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 0x0600 /* Vista */
  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  * For mingw, as of v6.0.0, the function implementing the assert macro is
 162  * not marked as noreturn, so the compiler cannot delete code following an
 163  * assert(false) as unused.  We rely on this within the code base to delete
 164  * code that is unreachable when features are disabled.
 165  * All supported versions of Glib's g_assert() satisfy this requirement.
 166  */
 167 #ifdef __MINGW32__
 168 #undef assert
 169 #define assert(x)  g_assert(x)
 170 #endif
 171
 172 /*
 173  * According to waitpid man page:
 174  * WCOREDUMP
 175  *  This  macro  is  not  specified  in POSIX.1-2001 and is not
 176  *  available on some UNIX implementations (e.g., AIX, SunOS).
 177  *  Therefore, enclose its use inside #ifdef WCOREDUMP ... #endif.
 178  */
 179 #ifndef WCOREDUMP
 180 #define WCOREDUMP(status) 0
 181 #endif
 182 /*
 183  * We have a lot of unaudited code that may fail in strange ways, or
 184  * even be a security risk during migration, if you disable assertions
 185  * at compile-time.  You may comment out these safety checks if you
 186  * absolutely want to disable assertion overhead, but it is not
 187  * supported upstream so the risk is all yours.  Meanwhile, please
 188  * submit patches to remove any side-effects inside an assertion, or
 189  * fixing error handling that should use Error instead of assert.
 190  */
 191 #ifdef NDEBUG
 192 #error building with NDEBUG is not supported
 193 #endif
 194 #ifdef G_DISABLE_ASSERT
 195 #error building with G_DISABLE_ASSERT is not supported
 196 #endif
 197
 198 #ifndef O_LARGEFILE
 199 #define O_LARGEFILE 0
 200 #endif
 201 #ifndef O_BINARY
 202 #define O_BINARY 0
 203 #endif
 204 #ifndef MAP_ANONYMOUS
 205 #define MAP_ANONYMOUS MAP_ANON
 206 #endif
 207 #ifndef MAP_FIXED_NOREPLACE
 208 #define MAP_FIXED_NOREPLACE 0
 209 #endif
 210 #ifndef MAP_NORESERVE
 211 #define MAP_NORESERVE 0
 212 #endif
 213 #ifndef ENOMEDIUM
 214 #define ENOMEDIUM ENODEV
 215 #endif
 216 #if !defined(ENOTSUP)
 217 #define ENOTSUP 4096
 218 #endif
 219 #if !defined(ECANCELED)
 220 #define ECANCELED 4097
 221 #endif
 222 #if !defined(EMEDIUMTYPE)
 223 #define EMEDIUMTYPE 4098
 224 #endif
 225 #if !defined(ESHUTDOWN)
 226 #define ESHUTDOWN 4099
 227 #endif
 228
 229 #define TFR(expr) do { if ((expr) != -1) break; } while (errno == EINTR)
 230
 231 /* time_t may be either 32 or 64 bits depending on the host OS, and
 232  * can be either signed or unsigned, so we can't just hardcode a
 233  * specific maximum value. This is not a C preprocessor constant,
 234  * so you can't use TIME_MAX in an #ifdef, but for our purposes
 235  * this isn't a problem.
 236  */
 237
 238 /* The macros TYPE_SIGNED, TYPE_WIDTH, and TYPE_MAXIMUM are from
 239  * Gnulib, and are under the LGPL v2.1 or (at your option) any
 240  * later version.
 241  */
 242
 243 /* True if the real type T is signed.  */
 244 #define TYPE_SIGNED(t) (!((t)0 < (t)-1))
 245
 246 /* The width in bits of the integer type or expression T.
 247  * Padding bits are not supported.
 248  */
 249 #define TYPE_WIDTH(t) (sizeof(t) * CHAR_BIT)
 250
 251 /* The maximum and minimum values for the integer type T.  */
 252 #define TYPE_MAXIMUM(t)                                                \
 253   ((t) (!TYPE_SIGNED(t)                                                \
 254         ? (t)-1                                                        \
 255         : ((((t)1 << (TYPE_WIDTH(t) - 2)) - 1) * 2 + 1)))
 256
 257 #ifndef TIME_MAX
 258 #define TIME_MAX TYPE_MAXIMUM(time_t)
 259 #endif
 260
 261 /* Mac OSX has a <stdint.h> bug that incorrectly defines SIZE_MAX with
 262  * the wrong type. Our replacement isn't usable in preprocessor
 263  * expressions, but it is sufficient for our needs. */
 264 #ifdef HAVE_BROKEN_SIZE_MAX
 265 #undef SIZE_MAX
 266 #define SIZE_MAX ((size_t)-1)
 267 #endif
 268
 269 /*
 270  * Two variations of MIN/MAX macros. The first is for runtime use, and
 271  * evaluates arguments only once (so it is safe even with side
 272  * effects), but will not work in constant contexts (such as array
 273  * size declarations) because of the '{}'.  The second is for constant
 274  * expression use, where evaluating arguments twice is safe because
 275  * the result is going to be constant anyway, but will not work in a
 276  * runtime context because of a void expression where a value is
 277  * expected.  Thus, both gcc and clang will fail to compile if you use
 278  * the wrong macro (even if the error may seem a bit cryptic).
