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freebsd-dev/lib/libc/stdio/snprintf.c

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BSD 4.4 Lite Lib Sources
1994-05-27 05:00:24 +00:00
/*-
* Copyright (c) 1990, 1993
* The Regents of the University of California. All rights reserved.
*
* This code is derived from software contributed to Berkeley by
* Chris Torek.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. All advertising materials mentioning features or use of this software
* must display the following acknowledgement:
* This product includes software developed by the University of
* California, Berkeley and its contributors.
* 4. Neither the name of the University nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*/
#if defined(LIBC_SCCS) && !defined(lint)
Suggested by: Bruce Evans, Jeffrey Hsu, Gary Palmer Added $Id$'s to files that were lacking them (gpalmer), made some cosmetic changes to conform to style guidelines (bde) and checked against NetBSD and Lite2 to remove unnecessary divergences (hsu, bde) One last code cleanup:- Removed spurious casts in fseek.c and stdio.c. Added missing function argument in fwalk.c. Added missing header include in flags.c and rget.c. Put in casts where int's were being passed as size_t's. Put in missing prototypes for static functions. Changed second args of __sflags() inflags.c and writehook() in vasprintf.c from char * to const char * to conform to prototypes. This directory now compiles with no warnings with -Wall under gcc-2.6.3 and with considerably less warnings than before with the ultra-pedantic script I used for testing. (Most of the remaining ones are due to const poisoning).
1996-06-22 10:34:15 +00:00
#if 0
BSD 4.4 Lite Lib Sources
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static char sccsid[] = "@(#)snprintf.c 8.1 (Berkeley) 6/4/93";
Suggested by: Bruce Evans, Jeffrey Hsu, Gary Palmer Added $Id$'s to files that were lacking them (gpalmer), made some cosmetic changes to conform to style guidelines (bde) and checked against NetBSD and Lite2 to remove unnecessary divergences (hsu, bde) One last code cleanup:- Removed spurious casts in fseek.c and stdio.c. Added missing function argument in fwalk.c. Added missing header include in flags.c and rget.c. Put in casts where int's were being passed as size_t's. Put in missing prototypes for static functions. Changed second args of __sflags() inflags.c and writehook() in vasprintf.c from char * to const char * to conform to prototypes. This directory now compiles with no warnings with -Wall under gcc-2.6.3 and with considerably less warnings than before with the ultra-pedantic script I used for testing. (Most of the remaining ones are due to const poisoning).
1996-06-22 10:34:15 +00:00
#endif
static const char rcsid[] =
1) Oops! Insert again if (n == 0) return 0. 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
1997-12-24 20:24:08 +00:00
"$Id: snprintf.c,v 1.7 1997/12/24 14:32:39 ache Exp $";
BSD 4.4 Lite Lib Sources
1994-05-27 05:00:24 +00:00
#endif /* LIBC_SCCS and not lint */
#include <stdio.h>
#if __STDC__
#include <stdarg.h>
#else
#include <varargs.h>
#endif
1) Oops! Insert again if (n == 0) return 0. 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
1997-12-24 20:24:08 +00:00
#include <limits.h>
BSD 4.4 Lite Lib Sources
1994-05-27 05:00:24 +00:00
#if __STDC__
Reviewed by: julian and (hsu?) Submitted by: John Birrel(L?) changes for threadsafe operations
1996-01-22 00:02:33 +00:00
int
BSD 4.4 Lite Lib Sources
1994-05-27 05:00:24 +00:00
snprintf(char *str, size_t n, char const *fmt, ...)
#else
Reviewed by: julian and (hsu?) Submitted by: John Birrel(L?) changes for threadsafe operations
1996-01-22 00:02:33 +00:00
int
BSD 4.4 Lite Lib Sources
1994-05-27 05:00:24 +00:00
snprintf(str, n, fmt, va_alist)
char *str;
size_t n;
char *fmt;
va_dcl
#endif
{
int ret;
va_list ap;
FILE f;
1) Oops! Insert again if (n == 0) return 0. 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
1997-12-24 20:24:08 +00:00
if (n == 0)
return (0);
if (--n > INT_MAX)
BSD 4.4 Lite Lib Sources
1994-05-27 05:00:24 +00:00
return (EOF);
#if __STDC__
va_start(ap, fmt);
#else
va_start(ap);
#endif
Reviewed by: julian and (hsu?) Submitted by: John Birrel(L?) changes for threadsafe operations
1996-01-22 00:02:33 +00:00
f._file = -1;
BSD 4.4 Lite Lib Sources
1994-05-27 05:00:24 +00:00
f._flags = __SWR | __SSTR;
f._bf._base = f._p = (unsigned char *)str;
snprintf return value fixes to conform Single Unix specs: 1) if buffer size is smaller than arguments size, return buffer size, not arguments size as before. 2) if buffer size is 0, return 0, not EOF as before. (now it is compatible with Linux and Apache implementations too). NOTE: Single Unix specs says: If the value of n {buffer size} is zero on a call to snprintf(), an unspecified value less than 1 is returned. It means we can't return EOF since EOF can take *any* value in general not especially < 1. Better variant will be return -1 (it is less then 1 and different with n == 1 case) but -1 value is already occuped by EOF in our implementation, so we can't distinguish true IO error in that case. So 0 here is only possible case still conforming to Single Unix specs.
1997-12-24 12:31:32 +00:00
f._bf._size = f._w = n;
BSD 4.4 Lite Lib Sources
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ret = vfprintf(&f, fmt, ap);
*f._p = 0;
va_end(ap);
snprintf return value fixes to conform Single Unix specs: 1) if buffer size is smaller than arguments size, return buffer size, not arguments size as before. 2) if buffer size is 0, return 0, not EOF as before. (now it is compatible with Linux and Apache implementations too). NOTE: Single Unix specs says: If the value of n {buffer size} is zero on a call to snprintf(), an unspecified value less than 1 is returned. It means we can't return EOF since EOF can take *any* value in general not especially < 1. Better variant will be return -1 (it is less then 1 and different with n == 1 case) but -1 value is already occuped by EOF in our implementation, so we can't distinguish true IO error in that case. So 0 here is only possible case still conforming to Single Unix specs.
1997-12-24 12:31:32 +00:00
return (ret > (int)n ? n : ret);
BSD 4.4 Lite Lib Sources
1994-05-27 05:00:24 +00:00
}
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