libiberty/vsnprintf.c

   1 /* Implement the vsnprintf function.
   2    Copyright (C) 2003 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, 59 Temple Place - Suite 330, Boston, MA 02111-1307, 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 vsprintf, but it will print at most
  31 @var{n} characters.  On error the return value is -1, otherwise it
  32 returns the number of characters that would have been printed had
  33 @var{n} been sufficiently large, regardless of the actual value of
  34 @var{n}.  Note some pre-C99 system libraries do not implement this
  35 correctly so users cannot generally rely on the return value if the
  36 system version of this function is used.
  37
  38 @end deftypefn
  39
  40 */
  41
  42 #include "config.h"
  43 #include "ansidecl.h"
  44
  45 #ifdef ANSI_PROTOTYPES
  46 #include <stdarg.h>
  47 #else
  48 #include <varargs.h>
  49 #endif
  50 #ifdef HAVE_STRING_H
  51 #include <string.h>
  52 #endif
  53 #ifdef HAVE_STDLIB_H
  54 #include <stdlib.h>
  55 #endif
  56
  57 #include "libiberty.h"
  58
  59 /* This implementation relies on a working vasprintf.  */
  60 int
  61 vsnprintf (s, n, format, ap)
  62      char * s;
  63      size_t n;
  64      const char *format;
  65      va_list ap;
  66 {
  67   char *buf = 0;
  68   int result = vasprintf (&buf, format, ap);
  69
  70   if (!buf)
  71     return -1;
  72   if (result < 0)
  73     {
  74       free (buf);
  75       return -1;
  76     }
  77
  78   result = strlen (buf);
  79   if (n > 0)
  80     {
  81       if ((long) n > result)
  82         memcpy (s, buf, result+1);
  83       else
  84         {
  85           memcpy (s, buf, n-1);
  86           s[n - 1] = 0;
  87         }
  88     }
  89   free (buf);
  90   return result;
  91 }
  92
  93 #ifdef TEST
  94 /* Set the buffer to a known state.  */
  95 #define CLEAR(BUF) do { memset ((BUF), 'X', sizeof (BUF)); (BUF)[14] = '\0'; } while (0)
  96 /* For assertions.  */
  97 #define VERIFY(P) do { if (!(P)) abort(); } while (0)
  98
  99 static int ATTRIBUTE_PRINTF_3
 100 checkit VPARAMS ((char *s, size_t n, const char *format, ...))
 101 {
 102   int result;
 103   VA_OPEN (ap, format);
 104   VA_FIXEDARG (ap, char *, s);
 105   VA_FIXEDARG (ap, size_t, n);
 106   VA_FIXEDARG (ap, const char *, format);
 107   result = vsnprintf (s, n, format, ap);
 108   VA_CLOSE (ap);
 109   return result;
 110 }
 111
 112 extern int main PARAMS ((void));
 113 int
 114 main ()
 115 {
 116   char buf[128];
 117   int status;
 118
 119   CLEAR (buf);
 120   status = checkit (buf, 10, "%s:%d", "foobar", 9);
 121   VERIFY (status==8 && memcmp (buf, "foobar:9\0XXXXX\0", 15) == 0);
 122
 123   CLEAR (buf);
 124   status = checkit (buf, 9, "%s:%d", "foobar", 9);
 125   VERIFY (status==8 && memcmp (buf, "foobar:9\0XXXXX\0", 15) == 0);
 126
 127   CLEAR (buf);
 128   status = checkit (buf, 8, "%s:%d", "foobar", 9);
 129   VERIFY (status==8 && memcmp (buf, "foobar:\0XXXXXX\0", 15) == 0);
 130
 131   CLEAR (buf);
 132   status = checkit (buf, 7, "%s:%d", "foobar", 9);
 133   VERIFY (status==8 && memcmp (buf, "foobar\0XXXXXXX\0", 15) == 0);
 134
 135   CLEAR (buf);
 136   status = checkit (buf, 6, "%s:%d", "foobar", 9);
 137   VERIFY (status==8 && memcmp (buf, "fooba\0XXXXXXXX\0", 15) == 0);
 138
 139   CLEAR (buf);
 140   status = checkit (buf, 2, "%s:%d", "foobar", 9);
 141   VERIFY (status==8 && memcmp (buf, "f\0XXXXXXXXXXXX\0", 15) == 0);
 142
 143   CLEAR (buf);
 144   status = checkit (buf, 1, "%s:%d", "foobar", 9);
 145   VERIFY (status==8 && memcmp (buf, "\0XXXXXXXXXXXXX\0", 15) == 0);
 146
 147   CLEAR (buf);
 148   status = checkit (buf, 0, "%s:%d", "foobar", 9);
 149   VERIFY (status==8 && memcmp (buf, "XXXXXXXXXXXXXX\0", 15) == 0);
 150
 151   return 0;
 152 }
 153 #endif /* TEST */