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qemu-e2k/include/qemu/osdep.h
Marc-André Lureau 9e6bdef224 util: add qemu_write_pidfile() 
There are variants of qemu_create_pidfile() in qemu-pr-helper and
qemu-ga. Let's have a common implementation in libqemuutil.

The code is initially based from pr-helper write_pidfile(), with
various improvements and suggestions from Daniel Berrangé:

  QEMU will leave the pidfile existing on disk when it exits which
  initially made me think it avoids the deletion race. The app
  managing QEMU, however, may well delete the pidfile after it has
  seen QEMU exit, and even if the app locks the pidfile before
  deleting it, there is still a race.

  eg consider the following sequence

        QEMU 1        libvirtd        QEMU 2

  1.    lock(pidfile)

  2.    exit()

  3.                 open(pidfile)

  4.                 lock(pidfile)

  5.                                  open(pidfile)

  6.                 unlink(pidfile)

  7.                 close(pidfile)

  8.                                  lock(pidfile)

  IOW, at step 8 the new QEMU has successfully acquired the lock, but
  the pidfile no longer exists on disk because it was deleted after
  the original QEMU exited.

  While we could just say no external app should ever delete the
  pidfile, I don't think that is satisfactory as people don't read
  docs, and admins don't like stale pidfiles being left around on
  disk.

  To make this robust, I think we might want to copy libvirt's
  approach to pidfile acquisition which runs in a loop and checks that
  the file on disk /after/ acquiring the lock matches the file that
  was locked. Then we could in fact safely let QEMU delete its own
  pidfiles on clean exit..

Signed-off-by: Marc-André Lureau <marcandre.lureau@redhat.com>
Message-Id: <20180831145314.14736-2-marcandre.lureau@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
2018-10-02 18:47:55 +02:00

