win32fseek.c

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/*-------------------------------------------------------------------------
 *
 * win32fseek.c
 *    Replacements for fseeko() and ftello().
 *
 * Portions Copyright (c) 1996-2025, PostgreSQL Global Development Group
 *
 * IDENTIFICATION
 *    src/port/win32fseek.c
 *
 *-------------------------------------------------------------------------
 */
 
#ifdef FRONTEND
#include "postgres_fe.h"
#else
#include "postgres.h"
#endif
 
#ifdef _MSC_VER
 
/*
 * _pgfseeko64
 *
 * Calling fseek() on a handle to a non-seeking device such as a pipe or
 * a communications device is not supported, and fseek() may not return
 * an error.  This wrapper relies on the file type to check which cases
 * are supported.
 */
int
_pgfseeko64(FILE *stream, pgoff_t offset, int origin)
{
    DWORD       fileType;
    HANDLE      hFile = (HANDLE) _get_osfhandle(_fileno(stream));
 
    fileType = pgwin32_get_file_type(hFile);
    if (errno != 0)
        return -1;
 
    if (fileType == FILE_TYPE_DISK)
        return _fseeki64(stream, offset, origin);
    else if (fileType == FILE_TYPE_CHAR || fileType == FILE_TYPE_PIPE)
        errno = ESPIPE;
    else
        errno = EINVAL;
 
    return -1;
}
 
/*
 * _pgftello64
 *
 * Same as _pgfseeko64().
 */
pgoff_t
_pgftello64(FILE *stream)
{
    DWORD       fileType;
    HANDLE      hFile = (HANDLE) _get_osfhandle(_fileno(stream));
 
    fileType = pgwin32_get_file_type(hFile);
    if (errno != 0)
        return -1;
 
    if (fileType == FILE_TYPE_DISK)
        return _ftelli64(stream);
    else if (fileType == FILE_TYPE_CHAR || fileType == FILE_TYPE_PIPE)
        errno = ESPIPE;
    else
        errno = EINVAL;
 
    return -1;
}
 
#endif                          /* _MSC_VER */