qemu/include/qemu/osdep.h
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   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
  72QEMU_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
 155extern "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 */
 240G_NORETURN extern
 241void 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_NORESERVE
 293#define MAP_NORESERVE 0
 294#endif
 295#ifndef ENOMEDIUM
 296#define ENOMEDIUM ENODEV
 297#endif
 298#if !defined(ENOTSUP)
 299#define ENOTSUP 4096
 300#endif
 301#if !defined(ECANCELED)
 302#define ECANCELED 4097
 303#endif
 304#if !defined(EMEDIUMTYPE)
 305#define EMEDIUMTYPE 4098
 306#endif
 307#if !defined(ESHUTDOWN)
 308#define ESHUTDOWN 4099
 309#endif
 310
 311#define RETRY_ON_EINTR(expr) \
 312    (__extension__                                          \
 313        ({ typeof(expr) __result;                               \
 314           do {                                             \
 315                __result = (expr);         \
 316           } while (__result == -1 && errno == EINTR);     \
 317           __result; }))
 318
 319/* time_t may be either 32 or 64 bits depending on the host OS, and
 320 * can be either signed or unsigned, so we can't just hardcode a
 321 * specific maximum value. This is not a C preprocessor constant,
 322 * so you can't use TIME_MAX in an #ifdef, but for our purposes
 323 * this isn't a problem.
 324 */
 325
 326/* The macros TYPE_SIGNED, TYPE_WIDTH, and TYPE_MAXIMUM are from
 327 * Gnulib, and are under the LGPL v2.1 or (at your option) any
 328 * later version.
 329 */
 330
 331/* True if the real type T is signed.  */
 332#define TYPE_SIGNED(t) (!((t)0 < (t)-1))
 333
 334/* The width in bits of the integer type or expression T.
 335 * Padding bits are not supported.
 336 */
 337#define TYPE_WIDTH(t) (sizeof(t) * CHAR_BIT)
 338
 339/* The maximum and minimum values for the integer type T.  */
 340#define TYPE_MAXIMUM(t)                                                \
 341  ((t) (!TYPE_SIGNED(t)                                                \
 342        ? (t)-1                                                        \
 343        : ((((t)1 << (TYPE_WIDTH(t) - 2)) - 1) * 2 + 1)))
 344
 345#ifndef TIME_MAX
 346#define TIME_MAX TYPE_MAXIMUM(time_t)
 347#endif
 348
 349/* Mac OSX has a <stdint.h> bug that incorrectly defines SIZE_MAX with
 350 * the wrong type. Our replacement isn't usable in preprocessor
 351 * expressions, but it is sufficient for our needs. */
 352#ifdef HAVE_BROKEN_SIZE_MAX
 353#undef SIZE_MAX
 354#define SIZE_MAX ((size_t)-1)
 355#endif
 356
 357/*
 358 * Two variations of MIN/MAX macros. The first is for runtime use, and
 359 * evaluates arguments only once (so it is safe even with side
 360 * effects), but will not work in constant contexts (such as array
 361 * size declarations) because of the '{}'.  The second is for constant
 362 * expression use, where evaluating arguments twice is safe because
 363 * the result is going to be constant anyway, but will not work in a
 364 * runtime context because of a void expression where a value is
 365 * expected.  Thus, both gcc and clang will fail to compile if you use
 366 * the wrong macro (even if the error may seem a bit cryptic).
 367 *
 368 * Note that neither form is usable as an #if condition; if you truly
 369 * need to write conditional code that depends on a minimum or maximum
 370 * determined by the pre-processor instead of the compiler, you'll
 371 * have to open-code it.  Sadly, Coverity is severely confused by the
 372 * constant variants, so we have to dumb things down there.