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/*
* OS includes and handling of OS dependencies
*
* This header exists to pull in some common system headers that
* most code in QEMU will want, and to fix up some possible issues with
* it (missing defines, Windows weirdness, and so on).
*
* To avoid getting into possible circular include dependencies, this
* file should not include any other QEMU headers, with the exceptions
* of config-host.h, config-target.h, qemu/compiler.h,
* sysemu/os-posix.h, sysemu/os-win32.h, glib-compat.h and
* qemu/typedefs.h, all of which are doing a similar job to this file
* and are under similar constraints.
*
* This header also contains prototypes for functions defined in
* os-*.c and util/oslib-*.c; those would probably be better split
* out into separate header files.
*
* In an ideal world this header would contain only:
* (1) things which everybody needs
* (2) things without which code would work on most platforms but
* fail to compile or misbehave on a minority of host OSes
*
* This work is licensed under the terms of the GNU GPL, version 2 or later.
* See the COPYING file in the top-level directory.
*/
#ifndef QEMU_OSDEP_H
#define QEMU_OSDEP_H
#include "config-host.h"
#ifdef NEED_CPU_H
#include "config-target.h"
#else
#include "exec/poison.h"
#endif
#ifdef __COVERITY__
/* Coverity does not like the new _Float* types that are used by
* recent glibc, and croaks on every single file that includes
* stdlib.h. These typedefs are enough to please it.
*
* Note that these fix parse errors so they cannot be placed in
* scripts/coverity-model.c.
*/
typedef float _Float32;
typedef double _Float32x;
typedef double _Float64;
typedef __float80 _Float64x;
typedef __float128 _Float128;
#endif
#include "qemu/compiler.h"
/* Older versions of C++ don't get definitions of various macros from
* stdlib.h unless we define these macros before first inclusion of
* that system header.
*/
#ifndef __STDC_CONSTANT_MACROS
#define __STDC_CONSTANT_MACROS
#endif
#ifndef __STDC_LIMIT_MACROS
#define __STDC_LIMIT_MACROS
#endif
#ifndef __STDC_FORMAT_MACROS
#define __STDC_FORMAT_MACROS
#endif
/* The following block of code temporarily renames the daemon() function so the
* compiler does not see the warning associated with it in stdlib.h on OSX
*/
#ifdef __APPLE__
#define daemon qemu_fake_daemon_function
#include <stdlib.h>
#undef daemon
extern int daemon(int, int);
#endif
#include <stdarg.h>
#include <stddef.h>
#include <stdbool.h>
#include <stdint.h>
#include <sys/types.h>
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <strings.h>
#include <inttypes.h>
#include <limits.h>
/* Put unistd.h before time.h as that triggers localtime_r/gmtime_r
* function availability on recentish Mingw-w64 platforms. */
#include <unistd.h>
#include <time.h>
#include <ctype.h>
#include <errno.h>
#include <fcntl.h>
#include <sys/stat.h>
#include <sys/time.h>
#include <assert.h>
/* setjmp must be declared before sysemu/os-win32.h
* because it is redefined there. */
#include <setjmp.h>
#include <signal.h>
#ifdef __OpenBSD__
#include <sys/signal.h>
#endif
#ifndef _WIN32
#include <sys/wait.h>
#else
#define WIFEXITED(x) 1
#define WEXITSTATUS(x) (x)
#endif
#ifdef _WIN32
#include "sysemu/os-win32.h"
#endif
#ifdef CONFIG_POSIX
#include "sysemu/os-posix.h"
#endif
#include "glib-compat.h"
