reactos/posix/lib/psxdll/unistd/read.c

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/* $Id: read.c,v 1.4 2002/10/29 04:45:48 rex Exp $
*/
/*
* COPYRIGHT: See COPYING in the top level directory
* PROJECT: ReactOS POSIX+ Subsystem
* FILE: subsys/psx/lib/psxdll/unistd/read.c
* PURPOSE: Read from a file
* PROGRAMMER: KJK::Hyperion <noog@libero.it>
* UPDATE HISTORY:
* 15/02/2002: Created
*/
#include <ddk/ntddk.h>
#include <fcntl.h>
#include <unistd.h>
#include <sys/types.h>
#include <psx/debug.h>
#include <psx/errno.h>
ssize_t __read(int fildes, void *buf, size_t nbyte, off_t *offset)
{
HANDLE hFile;
NTSTATUS nErrCode;
IO_STATUS_BLOCK isbStatus;
/* get the file handle for the specified file descriptor */
if(fcntl(fildes, F_GETFH, &hFile) == -1)
return (-1);
if(offset != NULL)
{
/* NT always moves the file pointer, while Unix pread() must not: we have to
duplicate the handle and work on the duplicate */ /* FIXME? better save
the file position and restore it later? */
HANDLE hDupFile;
/* duplicate the handle */
nErrCode = NtDuplicateObject
(
NtCurrentProcess(),
hFile,
NtCurrentProcess(),
&hDupFile,
0,
0,
DUPLICATE_SAME_ACCESS
);
/* failure */
if(!NT_SUCCESS(nErrCode))
{
errno = __status_to_errno(nErrCode);
return (0);
}
/* read data from file at the specified offset */
nErrCode = NtReadFile
(
hDupFile,
NULL,
NULL,
NULL,
&isbStatus,
buf,
nbyte,
(PLARGE_INTEGER)offset,
NULL
);
NtClose(hDupFile);
/* failure */
if(!NT_SUCCESS(nErrCode))
{
errno = __status_to_errno(nErrCode);
return (0);
}
}
else
{
/* read data from file at the current offset */
nErrCode = NtReadFile
(
hFile,
NULL,
NULL,
NULL,
&isbStatus,
buf,
nbyte,
NULL,
NULL
);
/* failure */
if(!NT_SUCCESS(nErrCode))
{
errno = __status_to_errno(nErrCode);
return (0);
}
}
return ((ssize_t)isbStatus.Information);
}
ssize_t read(int fildes, void *buf, size_t nbyte)
{
return (__read(fildes, buf, nbyte, NULL));
}
ssize_t pread(int fildes, void *buf, size_t nbyte, off_t offset)
{
return (__read(fildes, buf, nbyte, &offset));
}
/* EOF */