295 lines
9.3 KiB
C
295 lines
9.3 KiB
C
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/***
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*dup2.c - Duplicate file handles
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*
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* Copyright (c) 1989-2001, Microsoft Corporation. All rights reserved.
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*
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*Purpose:
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* defines _dup2() - duplicate file handles
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*
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*Revision History:
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* 06-09-89 PHG Module created, based on asm version
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* 03-12-90 GJF Made calling type _CALLTYPE2 (for now), added #include
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* <cruntime.h> and fixed the copyright. Also, cleaned up
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* the formatting a bit.
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* 04-03-90 GJF Now _CALLTYPE1.
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* 07-24-90 SBM Removed '32' from API names
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* 08-14-90 SBM Compiles cleanly with -W3
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* 09-28-90 GJF New-style function declarator.
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* 12-04-90 GJF Appended Win32 version onto the source with #ifdef-s.
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* It is enough different that there is little point in
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* trying to more closely merge the two versions.
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* 12-04-90 SRW Changed to include <oscalls.h> instead of <doscalls.h>
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* 12-06-90 SRW Changed to use _osfile and _osfhnd instead of _osfinfo
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* 01-16-91 GJF ANSI naming.
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* 02-07-91 SRW Changed to call _get_osfhandle [_WIN32_]
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* 02-18-91 SRW Changed to call _free_osfhnd [_WIN32_]
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* 02-25-91 SRW Renamed _get_free_osfhnd to be _alloc_osfhnd [_WIN32_]
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* 02-13-92 GJF Replaced _nfile by _nhandle for Win32.
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* 09-04-92 GJF Check for unopened fh1 and gracefully handle fh1 ==
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* fh2.
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* 04-06-93 SKS Replace _CRTAPI* with __cdecl
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* 09-06-94 CFW Remove Cruiser support.
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* 09-06-94 CFW Replace MTHREAD with _MT.
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* 12-03-94 SKS Clean up OS/2 references
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* 01-04-95 GJF _WIN32_ -> _WIN32
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* 02-15-95 GJF Appended Mac version of source file (somewhat cleaned
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* up), with appropriate #ifdef-s.
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* 06-11-95 GJF Replaced _osfile[] with _osfile() (macro referencing
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* field in ioinfo struct).
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* 06-26-95 GJF Added support to grow the ioinfo arrays in order to
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* ensure an ioinfo struct exists for fh2.
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* 05-16-96 GJF Clear FNOINHERIT (new) bit on _osfile. Also, detab-ed.
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* 07-08-96 GJF Replaced defined(_WIN32) with !defined(_MAC), and
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* defined(_M_M68K) || defined(_M_MPPC) with
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* defined(_MAC). Removed DLL_FOR_WIN32S. Also, cleaned
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* up the format a bit.
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* 12-17-97 GJF Exception-safe locking.
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* 02-07-98 GJF Changes for Win64: use intptr_t for anything holding
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* a HANDLE value.
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* 05-17-99 PML Remove all Macintosh support.
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*
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*******************************************************************************/
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#include <cruntime.h>
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#include <io.h>
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#include <oscalls.h>
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#include <msdos.h>
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#include <mtdll.h>
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#include <errno.h>
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#include <stdlib.h>
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#include <internal.h>
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#include <malloc.h>
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#include <dbgint.h>
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static int __cdecl extend_ioinfo_arrays(int);
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#ifdef _MT
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static int __cdecl _dup2_lk(int, int);
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#endif
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/***
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*int _dup2(fh1, fh2) - force handle 2 to refer to handle 1
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*
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*Purpose:
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* Forces file handle 2 to refer to the same file as file
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* handle 1. If file handle 2 referred to an open file, that file
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* is closed.
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*
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* Multi-thread: We must hold 2 lowio locks at the same time
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* to ensure multi-thread integrity. In order to prevent deadlock,
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* we always get the lower file handle lock first. Order of unlocking
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* does not matter. If you modify this routine, make sure you don't
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* cause any deadlocks! Scary stuff, kids!!
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*
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*Entry:
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* int fh1 - file handle to duplicate
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* int fh2 - file handle to assign to file handle 1
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*
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*Exit:
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* returns 0 if successful, -1 (and sets errno) if fails.
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*
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*Exceptions:
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*
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*******************************************************************************/
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int __cdecl _dup2 (
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int fh1,
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int fh2
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)
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{
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#ifdef _MT
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int retcode;
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#else
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ULONG dosretval; /* o.s. return code */
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intptr_t new_osfhandle;
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#endif
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/* validate file handles */
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if ( ((unsigned)fh1 >= (unsigned)_nhandle) ||
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!(_osfile(fh1) & FOPEN) ||
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((unsigned)fh2 >= _NHANDLE_) )
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{
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/* handle out of range */
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errno = EBADF;
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_doserrno = 0; /* not an OS error */
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return -1;
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}
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/*
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* Make sure there is an ioinfo struct corresponding to fh2.