 279  *
 280  * Note that neither form is usable as an #if condition; if you truly
 281  * need to write conditional code that depends on a minimum or maximum
 282  * determined by the pre-processor instead of the compiler, you'll
 283  * have to open-code it.  Sadly, Coverity is severely confused by the
 284  * constant variants, so we have to dumb things down there.
 285  */
 286 #undef MIN
 287 #define MIN(a, b)                                       \
 288     ({                                                  \
 289         typeof(1 ? (a) : (b)) _a = (a), _b = (b);       \
 290         _a < _b ? _a : _b;                              \
 291     })
 292 #undef MAX
 293 #define MAX(a, b)                                       \
 294     ({                                                  \
 295         typeof(1 ? (a) : (b)) _a = (a), _b = (b);       \
 296         _a > _b ? _a : _b;                              \
 297     })
 298
 299 #ifdef __COVERITY__
 300 # define MIN_CONST(a, b) ((a) < (b) ? (a) : (b))
 301 # define MAX_CONST(a, b) ((a) > (b) ? (a) : (b))
 302 #else
 303 # define MIN_CONST(a, b)                                        \
 304     __builtin_choose_expr(                                      \
 305         __builtin_constant_p(a) && __builtin_constant_p(b),     \
 306         (a) < (b) ? (a) : (b),                                  \
 307         ((void)0))
 308 # define MAX_CONST(a, b)                                        \
 309     __builtin_choose_expr(                                      \
 310         __builtin_constant_p(a) && __builtin_constant_p(b),     \
 311         (a) > (b) ? (a) : (b),                                  \
 312         ((void)0))
 313 #endif
 314
 315 /*
 316  * Minimum function that returns zero only if both values are zero.
 317  * Intended for use with unsigned values only.
 318  */
 319 #ifndef MIN_NON_ZERO
 320 #define MIN_NON_ZERO(a, b)                              \
 321     ({                                                  \
 322         typeof(1 ? (a) : (b)) _a = (a), _b = (b);       \
 323         _a == 0 ? _b : (_b == 0 || _b > _a) ? _a : _b;  \
 324     })
 325 #endif
 326
 327 /*
 328  * Round number down to multiple. Safe when m is not a power of 2 (see
 329  * ROUND_DOWN for a faster version when a power of 2 is guaranteed).
 330  */
 331 #define QEMU_ALIGN_DOWN(n, m) ((n) / (m) * (m))
 332
 333 /*
 334  * Round number up to multiple. Safe when m is not a power of 2 (see
 335  * ROUND_UP for a faster version when a power of 2 is guaranteed).
 336  */
 337 #define QEMU_ALIGN_UP(n, m) QEMU_ALIGN_DOWN((n) + (m) - 1, (m))
 338
 339 /* Check if n is a multiple of m */
 340 #define QEMU_IS_ALIGNED(n, m) (((n) % (m)) == 0)
 341
 342 /* n-byte align pointer down */
 343 #define QEMU_ALIGN_PTR_DOWN(p, n) \
 344     ((typeof(p))QEMU_ALIGN_DOWN((uintptr_t)(p), (n)))
 345
 346 /* n-byte align pointer up */
 347 #define QEMU_ALIGN_PTR_UP(p, n) \
 348     ((typeof(p))QEMU_ALIGN_UP((uintptr_t)(p), (n)))
 349
 350 /* Check if pointer p is n-bytes aligned */
 351 #define QEMU_PTR_IS_ALIGNED(p, n) QEMU_IS_ALIGNED((uintptr_t)(p), (n))
 352
 353 /*
 354  * Round number down to multiple. Requires that d be a power of 2 (see
 355  * QEMU_ALIGN_UP for a safer but slower version on arbitrary
 356  * numbers); works even if d is a smaller type than n.
