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 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 #include <stdarg.h>
  46 #ifdef HAVE_STRING_H
  47 #include <string.h>
  48 #endif
  49 #ifdef HAVE_STDLIB_H
  50 #include <stdlib.h>
  51 #endif
  52
  53 #include "libiberty.h"
  54
  55 /* This implementation relies on a working vasprintf.  */
  56 int
  57 vsnprintf (char *s, size_t n, const char *format, va_list ap)
  58 {
  59   char *buf = 0;
  60   int result = vasprintf (&buf, format, ap);
  61
  62   if (!buf)
  63     return -1;
  64   if (result < 0)
  65     {
  66       free (buf);
  67       return -1;
  68     }
  69
  70   result = strlen (buf);
  71   if (n > 0)
  72     {
  73       if ((long) n > result)
  74         memcpy (s, buf, result+1);
  75       else
  76         {
  77           memcpy (s, buf, n-1);
  78           s[n - 1] = 0;
  79         }
  80     }
  81   free (buf);
  82   return result;
  83 }
  84
  85 #ifdef TEST
  86 /* Set the buffer to a known state.  */
  87 #define CLEAR(BUF) do { memset ((BUF), 'X', sizeof (BUF)); (BUF)[14] = '\0'; } while (0)
  88 /* For assertions.  */
  89 #define VERIFY(P) do { if (!(P)) abort(); } while (0)
  90
  91 static int ATTRIBUTE_PRINTF_3
  92 checkit (char *s, size_t n, const char *format, ...)
  93 {
  94   int result;
  95   VA_OPEN (ap, format);
  96   VA_FIXEDARG (ap, char *, s);
  97   VA_FIXEDARG (ap, size_t, n);
  98   VA_FIXEDARG (ap, const char *, format);
  99   result = vsnprintf (s, n, format, ap);
 100   VA_CLOSE (ap);
 101   return result;
 102 }
 103
 104 extern int main (void);
 105 int
 106 main (void)
 107 {
 108   char buf[128];
 109   int status;
 110
 111   CLEAR (buf);
 112   status = checkit (buf, 10, "%s:%d", "foobar", 9);
 113   VERIFY (status==8 && memcmp (buf, "foobar:9\0XXXXX\0", 15) == 0);
 114
 115   CLEAR (buf);
 116   status = checkit (buf, 9, "%s:%d", "foobar", 9);
 117   VERIFY (status==8 && memcmp (buf, "foobar:9\0XXXXX\0", 15) == 0);
 118
 119   CLEAR (buf);
 120   status = checkit (buf, 8, "%s:%d", "foobar", 9);
 121   VERIFY (status==8 && memcmp (buf, "foobar:\0XXXXXX\0", 15) == 0);
 122
 123   CLEAR (buf);
 124   status = checkit (buf, 7, "%s:%d", "foobar", 9);
 125   VERIFY (status==8 && memcmp (buf, "foobar\0XXXXXXX\0", 15) == 0);
 126
 127   CLEAR (buf);
 128   status = checkit (buf, 6, "%s:%d", "foobar", 9);
 129   VERIFY (status==8 && memcmp (buf, "fooba\0XXXXXXXX\0", 15) == 0);
 130
 131   CLEAR (buf);
 132   status = checkit (buf, 2, "%s:%d", "foobar", 9);
 133   VERIFY (status==8 && memcmp (buf, "f\0XXXXXXXXXXXX\0", 15) == 0);
 134
 135   CLEAR (buf);
 136   status = checkit (buf, 1, "%s:%d", "foobar", 9);
 137   VERIFY (status==8 && memcmp (buf, "\0XXXXXXXXXXXXX\0", 15) == 0);
 138
 139   CLEAR (buf);
 140   status = checkit (buf, 0, "%s:%d", "foobar", 9);
 141   VERIFY (status==8 && memcmp (buf, "XXXXXXXXXXXXXX\0", 15) == 0);
 142
 143   return 0;
 144 }
 145 #endif /* TEST */