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  * qemu_build_not_reached()
 174  *
 175  * The compiler, during optimization, is expected to prove that a call
 176  * to this function cannot be reached and remove it.  If the compiler
 177  * supports QEMU_ERROR, this will be reported at compile time; otherwise
 178  * this will be reported at link time due to the missing symbol.
 179  */
 180 extern G_NORETURN
 181 void QEMU_ERROR("code path is reachable")
 182     qemu_build_not_reached_always(void);
 183 #if defined(__OPTIMIZE__) && !defined(__NO_INLINE__)
 184 #define qemu_build_not_reached()  qemu_build_not_reached_always()
 185 #else
 186 #define qemu_build_not_reached()  g_assert_not_reached()
 187 #endif
 188
 189 /*
 190  * According to waitpid man page:
 191  * WCOREDUMP
 192  *  This  macro  is  not  specified  in POSIX.1-2001 and is not
 193  *  available on some UNIX implementations (e.g., AIX, SunOS).
 194  *  Therefore, enclose its use inside #ifdef WCOREDUMP ... #endif.
 195  */
 196 #ifndef WCOREDUMP
 197 #define WCOREDUMP(status) 0
 198 #endif
 199 /*
 200  * We have a lot of unaudited code that may fail in strange ways, or
 201  * even be a security risk during migration, if you disable assertions
 202  * at compile-time.  You may comment out these safety checks if you
 203  * absolutely want to disable assertion overhead, but it is not
 204  * supported upstream so the risk is all yours.  Meanwhile, please
 205  * submit patches to remove any side-effects inside an assertion, or
 206  * fixing error handling that should use Error instead of assert.
 207  */
 208 #ifdef NDEBUG
 209 #error building with NDEBUG is not supported
 210 #endif
 211 #ifdef G_DISABLE_ASSERT
 212 #error building with G_DISABLE_ASSERT is not supported
 213 #endif
 214
 215 #ifndef O_LARGEFILE
 216 #define O_LARGEFILE 0
 217 #endif
 218 #ifndef O_BINARY
 219 #define O_BINARY 0
 220 #endif
 221 #ifndef MAP_ANONYMOUS
 222 #define MAP_ANONYMOUS MAP_ANON
 223 #endif
 224 #ifndef MAP_FIXED_NOREPLACE
 225 #define MAP_FIXED_NOREPLACE 0
 226 #endif
 227 #ifndef MAP_NORESERVE
 228 #define MAP_NORESERVE 0
 229 #endif
 230 #ifndef ENOMEDIUM
 231 #define ENOMEDIUM ENODEV
 232 #endif
 233 #if !defined(ENOTSUP)
 234 #define ENOTSUP 4096
 235 #endif
 236 #if !defined(ECANCELED)
 237 #define ECANCELED 4097
 238 #endif
 239 #if !defined(EMEDIUMTYPE)
 240 #define EMEDIUMTYPE 4098
 241 #endif
 242 #if !defined(ESHUTDOWN)
 243 #define ESHUTDOWN 4099
 244 #endif
 245
 246 #define TFR(expr) do { if ((expr) != -1) break; } while (errno == EINTR)
 247
 248 /* time_t may be either 32 or 64 bits depending on the host OS, and
 249  * can be either signed or unsigned, so we can't just hardcode a
 250  * specific maximum value. This is not a C preprocessor constant,
 251  * so you can't use TIME_MAX in an #ifdef, but for our purposes
 252  * this isn't a problem.
 253  */
 254
 255 /* The macros TYPE_SIGNED, TYPE_WIDTH, and TYPE_MAXIMUM are from
 256  * Gnulib, and are under the LGPL v2.1 or (at your option) any
 257  * later version.
 258  */
 259
 260 /* True if the real type T is signed.  */
 261 #define TYPE_SIGNED(t) (!((t)0 < (t)-1))
 262
 263 /* The width in bits of the integer type or expression T.
 264  * Padding bits are not supported.
