     /* Kernel timer ID (POSIX timers) */
 492     uint32_t ssi_band;    /* Band event (SIGIO) */
 493     uint32_t ssi_overrun; /* POSIX timer overrun count */
 494     uint32_t ssi_trapno;  /* Trap number that caused signal */
 495     int32_t  ssi_status;  /* Exit status or signal (SIGCHLD) */
 496     int32_t  ssi_int;     /* Integer sent by sigqueue(2) */
 497     uint64_t ssi_ptr;     /* Pointer sent by sigqueue(2) */
 498     uint64_t ssi_utime;   /* User CPU time consumed (SIGCHLD) */
 499     uint64_t ssi_stime;   /* System CPU time consumed (SIGCHLD) */
 500     uint64_t ssi_addr;    /* Address that generated signal
 501                              (for hardware-generated signals) */
 502     uint8_t  pad[48];     /* Pad size to 128 bytes (allow for
 503                              additional fields in the future) */
 504 };
 505
 506 int qemu_signalfd(const sigset_t *mask);
 507 void sigaction_invoke(struct sigaction *action,
 508                       struct qemu_signalfd_siginfo *info);
 509 #endif
 510
 511 /*
 512  * Don't introduce new usage of this function, prefer the following
 513  * qemu_open/qemu_create that take an "Error **errp"
 514  */
 515 int qemu_open_old(const char *name, int flags, ...);
 516 int qemu_open(const char *name, int flags, Error **errp);
 517 int qemu_create(const char *name, int flags, mode_t mode, Error **errp);
 518 int qemu_close(int fd);
 519 int qemu_unlink(const char *name);
 520 #ifndef _WIN32
 521 int qemu_dup_flags(int fd, int flags);
 522 int qemu_dup(int fd);
 523 int qemu_lock_fd(int fd, int64_t start, int64_t len, bool exclusive);
 524 int qemu_unlock_fd(int fd, int64_t start, int64_t len);
 525 int qemu_lock_fd_test(int fd, int64_t start, int64_t len, bool exclusive);
 526 bool qemu_has_ofd_lock(void);
 527 #endif
 528
 529 #if defined(__HAIKU__) && defined(__i386__)
 530 #define FMT_pid "%ld"
 531 #elif defined(WIN64)
 532 #define FMT_pid "%" PRId64
 533 #else
 534 #define FMT_pid "%d"
 535 #endif
 536
 537 bool qemu_write_pidfile(const char *pidfile, Error **errp);
 538
 539 int qemu_get_thread_id(void);
 540
 541 #ifndef CONFIG_IOVEC
 542 struct iovec {
 543     void *iov_base;
 544     size_t iov_len;
 545 };
 546 /*
 547  * Use the same value as Linux for now.
 548  */
 549 #define IOV_MAX 1024
 550
 551 ssize_t readv(int fd, const struct iovec *iov, int iov_cnt);
 552 ssize_t writev(int fd, const struct iovec *iov, int iov_cnt);
 553 #endif
 554
 555 #ifdef _WIN32
 556 static inline void qemu_timersub(const struct timeval *val1,
 557                                  const struct timeval *val2,
 558                                  struct timeval *res)
 559 {
 560     res->tv_sec = val1->tv_sec - val2->tv_sec;
 561     if (val1->tv_usec < val2->tv_usec) {
 562         res->tv_sec--;
 563         res->tv_usec = val1->tv_usec - val2->tv_usec + 1000 * 1000;
 564     } else {
 565         res->tv_usec = val1->tv_usec - val2->tv_usec;
 566     }
 567 }
 568 #else
 569 #define qemu_timersub timersub
 570 #endif
 571
 572 ssize_t qemu_write_full(int fd, const void *buf, size_t count)
 573     G_GNUC_WARN_UNUSED_RESULT;
 574
 575 void qemu_set_cloexec(int fd);
 576
 577 /* Return a dynamically allocated directory path that is appropriate for storing
 578  * local state.
 579  *
 580  * The caller is responsible for releasing the value returned with g_free()
 581  * after use.
 582  */
 583 char *qemu_get_local_state_dir(void);
 584
 585 /**
 586  * qemu_getauxval:
 587  * @type: the auxiliary vector key to lookup
 588  *
 589  * Search the auxiliary vector for @type, returning the value
 590  * or 0 if @type is not present.
