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/***
*chsize.c - change size of a file** Copyright (c) 1985-2001, Microsoft Corporation. All rights reserved.**Purpose:* contains the _chsize() function - changes the size of a file.**Revision History:* 03-13-84 RN initial version* 05-17-86 SKS ported to OS/2* 07-07-87 JCR Added (_doserrno == 5) check that is in DOS 3.2 version* 10-29-87 JCR Multi-thread support; also, re-wrote for efficiency* 12-11-87 JCR Added "_LOAD_DS" to declaration* 05-25-88 PHG Merged DLL and normal versions* 10-03-88 GJF Changed DOSNEWSIZE to SYSNEWSIZE* 10-10-88 GJF Made API names match DOSCALLS.H* 04-13-89 JCR New syscall interface* 05-25-89 JCR 386 OS/2 calls use '_syscall' calling convention* 03-12-90 GJF Replaced _LOAD_DS with _CALLTYPE1, added #include* <cruntime.h>, removed #include <register.h> and fixed* the copyright. Also, cleaned up the formatting a bit.* 04-04-90 GJF Added #include <string.h>, removed #include <dos.h>.* 05-21-90 GJF Fixed stack checking pragma syntax.* 07-24-90 SBM Replaced <assertm.h> by <assert.h>, removed '32'* from API names* 09-28-90 GJF New-style function declarator.* 12-03-90 GJF Appended Win32 version of the function. It is based* on the Cruiser version and probably could be merged* in later (much later).* 12-04-90 SRW Changed to include <oscalls.h> instead of <doscalls.h>* 12-06-90 SRW Changed to use _osfile and _osfhnd instead of _osfinfo* 12-28-90 SRW Added _CRUISER_ conditional around check_stack pragma* 01-16-91 GJF ANSI naming. Also, fixed _chsize_lk parameter decls.* 02-07-91 SRW Changed to call _get_osfhandle [_WIN32_]* 04-09-91 PNT Added _MAC_ conditional* 02-13-92 GJF Replaced _nfile by _nhandle for Win32.* 05-01-92 GJF Fixed embarrassing bug (didn't work for Win32)!* 04-06-93 SKS Replace _CRTAPI* with __cdecl* 05-11-93 GJF Replaced BUFSIZ with _INTERNAL_BUFSIZ.* 09-06-94 CFW Remove Cruiser support.* 09-06-94 CFW Replace MTHREAD with _MT.* 01-07-95 CFW Mac merge.* 02-06-95 CFW assert -> _ASSERTE.* 06-27-95 GJF Added check that the file handle is open.* 07-03-96 GJF Replaced defined(_WIN32) with !defined(_MAC), and* defined(_M_M68K) || defined(_M_MPPC) with * defined(_MAC). Also, detab-ed and cleaned up the * format a bit.* 12-17-97 GJF Exception-safe locking.* 05-17-99 PML Remove all Macintosh support.* 06-25-01 BWT Alloc blank buffer off the heap instead of the stack (ntbug: 423988)********************************************************************************/
#include <cruntime.h>
#include <errno.h>
#include <stdlib.h>
#include <stdio.h>
#include <dbgint.h>
#include <fcntl.h>
#include <msdos.h>
#include <io.h>
#include <string.h>
#include <windows.h>
#include <internal.h>
#include <mtdll.h>
/***
*int _chsize(filedes, size) - change size of a file**Purpose:* Change file size. Assume file is open for writing, or we can't do it.* The DOS way to do this is to go to the right spot and write 0 bytes. The* Xenix way to do this is to make a system call. We write '\0' bytes because* DOS won't do this for you if you lseek beyond eof, though Xenix will.**Entry:* int filedes - file handle to change size of* long size - new size of file**Exit:* return 0 if successful* returns -1 and sets errno if fails**Exceptions:********************************************************************************/
#ifdef _MT
/* define normal version that locks/unlocks, validates fh */
int __cdecl _chsize ( REG1 int filedes, long size ){ int r; /* return value */
if ( ((unsigned)filedes >= (unsigned)_nhandle) || !(_osfile(filedes) & FOPEN) ) { errno = EBADF; return(-1); }
_lock_fh(filedes);
__try { if ( _osfile(filedes) & FOPEN ) r = _chsize_lk(filedes,size); else { errno = EBADF; r = -1; } } __finally { _unlock_fh(filedes); }
return r;}
/* now define version that doesn't lock/unlock, validate fh */int __cdecl _chsize_lk ( REG1 int filedes, long size ){ long filend; long extend; long place; int cnt; int oldmode; int retval = 0; /* assume good return */
#else
/* now define normal version */
int __cdecl _chsize ( REG1 int filedes, long size ){ long filend; long extend; long place; int cnt; int oldmode; int retval = 0; /* assume good return */
if ( ((unsigned)filedes >= (unsigned)_nhandle) || !(_osfile(filedes) & FOPEN) ) { errno = EBADF; return(-1); }
#endif
_ASSERTE(size >= 0);
/* Get current file position and seek to end */ if ( ((place = _lseek_lk(filedes, 0L, SEEK_CUR)) == -1L) || ((filend = _lseek_lk(filedes, 0L, SEEK_END)) == -1L) ) return -1;
extend = size - filend;
/* Grow or shrink the file as necessary */
if (extend > 0L) {
/* extending the file */ char *bl = HeapAlloc(GetProcessHeap(), HEAP_ZERO_MEMORY, _INTERNAL_BUFSIZ);
if (!bl) { errno = ENOMEM; retval= -1; } else { oldmode = _setmode_lk(filedes, _O_BINARY); /* pad out with nulls */ do { cnt = (extend >= (long)_INTERNAL_BUFSIZ ) ? _INTERNAL_BUFSIZ : (int)extend; if ( (cnt = _write_lk( filedes, bl, (extend >= (long)_INTERNAL_BUFSIZ) ? _INTERNAL_BUFSIZ : (int)extend )) == -1 ) { /* Error on write */ if (_doserrno == ERROR_ACCESS_DENIED) errno = EACCES; retval = cnt; break; /* leave write loop */ } } while ((extend -= (long)cnt) > 0L); _setmode_lk(filedes, oldmode);
HeapFree(GetProcessHeap(), 0, bl); }
/* retval set correctly */ }
else if ( extend < 0L ) { /* shortening the file */
/*
* Set file pointer to new eof...and truncate it there. */ _lseek_lk(filedes, size, SEEK_SET);
if ( (retval = SetEndOfFile((HANDLE)_get_osfhandle(filedes)) ? 0 : -1) == -1 ) { errno = EACCES; _doserrno = GetLastError(); } }
/* else */ /* no file change needed */ /* retval = 0; */
/* Common return code */
_lseek_lk(filedes, place, SEEK_SET); return retval;}
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