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/*
* Copyright (C) 2013 Internet Systems Consortium, Inc. ("ISC")
*
* Permission to use, copy, modify, and/or distribute this software for any
* purpose with or without fee is hereby granted, provided that the above
* copyright notice and this permission notice appear in all copies.
*
* THE SOFTWARE IS PROVIDED "AS IS" AND ISC DISCLAIMS ALL WARRANTIES WITH
* REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
* AND FITNESS. IN NO EVENT SHALL ISC BE LIABLE FOR ANY SPECIAL, DIRECT,
* INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM
* LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE
* OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
* PERFORMANCE OF THIS SOFTWARE.
*/
#include <io.h>
#include <stdio.h>
#include <windows.h>
#include "pread.h"
static CRITICAL_SECTION preadsc;
/* http://stackoverflow.com/a/2390626/1392778 */
#ifdef _MSC_VER
#pragma section(".CRT$XCU", read)
#define INITIALIZER2_(f, p) \
static void __cdecl f(void); \
__declspec(allocate(".CRT$XCU")) void(__cdecl * f##_)(void) = f; \
__pragma(comment(linker, "/include:" p #f "_")) static void __cdecl f(void)
#ifdef _WIN64
#define INITIALIZER(f) INITIALIZER2_(f, "")
#else
#define INITIALIZER(f) INITIALIZER2_(f, "_")
#endif
#elif defined(__GNUC__)
#define INITIALIZER(f) \
static void f(void) __attribute__((constructor)); \
static void f(void)
#endif
#ifdef _WIN64
int pread(int fd, void *buf, unsigned int nbyte, __int64 offset) {
int cc = -1;
__int64 prev = (__int64)-1L;
EnterCriticalSection(&preadsc);
prev = _lseeki64(fd, 0L, SEEK_CUR);
if (prev == (__int64)-1L) {
goto done;
}
if (_lseeki64(fd, offset, SEEK_SET) != offset) {
goto done;
}
cc = _read(fd, buf, nbyte);
done:
if (prev != (__int64)-1L) {
(void)_lseeki64(fd, prev, SEEK_SET);
}
LeaveCriticalSection(&preadsc);
return cc;
}
#else
int pread(int fd, void *buf, unsigned int nbyte, long offset) {
int cc = -1;
long prev = -1L;
EnterCriticalSection(&preadsc);
prev = _lseek(fd, 0L, SEEK_CUR);
if (prev == -1L) {
goto done;
}
if (_lseek(fd, offset, SEEK_SET) != offset) {
goto done;
}
cc = _read(fd, buf, nbyte);
done:
if (prev != -1L) {
(void)_lseek(fd, prev, SEEK_SET);
}
LeaveCriticalSection(&preadsc);
return cc;
}
#endif
static void deinitialize(void) { DeleteCriticalSection(&preadsc); }
INITIALIZER(initialize) {
InitializeCriticalSection(&preadsc);
atexit(deinitialize);
}
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