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*/
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if ( (fh2 >= _nhandle) && (extend_ioinfo_arrays(fh2) != 0) ) {
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errno = ENOMEM;
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return -1;
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}
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#ifdef _MT
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/* get the two file handle locks; in order to prevent deadlock,
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get the lowest handle lock first. */
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if ( fh1 < fh2 ) {
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_lock_fh(fh1);
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_lock_fh(fh2);
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}
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else if ( fh1 > fh2 ) {
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_lock_fh(fh2);
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_lock_fh(fh1);
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}
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__try {
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retcode = _dup2_lk(fh1, fh2);
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}
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__finally {
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_unlock_fh(fh1);
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_unlock_fh(fh2);
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}
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return retcode;
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}
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static int __cdecl _dup2_lk (
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int fh1,
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int fh2
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)
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{
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ULONG dosretval; /* o.s. return code */
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intptr_t new_osfhandle;
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/*
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* Re-test and take care of case of unopened source handle. This is
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* necessary only in the multi-thread case where the file have been
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* closed by another thread before the lock was asserted, but after
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* the initial test above.
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*/
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if ( !(_osfile(fh1) & FOPEN) ) {
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/*
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* Source handle isn't open, bail out with an error.
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* Note that the DuplicateHandle API will not detect this
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* error since it implies that _osfhnd(fh1) ==
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* INVALID_HANDLE_VALUE, and this is a legal HANDLE value
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* (it's the HANDLE for the current process).
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*/
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errno = EBADF;
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_doserrno = 0; /* not an OS error */
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return -1;
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}
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#endif /* _MT */
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/*
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* Take of the case of equal handles.
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*/
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if ( fh1 == fh2 )
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/*
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* Since fh1 is known to be open, return 0 indicating success.
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* This is in conformance with the POSIX specification for
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* dup2.
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*/
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return 0;
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/*
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* if fh2 is open, close it.
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*/
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if ( _osfile(fh2) & FOPEN )
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/*
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* close the handle. ignore the possibility of an error - an
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* error simply means that an OS handle value may remain bound
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* for the duration of the process. Use _close_lk as we
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* already own lock
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*/
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(void) _close_lk(fh2);
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/* Duplicate source file onto target file */
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if ( !(DuplicateHandle(GetCurrentProcess(),
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(HANDLE)_get_osfhandle(fh1),
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GetCurrentProcess(),
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(PHANDLE)&new_osfhandle,
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0L,
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TRUE,
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DUPLICATE_SAME_ACCESS)) )
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{
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dosretval = GetLastError();
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}
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else {
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_set_osfhnd(fh2, new_osfhandle);
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dosretval = 0;
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}
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if (dosretval) {
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_dosmaperr(dosretval);
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return -1;
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}
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/* copy the _osfile information, with the FNOINHERIT bit cleared */
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_osfile(fh2) = _osfile(fh1) & ~FNOINHERIT;
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return 0;
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}
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/***
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*static int extend_ioinfo_arrays( int fh ) - extend ioinfo arrays to fh
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*
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*Purpose:
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* Allocate and initialize arrays of ioinfo structs,filling in
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* __pioinfo[],until there is an ioinfo struct corresponding to fh.
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*
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* Note: It is assumed the fh < _NHANDLE_!
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*
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*Entry:
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* int fh - C file handle corresponding to ioinfo
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*
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*Exit:
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* returns 0 if successful, -1
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*
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*Exceptions:
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*
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*******************************************************************************/
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static int __cdecl extend_ioinfo_arrays(
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int fh
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)
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{
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ioinfo *pio;
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int i;
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/*
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* Walk __pioinfo[], allocating an array of ioinfo structs for each
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* empty entry, until there is an ioinfo struct corresponding to fh.
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*/
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for ( i = 0 ; fh >= _nhandle ; i++ ) {
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if ( __pioinfo[i] == NULL ) {
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if ( (pio = _malloc_crt( IOINFO_ARRAY_ELTS * sizeof(ioinfo) ))
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!= NULL )
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{
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__pioinfo[i] = pio;
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_nhandle += IOINFO_ARRAY_ELTS;
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for ( ; pio < __pioinfo[i] + IOINFO_ARRAY_ELTS ; pio++ ) {
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pio->osfile = 0;
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pio->osfhnd = (intptr_t)INVALID_HANDLE_VALUE;
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pio->pipech = 10;
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#ifdef _MT
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pio->lockinitflag = 0;
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#endif
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}
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}
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else {
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/*
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* Couldn't allocate another array, return failure.
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*/
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return -1;
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}
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}
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}
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return 0;
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}
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