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e0b123f6d0
Final word is Bruce's quote:
C9x specifies the BSD4.4-Lite behaviour:
[#3] ... Thus, the
null-terminated output has been completely written if and
only if the returned value is less than n.
It means that if we not have any null-terminated output as for n == 0
we can't return value less than n, so we forced to return value
equal to n i.e. 0
The next good thing is glibc compatibility, of course.
2) Do check for too big n in machine-independent way.
3) Minor optimization assuming EOF is < 0
70 lines
2.5 KiB
C
70 lines
2.5 KiB
C
/*-
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* Copyright (c) 1990, 1993
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* The Regents of the University of California. All rights reserved.
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*
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* This code is derived from software contributed to Berkeley by
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* Chris Torek.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. All advertising materials mentioning features or use of this software
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* must display the following acknowledgement:
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* This product includes software developed by the University of
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* California, Berkeley and its contributors.
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* 4. Neither the name of the University nor the names of its contributors
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* may be used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*/
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#if defined(LIBC_SCCS) && !defined(lint)
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#if 0
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static char sccsid[] = "@(#)vsnprintf.c 8.1 (Berkeley) 6/4/93";
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#endif
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static const char rcsid[] =
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"$Id: vsnprintf.c,v 1.7 1997/12/24 14:32:40 ache Exp $";
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#endif /* LIBC_SCCS and not lint */
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#include <stdio.h>
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#include <limits.h>
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int
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vsnprintf(str, n, fmt, ap)
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char *str;
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size_t n;
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const char *fmt;
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_BSD_VA_LIST_ ap;
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{
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int ret;
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FILE f;
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if (n == 0)
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return (0);
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if (--n > INT_MAX)
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return (EOF);
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f._file = -1;
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f._flags = __SWR | __SSTR;
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f._bf._base = f._p = (unsigned char *)str;
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f._bf._size = f._w = n;
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ret = vfprintf(&f, fmt, ap);
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*f._p = 0;
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return (ret > (int)n ? n : ret);
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}
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