libiberty/vsnprintf.c

   1 /* Implement the vsnprintf function.
   2    Copyright (C) 2003, 2004, 2005 Free Software Foundation, Inc.
   3    Written by Kaveh R. Ghazi <ghazi@caip.rutgers.edu>.
   4
   5 This file is part of the libiberty library.  This library is free
   6 software; you can redistribute it and/or modify it under the
   7 terms of the GNU General Public License as published by the
   8 Free Software Foundation; either version 2, or (at your option)
   9 any later version.
  10
  11 This library is distributed in the hope that it will be useful,
  12 but WITHOUT ANY WARRANTY; without even the implied warranty of
  13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14 GNU General Public License for more details.
  15
  16 You should have received a copy of the GNU General Public License
  17 along with GNU CC; see the file COPYING.  If not, write to
  18 the Free Software Foundation, 51 Franklin Street - Fifth Floor, Boston, MA 02110-1301, USA.
  19
  20 As a special exception, if you link this library with files
  21 compiled with a GNU compiler to produce an executable, this does not cause
  22 the resulting executable to be covered by the GNU General Public License.
  23 This exception does not however invalidate any other reasons why
  24 the executable file might be covered by the GNU General Public License. */
  25
  26 /*
  27
  28 @deftypefn Supplemental int vsnprintf (char *@var{buf}, size_t @var{n}, const char *@var{format}, va_list @var{ap})
  29
  30 This function is similar to @code{vsprintf}, but it will write to
  31 @var{buf} at most @code{@var{n}-1} bytes of text, followed by a
  32 terminating null byte, for a total of @var{n} bytes.  On error the
  33 return value is -1, otherwise it returns the number of characters that
  34 would have been printed had @var{n} been sufficiently large,
  35 regardless of the actual value of @var{n}.  Note some pre-C99 system
  36 libraries do not implement this correctly so users cannot generally
  37 rely on the return value if the system version of this function is
  38 used.
  39
  40 @end deftypefn
  41
  42 */
  43
  44 #include "config.h"
  45 #include "ansidecl.h"
  46
  47 #include <stdarg.h>
  48 #ifdef HAVE_STRING_H
  49 #include <string.h>
  50 #endif
  51 #ifdef HAVE_STDLIB_H
  52 #include <stdlib.h>
  53 #endif
  54
  55 #include "libiberty.h"
  56
  57 /* This implementation relies on a working vasprintf.  */
  58 int
  59 vsnprintf (char *s, size_t n, const char *format, va_list ap)
  60 {
  61   char *buf = 0;
  62   int result = vasprintf (&buf, format, ap);
  63
  64   if (!buf)
  65     return -1;
  66   if (result < 0)
  67     {
  68       free (buf);
  69       return -1;
  70     }
  71
  72   result = strlen (buf);
  73   if (n > 0)
  74     {
  75       if ((long) n > result)
  76         memcpy (s, buf, result+1);
  77       else
  78         {
  79           memcpy (s, buf, n-1);
  80           s[n - 1] = 0;
  81         }
  82     }
  83   free (buf);
  84   return result;
  85 }
  86
  87 #ifdef TEST
  88 /* Set the buffer to a known state.  */
  89 #define CLEAR(BUF) do { memset ((BUF), 'X', sizeof (BUF)); (BUF)[14] = '\0'; } while (0)
  90 /* For assertions.  */
  91 #define VERIFY(P) do { if (!(P)) abort(); } while (0)
  92
  93 static int ATTRIBUTE_PRINTF_3
  94 checkit (char *s, size_t n, const char *format, ...)
  95 {
  96   int result;
  97   VA_OPEN (ap, format);
  98   VA_FIXEDARG (ap, char *, s);
  99   VA_FIXEDARG (ap, size_t, n);
 100   VA_FIXEDARG (ap, const char *, format);
 101   result = vsnprintf (s, n, format, ap);
 102   VA_CLOSE (ap);
 103   return result;
 104 }
 105
 106 extern int main (void);
 107 int
 108 main (void)
 109 {
 110   char buf[128];
 111   int status;
 112
 113   CLEAR (buf);
 114   status = checkit (buf, 10, "%s:%d", "foobar", 9);
 115   VERIFY (status==8 && memcmp (buf, "foobar:9\0XXXXX\0", 15) == 0);
 116
 117   CLEAR (buf);
 118   status = checkit (buf, 9, "%s:%d", "foobar", 9);
 119   VERIFY (status==8 && memcmp (buf, "foobar:9\0XXXXX\0", 15) == 0);
 120
 121   CLEAR (buf);
 122   status = checkit (buf, 8, "%s:%d", "foobar", 9);
 123   VERIFY (status==8 && memcmp (buf, "foobar:\0XXXXXX\0", 15) == 0);
 124
 125   CLEAR (buf);
 126   status = checkit (buf, 7, "%s:%d", "foobar", 9);
 127   VERIFY (status==8 && memcmp (buf, "foobar\0XXXXXXX\0", 15) == 0);
 128
 129   CLEAR (buf);
 130   status = checkit (buf, 6, "%s:%d", "foobar", 9);
 131   VERIFY (status==8 && memcmp (buf, "fooba\0XXXXXXXX\0", 15) == 0);
 132
 133   CLEAR (buf);
 134   status = checkit (buf, 2, "%s:%d", "foobar", 9);
 135   VERIFY (status==8 && memcmp (buf, "f\0XXXXXXXXXXXX\0", 15) == 0);
 136
 137   CLEAR (buf);
 138   status = checkit (buf, 1, "%s:%d", "foobar", 9);
 139   VERIFY (status==8 && memcmp (buf, "\0XXXXXXXXXXXXX\0", 15) == 0);
 140
 141   CLEAR (buf);
 142   status = checkit (buf, 0, "%s:%d", "foobar", 9);
 143   VERIFY (status==8 && memcmp (buf, "XXXXXXXXXXXXXX\0", 15) == 0);
 144
 145   return 0;
 146 }
 147 #endif /* TEST */