 373 */
 374#undef MIN
 375#define MIN(a, b)                                       \
 376    ({                                                  \
 377        typeof(1 ? (a) : (b)) _a = (a), _b = (b);       \
 378        _a < _b ? _a : _b;                              \
 379    })
 380#undef MAX
 381#define MAX(a, b)                                       \
 382    ({                                                  \
 383        typeof(1 ? (a) : (b)) _a = (a), _b = (b);       \
 384        _a > _b ? _a : _b;                              \
 385    })
 386
 387#ifdef __COVERITY__
 388# define MIN_CONST(a, b) ((a) < (b) ? (a) : (b))
 389# define MAX_CONST(a, b) ((a) > (b) ? (a) : (b))
 390#else
 391# define MIN_CONST(a, b)                                        \
 392    __builtin_choose_expr(                                      \
 393        __builtin_constant_p(a) && __builtin_constant_p(b),     \
 394        (a) < (b) ? (a) : (b),                                  \
 395        ((void)0))
 396# define MAX_CONST(a, b)                                        \
 397    __builtin_choose_expr(                                      \
 398        __builtin_constant_p(a) && __builtin_constant_p(b),     \
 399        (a) > (b) ? (a) : (b),                                  \
 400        ((void)0))
 401#endif
 402
 403/*
 404 * Minimum function that returns zero only if both values are zero.
 405 * Intended for use with unsigned values only.
 406 */
 407#ifndef MIN_NON_ZERO
 408#define MIN_NON_ZERO(a, b)                              \
 409    ({                                                  \
 410        typeof(1 ? (a) : (b)) _a = (a), _b = (b);       \
 411        _a == 0 ? _b : (_b == 0 || _b > _a) ? _a : _b;  \
 412    })
 413#endif
 414
 415/*
 416 * Round number down to multiple. Safe when m is not a power of 2 (see
 417 * ROUND_DOWN for a faster version when a power of 2 is guaranteed).
 418 */
 419#define QEMU_ALIGN_DOWN(n, m) ((n) / (m) * (m))
 420
 421/*
 422 * Round number up to multiple. Safe when m is not a power of 2 (see
 423 * ROUND_UP for a faster version when a power of 2 is guaranteed).
 424 */
 425#define QEMU_ALIGN_UP(n, m) QEMU_ALIGN_DOWN((n) + (m) - 1, (m))
 426
 427/* Check if n is a multiple of m */
 428#define QEMU_IS_ALIGNED(n, m) (((n) % (m)) == 0)
 429
 430/* n-byte align pointer down */
 431#define QEMU_ALIGN_PTR_DOWN(p, n) \
 432    ((typeof(p))QEMU_ALIGN_DOWN((uintptr_t)(p), (n)))
 433
 434/* n-byte align pointer up */
 435#define QEMU_ALIGN_PTR_UP(p, n) \
 436    ((typeof(p))QEMU_ALIGN_UP((uintptr_t)(p), (n)))
 437
 438/* Check if pointer p is n-bytes aligned */
 439#define QEMU_PTR_IS_ALIGNED(p, n) QEMU_IS_ALIGNED((uintptr_t)(p), (n))
 440
 441/*
 442 * Round number down to multiple. Requires that d be a power of 2 (see
 443 * QEMU_ALIGN_UP for a safer but slower version on arbitrary
 444 * numbers); works even if d is a smaller type than n.
 445 */
 446#ifndef ROUND_DOWN
 447#define ROUND_DOWN(n, d) ((n) & -(0 ? (n) : (d)))
 448#endif
 449
 450/*
 451 * Round number up to multiple. Requires that d be a power of 2 (see
 452 * QEMU_ALIGN_UP for a safer but slower version on arbitrary
 453 * numbers); works even if d is a smaller type than n.
 454 */
 455#ifndef ROUND_UP
 456#define ROUND_UP(n, d) ROUND_DOWN((n) + (d) - 1, (d))
 457#endif
 458
 459#ifndef DIV_ROUND_UP
 460#define DIV_ROUND_UP(n, d) (((n) + (d) - 1) / (d))
 461#endif
 462
 463/*
 464 * &(x)[0] is always a pointer - if it's same type as x then the argument is a
 465 * pointer, not an array.
