184 lines
5.9 KiB
C
184 lines
5.9 KiB
C
/***
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*dup.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 _dup() - 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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* 09-03-92 GJF Added explicit check for unopened handles [_WIN32_].
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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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* 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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* 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). Also, cleaned 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 <oscalls.h>
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#include <errno.h>
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#include <mtdll.h>
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#include <io.h>
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#include <msdos.h>
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#include <internal.h>
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#include <stdlib.h>
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#ifdef _MT
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static int __cdecl _dup_lk(int);
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#endif
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/***
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*int _dup(fh) - duplicate a file handle
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*
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*Purpose:
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* Assigns another file handle to the file associated with the
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* handle fh. The next available file handle is assigned.
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*
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* Multi-thread: Be sure not to hold two file handle locks
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* at the same time!
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*
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*Entry:
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* int fh - file handle to duplicate
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*
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*Exit:
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* returns new file handle if successful
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* returns -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 _dup (
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int fh
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)
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{
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int newfh; /* variable for new file handle */
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#ifndef _MT
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ULONG dosretval; /* o.s. return value */
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char fileinfo; /* _osfile info for file */
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intptr_t new_osfhandle;
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#endif /* _MT */
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/* validate file handle */
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if ( ((unsigned)fh >= (unsigned)_nhandle) ||
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!(_osfile(fh) & FOPEN) )
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{
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errno = EBADF;
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_doserrno = 0; /* no o.s. error */
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return -1;
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}
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#ifndef _MT
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fileinfo = _osfile(fh); /* get file info for file */
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#endif
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#ifdef _MT
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_lock_fh(fh); /* lock file handle */
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__try {
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if ( _osfile(fh) & FOPEN )
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newfh = _dup_lk(fh);
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else {
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errno = EBADF;
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_doserrno = 0;
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newfh = -1;
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}
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}
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__finally {
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if ( newfh != -1 )
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_unlock_fh(newfh);
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_unlock_fh(fh);
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}
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return newfh;
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}
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static int __cdecl _dup_lk(
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int fh
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)
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{
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int newfh; /* variable for new file handle */
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ULONG dosretval; /* o.s. return value */
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char fileinfo; /* _osfile info for file */
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intptr_t new_osfhandle;
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fileinfo = _osfile(fh); /* get file info for file */
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if ( !(_osfile(fh) & FOPEN) )
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return -1;
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#endif /* _MT */
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/* create duplicate handle */
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if ( (newfh = _alloc_osfhnd()) == -1 )
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{
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errno = EMFILE; /* too many files error */
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_doserrno = 0L; /* not an OS error */
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_unlock_fh(fh);
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return -1; /* return error to caller */
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}
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/*
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* duplicate the file handle
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*/
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if ( !(DuplicateHandle(GetCurrentProcess(),
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(HANDLE)_get_osfhandle(fh),
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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(newfh, new_osfhandle);
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dosretval = 0;
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}
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if (dosretval) {
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/* o.s. error -- map and return */
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_dosmaperr(dosretval);
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return -1;
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}
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/*
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* copy the _osfile value, with the FNOINHERIT bit cleared
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*/
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_osfile(newfh) = fileinfo & ~FNOINHERIT;
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return newfh;
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}
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