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 0x0602 /* Windows 8 API (should be >= the one from 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 #ifdef __clang__
 175 #define coroutine_fn __attribute__((__annotate__("coroutine_fn")))
 176 #else
 177 #define coroutine_fn
 178 #endif
 179
 180 /**
 181  * Mark a function that can suspend when executed in coroutine context,
 182  * but can handle running in non-coroutine context too.
 183  */
 184 #ifdef __clang__
 185 #define coroutine_mixed_fn __attribute__((__annotate__("coroutine_mixed_fn")))
 186 #else
 187 #define coroutine_mixed_fn
 188 #endif
 189
 190 /**
 191  * Mark a function that should not be called from a coroutine context.
 192  * Usually there will be an analogous, coroutine_fn function that should
 193  * be used instead.
 194  *
 195  * When the function is also marked as coroutine_mixed_fn, the function should
 196  * only be called if the caller does not know whether it is in coroutine
 197  * context.
 198  *
 199  * Functions that are only no_coroutine_fn, on the other hand, should not
 200  * be called from within coroutines at all.  This for example includes
 201  * functions that block.
 202  *
 203  * In the future it would be nice to enable compiler or static checker
 204  * support for catching such errors.  This annotation is the first step
 205  * towards this, and in the meantime it serves as documentation.
 206  *
 207  * For example:
 208  *
 209  *   static void no_coroutine_fn foo(void) {
 210  *       ....
 211  *   }
 212  */
 213 #ifdef __clang__
 214 #define no_coroutine_fn __attribute__((__annotate__("no_coroutine_fn")))
 215 #else
 216 #define no_coroutine_fn
 217 #endif
 218
 219
 220 /*
 221  * For mingw, as of v6.0.0, the function implementing the assert macro is
 222  * not marked as noreturn, so the compiler cannot delete code following an
 223  * assert(false) as unused.  We rely on this within the code base to delete
 224  * code that is unreachable when features are disabled.
 225  * All supported versions of Glib's g_assert() satisfy this requirement.
 226  */
 227 #ifdef __MINGW32__
 228 #undef assert
 229 #define assert(x)  g_assert(x)
 230 #endif
 231
 232 /**
 233  * qemu_build_not_reached()
 234  *
 235  * The compiler, during optimization, is expected to prove that a call
 236  * to this function cannot be reached and remove it.  If the compiler
 237  * supports QEMU_ERROR, this will be reported at compile time; otherwise
 238  * this will be reported at link time due to the missing symbol.
 239  */
 240 G_NORETURN extern
 241 void QEMU_ERROR("code path is reachable")
 242     qemu_build_not_reached_always(void);
 243 #if defined(__OPTIMIZE__) && !defined(__NO_INLINE__)
 244 #define qemu_build_not_reached()  qemu_build_not_reached_always()
 245 #else
 246 #define qemu_build_not_reached()  g_assert_not_reached()
 247 #endif
 248
 249 /**
 250  * qemu_build_assert()
 251  *
 252  * The compiler, during optimization, is expected to prove that the
 253  * assertion is true.
 254  */
 255 #define qemu_build_assert(test)  while (!(test)) qemu_build_not_reached()
 256
 257 /*
 258  * According to waitpid man page:
 259  * WCOREDUMP
 260  *  This  macro  is  not  specified  in POSIX.1-2001 and is not
 261  *  available on some UNIX implementations (e.g., AIX, SunOS).
 262  *  Therefore, enclose its use inside #ifdef WCOREDUMP ... #endif.
 263  */
 264 #ifndef WCOREDUMP
 265 #define WCOREDUMP(status) 0
 266 #endif
 267 /*
 268  * We have a lot of unaudited code that may fail in strange ways, or
 269  * even be a security risk during migration, if you disable assertions
 270  * at compile-time.  You may comment out these safety checks if you
 271  * absolutely want to disable assertion overhead, but it is not
 272  * supported upstream so the risk is all yours.  Meanwhile, please
 273  * submit patches to remove any side-effects inside an assertion, or
 274  * fixing error handling that should use Error instead of assert.