 591  */
 592 unsigned long qemu_getauxval(unsigned long type);
 593
 594 void qemu_set_tty_echo(int fd, bool echo);
 595
 596 typedef struct ThreadContext ThreadContext;
 597
 598 /**
 599  * qemu_prealloc_mem:
 600  * @fd: the fd mapped into the area, -1 for anonymous memory
 601  * @area: start address of the are to preallocate
 602  * @sz: the size of the area to preallocate
 603  * @max_threads: maximum number of threads to use
 604  * @errp: returns an error if this function fails
 605  *
 606  * Preallocate memory (populate/prefault page tables writable) for the virtual
 607  * memory area starting at @area with the size of @sz. After a successful call,
 608  * each page in the area was faulted in writable at least once, for example,
 609  * after allocating file blocks for mapped files.
 610  */
 611 void qemu_prealloc_mem(int fd, char *area, size_t sz, int max_threads,
 612                        ThreadContext *tc, Error **errp);
 613
 614 /**
 615  * qemu_get_pid_name:
 616  * @pid: pid of a process
 617  *
 618  * For given @pid fetch its name. Caller is responsible for
 619  * freeing the string when no longer needed.
 620  * Returns allocated string on success, NULL on failure.
 621  */
 622 char *qemu_get_pid_name(pid_t pid);
 623
 624 /**
 625  * qemu_fork:
 626  *
 627  * A version of fork that avoids signal handler race
 628  * conditions that can lead to child process getting
 629  * signals that are otherwise only expected by the
 630  * parent. It also resets all signal handlers to the
 631  * default settings.
 632  *
 633  * Returns 0 to child process, pid number to parent
 634  * or -1 on failure.
 635  */
 636 pid_t qemu_fork(Error **errp);
 637
 638 /* Using intptr_t ensures that qemu_*_page_mask is sign-extended even
 639  * when intptr_t is 32-bit and we are aligning a long long.
 640  */
 641 static inline uintptr_t qemu_real_host_page_size(void)
 642 {
 643     return getpagesize();
 644 }
 645
 646 static inline intptr_t qemu_real_host_page_mask(void)
 647 {
 648     return -(intptr_t)qemu_real_host_page_size();
 649 }
 650
 651 /*
 652  * After using getopt or getopt_long, if you need to parse another set
 653  * of options, then you must reset optind.  Unfortunately the way to
 654  * do this varies between implementations of getopt.
 655  */
 656 static inline void qemu_reset_optind(void)
 657 {
 658 #ifdef HAVE_OPTRESET
 659     optind = 1;
 660     optreset = 1;
 661 #else
 662     optind = 0;
 663 #endif
 664 }
 665
 666 int qemu_fdatasync(int fd);
 667
 668 /**
 669  * Sync changes made to the memory mapped file back to the backing
 670  * storage. For POSIX compliant systems this will fallback
 671  * to regular msync call. Otherwise it will trigger whole file sync
 672  * (including the metadata case there is no support to skip that otherwise)
 673  *
 674  * @addr   - start of the memory area to be synced
 675  * @length - length of the are to be synced
 676  * @fd     - file descriptor for the file to be synced
 677  *           (mandatory only for POSIX non-compliant systems)
 678  */
 679 int qemu_msync(void *addr, size_t length, int fd);
 680
 681 /**
 682  * qemu_get_host_physmem:
 683  *
 684  * Operating system agnostic way of querying host memory.
 685  *
 686  * Returns amount of physical memory on the system. This is purely
 687  * advisery and may return 0 if we can't work it out. At the other
 688  * end we saturate to SIZE_MAX if you are lucky enough to have that
 689  * much memory.
 690  */
 691 size_t qemu_get_host_physmem(void);
 692
 693 /*
 694  * Toggle write/execute on the pages marked MAP_JIT
 695  * for the current thread.
 696  */
 697 #if defined(MAC_OS_VERSION_11_0) && \
 698     MAC_OS_X_VERSION_MIN_REQUIRED >= MAC_OS_VERSION_11_0
 699 static inline void qemu_thread_jit_execute(void)
 700 {
 701     pthread_jit_write_protect_np(true);
 702 }
 703
 704 static inline void qemu_thread_jit_write(void)
 705 {
 706     pthread_jit_write_protect_np(false);
 707 }
 708 #else
 709 static inline void qemu_thread_jit_write(void) {}
 710 static inline void qemu_thread_jit_execute(void) {}
 711 #endif
 712
 713 /**
 714  * Platforms which do not support system() return ENOSYS
 715  */
 716 #ifndef HAVE_SYSTEM_FUNCTION
 717 #define system platform_does_not_support_system
 718 static inline int platform_does_not_support_system(const char *command)
 719 {
 720     errno = ENOSYS;
 721     return -1;
 722 }
 723 #endif /* !HAVE_SYSTEM_FUNCTION */
 724
 725 #ifdef __cplusplus
 726 }
 727 #endif
 728
 729 #endif