204 lines
6.9 KiB
C
204 lines
6.9 KiB
C
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/***
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*setvbuf.c - set buffer size for a stream
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*
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* Copyright (c) 1985-2001, Microsoft Corporation. All rights reserved.
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*
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*Purpose:
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* defines setvbuf() - set the buffering mode and size for a stream.
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*
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*Revision History:
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* 09-19-83 RN initial version
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* 06-26-85 TC modified to allow user defined buffers of various sizes
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* 06-24-86 DFW kludged to fix incompatability with Xenix values of
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* _IOFBF, _IOLBF
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* 02-09-87 JCR added "buffer=&(_iob2[fileno(stream)]._charbuf);"
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* to handle _IONBF case
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* 02-25-87 JCR added support for default buffer and IBMC20-condition
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* code
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* 04-13-87 JCR changed type of szie from int to size_t (unsigned int)
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* and changed a related comparison
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* 06-29-87 JCR Took out the _OLD_IOFBF/_OLD_IOLBF kludge for MSC.
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* Should be taken out for IBM too...
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* 09-28-87 JCR Corrected _iob2 indexing (now uses _iob_index() macro).
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* 11-02-87 JCR Multi-thread support
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* 12-11-87 JCR Added "_LOAD_DS" to declaration
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* 05-27-88 PHG Merged DLL and normal versions
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* 06-06-88 JCR Optimized _iob2 references
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* 06-14-88 JCR Use near pointer to reference _iob[] entries
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* 08-09-88 JCR Buffer size can't be greater than INT_MAX
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* 08-25-88 GJF Don't use FP_OFF() macro for the 386
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* 08-18-89 GJF Clean up, now specific to OS/2 2.0 (i.e., 386 flat
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* model). Also fixed copyright and indents.
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* 02-15-90 GJF _iob[], _iob2[] merge. Also, cleanup, a little tuning
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* and fixed copyright.
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* 03-19-90 GJF Made calling type _CALLTYPE1, added #include
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* <cruntime.h> and removed #include <register.h>.
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* 05-29-90 SBM Use _flush, not [_]fflush[_lk]
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* 07-23-90 SBM Replaced <assertm.h> by <assert.h>
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* 10-03-90 GJF New-style function declarator.
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* 04-06-93 SKS Replace _CRTAPI* with __cdecl
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* 04-27-93 CFW Change _IONBF size to 2 bytes to hold wide char.
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* 06-22-93 GJF Set _IOSETVBUF (new) to indicate user-specified
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* buffering (in addition to setting _IOYOURBUF or
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* _IOMYBUF).
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* 11-12-93 GJF Return failure if size == 1 (instead of putting
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* 0 into stream->_bufsiz, preventing any i/o)
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* 04-05-94 GJF #ifdef-ed out _cflush reference for msvcrt*.dll, it
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* is unnecessary.
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* 01-10-95 CFW Debug CRT allocs.
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* 02-06-94 CFW assert -> _ASSERTE.
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* 02-20-95 GJF Merged in Mac version.
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* 03-07-95 GJF _[un]lock_str macros now take FILE * arg.
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* 03-02-98 GJF Exception-safe locking.
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* 01-04-99 GJF Changes for 64-bit size_t.
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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 <stdio.h>
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#include <file2.h>
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#include <malloc.h>
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#include <internal.h>
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#include <mtdll.h>
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#include <limits.h>
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#include <dbgint.h>
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/***
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*int setvbuf(stream, buffer, type, size) - set buffering for a file
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*
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*Purpose:
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* Controls buffering and buffer size for the specified stream. The
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* array pointed to by buf is used as a buffer, unless NULL, in which
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* case we'll allocate a buffer automatically. type specifies the type
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* of buffering: _IONBF = no buffer, _IOFBF = buffered, _IOLBF = same
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* as _IOFBF.
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*
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*Entry:
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* FILE *stream - stream to control buffer on
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* char *buffer - pointer to buffer to use (NULL means auto allocate)
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* int type - type of buffering (_IONBF, _IOFBF or _IOLBF)
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* size_t size - size of buffer
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*
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*Exit:
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* return 0 if successful
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* returns non-zero 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 setvbuf (
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FILE *str,
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char *buffer,
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int type,
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size_t size
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)
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{
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REG1 FILE *stream;
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int retval=0; /* assume good return */
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_ASSERTE(str != NULL);
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/*
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* (1) Make sure type is one of the three legal values.
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* (2) If we are buffering, make sure size is greater than 0.
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*/
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if ( (type != _IONBF) && ((size < 2) || (size > INT_MAX) ||
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((type != _IOFBF) && (type != _IOLBF))) )
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return(-1);
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/*
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* force size to be even by masking down to the nearest multiple
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* of 2
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*/
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size &= (size_t)~1;
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/*
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* Init stream pointers
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*/
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stream = str;
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#ifdef _MT
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/*
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* Lock the file
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*/
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_lock_str(stream);
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__try {
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#endif
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/*
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* Flush the current buffer and free it, if it is ours.
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*/
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_flush(stream);
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_freebuf(stream);
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/*
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* Clear a bunch of bits in stream->_flag (all bits related to
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* buffering and those which used to be in stream2->_flag2). Most
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* of these should never be set when setvbuf() is called, but it
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* doesn't cost anything to be safe.
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*/
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stream->_flag &= ~(_IOMYBUF | _IOYOURBUF | _IONBF |
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_IOSETVBUF | _IOFEOF | _IOFLRTN | _IOCTRLZ);
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/*
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* CASE 1: No Buffering.
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*/
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if (type & _IONBF) {
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stream->_flag |= _IONBF;
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buffer = (char *)&(stream->_charbuf);
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size = 2;
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}
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/*
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* NOTE: Cases 2 and 3 (below) cover type == _IOFBF or type == _IOLBF
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* Line buffering is treated as the same as full buffering, so the
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* _IOLBF bit in stream->_flag is never set. Finally, since _IOFBF is
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* defined to be 0, full buffering is simply assumed whenever _IONBF
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* is not set.
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*/
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/*
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* CASE 2: Default Buffering -- Allocate a buffer for the user.
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*/
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else if ( buffer == NULL ) {
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if ( (buffer = _malloc_crt(size)) == NULL ) {
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#ifndef CRTDLL
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/*
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* force library pre-termination procedure (placed here
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* because the code path should almost never be hit)
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*/
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_cflush++;
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#endif /* CRTDLL */
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retval = -1;
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goto done;
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}
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stream->_flag |= _IOMYBUF | _IOSETVBUF;
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}
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/*
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* CASE 3: User Buffering -- Use the buffer supplied by the user.
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*/
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else {
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stream->_flag |= _IOYOURBUF | _IOSETVBUF;
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}
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/*
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* Common return for all cases.
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*/
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stream->_bufsiz = (int)size;
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stream->_ptr = stream->_base = buffer;
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stream->_cnt = 0;
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done:
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#ifdef _MT
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; }
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__finally {
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_unlock_str(stream);
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}
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#endif
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return(retval);
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}
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