 357  */
 358 #ifndef ROUND_DOWN
 359 #define ROUND_DOWN(n, d) ((n) & -(0 ? (n) : (d)))
 360 #endif
 361
 362 /*
 363  * Round number up to multiple. Requires that d be a power of 2 (see
 364  * QEMU_ALIGN_UP for a safer but slower version on arbitrary
 365  * numbers); works even if d is a smaller type than n.
 366  */
 367 #ifndef ROUND_UP
 368 #define ROUND_UP(n, d) ROUND_DOWN((n) + (d) - 1, (d))
 369 #endif
 370
 371 #ifndef DIV_ROUND_UP
 372 #define DIV_ROUND_UP(n, d) (((n) + (d) - 1) / (d))
 373 #endif
 374
 375 /*
 376  * &(x)[0] is always a pointer - if it's same type as x then the argument is a
 377  * pointer, not an array.
 378  */
 379 #define QEMU_IS_ARRAY(x) (!__builtin_types_compatible_p(typeof(x), \
 380                                                         typeof(&(x)[0])))
 381 #ifndef ARRAY_SIZE
 382 #define ARRAY_SIZE(x) ((sizeof(x) / sizeof((x)[0])) + \
 383                        QEMU_BUILD_BUG_ON_ZERO(!QEMU_IS_ARRAY(x)))
 384 #endif
 385
 386 int qemu_daemon(int nochdir, int noclose);
 387 void *qemu_anon_ram_alloc(size_t size, uint64_t *align, bool shared,
 388                           bool noreserve);
 389 void qemu_anon_ram_free(void *ptr, size_t size);
 390
 391 #ifdef _WIN32
 392 #define HAVE_CHARDEV_SERIAL 1
 393 #elif defined(__linux__) || defined(__sun__) || defined(__FreeBSD__)    \
 394     || defined(__NetBSD__) || defined(__OpenBSD__) || defined(__DragonFly__) \
 395     || defined(__GLIBC__) || defined(__APPLE__)
 396 #define HAVE_CHARDEV_SERIAL 1
 397 #endif
 398
 399 #if defined(__linux__) || defined(__FreeBSD__) ||               \
 400     defined(__FreeBSD_kernel__) || defined(__DragonFly__)
 401 #define HAVE_CHARDEV_PARPORT 1
 402 #endif
 403
 404 #if defined(__HAIKU__)
 405 #define SIGIO SIGPOLL
 406 #endif
 407
 408 #ifdef HAVE_MADVISE_WITHOUT_PROTOTYPE
 409 /*
 410  * See MySQL bug #7156 (http://bugs.mysql.com/bug.php?id=7156) for discussion
 411  * about Solaris missing the madvise() prototype.
 412  */
 413 extern int madvise(char *, size_t, int);
 414 #endif
 415
 416 #if defined(CONFIG_LINUX)
 417 #ifndef BUS_MCEERR_AR
 418 #define BUS_MCEERR_AR 4
 419 #endif
 420 #ifndef BUS_MCEERR_AO
 421 #define BUS_MCEERR_AO 5
 422 #endif
 423 #endif
 424
 425 #if defined(__linux__) && \
 426     (defined(__x86_64__) || defined(__arm__) || defined(__aarch64__) \
 427      || defined(__powerpc64__))
 428    /* Use 2 MiB alignment so transparent hugepages can be used by KVM.