 275  */
 276 #ifdef NDEBUG
 277 #error building with NDEBUG is not supported
 278 #endif
 279 #ifdef G_DISABLE_ASSERT
 280 #error building with G_DISABLE_ASSERT is not supported
 281 #endif
 282
 283 #ifndef O_LARGEFILE
 284 #define O_LARGEFILE 0
 285 #endif
 286 #ifndef O_BINARY
 287 #define O_BINARY 0
 288 #endif
 289 #ifndef MAP_ANONYMOUS
 290 #define MAP_ANONYMOUS MAP_ANON
 291 #endif
 292 #ifndef MAP_FIXED_NOREPLACE
 293 #define MAP_FIXED_NOREPLACE 0
 294 #endif
 295 #ifndef MAP_NORESERVE
 296 #define MAP_NORESERVE 0
 297 #endif
 298 #ifndef ENOMEDIUM
 299 #define ENOMEDIUM ENODEV
 300 #endif
 301 #if !defined(ENOTSUP)
 302 #define ENOTSUP 4096
 303 #endif
 304 #if !defined(ECANCELED)
 305 #define ECANCELED 4097
 306 #endif
 307 #if !defined(EMEDIUMTYPE)
 308 #define EMEDIUMTYPE 4098
 309 #endif
 310 #if !defined(ESHUTDOWN)
 311 #define ESHUTDOWN 4099
 312 #endif
 313
 314 #define RETRY_ON_EINTR(expr) \
 315     (__extension__                                          \
 316         ({ typeof(expr) __result;                               \
 317            do {                                             \
 318                 __result = (expr);         \
 319            } while (__result == -1 && errno == EINTR);     \
 320            __result; }))
 321
 322 /* time_t may be either 32 or 64 bits depending on the host OS, and
 323  * can be either signed or unsigned, so we can't just hardcode a
 324  * specific maximum value. This is not a C preprocessor constant,
 325  * so you can't use TIME_MAX in an #ifdef, but for our purposes
 326  * this isn't a problem.
 327  */
 328
 329 /* The macros TYPE_SIGNED, TYPE_WIDTH, and TYPE_MAXIMUM are from
 330  * Gnulib, and are under the LGPL v2.1 or (at your option) any
 331  * later version.
 332  */
 333
 334 /* True if the real type T is signed.  */
 335 #define TYPE_SIGNED(t) (!((t)0 < (t)-1))
 336
 337 /* The width in bits of the integer type or expression T.
 338  * Padding bits are not supported.
 339  */
 340 #define TYPE_WIDTH(t) (sizeof(t) * CHAR_BIT)
 341
 342 /* The maximum and minimum values for the integer type T.  */
 343 #define TYPE_MAXIMUM(t)                                                \
 344   ((t) (!TYPE_SIGNED(t)                                                \
 345         ? (t)-1                                                        \
 346         : ((((t)1 << (TYPE_WIDTH(t) - 2)) - 1) * 2 + 1)))
 347
 348 #ifndef TIME_MAX
 349 #define TIME_MAX TYPE_MAXIMUM(time_t)
 350 #endif
 351
 352 /* Mac OSX has a <stdint.h> bug that incorrectly defines SIZE_MAX with
 353  * the wrong type. Our replacement isn't usable in preprocessor
 354  * expressions, but it is sufficient for our needs. */
 355 #ifdef HAVE_BROKEN_SIZE_MAX
 356 #undef SIZE_MAX
 357 #define SIZE_MAX ((size_t)-1)
 358 #endif
 359
 360 /*
 361  * Two variations of MIN/MAX macros. The first is for runtime use, and
 362  * evaluates arguments only once (so it is safe even with side
 363  * effects), but will not work in constant contexts (such as array
 364  * size declarations) because of the '{}'.  The second is for constant
 365  * expression use, where evaluating arguments twice is safe because
 366  * the result is going to be constant anyway, but will not work in a
 367  * runtime context because of a void expression where a value is
 368  * expected.  Thus, both gcc and clang will fail to compile if you use
 369  * the wrong macro (even if the error may seem a bit cryptic).
 370  *
 371  * Note that neither form is usable as an #if condition; if you truly
 372  * need to write conditional code that depends on a minimum or maximum
 373  * determined by the pre-processor instead of the compiler, you'll
 374  * have to open-code it.  Sadly, Coverity is severely confused by the
 375  * constant variants, so we have to dumb things down there.