#include "qemu/typedefs.h"
/*
* According to waitpid man page:
* WCOREDUMP
* This macro is not specified in POSIX.1-2001 and is not
* available on some UNIX implementations (e.g., AIX, SunOS).
* Therefore, enclose its use inside #ifdef WCOREDUMP ... #endif.
*/
#ifndef WCOREDUMP
#define WCOREDUMP(status) 0
#endif
/*
* We have a lot of unaudited code that may fail in strange ways, or
* even be a security risk during migration, if you disable assertions
* at compile-time. You may comment out these safety checks if you
* absolutely want to disable assertion overhead, but it is not
* supported upstream so the risk is all yours. Meanwhile, please
* submit patches to remove any side-effects inside an assertion, or
* fixing error handling that should use Error instead of assert.
*/
#ifdef NDEBUG
#error building with NDEBUG is not supported
#endif
#ifdef G_DISABLE_ASSERT
#error building with G_DISABLE_ASSERT is not supported
#endif
#ifndef O_LARGEFILE
#define O_LARGEFILE 0
#endif
#ifndef O_BINARY
#define O_BINARY 0
#endif
#ifndef MAP_ANONYMOUS
#define MAP_ANONYMOUS MAP_ANON
#endif
#ifndef ENOMEDIUM
#define ENOMEDIUM ENODEV
#endif
#if !defined(ENOTSUP)
#define ENOTSUP 4096
#endif
#if !defined(ECANCELED)
#define ECANCELED 4097
#endif
#if !defined(EMEDIUMTYPE)
#define EMEDIUMTYPE 4098
#endif
#if !defined(ESHUTDOWN)
#define ESHUTDOWN 4099
#endif
/* time_t may be either 32 or 64 bits depending on the host OS, and
* can be either signed or unsigned, so we can't just hardcode a
* specific maximum value. This is not a C preprocessor constant,
* so you can't use TIME_MAX in an #ifdef, but for our purposes
* this isn't a problem.
*/
/* The macros TYPE_SIGNED, TYPE_WIDTH, and TYPE_MAXIMUM are from
* Gnulib, and are under the LGPL v2.1 or (at your option) any
* later version.
*/
/* True if the real type T is signed. */
#define TYPE_SIGNED(t) (!((t)0 < (t)-1))
/* The width in bits of the integer type or expression T.
* Padding bits are not supported.
*/
#define TYPE_WIDTH(t) (sizeof(t) * CHAR_BIT)
/* The maximum and minimum values for the integer type T. */
#define TYPE_MAXIMUM(t) \
((t) (!TYPE_SIGNED(t) \
? (t)-1 \
: ((((t)1 << (TYPE_WIDTH(t) - 2)) - 1) * 2 + 1)))
#ifndef TIME_MAX
#define TIME_MAX TYPE_MAXIMUM(time_t)
#endif
/* HOST_LONG_BITS is the size of a native pointer in bits. */
#if UINTPTR_MAX == UINT32_MAX
# define HOST_LONG_BITS 32
#elif UINTPTR_MAX == UINT64_MAX
# define HOST_LONG_BITS 64
#else
# error Unknown pointer size
#endif
/* Mac OSX has a <stdint.h> bug that incorrectly defines SIZE_MAX with
* the wrong type. Our replacement isn't usable in preprocessor
* expressions, but it is sufficient for our needs. */
#if defined(HAVE_BROKEN_SIZE_MAX) && HAVE_BROKEN_SIZE_MAX
#undef SIZE_MAX
#define SIZE_MAX ((size_t)-1)
#endif
#ifndef MIN
#define MIN(a, b) (((a) < (b)) ? (a) : (b))
#endif
#ifndef MAX
#define MAX(a, b) (((a) > (b)) ? (a) : (b))
#endif
/* Minimum function that returns zero only iff both values are zero.
* Intended for use with unsigned values only. */
#ifndef MIN_NON_ZERO
#define MIN_NON_ZERO(a, b) ((a) == 0 ? (b) : \
((b) == 0 ? (a) : (MIN(a, b))))
#endif
/* Round number down to multiple */
#define QEMU_ALIGN_DOWN(n, m) ((n) / (m) * (m))
/* Round number up to multiple. Safe when m is not a power of 2 (see
* ROUND_UP for a faster version when a power of 2 is guaranteed) */
