libiberty/vsnprintf.c

   1 /* Implement the vsnprintf function.
   2    Copyright (C) 2003-2023 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_list ap;
  99   va_start (ap, format);
 100   result = vsnprintf (s, n, format, ap);
 101   va_end (ap);
 102   return result;
 103 }
 104
 105 extern int main (void);
 106 int
 107 main (void)
 108 {
 109   char buf[128];
 110   int status;
 111
 112   CLEAR (buf);
 113   status = checkit (buf, 10, "%s:%d", "foobar", 9);
 114   VERIFY (status==8 && memcmp (buf, "foobar:9\0XXXXX\0", 15) == 0);
 115
 116   CLEAR (buf);
 117   status = checkit (buf, 9, "%s:%d", "foobar", 9);
 118   VERIFY (status==8 && memcmp (buf, "foobar:9\0XXXXX\0", 15) == 0);
 119
 120   CLEAR (buf);
 121   status = checkit (buf, 8, "%s:%d", "foobar", 9);
 122   VERIFY (status==8 && memcmp (buf, "foobar:\0XXXXXX\0", 15) == 0);
 123
 124   CLEAR (buf);
 125   status = checkit (buf, 7, "%s:%d", "foobar", 9);
 126   VERIFY (status==8 && memcmp (buf, "foobar\0XXXXXXX\0", 15) == 0);
 127
 128   CLEAR (buf);
 129   status = checkit (buf, 6, "%s:%d", "foobar", 9);
 130   VERIFY (status==8 && memcmp (buf, "fooba\0XXXXXXXX\0", 15) == 0);
 131
 132   CLEAR (buf);
 133   status = checkit (buf, 2, "%s:%d", "foobar", 9);
 134   VERIFY (status==8 && memcmp (buf, "f\0XXXXXXXXXXXX\0", 15) == 0);
 135
 136   CLEAR (buf);
 137   status = checkit (buf, 1, "%s:%d", "foobar", 9);
 138   VERIFY (status==8 && memcmp (buf, "\0XXXXXXXXXXXXX\0", 15) == 0);
 139
 140   CLEAR (buf);
 141   status = checkit (buf, 0, "%s:%d", "foobar", 9);
 142   VERIFY (status==8 && memcmp (buf, "XXXXXXXXXXXXXX\0", 15) == 0);
 143
 144   return 0;
 145 }
 146 #endif /* TEST */