 376  */
 377 #undef MIN
 378 #define MIN(a, b)                                       \
 379     ({                                                  \
 380         typeof(1 ? (a) : (b)) _a = (a), _b = (b);       \
 381         _a < _b ? _a : _b;                              \
 382     })
 383 #undef MAX
 384 #define MAX(a, b)                                       \
 385     ({                                                  \
 386         typeof(1 ? (a) : (b)) _a = (a), _b = (b);       \
 387         _a > _b ? _a : _b;                              \
 388     })
 389
 390 #ifdef __COVERITY__
 391 # define MIN_CONST(a, b) ((a) < (b) ? (a) : (b))
 392 # define MAX_CONST(a, b) ((a) > (b) ? (a) : (b))
 393 #else
 394 # define MIN_CONST(a, b)                                        \
 395     __builtin_choose_expr(                                      \
 396         __builtin_constant_p(a) && __builtin_constant_p(b),     \
 397         (a) < (b) ? (a) : (b),                                  \
 398         ((void)0))
 399 # define MAX_CONST(a, b)                                        \
 400     __builtin_choose_expr(                                      \
 401         __builtin_constant_p(a) && __builtin_constant_p(b),     \
 402         (a) > (b) ? (a) : (b),                                  \
 403         ((void)0))
 404 #endif
 405
 406 /*
 407  * Minimum function that returns zero only if both values are zero.
 408  * Intended for use with unsigned values only.
 409  */
 410 #ifndef MIN_NON_ZERO
 411 #define MIN_NON_ZERO(a, b)                              \
 412     ({                                                  \
 413         typeof(1 ? (a) : (b)) _a = (a), _b = (b);       \
 414         _a == 0 ? _b : (_b == 0 || _b > _a) ? _a : _b;  \
 415     })
 416 #endif
 417
 418 /*
 419  * Round number down to multiple. Safe when m is not a power of 2 (see
 420  * ROUND_DOWN for a faster version when a power of 2 is guaranteed).
 421  */
 422 #define QEMU_ALIGN_DOWN(n, m) ((n) / (m) * (m))
 423
 424 /*
 425  * Round number up to multiple. Safe when m is not a power of 2 (see
 426  * ROUND_UP for a faster version when a power of 2 is guaranteed).
 427  */
 428 #define QEMU_ALIGN_UP(n, m) QEMU_ALIGN_DOWN((n) + (m) - 1, (m))
 429
 430 /* Check if n is a multiple of m */
 431 #define QEMU_IS_ALIGNED(n, m) (((n) % (m)) == 0)
 432
 433 /* n-byte align pointer down */
 434 #define QEMU_ALIGN_PTR_DOWN(p, n) \
 435     ((typeof(p))QEMU_ALIGN_DOWN((uintptr_t)(p), (n)))
 436
 437 /* n-byte align pointer up */
 438 #define QEMU_ALIGN_PTR_UP(p, n) \
 439     ((typeof(p))QEMU_ALIGN_UP((uintptr_t)(p), (n)))
 440
 441 /* Check if pointer p is n-bytes aligned */
 442 #define QEMU_PTR_IS_ALIGNED(p, n) QEMU_IS_ALIGNED((uintptr_t)(p), (n))
 443
 444 /*
 445  * Round number down to multiple. Requires that d be a power of 2 (see
 446  * QEMU_ALIGN_UP for a safer but slower version on arbitrary
 447  * numbers); works even if d is a smaller type than n.
 448  */
 449 #ifndef ROUND_DOWN
 450 #define ROUND_DOWN(n, d) ((n) & -(0 ? (n) : (d)))
 451 #endif
 452
 453 /*
 454  * Round number up to multiple. Requires that d be a power of 2 (see
 455  * QEMU_ALIGN_UP for a safer but slower version on arbitrary
 456  * numbers); works even if d is a smaller type than n.
 457  */
 458 #ifndef ROUND_UP
 459 #define ROUND_UP(n, d) ROUND_DOWN((n) + (d) - 1, (d))
 460 #endif
 461
 462 #ifndef DIV_ROUND_UP
 463 #define DIV_ROUND_UP(n, d) (((n) + (d) - 1) / (d))
 464 #endif
 465
 466 /*
 467  * &(x)[0] is always a pointer - if it's same type as x then the argument is a
 468  * pointer, not an array.