 466 */
 467#define QEMU_IS_ARRAY(x) (!__builtin_types_compatible_p(typeof(x), \
 468                                                        typeof(&(x)[0])))
 469#ifndef ARRAY_SIZE
 470#define ARRAY_SIZE(x) ((sizeof(x) / sizeof((x)[0])) + \
 471                       QEMU_BUILD_BUG_ON_ZERO(!QEMU_IS_ARRAY(x)))
 472#endif
 473
 474int qemu_daemon(int nochdir, int noclose);
 475void *qemu_anon_ram_alloc(size_t size, uint64_t *align, bool shared,
 476                          bool noreserve);
 477void qemu_anon_ram_free(void *ptr, size_t size);
 478
 479#ifdef _WIN32
 480#define HAVE_CHARDEV_SERIAL 1
 481#elif defined(__linux__) || defined(__sun__) || defined(__FreeBSD__)    \
 482    || defined(__NetBSD__) || defined(__OpenBSD__) || defined(__DragonFly__) \
 483    || defined(__GLIBC__) || defined(__APPLE__)
 484#define HAVE_CHARDEV_SERIAL 1
 485#endif
 486
 487#if defined(__HAIKU__)
 488#define SIGIO SIGPOLL
 489#endif
 490
 491#ifdef HAVE_MADVISE_WITHOUT_PROTOTYPE
 492/*
 493 * See MySQL bug #7156 (http://bugs.mysql.com/bug.php?id=7156) for discussion
 494 * about Solaris missing the madvise() prototype.
 495 */
 496extern int madvise(char *, size_t, int);
 497#endif
 498
 499#if defined(CONFIG_LINUX)
 500#ifndef BUS_MCEERR_AR
 501#define BUS_MCEERR_AR 4
 502#endif
 503#ifndef BUS_MCEERR_AO
 504#define BUS_MCEERR_AO 5
 505#endif
 506#endif
 507
 508#if defined(__linux__) && \
 509    (defined(__x86_64__) || defined(__arm__) || defined(__aarch64__) \
 510     || defined(__powerpc64__))
 511   /* Use 2 MiB alignment so transparent hugepages can be used by KVM.
 512      Valgrind does not support alignments larger than 1 MiB,
 513      therefore we need special code which handles running on Valgrind. */
 514#  define QEMU_VMALLOC_ALIGN (512 * 4096)
 515#elif defined(__linux__) && defined(__s390x__)
 516   /* Use 1 MiB (segment size) alignment so gmap can be used by KVM. */
 517#  define QEMU_VMALLOC_ALIGN (256 * 4096)
 518#elif defined(__linux__) && defined(__sparc__)
 519#  define QEMU_VMALLOC_ALIGN MAX(qemu_real_host_page_size(), SHMLBA)
 520#else
 521#  define QEMU_VMALLOC_ALIGN qemu_real_host_page_size()
 522#endif
 523
 524#ifdef CONFIG_POSIX
 525struct qemu_signalfd_siginfo {
 526    uint32_t ssi_signo;   /* Signal number */
 527    int32_t  ssi_errno;   /* Error number (unused) */
 528    int32_t  ssi_code;    /* Signal code */
 529    uint32_t ssi_pid;     /* PID of sender */
 530    uint32_t ssi_uid;     /* Real UID of sender */
 531    int32_t  ssi_fd;      /* File descriptor (SIGIO) */
 532    uint32_t ssi_tid;     /* Kernel timer ID (POSIX timers) */
 533    uint32_t ssi_band;    /* Band event (SIGIO) */
 534    uint32_t ssi_overrun; /* POSIX timer overrun count */
 535    uint32_t ssi_trapno;  /* Trap number that caused signal */
 536    int32_t  ssi_status;  /* Exit status or signal (SIGCHLD) */
 537    int32_t  ssi_int;     /* Integer sent by sigqueue(2) */
 538    uint64_t ssi_ptr;     /* Pointer sent by sigqueue(2) */
 539    uint64_t ssi_utime;   /* User CPU time consumed (SIGCHLD) */
 540    uint64_t ssi_stime;   /* System CPU time consumed (SIGCHLD) */
 541    uint64_t ssi_addr;    /* Address that generated signal
 542                             (for hardware-generated signals) */
 543    uint8_t  pad[48];     /* Pad size to 128 bytes (allow for
 544                             additional fields in the future) */
 545};
 546
 547int qemu_signalfd(const sigset_t *mask);
