libiberty/vsnprintf.c

   1 /* Implement the vsnprintf function.
   2    Copyright (C) 2003, 2004, 2005, 2011 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}, @
  29   const char *@var{format}, va_list @var{ap})
  30
  31 This function is similar to @code{vsprintf}, but it will write to
  32 @var{buf} at most @code{@var{n}-1} bytes of text, followed by a
  33 terminating null byte, for a total of @var{n} bytes.  On error the
  34 return value is -1, otherwise it returns the number of characters that
  35 would have been printed had @var{n} been sufficiently large,
  36 regardless of the actual value of @var{n}.  Note some pre-C99 system
  37 libraries do not implement this correctly so users cannot generally
  38 rely on the return value if the system version of this function is
  39 used.
  40
  41 @end deftypefn
  42
  43 */
  44
  45 #include "config.h"
  46 #include "ansidecl.h"
  47
  48 #include <stdarg.h>
  49 #ifdef HAVE_STRING_H
  50 #include <string.h>
  51 #endif
  52 #ifdef HAVE_STDLIB_H
  53 #include <stdlib.h>
  54 #endif
  55
  56 #include "libiberty.h"
  57
  58 /* This implementation relies on a working vasprintf.  */
  59 int
  60 vsnprintf (char *s, size_t n, const char *format, va_list ap)
  61 {
  62   char *buf = 0;
  63   int result = vasprintf (&buf, format, ap);
  64
  65   if (!buf)
  66     return -1;
  67   if (result < 0)
  68     {
  69       free (buf);
  70       return -1;
  71     }
  72
  73   result = strlen (buf);
  74   if (n > 0)
  75     {
  76       if ((long) n > result)
  77         memcpy (s, buf, result+1);
  78       else
  79         {
  80           memcpy (s, buf, n-1);
  81           s[n - 1] = 0;
  82         }
  83     }
  84   free (buf);
  85   return result;
  86 }
  87
  88 #ifdef TEST
  89 /* Set the buffer to a known state.  */
  90 #define CLEAR(BUF) do { memset ((BUF), 'X', sizeof (BUF)); (BUF)[14] = '\0'; } while (0)
  91 /* For assertions.  */
  92 #define VERIFY(P) do { if (!(P)) abort(); } while (0)
  93
  94 static int ATTRIBUTE_PRINTF_3
  95 checkit (char *s, size_t n, const char *format, ...)
  96 {
  97   int result;
  98   VA_OPEN (ap, format);
  99   VA_FIXEDARG (ap, char *, s);
 100   VA_FIXEDARG (ap, size_t, n);
 101   VA_FIXEDARG (ap, const char *, format);
 102   result = vsnprintf (s, n, format, ap);
 103   VA_CLOSE (ap);
 104   return result;
 105 }
 106
 107 extern int main (void);
 108 int
 109 main (void)
 110 {
 111   char buf[128];
 112   int status;
 113
 114   CLEAR (buf);
 115   status = checkit (buf, 10, "%s:%d", "foobar", 9);
 116   VERIFY (status==8 && memcmp (buf, "foobar:9\0XXXXX\0", 15) == 0);
 117
 118   CLEAR (buf);
 119   status = checkit (buf, 9, "%s:%d", "foobar", 9);
 120   VERIFY (status==8 && memcmp (buf, "foobar:9\0XXXXX\0", 15) == 0);
 121
 122   CLEAR (buf);
 123   status = checkit (buf, 8, "%s:%d", "foobar", 9);
 124   VERIFY (status==8 && memcmp (buf, "foobar:\0XXXXXX\0", 15) == 0);
 125
 126   CLEAR (buf);
 127   status = checkit (buf, 7, "%s:%d", "foobar", 9);
 128   VERIFY (status==8 && memcmp (buf, "foobar\0XXXXXXX\0", 15) == 0);
 129
 130   CLEAR (buf);
 131   status = checkit (buf, 6, "%s:%d", "foobar", 9);
 132   VERIFY (status==8 && memcmp (buf, "fooba\0XXXXXXXX\0", 15) == 0);
 133
 134   CLEAR (buf);
 135   status = checkit (buf, 2, "%s:%d", "foobar", 9);
 136   VERIFY (status==8 && memcmp (buf, "f\0XXXXXXXXXXXX\0", 15) == 0);
 137
 138   CLEAR (buf);
 139   status = checkit (buf, 1, "%s:%d", "foobar", 9);
 140   VERIFY (status==8 && memcmp (buf, "\0XXXXXXXXXXXXX\0", 15) == 0);
 141
 142   CLEAR (buf);
 143   status = checkit (buf, 0, "%s:%d", "foobar", 9);
 144   VERIFY (status==8 && memcmp (buf, "XXXXXXXXXXXXXX\0", 15) == 0);
 145
 146   return 0;
 147 }
 148 #endif /* TEST */