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This commit is contained in:
Roland McGrath
1995-02-18 01:27:10 +00:00
commit 28f540f45b
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stdio/fwrite.c Normal file
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/* Copyright (C) 1991, 1992, 1993, 1994 Free Software Foundation, Inc.
This file is part of the GNU C Library.
The GNU C Library is free software; you can redistribute it and/or
modify it under the terms of the GNU Library General Public License as
published by the Free Software Foundation; either version 2 of the
License, or (at your option) any later version.
The GNU C Library is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
Library General Public License for more details.
You should have received a copy of the GNU Library General Public
License along with the GNU C Library; see the file COPYING.LIB. If
not, write to the Free Software Foundation, Inc., 675 Mass Ave,
Cambridge, MA 02139, USA. */
#include <ansidecl.h>
#include <errno.h>
#include <stdio.h>
#include <string.h>
/* Write NMEMB chunks of SIZE bytes each from PTR onto STREAM. */
size_t
DEFUN(fwrite, (ptr, size, nmemb, stream),
CONST PTR ptr AND size_t size AND
size_t nmemb AND register FILE *stream)
{
register CONST unsigned char *p = (CONST unsigned char *) ptr;
register size_t to_write = size * nmemb;
register size_t written = 0;
int newlinep;
size_t buffer_space;
int default_func;
if (!__validfp (stream) || !stream->__mode.__write)
{
errno = EINVAL;
return 0;
}
if (ferror (stream))
return 0;
if (p == NULL || to_write == 0)
return 0;
if (!stream->__seen || stream->__put_limit == stream->__buffer)
{
/* This stream has never been seen before.
Calling __flshfp will give it a buffer
and I/O functions if it needs them. */
if (__flshfp (stream, *p++) == EOF)
return 0;
if (--to_write == 0)
return 1;
else
++written;
}
default_func
= stream->__room_funcs.__output == __default_room_functions.__output;
{
int save = errno;
if (__stdio_check_offset (stream) == EOF && errno != ESPIPE)
{
stream->__error = 1;
goto done;
}
errno = save;
}
if (stream->__buffer == NULL && default_func &&
stream->__offset == stream->__target)
write_through:
/* This is an unbuffered stream using the standard output
buffer-flushing function, so we just do a straight write. */
{
int count = (stream->__io_funcs.__write == NULL ? to_write :
(*stream->__io_funcs.__write) (stream->__cookie,
(CONST char *) p,
to_write));
if (count > 0)
{
written += count;
if (stream->__offset != -1)
{
stream->__offset += count;
stream->__target = stream->__offset;
}
to_write -= count;
p += count;
}
else
stream->__error = 1;
goto done;
}
/* We ignore the end pointer here since we want to find out how much space
is really in the buffer, even for a line-buffered stream. */
buffer_space = stream->__bufsize - (stream->__bufp - stream->__buffer);
newlinep = (stream->__linebuf &&
memchr ((CONST PTR) p, '\n', to_write) != NULL);
if (newlinep && stream->__bufp == stream->__buffer &&
stream->__offset == stream->__target)
/* The buffer's empty, and we want to write our data
out soon anyway, so just write it straight out. */
goto write_through;
if (stream->__bufsize == 0 && !default_func)
{
/* No buffer, and a special function.
We can't do much better than putc. */
while (to_write-- > 0)
{
if (__flshfp (stream, *p++) == EOF)
break;
else
++written;
}
}
else if (!default_func || buffer_space >= to_write)
fill_buffer:
/* There is enough room in the buffer for everything we
want to write or the user has specified his own output
buffer-flushing/expanding function. */
while (to_write > 0)
{
register size_t n = to_write;
if (n > buffer_space)
n = buffer_space;
buffer_space -= n;
written += n;
to_write -= n;
if (n < 20)
while (n-- > 0)
*stream->__bufp++ = *p++;
else
{
memcpy ((PTR) stream->__bufp, (PTR) p, n);
stream->__bufp += n;
p += n;
}
if (buffer_space == 0 || (to_write == 0 && newlinep))
{
/* We've filled the buffer, so flush it. */
if (fflush (stream) == EOF)
break;
/* Reset our record of the space available in the buffer,
since we have just flushed it. */
check_space:
buffer_space = (stream->__bufsize -
(stream->__bufp - stream->__buffer));
if (buffer_space == 0)
{
/* With a custom output-room function, flushing might
not create any buffer space. Try writing a single
character to create the space. */
if (__flshfp (stream, *p++) == EOF)
goto done;
++written;
--to_write;
goto check_space;
}
}
}
else
{
/* It won't all fit in the buffer. */
if (stream->__bufp != stream->__buffer)
{
/* There are characters in the buffer. Flush them. */
if (__flshfp (stream, EOF) == EOF)
goto done;
}
/* The buffer has been flushed.
Now either fill it or write directly. */
buffer_space = stream->__bufsize - (stream->__bufp - stream->__buffer);
if (stream->__offset == stream->__target &&
(buffer_space < to_write || newlinep))
/* What we have to write is bigger than the buffer,
or it contains a newline and we're line-buffered,
so write it out. */
goto write_through;
else
/* It will fit in the buffer. */
goto fill_buffer;
}
done:;
return (size_t) written / size;
}