lib/c-vasnprintf.h

   1 /* vsprintf with automatic memory allocation in C locale.
   2    Copyright (C) 2002-2004, 2007-2020 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 #ifdef __cplusplus
  27 extern "C" {
  28 #endif
  29
  30 /* Write formatted output to a string dynamically allocated with malloc().
  31    You can pass a preallocated buffer for the result in RESULTBUF and its
  32    size in *LENGTHP; otherwise you pass RESULTBUF = NULL.
  33    If successful, return the address of the string (this may be = RESULTBUF
  34    if no dynamic memory allocation was necessary) and set *LENGTHP to the
  35    number of resulting bytes, excluding the trailing NUL.  Upon error, set
  36    errno and return NULL.
  37
  38    When dynamic memory allocation occurs, the preallocated buffer is left
  39    alone (with possibly modified contents).  This makes it possible to use
  40    a statically allocated or stack-allocated buffer, like this:
  41
  42           char buf[100];
  43           size_t len = sizeof (buf);
  44           char *output = vasnprintf (buf, &len, format, args);
  45           if (output == NULL)
  46             ... error handling ...;
  47           else
  48             {
  49               ... use the output string ...;
  50               if (output != buf)
  51                 free (output);
  52             }
  53
  54    Formatting takes place in the C locale, that is, the decimal point used in
  55    floating-point formatting directives is always '.'.
  56   */
  57 extern char *c_vasnprintf (char *restrict resultbuf, size_t *lengthp,
  58                            const char *format, va_list args)
  59        _GL_ATTRIBUTE_FORMAT ((__printf__, 3, 0));
  60
  61 #ifdef __cplusplus
  62 }
  63 #endif
  64
  65 #endif /* _C_VASNPRINTF_H */