 265  */
 266 #define TYPE_WIDTH(t) (sizeof(t) * CHAR_BIT)
 267
 268 /* The maximum and minimum values for the integer type T.  */
 269 #define TYPE_MAXIMUM(t)                                                \
 270   ((t) (!TYPE_SIGNED(t)                                                \
 271         ? (t)-1                                                        \
 272         : ((((t)1 << (TYPE_WIDTH(t) - 2)) - 1) * 2 + 1)))
 273
 274 #ifndef TIME_MAX
 275 #define TIME_MAX TYPE_MAXIMUM(time_t)
 276 #endif
 277
 278 /* Mac OSX has a <stdint.h> bug that incorrectly defines SIZE_MAX with
 279  * the wrong type. Our replacement isn't usable in preprocessor
 280  * expressions, but it is sufficient for our needs. */
 281 #ifdef HAVE_BROKEN_SIZE_MAX
 282 #undef SIZE_MAX
 283 #define SIZE_MAX ((size_t)-1)
 284 #endif
 285
 286 /*
 287  * Two variations of MIN/MAX macros. The first is for runtime use, and
 288  * evaluates arguments only once (so it is safe even with side
 289  * effects), but will not work in constant contexts (such as array
 290  * size declarations) because of the '{}'.  The second is for constant
 291  * expression use, where evaluating arguments twice is safe because
 292  * the result is going to be constant anyway, but will not work in a
 293  * runtime context because of a void expression where a value is
 294  * expected.  Thus, both gcc and clang will fail to compile if you use
 295  * the wrong macro (even if the error may seem a bit cryptic).
 296  *
 297  * Note that neither form is usable as an #if condition; if you truly
 298  * need to write conditional code that depends on a minimum or maximum
 299  * determined by the pre-processor instead of the compiler, you'll
 300  * have to open-code it.  Sadly, Coverity is severely confused by the
 301  * constant variants, so we have to dumb things down there.
 302  */
 303 #undef MIN
 304 #define MIN(a, b)                                       \
 305     ({                                                  \
 306         typeof(1 ? (a) : (b)) _a = (a), _b = (b);       \
 307         _a < _b ? _a : _b;                              \
 308     })
 309 #undef MAX
 310 #define MAX(a, b)                                       \
 311     ({                                                  \
 312         typeof(1 ? (a) : (b)) _a = (a), _b = (b);       \
 313         _a > _b ? _a : _b;                              \
 314     })
 315
 316 #ifdef __COVERITY__
 317 # define MIN_CONST(a, b) ((a) < (b) ? (a) : (b))
 318 # define MAX_CONST(a, b) ((a) > (b) ? (a) : (b))
 319 #else
 320 # define MIN_CONST(a, b)                                        \
 321     __builtin_choose_expr(                                      \
 322         __builtin_constant_p(a) && __builtin_constant_p(b),     \
 323         (a) < (b) ? (a) : (b),                                  \
 324         ((void)0))
 325 # define MAX_CONST(a, b)                                        \
 326     __builtin_choose_expr(                                      \
 327         __builtin_constant_p(a) && __builtin_constant_p(b),     \
 328         (a) > (b) ? (a) : (b),                                  \
 329         ((void)0))
 330 #endif
 331
 332 /*
 333  * Minimum function that returns zero only if both values are zero.
 334  * Intended for use with unsigned values only.
 335  */
 336 #ifndef MIN_NON_ZERO
 337 #define MIN_NON_ZERO(a, b)                              \
 338     ({                                                  \
 339         typeof(1 ? (a) : (b)) _a = (a), _b = (b);       \
 340         _a == 0 ? _b : (_b == 0 || _b > _a) ? _a : _b;  \
 341     })
 342 #endif
 343
 344 /*
 345  * Round number down to multiple. Safe when m is not a power of 2 (see
 346  * ROUND_DOWN for a faster version when a power of 2 is guaranteed).
 347  */
 348 #define QEMU_ALIGN_DOWN(n, m) ((n) / (m) * (m))
 349
 350 /*
 351  * Round number up to multiple. Safe when m is not a power of 2 (see
 352  * ROUND_UP for a faster version when a power of 2 is guaranteed).
 353  */
 354 #define QEMU_ALIGN_UP(n, m) QEMU_ALIGN_DOWN((n) + (m) - 1, (m))
 355
 356 /* Check if n is a multiple of m */
 357 #define QEMU_IS_ALIGNED(n, m) (((n) % (m)) == 0)
 358
 359 /* n-byte align pointer down */
 360 #define QEMU_ALIGN_PTR_DOWN(p, n) \
 361     ((typeof(p))QEMU_ALIGN_DOWN((uintptr_t)(p), (n)))
 362
 363 /* n-byte align pointer up */
 364 #define QEMU_ALIGN_PTR_UP(p, n) \
 365     ((typeof(p))QEMU_ALIGN_UP((uintptr_t)(p), (n)))
 366
 367 /* Check if pointer p is n-bytes aligned */
 368 #define QEMU_PTR_IS_ALIGNED(p, n) QEMU_IS_ALIGNED((uintptr_t)(p), (n))
 369
 370 /*
 371  * Round number down to multiple. Requires that d be a power of 2 (see
 372  * QEMU_ALIGN_UP for a safer but slower version on arbitrary
 373  * numbers); works even if d is a smaller type than n.