 469  */
 470 #define QEMU_IS_ARRAY(x) (!__builtin_types_compatible_p(typeof(x), \
 471                                                         typeof(&(x)[0])))
 472 #ifndef ARRAY_SIZE
 473 #define ARRAY_SIZE(x) ((sizeof(x) / sizeof((x)[0])) + \
 474                        QEMU_BUILD_BUG_ON_ZERO(!QEMU_IS_ARRAY(x)))
 475 #endif
 476
 477 int qemu_daemon(int nochdir, int noclose);
 478 void *qemu_anon_ram_alloc(size_t size, uint64_t *align, bool shared,
 479                           bool noreserve);
 480 void qemu_anon_ram_free(void *ptr, size_t size);
 481
 482 #ifdef _WIN32
 483 #define HAVE_CHARDEV_SERIAL 1
 484 #elif defined(__linux__) || defined(__sun__) || defined(__FreeBSD__)    \
 485     || defined(__NetBSD__) || defined(__OpenBSD__) || defined(__DragonFly__) \
 486     || defined(__GLIBC__) || defined(__APPLE__)
 487 #define HAVE_CHARDEV_SERIAL 1
 488 #endif
 489
 490 #if defined(__HAIKU__)
 491 #define SIGIO SIGPOLL
 492 #endif
 493
 494 #ifdef HAVE_MADVISE_WITHOUT_PROTOTYPE
 495 /*
 496  * See MySQL bug #7156 (http://bugs.mysql.com/bug.php?id=7156) for discussion
 497  * about Solaris missing the madvise() prototype.
 498  */
 499 extern int madvise(char *, size_t, int);
 500 #endif
 501
 502 #if defined(CONFIG_LINUX)
 503 #ifndef BUS_MCEERR_AR
 504 #define BUS_MCEERR_AR 4
 505 #endif
 506 #ifndef BUS_MCEERR_AO
 507 #define BUS_MCEERR_AO 5
 508 #endif
 509 #endif
 510
 511 #if defined(__linux__) && \
 512     (defined(__x86_64__) || defined(__arm__) || defined(__aarch64__) \
 513      || defined(__powerpc64__))
 514    /* Use 2 MiB alignment so transparent hugepages can be used by KVM.
 515       Valgrind does not support alignments larger than 1 MiB,
 516       therefore we need special code which handles running on Valgrind. */
 517 #  define QEMU_VMALLOC_ALIGN (512 * 4096)
 518 #elif defined(__linux__) && defined(__s390x__)
 519    /* Use 1 MiB (segment size) alignment so gmap can be used by KVM. */
 520 #  define QEMU_VMALLOC_ALIGN (256 * 4096)
 521 #elif defined(__linux__) && defined(__sparc__)
 522 #  define QEMU_VMALLOC_ALIGN MAX(qemu_real_host_page_size(), SHMLBA)
 523 #else
 524 #  define QEMU_VMALLOC_ALIGN qemu_real_host_page_size()
 525 #endif
 526
 527 #ifdef CONFIG_POSIX
 528 struct qemu_signalfd_siginfo {
 529     uint32_t ssi_signo;   /* Signal number */
 530     int32_t  ssi_errno;   /* Error number (unused) */
 531     int32_t  ssi_code;    /* Signal code */
 532     uint32_t ssi_pid;     /* PID of sender */
 533     uint32_t ssi_uid;     /* Real UID of sender */
 534     int32_t  ssi_fd;      /* File descriptor (SIGIO) */
 535     uint32_t ssi_tid;     /* Kernel timer ID (POSIX timers) */
 536     uint32_t ssi_band;    /* Band event (SIGIO) */
 537     uint32_t ssi_overrun; /* POSIX timer overrun count */
 538     uint32_t ssi_trapno;  /* Trap number that caused signal */
 539     int32_t  ssi_status;  /* Exit status or signal (SIGCHLD) */
 540     int32_t  ssi_int;     /* Integer sent by sigqueue(2) */
 541     uint64_t ssi_ptr;     /* Pointer sent by sigqueue(2) */
 542     uint64_t ssi_utime;   /* User CPU time consumed (SIGCHLD) */