 429       Valgrind does not support alignments larger than 1 MiB,
 430       therefore we need special code which handles running on Valgrind. */
 431 #  define QEMU_VMALLOC_ALIGN (512 * 4096)
 432 #elif defined(__linux__) && defined(__s390x__)
 433    /* Use 1 MiB (segment size) alignment so gmap can be used by KVM. */
 434 #  define QEMU_VMALLOC_ALIGN (256 * 4096)
 435 #elif defined(__linux__) && defined(__sparc__)
 436 #  define QEMU_VMALLOC_ALIGN MAX(qemu_real_host_page_size(), SHMLBA)
 437 #else
 438 #  define QEMU_VMALLOC_ALIGN qemu_real_host_page_size()
 439 #endif
 440
 441 #ifdef CONFIG_POSIX
 442 struct qemu_signalfd_siginfo {
 443     uint32_t ssi_signo;   /* Signal number */
 444     int32_t  ssi_errno;   /* Error number (unused) */
 445     int32_t  ssi_code;    /* Signal code */
 446     uint32_t ssi_pid;     /* PID of sender */
 447     uint32_t ssi_uid;     /* Real UID of sender */
 448     int32_t  ssi_fd;      /* File descriptor (SIGIO) */
 449     uint32_t ssi_tid;     /* Kernel timer ID (POSIX timers) */
 450     uint32_t ssi_band;    /* Band event (SIGIO) */
 451     uint32_t ssi_overrun; /* POSIX timer overrun count */
 452     uint32_t ssi_trapno;  /* Trap number that caused signal */
 453     int32_t  ssi_status;  /* Exit status or signal (SIGCHLD) */
 454     int32_t  ssi_int;     /* Integer sent by sigqueue(2) */
 455     uint64_t ssi_ptr;     /* Pointer sent by sigqueue(2) */
 456     uint64_t ssi_utime;   /* User CPU time consumed (SIGCHLD) */
 457     uint64_t ssi_stime;   /* System CPU time consumed (SIGCHLD) */
 458     uint64_t ssi_addr;    /* Address that generated signal
 459                              (for hardware-generated signals) */
 460     uint8_t  pad[48];     /* Pad size to 128 bytes (allow for
 461                              additional fields in the future) */
 462 };
 463
 464 int qemu_signalfd(const sigset_t *mask);
 465 void sigaction_invoke(struct sigaction *action,
 466                       struct qemu_signalfd_siginfo *info);
 467 #endif
 468
 469 /*
 470  * Don't introduce new usage of this function, prefer the following
 471  * qemu_open/qemu_create that take an "Error **errp"
 472  */
 473 int qemu_open_old(const char *name, int flags, ...);
 474 int qemu_open(const char *name, int flags, Error **errp);
 475 int qemu_create(const char *name, int flags, mode_t mode, Error **errp);
 476 int qemu_close(int fd);
 477 int qemu_unlink(const char *name);
 478 #ifndef _WIN32
 479 int qemu_dup_flags(int fd, int flags);
 480 int qemu_dup(int fd);
 481 int qemu_lock_fd(int fd, int64_t start, int64_t len, bool exclusive);
 482 int qemu_unlock_fd(int fd, int64_t start, int64_t len);
 483 int qemu_lock_fd_test(int fd, int64_t start, int64_t len, bool exclusive);
 484 bool qemu_has_ofd_lock(void);
 485 #endif
 486
 487 #if defined(__HAIKU__) && defined(__i386__)
 488 #define FMT_pid "%ld"
 489 #elif defined(WIN64)
 490 #define FMT_pid "%" PRId64
 491 #else
 492 #define FMT_pid "%d"
 493 #endif
 494
 495 bool qemu_write_pidfile(const char *pidfile, Error **errp);
 496
 497 int qemu_get_thread_id(void);
 498
 499 #ifndef CONFIG_IOVEC
 500 struct iovec {
 501     void *iov_base;
 502     size_t iov_len;
 503 };
 504 /*
 505  * Use the same value as Linux for now.
 506  */
 507 #define IOV_MAX 1024
 508
 509 ssize_t readv(int fd, const struct iovec *iov, int iov_cnt);
 510 ssize_t writev(int fd, const struct iovec *iov, int iov_cnt);
 511 #endif
 512
 513 #ifdef _WIN32
 514 static inline void qemu_timersub(const struct timeval *val1,
 515                                  const struct timeval *val2,
 516                                  struct timeval *res)
 517 {
 518     res->tv_sec = val1->tv_sec - val2->tv_sec;
 519     if (val1->tv_usec < val2->tv_usec) {
 520         res->tv_sec--;
 521         res->tv_usec = val1->tv_usec - val2->tv_usec + 1000 * 1000;
 522     } else {
 523         res->tv_usec = val1->tv_usec - val2->tv_usec;
 524     }
 525 }
 526 #else
 527 #define qemu_timersub timersub
 528 #endif
 529
 530 ssize_t qemu_write_full(int fd, const void *buf, size_t count)
 531     G_GNUC_WARN_UNUSED_RESULT;
 532
 533 #ifndef _WIN32
 534 int qemu_pipe(int pipefd[2]);
 535 #endif
 536
 537 void qemu_set_cloexec(int fd);
 538
 539 void fips_set_state(bool requested);
 540 bool fips_get_state(void);
 541
 542 /* Return a dynamically allocated pathname denoting a file or directory that is
 543  * appropriate for storing local state.
 544  *
 545  * @relative_pathname need not start with a directory separator; one will be
 546  * added automatically.
 547  *
 548  * The caller is responsible for releasing the value returned with g_free()
 549  * after use.