 374  */
 375 #ifndef ROUND_DOWN
 376 #define ROUND_DOWN(n, d) ((n) & -(0 ? (n) : (d)))
 377 #endif
 378
 379 /*
 380  * Round number up to multiple. Requires that d be a power of 2 (see
 381  * QEMU_ALIGN_UP for a safer but slower version on arbitrary
 382  * numbers); works even if d is a smaller type than n.
 383  */
 384 #ifndef ROUND_UP
 385 #define ROUND_UP(n, d) ROUND_DOWN((n) + (d) - 1, (d))
 386 #endif
 387
 388 #ifndef DIV_ROUND_UP
 389 #define DIV_ROUND_UP(n, d) (((n) + (d) - 1) / (d))
 390 #endif
 391
 392 /*
 393  * &(x)[0] is always a pointer - if it's same type as x then the argument is a
 394  * pointer, not an array.
 395  */
 396 #define QEMU_IS_ARRAY(x) (!__builtin_types_compatible_p(typeof(x), \
 397                                                         typeof(&(x)[0])))
 398 #ifndef ARRAY_SIZE
 399 #define ARRAY_SIZE(x) ((sizeof(x) / sizeof((x)[0])) + \
 400                        QEMU_BUILD_BUG_ON_ZERO(!QEMU_IS_ARRAY(x)))
 401 #endif
 402
 403 int qemu_daemon(int nochdir, int noclose);
 404 void *qemu_anon_ram_alloc(size_t size, uint64_t *align, bool shared,
 405                           bool noreserve);
 406 void qemu_anon_ram_free(void *ptr, size_t size);
 407
 408 #ifdef _WIN32
 409 #define HAVE_CHARDEV_SERIAL 1
 410 #elif defined(__linux__) || defined(__sun__) || defined(__FreeBSD__)    \
 411     || defined(__NetBSD__) || defined(__OpenBSD__) || defined(__DragonFly__) \
 412     || defined(__GLIBC__) || defined(__APPLE__)
 413 #define HAVE_CHARDEV_SERIAL 1
 414 #endif
 415
 416 #if defined(__linux__) || defined(__FreeBSD__) ||               \
 417     defined(__FreeBSD_kernel__) || defined(__DragonFly__)
 418 #define HAVE_CHARDEV_PARPORT 1
 419 #endif
 420
 421 #if defined(__HAIKU__)
 422 #define SIGIO SIGPOLL
 423 #endif
 424
 425 #ifdef HAVE_MADVISE_WITHOUT_PROTOTYPE
 426 /*
 427  * See MySQL bug #7156 (http://bugs.mysql.com/bug.php?id=7156) for discussion
 428  * about Solaris missing the madvise() prototype.
 429  */
 430 extern int madvise(char *, size_t, int);
 431 #endif
 432
 433 #if defined(CONFIG_LINUX)
 434 #ifndef BUS_MCEERR_AR
 435 #define BUS_MCEERR_AR 4
 436 #endif
 437 #ifndef BUS_MCEERR_AO
 438 #define BUS_MCEERR_AO 5
 439 #endif
 440 #endif
 441
 442 #if defined(__linux__) && \
 443     (defined(__x86_64__) || defined(__arm__) || defined(__aarch64__) \
 444      || defined(__powerpc64__))
 445    /* Use 2 MiB alignment so transparent hugepages can be used by KVM.