 548void sigaction_invoke(struct sigaction *action,
 549                      struct qemu_signalfd_siginfo *info);
 550#endif
 551
 552/*
 553 * Don't introduce new usage of this function, prefer the following
 554 * qemu_open/qemu_create that take an "Error **errp"
 555 */
 556int qemu_open_old(const char *name, int flags, ...);
 557int qemu_open(const char *name, int flags, Error **errp);
 558int qemu_create(const char *name, int flags, mode_t mode, Error **errp);
 559int qemu_close(int fd);
 560int qemu_unlink(const char *name);
 561#ifndef _WIN32
 562int qemu_dup_flags(int fd, int flags);
 563int qemu_dup(int fd);
 564int qemu_lock_fd(int fd, int64_t start, int64_t len, bool exclusive);
 565int qemu_unlock_fd(int fd, int64_t start, int64_t len);
 566int qemu_lock_fd_test(int fd, int64_t start, int64_t len, bool exclusive);
 567bool qemu_has_ofd_lock(void);
 568#endif
 569
 570#if defined(__HAIKU__) && defined(__i386__)
 571#define FMT_pid "%ld"
 572#elif defined(WIN64)
 573#define FMT_pid "%" PRId64
 574#else
 575#define FMT_pid "%d"
 576#endif
 577
 578bool qemu_write_pidfile(const char *pidfile, Error **errp);
 579
 580int qemu_get_thread_id(void);
 581
 582#ifndef CONFIG_IOVEC
 583struct iovec {
 584    void *iov_base;
 585    size_t iov_len;
 586};
 587/*
 588 * Use the same value as Linux for now.
 589 */
 590#define IOV_MAX 1024
 591
 592ssize_t readv(int fd, const struct iovec *iov, int iov_cnt);
 593ssize_t writev(int fd, const struct iovec *iov, int iov_cnt);
 594#endif
 595
 596#ifdef _WIN32
 597static inline void qemu_timersub(const struct timeval *val1,
 598                                 const struct timeval *val2,
 599                                 struct timeval *res)
 600{
 601    res->tv_sec = val1->tv_sec - val2->tv_sec;
 602    if (val1->tv_usec < val2->tv_usec) {
 603        res->tv_sec--;
 604        res->tv_usec = val1->tv_usec - val2->tv_usec + 1000 * 1000;
 605    } else {
 606        res->tv_usec = val1->tv_usec - val2->tv_usec;
 607    }
 608}
 609#else
 610#define qemu_timersub timersub
 611#endif
 612
 613ssize_t qemu_write_full(int fd, const void *buf, size_t count)
 614    G_GNUC_WARN_UNUSED_RESULT;
 615
 616void qemu_set_cloexec(int fd);
 617
 618/* Return a dynamically allocated directory path that is appropriate for storing
 619 * local state.
 620 *
 621 * The caller is responsible for releasing the value returned with g_free()
 622 * after use.
 623 */
 624char *qemu_get_local_state_dir(void);
 625
 626/**
 627 * qemu_getauxval:
 628 * @type: the auxiliary vector key to lookup
 629 *
 630 * Search the auxiliary vector for @type, returning the value
 631 * or 0 if @type is not present.
 632 */
 633unsigned long qemu_getauxval(unsigned long type);
 634
 635void qemu_set_tty_echo(int fd, bool echo);
 636
 637typedef struct ThreadContext ThreadContext;
 638
 639/**
 640 * qemu_prealloc_mem:
 641 * @fd: the fd mapped into the area, -1 for anonymous memory
 642 * @area: start address of the are to preallocate
 643 * @sz: the size of the area to preallocate
 644 * @max_threads: maximum number of threads to use
 645 * @errp: returns an error if this function fails
 646 *
 647 * Preallocate memory (populate/prefault page tables writable) for the virtual
 648 * memory area starting at @area with the size of @sz. After a successful call,
 649 * each page in the area was faulted in writable at least once, for example,
 650 * after allocating file blocks for mapped files.