 550  */
 551 char *qemu_get_local_state_pathname(const char *relative_pathname);
 552
 553 /* Find program directory, and save it for later usage with
 554  * qemu_get_exec_dir().
 555  * Try OS specific API first, if not working, parse from argv0. */
 556 void qemu_init_exec_dir(const char *argv0);
 557
 558 /* Get the saved exec dir.  */
 559 const char *qemu_get_exec_dir(void);
 560
 561 /**
 562  * qemu_getauxval:
 563  * @type: the auxiliary vector key to lookup
 564  *
 565  * Search the auxiliary vector for @type, returning the value
 566  * or 0 if @type is not present.
 567  */
 568 unsigned long qemu_getauxval(unsigned long type);
 569
 570 void qemu_set_tty_echo(int fd, bool echo);
 571
 572 void os_mem_prealloc(int fd, char *area, size_t sz, int smp_cpus,
 573                      Error **errp);
 574
 575 /**
 576  * qemu_get_pid_name:
 577  * @pid: pid of a process
 578  *
 579  * For given @pid fetch its name. Caller is responsible for
 580  * freeing the string when no longer needed.
 581  * Returns allocated string on success, NULL on failure.
 582  */
 583 char *qemu_get_pid_name(pid_t pid);
 584
 585 /**
 586  * qemu_fork:
 587  *
 588  * A version of fork that avoids signal handler race
 589  * conditions that can lead to child process getting
 590  * signals that are otherwise only expected by the
 591  * parent. It also resets all signal handlers to the
 592  * default settings.
 593  *
 594  * Returns 0 to child process, pid number to parent
 595  * or -1 on failure.
 596  */
 597 pid_t qemu_fork(Error **errp);
 598
 599 /* Using intptr_t ensures that qemu_*_page_mask is sign-extended even
 600  * when intptr_t is 32-bit and we are aligning a long long.
 601  */
 602 static inline uintptr_t qemu_real_host_page_size(void)
 603 {
 604     return getpagesize();
 605 }
 606
 607 static inline intptr_t qemu_real_host_page_mask(void)
 608 {
 609     return -(intptr_t)qemu_real_host_page_size();
 610 }
 611
 612 /*
 613  * After using getopt or getopt_long, if you need to parse another set
 614  * of options, then you must reset optind.  Unfortunately the way to
 615  * do this varies between implementations of getopt.
 616  */
 617 static inline void qemu_reset_optind(void)
 618 {
 619 #ifdef HAVE_OPTRESET
 620     optind = 1;
 621     optreset = 1;
 622 #else
 623     optind = 0;
 624 #endif
 625 }
 626
 627 /**
 628  * qemu_get_host_name:
 629  * @errp: Error object
 630  *
 631  * Operating system agnostic way of querying host name.
 632  *
 633  * Returns allocated hostname (caller should free), NULL on failure.
 634  */
 635 char *qemu_get_host_name(Error **errp);
 636
 637 /**
 638  * qemu_get_host_physmem:
 639  *
 640  * Operating system agnostic way of querying host memory.
 641  *
 642  * Returns amount of physical memory on the system. This is purely
 643  * advisery and may return 0 if we can't work it out. At the other
 644  * end we saturate to SIZE_MAX if you are lucky enough to have that
 645  * much memory.
 646  */
 647 size_t qemu_get_host_physmem(void);
 648
 649 /*
 650  * Toggle write/execute on the pages marked MAP_JIT
 651  * for the current thread.
 652  */
 653 #if defined(MAC_OS_VERSION_11_0) && \
 654     MAC_OS_X_VERSION_MIN_REQUIRED >= MAC_OS_VERSION_11_0
 655 static inline void qemu_thread_jit_execute(void)
 656 {
 657     pthread_jit_write_protect_np(true);
 658 }
 659
 660 static inline void qemu_thread_jit_write(void)
 661 {
 662     pthread_jit_write_protect_np(false);
 663 }
 664 #else
 665 static inline void qemu_thread_jit_write(void) {}
 666 static inline void qemu_thread_jit_execute(void) {}
 667 #endif
 668
 669 /**
 670  * Platforms which do not support system() return ENOSYS
 671  */
 672 #ifndef HAVE_SYSTEM_FUNCTION
 673 #define system platform_does_not_support_system
 674 static inline int platform_does_not_support_system(const char *command)
 675 {
 676     errno = ENOSYS;
 677     return -1;
 678 }
 679 #endif /* !HAVE_SYSTEM_FUNCTION */
 680
 681 #ifdef __cplusplus
 682 }
 683 #endif
 684
 685 #endif