PostgreSQL Source Code: src/port/win32pread.c Source File

PostgreSQL Source Code git master
win32pread.c
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1/*-------------------------------------------------------------------------
2 *
3 * win32pread.c
4 * Implementation of pread(2) for Windows.
5 *
6 * Portions Copyright (c) 1996-2025, PostgreSQL Global Development Group
7 *
8 * IDENTIFICATION
9 * src/port/win32pread.c
10 *
11 *-------------------------------------------------------------------------
12 */
13
14
15#include "c.h"
16
17#include <windows.h>
18
19ssize_t
20 pg_pread(int fd, void *buf, size_t size, off_t offset)
21{
22 OVERLAPPED overlapped = {0};
23 HANDLE handle;
24 DWORD result;
25
26 handle = (HANDLE) _get_osfhandle(fd);
27 if (handle == INVALID_HANDLE_VALUE)
28 {
29 errno = EBADF;
30 return -1;
31 }
32
33 /* Avoid overflowing DWORD. */
34 size = Min(size, 1024 * 1024 * 1024);
35
36 /* Note that this changes the file position, despite not using it. */
37 overlapped.Offset = offset;
38 if (!ReadFile(handle, buf, size, &result, &overlapped))
39 {
40 if (GetLastError() == ERROR_HANDLE_EOF)
41 return 0;
42
43 _dosmaperr(GetLastError());
44 return -1;
45 }
46
47 return result;
48}
#define Min(x, y)
Definition: c.h:1003
static char * buf
Definition: pg_test_fsync.c:72
static int fd(const char *x, int i)
Definition: preproc-init.c:105
void _dosmaperr(unsigned long)
Definition: win32error.c:177
ssize_t pg_pread(int fd, void *buf, size_t size, off_t offset)
Definition: win32pread.c:20

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