 543     uint64_t ssi_stime;   /* System CPU time consumed (SIGCHLD) */
 544     uint64_t ssi_addr;    /* Address that generated signal
 545                              (for hardware-generated signals) */
 546     uint8_t  pad[48];     /* Pad size to 128 bytes (allow for
 547                              additional fields in the future) */
 548 };
 549
 550 int qemu_signalfd(const sigset_t *mask);
 551 void sigaction_invoke(struct sigaction *action,
 552                       struct qemu_signalfd_siginfo *info);
 553 #endif
 554
 555 /*
 556  * Don't introduce new usage of this function, prefer the following
 557  * qemu_open/qemu_create that take an "Error **errp"
 558  */
 559 int qemu_open_old(const char *name, int flags, ...);
 560 int qemu_open(const char *name, int flags, Error **errp);
 561 int qemu_create(const char *name, int flags, mode_t mode, Error **errp);
 562 int qemu_close(int fd);
 563 int qemu_unlink(const char *name);
 564 #ifndef _WIN32
 565 int qemu_dup_flags(int fd, int flags);
 566 int qemu_dup(int fd);
 567 int qemu_lock_fd(int fd, int64_t start, int64_t len, bool exclusive);
 568 int qemu_unlock_fd(int fd, int64_t start, int64_t len);
 569 int qemu_lock_fd_test(int fd, int64_t start, int64_t len, bool exclusive);
 570 bool qemu_has_ofd_lock(void);
 571 #endif
 572
 573 #if defined(__HAIKU__) && defined(__i386__)
 574 #define FMT_pid "%ld"
 575 #elif defined(WIN64)
 576 #define FMT_pid "%" PRId64
 577 #else
 578 #define FMT_pid "%d"
 579 #endif
 580
 581 bool qemu_write_pidfile(const char *pidfile, Error **errp);
 582
 583 int qemu_get_thread_id(void);
 584
 585 #ifndef CONFIG_IOVEC
 586 struct iovec {
 587     void *iov_base;
 588     size_t iov_len;
 589 };
 590 /*
 591  * Use the same value as Linux for now.
 592  */
 593 #define IOV_MAX 1024
 594
 595 ssize_t readv(int fd, const struct iovec *iov, int iov_cnt);
 596 ssize_t writev(int fd, const struct iovec *iov, int iov_cnt);
 597 #endif
 598
 599 #ifdef _WIN32
 600 static inline void qemu_timersub(const struct timeval *val1,
 601                                  const struct timeval *val2,
 602                                  struct timeval *res)
 603 {
 604     res->tv_sec = val1->tv_sec - val2->tv_sec;
 605     if (val1->tv_usec < val2->tv_usec) {
 606         res->tv_sec--;
 607         res->tv_usec = val1->tv_usec - val2->tv_usec + 1000 * 1000;
 608     } else {
 609         res->tv_usec = val1->tv_usec - val2->tv_usec;
 610     }
 611 }
 612 #else
 613 #define qemu_timersub timersub
 614 #endif
 615
 616 ssize_t qemu_write_full(int fd, const void *buf, size_t count)
 617     G_GNUC_WARN_UNUSED_RESULT;
 618
 619 void qemu_set_cloexec(int fd);
 620
 621 /* Return a dynamically allocated directory path that is appropriate for storing
 622  * local state.
 623  *
 624  * The caller is responsible for releasing the value returned with g_free()
 625  * after use.
 626  */
 627 char *qemu_get_local_state_dir(void);
 628
 629 /**
 630  * qemu_getauxval:
 631  * @type: the auxiliary vector key to lookup
 632  *
 633  * Search the auxiliary vector for @type, returning the value
 634  * or 0 if @type is not present.
