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117 lines
2.1 KiB
C
117 lines
2.1 KiB
C
/* $Id: read.c,v 1.2 2002/03/21 22:46:30 hyperion Exp $
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*/
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/*
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* COPYRIGHT: See COPYING in the top level directory
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* PROJECT: ReactOS POSIX+ Subsystem
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* FILE: subsys/psx/lib/psxdll/unistd/read.c
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* PURPOSE: Read from a file
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* PROGRAMMER: KJK::Hyperion <noog@libero.it>
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* UPDATE HISTORY:
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* 15/02/2002: Created
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*/
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#include <ddk/ntddk.h>
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#include <fcntl.h>
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#include <unistd.h>
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#include <sys/types.h>
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#include <psx/debug.h>
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#include <psx/errno.h>
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ssize_t __read(int fildes, void *buf, size_t nbyte, off_t *offset)
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{
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HANDLE hFile;
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NTSTATUS nErrCode;
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IO_STATUS_BLOCK isbStatus;
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/* get the file handle for the specified file descriptor */
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if(fcntl(fildes, F_GETFH, &hFile) == -1)
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return (-1);
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if(offset != NULL)
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{
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/* NT always moves the file pointer, while Unix pread() must not: we have to
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duplicate the handle and work on the duplicate */ /* FIXME? better save
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the file position and restore it later? */
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HANDLE hDupFile;
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/* duplicate the handle */
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nErrCode = NtDuplicateObject
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(
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NtCurrentProcess(),
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hFile,
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NtCurrentProcess(),
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&hDupFile,
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0,
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0,
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DUPLICATE_SAME_ACCESS
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);
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/* failure */
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if(!NT_SUCCESS(nErrCode))
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{
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errno = __status_to_errno(nErrCode);
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return (0);
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}
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/* read data from file at the specified offset */
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nErrCode = NtReadFile
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(
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hDupFile,
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NULL,
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NULL,
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NULL,
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&isbStatus,
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buf,
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nbyte,
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(PLARGE_INTEGER)offset,
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NULL
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);
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NtClose(hDupFile);
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/* failure */
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if(!NT_SUCCESS(nErrCode))
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{
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errno = __status_to_errno(nErrCode);
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return (0);
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}
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}
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else
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{
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/* read data from file at the current offset */
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nErrCode = NtReadFile
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(
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hFile,
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NULL,
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NULL,
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NULL,
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&isbStatus,
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buf,
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nbyte,
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NULL,
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NULL
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);
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/* failure */
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if(!NT_SUCCESS(nErrCode))
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{
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errno = __status_to_errno(nErrCode);
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return (0);
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}
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}
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return ((ssize_t)isbStatus.Information);
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}
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ssize_t read(int fildes, void *buf, size_t nbyte)
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{
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return (__read(fildes, buf, nbyte, NULL));
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}
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ssize_t pread(int fildes, void *buf, size_t nbyte, off_t offset)
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{
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return (__read(fildes, buf, nbyte, &offset));
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}
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/* EOF */
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