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/***
*fwrite.c - read from a stream
*
* Copyright (c) 1989-1992, Microsoft Corporation. All rights reserved.
*
*Purpose:
* Write to the specified stream from the user's buffer.
*
*Revision History:
* 06-23-89 PHG Module created, based on asm version
* 01-18-90 GJF Must call _fflush_lk() rather than fflush().
* 02-15-90 GJF _iob[], _iob2[] merge. Also, fixed copyright and
* indents.
* 03-19-90 GJF Made calling type _CALLTYPE1 and added #include
* <cruntime.h>. Also, fixed compiler warning.
* 05-29-90 SBM Use _flush, not [_]fflush[_lk]
* 07-26-90 SBM Added #include <internal.h>
* 08-14-90 SBM Compiles cleanly with -W3
* 10-02-90 GJF New-style function declarators.
* 01-22-91 GJF ANSI naming.
* 03-27-92 DJM POSIX support.
* 08-26-92 GJF Include unistd.h for POSIX build.
*
*******************************************************************************/
#include <cruntime.h>
#ifdef _POSIX_
#include <unistd.h>
#endif
#include <stdio.h>
#include <os2dll.h>
#include <io.h>
#include <string.h>
#include <file2.h>
#include <internal.h>
/***
*size_t fwrite(void *buffer, size_t size, size_t count, FILE *stream) -
* write to the specified stream from the specified buffer.
*
*Purpose:
* Write 'count' items of size 'size' to the specified stream from
* the specified buffer. Return when 'count' items have been written
* or no more items can be written to the stream.
*
*Entry:
* buffer - pointer to user's buffer
* size - size of the item to write
* count - number of items to write
* stream - stream to write to
*
*Exit:
* Returns the number of (whole) items that were written to the stream.
* This may be less than 'count' if an error or eof occurred. In this
* case, ferror() or feof() should be used to distinguish between the
* two conditions.
*
*Notes:
* fwrite will attempt to buffer the stream (side effect of the _flsbuf
* call) if necessary.
*
* No more than 0xFFFE bytes may be written out at a time by a call to
* write(). Further, write() does not handle huge buffers. Therefore,
* in large data models, the write request is broken down into chunks
* that do not violate these considerations. Each of these chunks is
* processed much like an fwrite() call in a small data model (by a
* call to _nfwrite()).
*
* This code depends on _iob[] being a near array.
*
* MTHREAD/DLL - Handled in just two layers since it is small data
* model. The outer layer, fwrite(), handles stream locking/unlocking
* and calls _fwrite_lk() to do the work. _fwrite_lk() is the same as
* the single-thread, small data model version of fwrite().
*
*******************************************************************************/
#ifdef MTHREAD
/* define locking/unlocking version */
size_t _CALLTYPE1 fwrite (
const void *buffer,
size_t size,
size_t count,
FILE *stream
)
{
int index;
size_t retval;
index = _iob_index(stream);
_lock_str(index); /* lock stream */
retval = _fwrite_lk(buffer, size, count, stream); /* do the read */
_unlock_str(index); /* unlock stream */
return retval;
}
#endif
/* define the normal version */
#ifdef MTHREAD
size_t _CALLTYPE1 _fwrite_lk (
#else
size_t _CALLTYPE1 fwrite (
#endif
const void *buffer,
size_t size,
size_t num,
FILE *stream
)
{
const char *data; /* point to where data comes from next */
unsigned total; /* total bytes to write */
unsigned count; /* num bytes left to write */
unsigned bufsize; /* size of stream buffer */
unsigned nbytes; /* number of bytes to write now */
unsigned nwritten; /* number of bytes written */
int c; /* a temp char */
/* initialize local vars */
data = buffer;
count = total = size * num;
if (anybuf(stream))
/* already has buffer, use its size */
bufsize = stream->_bufsiz;
else
/* assume will get BUFSIZ buffer */
bufsize = BUFSIZ;
/* here is the main loop -- we go through here until we're done */
while (count != 0) {
/* if the buffer is big and has room, copy data to buffer */
if (bigbuf(stream) && stream->_cnt != 0) {
/* how much do we want? */
nbytes = (count < (unsigned)stream->_cnt) ? count : stream->_cnt;
memcpy(stream->_ptr, data, nbytes);
/* update stream and amt of data written */
count -= nbytes;
stream->_cnt -= nbytes;
stream->_ptr += nbytes;
data += nbytes;
}
else if (count >= bufsize) {
/* If we have more than bufsize chars to write, write
data by calling write with an integral number of
bufsiz blocks. If we reach here and we have a big
buffer, it must be full so _flush it. */
if (bigbuf(stream)) {
if (_flush(stream)) {
/* error, stream flags set -- we're out
of here */
return (total - count) / size;
}
}
/* calc chars to read -- (count/bufsize) * bufsize */
nbytes = count - count % bufsize;
#ifdef _POSIX_
nwritten = write(fileno(stream), data, nbytes);
#else
nwritten = _write(_fileno(stream), data, nbytes);
#endif
if (nwritten == (unsigned)EOF) {
/* error -- out of here */
stream->_flag |= _IOERR;
return (total - count) / size;
}
/* update count and data to reflect write */
count -= nwritten;
data += nwritten;
if (nwritten < nbytes) {
/* error -- out of here */
stream->_flag |= _IOERR;
return (total - count) / size;
}
}
else {
/* buffer full and not enough chars to do direct write,
so do a _flsbuf. */
c = *data; /* _flsbuf write one char, this is it */
if (_flsbuf(c, stream) == EOF) {
/* error or eof, stream flags set by _flsbuf */
return (total - count) / size;
}
/* _flsbuf wrote a char -- update count */
++data;
--count;
/* update buffer size */
bufsize = stream->_bufsiz > 0 ? stream->_bufsiz : 1;
}
}
/* we finished successfully, so just return num */
return num;
}
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