#define QEMU_ALIGN_UP(n, m) QEMU_ALIGN_DOWN((n) + (m) - 1, (m))
/* Check if n is a multiple of m */
#define QEMU_IS_ALIGNED(n, m) (((n) % (m)) == 0)
/* n-byte align pointer down */
#define QEMU_ALIGN_PTR_DOWN(p, n) \
((typeof(p))QEMU_ALIGN_DOWN((uintptr_t)(p), (n)))
/* n-byte align pointer up */
#define QEMU_ALIGN_PTR_UP(p, n) \
((typeof(p))QEMU_ALIGN_UP((uintptr_t)(p), (n)))
/* Check if pointer p is n-bytes aligned */
#define QEMU_PTR_IS_ALIGNED(p, n) QEMU_IS_ALIGNED((uintptr_t)(p), (n))
/* Round number up to multiple. Requires that d be a power of 2 (see
* QEMU_ALIGN_UP for a safer but slower version on arbitrary
* numbers); works even if d is a smaller type than n. */
#ifndef ROUND_UP
#define ROUND_UP(n, d) (((n) + (d) - 1) & -(0 ? (n) : (d)))
#endif
#ifndef DIV_ROUND_UP
#define DIV_ROUND_UP(n, d) (((n) + (d) - 1) / (d))
#endif
/*
* &(x)[0] is always a pointer - if it's same type as x then the argument is a
* pointer, not an array.
*/
#define QEMU_IS_ARRAY(x) (!__builtin_types_compatible_p(typeof(x), \
typeof(&(x)[0])))
#ifndef ARRAY_SIZE
#define ARRAY_SIZE(x) ((sizeof(x) / sizeof((x)[0])) + \
QEMU_BUILD_BUG_ON_ZERO(!QEMU_IS_ARRAY(x)))
#endif
int qemu_daemon(int nochdir, int noclose);
void *qemu_try_memalign(size_t alignment, size_t size);
void *qemu_memalign(size_t alignment, size_t size);
void *qemu_anon_ram_alloc(size_t size, uint64_t *align, bool shared);
void qemu_vfree(void *ptr);
void qemu_anon_ram_free(void *ptr, size_t size);
#define QEMU_MADV_INVALID -1
#if defined(CONFIG_MADVISE)
#define QEMU_MADV_WILLNEED MADV_WILLNEED
#define QEMU_MADV_DONTNEED MADV_DONTNEED
#ifdef MADV_DONTFORK
#define QEMU_MADV_DONTFORK MADV_DONTFORK
#else
#define QEMU_MADV_DONTFORK QEMU_MADV_INVALID
#endif
#ifdef MADV_MERGEABLE
#define QEMU_MADV_MERGEABLE MADV_MERGEABLE
#else
#define QEMU_MADV_MERGEABLE QEMU_MADV_INVALID
#endif
#ifdef MADV_UNMERGEABLE
#define QEMU_MADV_UNMERGEABLE MADV_UNMERGEABLE
#else
#define QEMU_MADV_UNMERGEABLE QEMU_MADV_INVALID
#endif
#ifdef MADV_DODUMP
#define QEMU_MADV_DODUMP MADV_DODUMP
#else
#define QEMU_MADV_DODUMP QEMU_MADV_INVALID
#endif
#ifdef MADV_DONTDUMP
#define QEMU_MADV_DONTDUMP MADV_DONTDUMP
#else
#define QEMU_MADV_DONTDUMP QEMU_MADV_INVALID
#endif
#ifdef MADV_HUGEPAGE
#define QEMU_MADV_HUGEPAGE MADV_HUGEPAGE
#else
#define QEMU_MADV_HUGEPAGE QEMU_MADV_INVALID
#endif
#ifdef MADV_NOHUGEPAGE
#define QEMU_MADV_NOHUGEPAGE MADV_NOHUGEPAGE
#else
#define QEMU_MADV_NOHUGEPAGE QEMU_MADV_INVALID
#endif
#ifdef MADV_REMOVE
#define QEMU_MADV_REMOVE MADV_REMOVE
#else
#define QEMU_MADV_REMOVE QEMU_MADV_INVALID
#endif
#elif defined(CONFIG_POSIX_MADVISE)
#define QEMU_MADV_WILLNEED POSIX_MADV_WILLNEED
#define QEMU_MADV_DONTNEED POSIX_MADV_DONTNEED
#define QEMU_MADV_DONTFORK QEMU_MADV_INVALID
#define QEMU_MADV_MERGEABLE QEMU_MADV_INVALID
#define QEMU_MADV_UNMERGEABLE QEMU_MADV_INVALID
#define QEMU_MADV_DODUMP QEMU_MADV_INVALID
#define QEMU_MADV_DONTDUMP QEMU_MADV_INVALID
#define QEMU_MADV_HUGEPAGE QEMU_MADV_INVALID
#define QEMU_MADV_NOHUGEPAGE QEMU_MADV_INVALID
#define QEMU_MADV_REMOVE QEMU_MADV_INVALID
#else /* no-op */
#define QEMU_MADV_WILLNEED QEMU_MADV_INVALID
#define QEMU_MADV_DONTNEED QEMU_MADV_INVALID
#define QEMU_MADV_DONTFORK QEMU_MADV_INVALID
#define QEMU_MADV_MERGEABLE QEMU_MADV_INVALID
#define QEMU_MADV_UNMERGEABLE QEMU_MADV_INVALID
#define QEMU_MADV_DODUMP QEMU_MADV_INVALID
