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/***
*write.c - write to a file handle** Copyright (c) 1989-2001, Microsoft Corporation. All rights reserved.**Purpose:* defines _write() - write to a file handle**Revision History:* 06-14-89 PHG Module created, based on asm version* 03-13-90 GJF Made calling type _CALLTYPE2 (for now), added #include* <cruntime.h>, fixed compiler warnings and fixed the* copyright. Also, cleaned up the formatting a bit.* 04-03-90 GJF Now _CALLTYPE1.* 07-24-90 SBM Removed '32' from API names* 08-14-90 SBM Compiles cleanly with -W3* 10-01-90 GJF New-style function declarators.* 12-04-90 GJF Appended Win32 version onto source with #ifdef-s.* Should come back latter and do a better merge.* 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* 12-28-90 SRW Added cast of void * to char * for Mips C Compiler* 01-17-91 GJF ANSI naming.* 02-25-91 MHL Adapt to ReadFile/WriteFile changes (_WIN32_)* 04-09-91 PNT Added _MAC_ conditional* 07-18-91 GJF Removed unreferenced local variable from _write_lk* routine [_WIN32_].* 10-24-91 GJF Added LPDWORD casts to make MIPS compiler happy.* ASSUMES THAT sizeof(int) == sizeof(DWORD).* 02-13-92 GJF Replaced _nfile by _nhandle for Win32.* 02-15-92 GJF Increased BUF_SIZE and simplified LF translation code* for Win32.* 04-06-93 SKS Replace _CRTAPI* with __cdecl* 09-06-94 CFW Remove Cruiser support.* 09-06-94 CFW Replace MTHREAD with _MT.* 12-03-94 SKS Clean up OS/2 references* 01-04-95 GJF _WIN32_ -> _WIN32* 02-15-95 GJF Appended Mac version of source file (somewhat cleaned* up), with appropriate #ifdef-s.* 06-12-95 GJF Changed _osfile[] and _osfhnd[] to _osfile() and* _osfhnd(), which reference __pioinfo[].* 06-27-95 GJF Added check that the file handle is open.* 07-09-96 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.* 12-30-97 GJF Exception-safe locking.* 03-03-98 RKP Forced number of bytes written to always be an int* 05-17-99 PML Remove all Macintosh support.* 11-10-99 GB Replaced lseek for lseeki64 so as to able to append* files longer than 4GB********************************************************************************/
#include <cruntime.h>
#include <oscalls.h>
#include <io.h>
#include <errno.h>
#include <msdos.h>
#include <mtdll.h>
#include <stdlib.h>
#include <string.h>
#include <internal.h>
#define BUF_SIZE 1025 /* size of LF translation buffer */
#define LF '\n' /* line feed */
#define CR '\r' /* carriage return */
#define CTRLZ 26 /* ctrl-z */
/***
*int _write(fh, buf, cnt) - write bytes to a file handle**Purpose:* Writes count bytes from the buffer to the handle specified.* If the file was opened in text mode, each LF is translated to* CR-LF. This does not affect the return value. In text* mode ^Z indicates end of file.** Multi-thread notes:* (1) _write() - Locks/unlocks file handle* _write_lk() - Does NOT lock/unlock file handle**Entry:* int fh - file handle to write to* char *buf - buffer to write from* unsigned int cnt - number of bytes to write**Exit:* returns number of bytes actually written.* This may be less than cnt, for example, if out of disk space.* returns -1 (and set errno) if fails.**Exceptions:********************************************************************************/
#ifdef _MT
/* define normal version that locks/unlocks, validates fh */int __cdecl _write ( int fh, const void *buf, unsigned cnt ){ int r; /* return value */