 635  */
 636 unsigned long qemu_getauxval(unsigned long type);
 637
 638 void qemu_set_tty_echo(int fd, bool echo);
 639
 640 typedef struct ThreadContext ThreadContext;
 641
 642 /**
 643  * qemu_prealloc_mem:
 644  * @fd: the fd mapped into the area, -1 for anonymous memory
 645  * @area: start address of the are to preallocate
 646  * @sz: the size of the area to preallocate
 647  * @max_threads: maximum number of threads to use
 648  * @errp: returns an error if this function fails
 649  *
 650  * Preallocate memory (populate/prefault page tables writable) for the virtual
 651  * memory area starting at @area with the size of @sz. After a successful call,
 652  * each page in the area was faulted in writable at least once, for example,
 653  * after allocating file blocks for mapped files.
 654  */
 655 void qemu_prealloc_mem(int fd, char *area, size_t sz, int max_threads,
 656                        ThreadContext *tc, Error **errp);
 657
 658 /**
 659  * qemu_get_pid_name:
 660  * @pid: pid of a process
 661  *
 662  * For given @pid fetch its name. Caller is responsible for
 663  * freeing the string when no longer needed.
 664  * Returns allocated string on success, NULL on failure.
 665  */
 666 char *qemu_get_pid_name(pid_t pid);
 667
 668 /* Using intptr_t ensures that qemu_*_page_mask is sign-extended even
 669  * when intptr_t is 32-bit and we are aligning a long long.
 670  */
 671 static inline uintptr_t qemu_real_host_page_size(void)
 672 {
 673     return getpagesize();
 674 }
 675
 676 static inline intptr_t qemu_real_host_page_mask(void)
 677 {
 678     return -(intptr_t)qemu_real_host_page_size();
 679 }
 680
 681 /*
 682  * After using getopt or getopt_long, if you need to parse another set
 683  * of options, then you must reset optind.  Unfortunately the way to
 684  * do this varies between implementations of getopt.
 685  */
 686 static inline void qemu_reset_optind(void)
 687 {
 688 #ifdef HAVE_OPTRESET
 689     optind = 1;
 690     optreset = 1;
 691 #else
 692     optind = 0;
 693 #endif
 694 }
 695
 696 int qemu_fdatasync(int fd);
 697
 698 /**
 699  * Sync changes made to the memory mapped file back to the backing
 700  * storage. For POSIX compliant systems this will fallback
 701  * to regular msync call. Otherwise it will trigger whole file sync
 702  * (including the metadata case there is no support to skip that otherwise)
 703  *
 704  * @addr   - start of the memory area to be synced
 705  * @length - length of the are to be synced
 706  * @fd     - file descriptor for the file to be synced
 707  *           (mandatory only for POSIX non-compliant systems)
 708  */
 709 int qemu_msync(void *addr, size_t length, int fd);
 710
 711 /**
 712  * qemu_get_host_physmem:
 713  *
 714  * Operating system agnostic way of querying host memory.
 715  *
 716  * Returns amount of physical memory on the system. This is purely
 717  * advisery and may return 0 if we can't work it out. At the other
 718  * end we saturate to SIZE_MAX if you are lucky enough to have that
 719  * much memory.
 720  */
 721 size_t qemu_get_host_physmem(void);
 722
 723 /*
 724  * Toggle write/execute on the pages marked MAP_JIT
 725  * for the current thread.
 726  */
 727 #if defined(MAC_OS_VERSION_11_0) && \
 728     MAC_OS_X_VERSION_MIN_REQUIRED >= MAC_OS_VERSION_11_0
 729 static inline void qemu_thread_jit_execute(void)
 730 {
 731     pthread_jit_write_protect_np(true);
 732 }
 733
 734 static inline void qemu_thread_jit_write(void)
 735 {
 736     pthread_jit_write_protect_np(false);
 737 }
 738 #else
 739 static inline void qemu_thread_jit_write(void) {}
 740 static inline void qemu_thread_jit_execute(void) {}
 741 #endif
 742
 743 /**
 744  * Platforms which do not support system() return ENOSYS
 745  */
 746 #ifndef HAVE_SYSTEM_FUNCTION
 747 #define system platform_does_not_support_system
 748 static inline int platform_does_not_support_system(const char *command)
 749 {
 750     errno = ENOSYS;
 751     return -1;
 752 }
 753 #endif /* !HAVE_SYSTEM_FUNCTION */
 754
 755 #ifdef __cplusplus
 756 }
 757 #endif
 758
 759 #endif