#define QEMU_MADV_DONTDUMP QEMU_MADV_INVALID
#define QEMU_MADV_HUGEPAGE QEMU_MADV_INVALID
#define QEMU_MADV_NOHUGEPAGE QEMU_MADV_INVALID
#define QEMU_MADV_REMOVE QEMU_MADV_INVALID
#endif
#ifdef _WIN32
#define HAVE_CHARDEV_SERIAL 1
#elif defined(__linux__) || defined(__sun__) || defined(__FreeBSD__) \
|| defined(__NetBSD__) || defined(__OpenBSD__) || defined(__DragonFly__) \
|| defined(__GLIBC__)
#define HAVE_CHARDEV_SERIAL 1
#endif
#if defined(__linux__) || defined(__FreeBSD__) || \
defined(__FreeBSD_kernel__) || defined(__DragonFly__)
#define HAVE_CHARDEV_PARPORT 1
#endif
#if defined(CONFIG_LINUX)
#ifndef BUS_MCEERR_AR
#define BUS_MCEERR_AR 4
#endif
#ifndef BUS_MCEERR_AO
#define BUS_MCEERR_AO 5
#endif
#endif
#if defined(__linux__) && \
(defined(__x86_64__) || defined(__arm__) || defined(__aarch64__) \
|| defined(__powerpc64__))
/* Use 2 MiB alignment so transparent hugepages can be used by KVM.
Valgrind does not support alignments larger than 1 MiB,
therefore we need special code which handles running on Valgrind. */
# define QEMU_VMALLOC_ALIGN (512 * 4096)
#elif defined(__linux__) && defined(__s390x__)
/* Use 1 MiB (segment size) alignment so gmap can be used by KVM. */
# define QEMU_VMALLOC_ALIGN (256 * 4096)
#elif defined(__linux__) && defined(__sparc__)
#include <sys/shm.h>
# define QEMU_VMALLOC_ALIGN MAX(getpagesize(), SHMLBA)
#else
# define QEMU_VMALLOC_ALIGN getpagesize()
#endif
#ifdef CONFIG_POSIX
struct qemu_signalfd_siginfo {
uint32_t ssi_signo; /* Signal number */
int32_t ssi_errno; /* Error number (unused) */
int32_t ssi_code; /* Signal code */
uint32_t ssi_pid; /* PID of sender */
uint32_t ssi_uid; /* Real UID of sender */
int32_t ssi_fd; /* File descriptor (SIGIO) */
uint32_t ssi_tid; /* Kernel timer ID (POSIX timers) */
uint32_t ssi_band; /* Band event (SIGIO) */
uint32_t ssi_overrun; /* POSIX timer overrun count */
uint32_t ssi_trapno; /* Trap number that caused signal */
int32_t ssi_status; /* Exit status or signal (SIGCHLD) */
int32_t ssi_int; /* Integer sent by sigqueue(2) */
uint64_t ssi_ptr; /* Pointer sent by sigqueue(2) */
uint64_t ssi_utime; /* User CPU time consumed (SIGCHLD) */
uint64_t ssi_stime; /* System CPU time consumed (SIGCHLD) */
uint64_t ssi_addr; /* Address that generated signal
(for hardware-generated signals) */
uint8_t pad[48]; /* Pad size to 128 bytes (allow for
additional fields in the future) */
};
int qemu_signalfd(const sigset_t *mask);
void sigaction_invoke(struct sigaction *action,
struct qemu_signalfd_siginfo *info);
#endif
int qemu_madvise(void *addr, size_t len, int advice);
int qemu_mprotect_rwx(void *addr, size_t size);
int qemu_mprotect_none(void *addr, size_t size);
int qemu_open(const char *name, int flags, ...);
int qemu_close(int fd);
#ifndef _WIN32
int qemu_dup(int fd);
#endif
int qemu_lock_fd(int fd, int64_t start, int64_t len, bool exclusive);
int qemu_unlock_fd(int fd, int64_t start, int64_t len);
int qemu_lock_fd_test(int fd, int64_t start, int64_t len, bool exclusive);
bool qemu_has_ofd_lock(void);
#if defined(__HAIKU__) && defined(__i386__)
#define FMT_pid "%ld"
#elif defined(WIN64)
#define FMT_pid "%" PRId64
#else
#define FMT_pid "%d"
#endif
bool qemu_write_pidfile(const char *pidfile, Error **errp);
int qemu_get_thread_id(void);
#ifndef CONFIG_IOVEC
struct iovec {
void *iov_base;
size_t iov_len;
