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snprintf return value fixes to conform Single Unix specs:

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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.
This commit is contained in:
Andrey A. Chernov 1997-12-24 12:31:32 +00:00
parent 86e2983aa5
commit 4ecaf22055
2 changed files with 16 additions and 6 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

11
lib/libc/stdio/snprintf.c
View File

@ -39,7 +39,7 @@
static char sccsid[] = "@(#)snprintf.c 8.1 (Berkeley) 6/4/93";
#endif
static const char rcsid[] =
"$Id$";
"$Id: snprintf.c,v 1.5 1997/02/22 15:02:29 peter Exp $";
#endif /* LIBC_SCCS and not lint */
#include <stdio.h>
@ -65,8 +65,11 @@ snprintf(str, n, fmt, va_alist)
va_list ap;
FILE f;
if (n == 0)
return (0);
if ((int)n < 1)
return (EOF);
n--;
#if __STDC__
va_start(ap, fmt);
#else
@ -75,9 +78,11 @@ snprintf(str, n, fmt, va_alist)
f._file = -1;
f._flags = __SWR | __SSTR;
f._bf._base = f._p = (unsigned char *)str;
f._bf._size = f._w = n - 1;
f._bf._size = f._w = n;
ret = vfprintf(&f, fmt, ap);
*f._p = 0;
va_end(ap);
return (ret);
if (ret == EOF)
return (ret);
return (ret > (int)n ? n : ret);
}

11
lib/libc/stdio/vsnprintf.c
View File

@ -39,7 +39,7 @@
static char sccsid[] = "@(#)vsnprintf.c 8.1 (Berkeley) 6/4/93";
#endif
static const char rcsid[] =
"$Id$";
"$Id: vsnprintf.c,v 1.5 1997/02/22 15:02:45 peter Exp $";
#endif /* LIBC_SCCS and not lint */
#include <stdio.h>
@ -54,13 +54,18 @@ vsnprintf(str, n, fmt, ap)
int ret;
FILE f;
if (n == 0)
return (0);
if ((int)n < 1)
return (EOF);
n--;
f._file = -1;
f._flags = __SWR | __SSTR;
f._bf._base = f._p = (unsigned char *)str;
f._bf._size = f._w = n - 1;
f._bf._size = f._w = n;
ret = vfprintf(&f, fmt, ap);
*f._p = 0;
return (ret);
if (ret == EOF)
return (ret);
return (ret > (int)n ? n : ret);
}