/* validate handle */ if ( ((unsigned)fh >= (unsigned)_nhandle) || !(_osfile(fh) & FOPEN) ) { /* out of range -- return error */ errno = EBADF; _doserrno = 0; /* not o.s. error */ return -1; }
_lock_fh(fh); /* lock file */
__try { if ( _osfile(fh) & FOPEN ) r = _write_lk(fh, buf, cnt); /* write bytes */ else { errno = EBADF; _doserrno = 0; /* not o.s. error */ r = -1; } } __finally { _unlock_fh(fh); /* unlock file */ }
return r;}
/* now define version that doesn't lock/unlock, validate fh */int __cdecl _write_lk ( int fh, const void *buf, unsigned cnt ){ int lfcount; /* count of line feeds */ int charcount; /* count of chars written so far */ int written; /* count of chars written on this write */ ULONG dosretval; /* o.s. return value */ char ch; /* current character */ char *p, *q; /* pointers into buf and lfbuf resp. */ char lfbuf[BUF_SIZE]; /* lf translation buffer */
#else
/* now define normal version */int __cdecl _write ( int fh, const void *buf, unsigned cnt ){ int lfcount; /* count of line feeds */ int charcount; /* count of chars written so far */ int written; /* count of chars written on this write */ ULONG dosretval; /* o.s. return value */ char ch; /* current character */ char *p, *q; /* pointers into buf and lfbuf resp. */ char lfbuf[BUF_SIZE]; /* lf translation buffer */
/* validate handle */ if ( ((unsigned)fh >= (unsigned)_nhandle) || !(_osfile(fh) & FOPEN) ) { /* out of range -- return error */ errno = EBADF; _doserrno = 0; /* not o.s. error */ return -1; }
#endif
lfcount = charcount = 0; /* nothing written yet */
if (cnt == 0) return 0; /* nothing to do */
if (_osfile(fh) & FAPPEND) { /* appending - seek to end of file; ignore error, because maybe
file doesn't allow seeking */#if _INTEGRAL_MAX_BITS >= 64 /*IFSTRIP=IGN*/
(void)_lseeki64_lk(fh, 0, FILE_END);#else
(void)_lseek_lk(fh, 0, FILE_END);#endif
}
/* check for text mode with LF's in the buffer */
if ( _osfile(fh) & FTEXT ) { /* text mode, translate LF's to CR/LF's on output */
p = (char *)buf; /* start at beginning of buffer */ dosretval = 0; /* no OS error yet */
while ( (unsigned)(p - (char *)buf) < cnt ) { q = lfbuf; /* start at beginning of lfbuf */
/* fill the lf buf, except maybe last char */ while ( q - lfbuf < BUF_SIZE - 1 && (unsigned)(p - (char *)buf) < cnt ) { ch = *p++; if ( ch == LF ) { ++lfcount; *q++ = CR; } *q++ = ch; }
/* write the lf buf and update total */ if ( WriteFile( (HANDLE)_osfhnd(fh), lfbuf, (int)(q - lfbuf), (LPDWORD)&written, NULL) ) { charcount += written; if (written < q - lfbuf) break; } else { dosretval = GetLastError(); break; } } } else { /* binary mode, no translation */ if ( WriteFile( (HANDLE)_osfhnd(fh), (LPVOID)buf, cnt, (LPDWORD)&written, NULL) ) { dosretval = 0; charcount = written; } else dosretval = GetLastError(); }
if (charcount == 0) { /* If nothing was written, first check if an o.s. error,
otherwise we return -1 and set errno to ENOSPC, unless a device and first char was CTRL-Z */ if (dosretval != 0) { /* o.s. error happened, map error */ if (dosretval == ERROR_ACCESS_DENIED) { /* wrong read/write mode should return EBADF, not
EACCES */ errno = EBADF; _doserrno = dosretval; } else _dosmaperr(dosretval); return -1; } else if ((_osfile(fh) & FDEV) && *(char *)buf == CTRLZ) return 0; else { errno = ENOSPC; _doserrno = 0; /* no o.s. error */ return -1; } } else /* return adjusted bytes written */ return charcount - lfcount;}
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