 651 */
 652void qemu_prealloc_mem(int fd, char *area, size_t sz, int max_threads,
 653                       ThreadContext *tc, Error **errp);
 654
 655/**
 656 * qemu_get_pid_name:
 657 * @pid: pid of a process
 658 *
 659 * For given @pid fetch its name. Caller is responsible for
 660 * freeing the string when no longer needed.
 661 * Returns allocated string on success, NULL on failure.
 662 */
 663char *qemu_get_pid_name(pid_t pid);
 664
 665/* Using intptr_t ensures that qemu_*_page_mask is sign-extended even
 666 * when intptr_t is 32-bit and we are aligning a long long.
 667 */
 668static inline uintptr_t qemu_real_host_page_size(void)
 669{
 670    return getpagesize();
 671}
 672
 673static inline intptr_t qemu_real_host_page_mask(void)
 674{
 675    return -(intptr_t)qemu_real_host_page_size();
 676}
 677
 678/*
 679 * After using getopt or getopt_long, if you need to parse another set
 680 * of options, then you must reset optind.  Unfortunately the way to
 681 * do this varies between implementations of getopt.
 682 */
 683static inline void qemu_reset_optind(void)
 684{
 685#ifdef HAVE_OPTRESET
 686    optind = 1;
 687    optreset = 1;
 688#else
 689    optind = 0;
 690#endif
 691}
 692
 693int qemu_fdatasync(int fd);
 694
 695/**
 696 * Sync changes made to the memory mapped file back to the backing
 697 * storage. For POSIX compliant systems this will fallback
 698 * to regular msync call. Otherwise it will trigger whole file sync
 699 * (including the metadata case there is no support to skip that otherwise)
 700 *
 701 * @addr   - start of the memory area to be synced
 702 * @length - length of the are to be synced
 703 * @fd     - file descriptor for the file to be synced
 704 *           (mandatory only for POSIX non-compliant systems)
 705 */
 706int qemu_msync(void *addr, size_t length, int fd);
 707
 708/**
 709 * qemu_get_host_physmem:
 710 *
 711 * Operating system agnostic way of querying host memory.
 712 *
 713 * Returns amount of physical memory on the system. This is purely
 714 * advisery and may return 0 if we can't work it out. At the other
 715 * end we saturate to SIZE_MAX if you are lucky enough to have that
 716 * much memory.
 717 */
 718size_t qemu_get_host_physmem(void);
 719
 720/*
 721 * Toggle write/execute on the pages marked MAP_JIT
 722 * for the current thread.
 723 */
 724#if defined(MAC_OS_VERSION_11_0) && \
 725    MAC_OS_X_VERSION_MIN_REQUIRED >= MAC_OS_VERSION_11_0
 726static inline void qemu_thread_jit_execute(void)
 727{
 728    pthread_jit_write_protect_np(true);
 729}
 730
 731static inline void qemu_thread_jit_write(void)
 732{
 733    pthread_jit_write_protect_np(false);
 734}
 735#else
 736static inline void qemu_thread_jit_write(void) {}
 737static inline void qemu_thread_jit_execute(void) {}
 738#endif
 739
 740/**
 741 * Platforms which do not support system() return ENOSYS
 742 */
 743#ifndef HAVE_SYSTEM_FUNCTION
 744#define system platform_does_not_support_system
 745static inline int platform_does_not_support_system(const char *command)
 746{
 747    errno = ENOSYS;
 748    return -1;
 749}
 750#endif /* !HAVE_SYSTEM_FUNCTION */
 751
 752#ifdef __cplusplus
 753}
 754#endif
 755
 756#endif
 757