};
/*
* Use the same value as Linux for now.
*/
#define IOV_MAX 1024
ssize_t readv(int fd, const struct iovec *iov, int iov_cnt);
ssize_t writev(int fd, const struct iovec *iov, int iov_cnt);
#else
#include <sys/uio.h>
#endif
#ifdef _WIN32
static inline void qemu_timersub(const struct timeval *val1,
const struct timeval *val2,
struct timeval *res)
{
res->tv_sec = val1->tv_sec - val2->tv_sec;
if (val1->tv_usec < val2->tv_usec) {
res->tv_sec--;
res->tv_usec = val1->tv_usec - val2->tv_usec + 1000 * 1000;
} else {
res->tv_usec = val1->tv_usec - val2->tv_usec;
}
}
#else
#define qemu_timersub timersub
#endif
void qemu_set_cloexec(int fd);
/* Starting on QEMU 2.5, qemu_hw_version() returns "2.5+" by default
* instead of QEMU_VERSION, so setting hw_version on MachineClass
* is no longer mandatory.
*
* Do NOT change this string, or it will break compatibility on all
* machine classes that don't set hw_version.
*/
#define QEMU_HW_VERSION "2.5+"
/* QEMU "hardware version" setting. Used to replace code that exposed
* QEMU_VERSION to guests in the past and need to keep compatibility.
* Do not use qemu_hw_version() in new code.
*/
void qemu_set_hw_version(const char *);
const char *qemu_hw_version(void);
void fips_set_state(bool requested);
bool fips_get_state(void);
/* Return a dynamically allocated pathname denoting a file or directory that is
* appropriate for storing local state.
*
* @relative_pathname need not start with a directory separator; one will be
* added automatically.
*
* The caller is responsible for releasing the value returned with g_free()
* after use.
*/
char *qemu_get_local_state_pathname(const char *relative_pathname);
/* Find program directory, and save it for later usage with
* qemu_get_exec_dir().
* Try OS specific API first, if not working, parse from argv0. */
void qemu_init_exec_dir(const char *argv0);
/* Get the saved exec dir.
* Caller needs to release the returned string by g_free() */
char *qemu_get_exec_dir(void);
/**
* qemu_getauxval:
* @type: the auxiliary vector key to lookup
*
* Search the auxiliary vector for @type, returning the value
* or 0 if @type is not present.
*/
unsigned long qemu_getauxval(unsigned long type);
void qemu_set_tty_echo(int fd, bool echo);
void os_mem_prealloc(int fd, char *area, size_t sz, int smp_cpus,
Error **errp);
/**
* qemu_get_pid_name:
* @pid: pid of a process
*
* For given @pid fetch its name. Caller is responsible for
* freeing the string when no longer needed.
* Returns allocated string on success, NULL on failure.
*/
char *qemu_get_pid_name(pid_t pid);
/**
* qemu_fork:
*
* A version of fork that avoids signal handler race
* conditions that can lead to child process getting
* signals that are otherwise only expected by the
* parent. It also resets all signal handlers to the
* default settings.
*
* Returns 0 to child process, pid number to parent
* or -1 on failure.
*/
pid_t qemu_fork(Error **errp);
/* Using intptr_t ensures that qemu_*_page_mask is sign-extended even
* when intptr_t is 32-bit and we are aligning a long long.
*/
extern uintptr_t qemu_real_host_page_size;
extern intptr_t qemu_real_host_page_mask;
extern int qemu_icache_linesize;
extern int qemu_icache_linesize_log;
extern int qemu_dcache_linesize;
extern int qemu_dcache_linesize_log;
#endif
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