lib/c-vasnprintf.h

   1 /* vsprintf with automatic memory allocation in C locale.
   2    Copyright (C) 2002-2004, 2007-2019 Free Software Foundation, Inc.
   3
   4    This program is free software; you can redistribute it and/or modify
   5    it under the terms of the GNU General Public License as published by
   6    the Free Software Foundation; either version 3, or (at your option)
   7    any later version.
   8
   9    This program is distributed in the hope that it will be useful,
  10    but WITHOUT ANY WARRANTY; without even the implied warranty of
  11    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  12    GNU General Public License for more details.
  13
  14    You should have received a copy of the GNU General Public License along
  15    with this program; if not, see <https://www.gnu.org/licenses/>.  */
  16
  17 #ifndef _C_VASNPRINTF_H
  18 #define _C_VASNPRINTF_H
  19
  20 /* Get va_list.  */
  21 #include <stdarg.h>
  22
  23 /* Get size_t.  */
  24 #include <stddef.h>
  25
  26 /* The __attribute__ feature is available in gcc versions 2.5 and later.
  27    The __-protected variants of the attributes 'format' and 'printf' are
  28    accepted by gcc versions 2.6.4 (effectively 2.7) and later.
  29    We enable _GL_ATTRIBUTE_FORMAT only if these are supported too, because
  30    gnulib and libintl do '#define printf __printf__' when they override
  31    the 'printf' function.  */
  32 #if __GNUC__ > 2 || (__GNUC__ == 2 && __GNUC_MINOR__ >= 7)
  33 # define _GL_ATTRIBUTE_FORMAT(spec) __attribute__ ((__format__ spec))
  34 #else
  35 # define _GL_ATTRIBUTE_FORMAT(spec) /* empty */
  36 #endif
  37
  38 #ifdef __cplusplus
  39 extern "C" {
  40 #endif
  41
  42 /* Write formatted output to a string dynamically allocated with malloc().
  43    You can pass a preallocated buffer for the result in RESULTBUF and its
  44    size in *LENGTHP; otherwise you pass RESULTBUF = NULL.
  45    If successful, return the address of the string (this may be = RESULTBUF
  46    if no dynamic memory allocation was necessary) and set *LENGTHP to the
  47    number of resulting bytes, excluding the trailing NUL.  Upon error, set
  48    errno and return NULL.
  49
  50    When dynamic memory allocation occurs, the preallocated buffer is left
  51    alone (with possibly modified contents).  This makes it possible to use
  52    a statically allocated or stack-allocated buffer, like this:
  53
  54           char buf[100];
  55           size_t len = sizeof (buf);
  56           char *output = vasnprintf (buf, &len, format, args);
  57           if (output == NULL)
  58             ... error handling ...;
  59           else
  60             {
  61               ... use the output string ...;
  62               if (output != buf)
  63                 free (output);
  64             }
  65
  66    Formatting takes place in the C locale, that is, the decimal point used in
  67    floating-point formatting directives is always '.'.
  68   */
  69 extern char *c_vasnprintf (char *resultbuf, size_t *lengthp, const char *format, va_list args)
  70        _GL_ATTRIBUTE_FORMAT ((__printf__, 3, 0));
  71
  72 #ifdef __cplusplus
  73 }
  74 #endif
  75
  76 #endif /* _C_VASNPRINTF_H */