 446       Valgrind does not support alignments larger than 1 MiB,
 447       therefore we need special code which handles running on Valgrind. */
 448 #  define QEMU_VMALLOC_ALIGN (512 * 4096)
 449 #elif defined(__linux__) && defined(__s390x__)
 450    /* Use 1 MiB (segment size) alignment so gmap can be used by KVM. */
 451 #  define QEMU_VMALLOC_ALIGN (256 * 4096)
 452 #elif defined(__linux__) && defined(__sparc__)
 453 #  define QEMU_VMALLOC_ALIGN MAX(qemu_real_host_page_size(), SHMLBA)
 454 #else
 455 #  define QEMU_VMALLOC_ALIGN qemu_real_host_page_size()
 456 #endif
 457
 458 #ifdef CONFIG_POSIX
 459 struct qemu_signalfd_siginfo {
 460     uint32_t ssi_signo;   /* Signal number */
 461     int32_t  ssi_errno;   /* Error number (unused) */
 462     int32_t  ssi_code;    /* Signal code */
 463     uint32_t ssi_pid;     /* PID of sender */
 464     uint32_t ssi_uid;     /* Real UID of sender */
 465     int32_t  ssi_fd;      /* File descriptor (SIGIO) */
 466     uint32_t ssi_tid;     /* Kernel timer ID (POSIX timers) */
 467     uint32_t ssi_band;    /* Band event (SIGIO) */
 468     uint32_t ssi_overrun; /* POSIX timer overrun count */
 469     uint32_t ssi_trapno;  /* Trap number that caused signal */
 470     int32_t  ssi_status;  /* Exit status or signal (SIGCHLD) */
 471     int32_t  ssi_int;     /* Integer sent by sigqueue(2) */
 472     uint64_t ssi_ptr;     /* Pointer sent by sigqueue(2) */
 473     uint64_t ssi_utime;   /* User CPU time consumed (SIGCHLD) */
 474     uint64_t ssi_stime;   /* System CPU time consumed (SIGCHLD) */
 475     uint64_t ssi_addr;    /* Address that generated signal
 476                              (for hardware-generated signals) */
 477     uint8_t  pad[48];     /* Pad size to 128 bytes (allow for
 478                              additional fields in the future) */
 479 };
 480
 481 int qemu_signalfd(const sigset_t *mask);
 482 void sigaction_invoke(struct sigaction *action,
 483                       struct qemu_signalfd_siginfo *info);
 484 #endif
 485
 486 /*
 487  * Don't introduce new usage of this function, prefer the following
 488  * qemu_open/qemu_create that take an "Error **errp"
 489  */
 490 int qemu_open_old(const char *name, int flags, ...);
 491 int qemu_open(const char *name, int flags, Error **errp);
 492 int qemu_create(const char *name, int flags, mode_t mode, Error **errp);
 493 int qemu_close(int fd);
 494 int qemu_unlink(const char *name);
 495 #ifndef _WIN32
 496 int qemu_dup_flags(int fd, int flags);
 497 int qemu_dup(int fd);
 498 int qemu_lock_fd(int fd, int64_t start, int64_t len, bool exclusive);
 499 int qemu_unlock_fd(int fd, int64_t start, int64_t len);
 500 int qemu_lock_fd_test(int fd, int64_t start, int64_t len, bool exclusive);
 501 bool qemu_has_ofd_lock(void);
 502 #endif
 503
 504 #if defined(__HAIKU__) && defined(__i386__)
 505 #define FMT_pid "%ld"
 506 #elif defined(WIN64)
 507 #define FMT_pid "%" PRId64
 508 #else
 509 #define FMT_pid "%d"
 510 #endif
 511
 512 bool qemu_write_pidfile(const char *pidfile, Error **errp);
 513
 514 int qemu_get_thread_id(void);
 515
 516 #ifndef CONFIG_IOVEC
 517 struct iovec {
 518     void *iov_base;
 519     size_t iov_len;
 520 };
 521 /*
 522  * Use the same value as Linux for now.
 523  */
 524 #define IOV_MAX 1024
 525
 526 ssize_t readv(int fd, const struct iovec *iov, int iov_cnt);
 527 ssize_t writev(int fd, const struct iovec *iov, int iov_cnt);
 528 #endif
 529
 530 #ifdef _WIN32
 531 static inline void qemu_timersub(const struct timeval *val1,
 532                                  const struct timeval *val2,
 533                                  struct timeval *res)
 534 {
 535     res->tv_sec = val1->tv_sec - val2->tv_sec;
 536     if (val1->tv_usec < val2->tv_usec) {
 537         res->tv_sec--;
 538         res->tv_usec = val1->tv_usec - val2->tv_usec + 1000 * 1000;
 539     } else {
 540         res->tv_usec = val1->tv_usec - val2->tv_usec;
 541     }
 542 }
 543 #else
 544 #define qemu_timersub timersub
 545 #endif
 546
 547 ssize_t qemu_write_full(int fd, const void *buf, size_t count)
 548     G_GNUC_WARN_UNUSED_RESULT;
 549
 550 #ifndef _WIN32
 551 int qemu_pipe(int pipefd[2]);
 552 #endif
 553
 554 void qemu_set_cloexec(int fd);
 555
 556 void fips_set_state(bool requested);
 557 bool fips_get_state(void);
 558
 559 /* Return a dynamically allocated directory path that is appropriate for storing
 560  * local state.
 561  *
 562  * The caller is responsible for releasing the value returned with g_free()
 563  * after use.
 564  */
 565 char *qemu_get_local_state_dir(void);
 566
 567 /* Find program directory, and save it for later usage with
 568  * qemu_get_exec_dir().
 569  * Try OS specific API first, if not working, parse from argv0. */
 570 void qemu_init_exec_dir(const char *argv0);
 571
 572 /* Get the saved exec dir.  */
 573 const char *qemu_get_exec_dir(void);
 574
 575 /**
 576  * qemu_getauxval:
 577  * @type: the auxiliary vector key to lookup
 578  *
 579  * Search the auxiliary vector for @type, returning the value
 580  * or 0 if @type is not present.
 581  */
 582 unsigned long qemu_getauxval(unsigned long type);
 583
 584 void qemu_set_tty_echo(int fd, bool echo);
 585
 586 void os_mem_prealloc(int fd, char *area, size_t sz, int smp_cpus,
 587                      Error **errp);
 588
 589 /**
 590  * qemu_get_pid_name:
 591  * @pid: pid of a process
 592  *
 593  * For given @pid fetch its name. Caller is responsible for
 594  * freeing the string when no longer needed.
 595  * Returns allocated string on success, NULL on failure.
 596  */
 597 char *qemu_get_pid_name(pid_t pid);
 598
 599 /**
 600  * qemu_fork:
 601  *
 602  * A version of fork that avoids signal handler race
 603  * conditions that can lead to child process getting
 604  * signals that are otherwise only expected by the
 605  * parent. It also resets all signal handlers to the
 606  * default settings.
 607  *
 608  * Returns 0 to child process, pid number to parent
 609  * or -1 on failure.
 610  */
 611 pid_t qemu_fork(Error **errp);
 612
 613 /* Using intptr_t ensures that qemu_*_page_mask is sign-extended even
 614  * when intptr_t is 32-bit and we are aligning a long long.
 615  */
 616 static inline uintptr_t qemu_real_host_page_size(void)
 617 {
 618     return getpagesize();
 619 }
 620
 621 static inline intptr_t qemu_real_host_page_mask(void)
 622 {
 623     return -(intptr_t)qemu_real_host_page_size();
 624 }
 625
 626 /*
 627  * After using getopt or getopt_long, if you need to parse another set
 628  * of options, then you must reset optind.  Unfortunately the way to
 629  * do this varies between implementations of getopt.
 630  */
 631 static inline void qemu_reset_optind(void)
 632 {
 633 #ifdef HAVE_OPTRESET
 634     optind = 1;
 635     optreset = 1;
 636 #else
 637     optind = 0;
 638 #endif
 639 }
 640
 641 int qemu_fdatasync(int fd);
 642
 643 /**
 644  * Sync changes made to the memory mapped file back to the backing
 645  * storage. For POSIX compliant systems this will fallback
 646  * to regular msync call. Otherwise it will trigger whole file sync
 647  * (including the metadata case there is no support to skip that otherwise)
 648  *
 649  * @addr   - start of the memory area to be synced
 650  * @length - length of the are to be synced
 651  * @fd     - file descriptor for the file to be synced
 652  *           (mandatory only for POSIX non-compliant systems)
 653  */
 654 int qemu_msync(void *addr, size_t length, int fd);
 655
 656 /**
 657  * qemu_get_host_physmem:
 658  *
 659  * Operating system agnostic way of querying host memory.
 660  *
 661  * Returns amount of physical memory on the system. This is purely
 662  * advisery and may return 0 if we can't work it out. At the other
 663  * end we saturate to SIZE_MAX if you are lucky enough to have that
 664  * much memory.
 665  */
 666 size_t qemu_get_host_physmem(void);
 667
 668 /*
 669  * Toggle write/execute on the pages marked MAP_JIT
 670  * for the current thread.
 671  */
 672 #if defined(MAC_OS_VERSION_11_0) && \
 673     MAC_OS_X_VERSION_MIN_REQUIRED >= MAC_OS_VERSION_11_0
 674 static inline void qemu_thread_jit_execute(void)
 675 {
 676     pthread_jit_write_protect_np(true);
 677 }
 678
 679 static inline void qemu_thread_jit_write(void)
 680 {
 681     pthread_jit_write_protect_np(false);
 682 }
 683 #else
 684 static inline void qemu_thread_jit_write(void) {}
 685 static inline void qemu_thread_jit_execute(void) {}
 686 #endif
 687
 688 /**
 689  * Platforms which do not support system() return ENOSYS
 690  */
 691 #ifndef HAVE_SYSTEM_FUNCTION
 692 #define system platform_does_not_support_system
 693 static inline int platform_does_not_support_system(const char *command)
 694 {
 695     errno = ENOSYS;
 696     return -1;
 697 }
 698 #endif /* !HAVE_SYSTEM_FUNCTION */
 699
 700 #ifdef __cplusplus
 701 }
 702 #endif
 703
 704 #endif