asprintf.h

   1 /*
   2  * This is free and unencumbered software released into the public domain.
   3  *
   4  * Anyone is free to copy, modify, publish, use, compile, sell, or
   5  * distribute this software, either in source code form or as a compiled
   6  * binary, for any purpose, commercial or non-commercial, and by any
   7  * means.
   8  *
   9  * In jurisdictions that recognize copyright laws, the author or authors
  10  * of this software dedicate any and all copyright interest in the
  11  * software to the public domain. We make this dedication for the benefit
  12  * of the public at large and to the detriment of our heirs and
  13  * successors. We intend this dedication to be an overt act of
  14  * relinquishment in perpetuity of all present and future rights to this
  15  * software under copyright law.
  16
  17  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
  18  * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
  19  * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.
  20  * IN NO EVENT SHALL THE AUTHORS BE LIABLE FOR ANY CLAIM, DAMAGES OR
  21  * OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
  22  * ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
  23  * OTHER DEALINGS IN THE SOFTWARE.
  24  *
  25  * For more information, please refer to <https://unlicense.org>
  26  */
  27
  28 /* https://git.datadissipation.net */
  29 #ifndef ASPRINTF_H_
  30  #define ASPRINTF_H_ 1
  31
  32  #ifdef ASPRINTF_INCLUDE_LIBC
  33   #include <stdarg.h>
  34   #include <stdio.h>
  35   #include <stdlib.h>
  36  #endif
  37
  38  #ifndef HAVE_ASPRINTF
  39   #define HAVE_ASPRINTF 1
  40   int i_vasprintf_(char **restrict strp, const char *restrict fmt, va_list ap);
  41   int i_asprintf_(char **restrict strp, const char *restrict fmt, ...);
  42   /*
  43    * Credit for a big part of the macro madness:
  44    * Jens Gustedt
  45    * https://gustedt.wordpress.com/2010/06/08/detect-empty-macro-arguments/
  46    */
  47
  48   /*
  49    * This isn't strict C99, because C99 requires at least one argument in "..."
  50    * for macros. Still, I haven't encountered a compiler that won't preprocess
  51    * this right (out of the popular ones, MSVC wasn't tested)
  52    */
  53   #define vasprintf(s, f, a)   i_vasprintf_(s, f, a)
  54   #define I_COND_COMMA_(...) ,
  55   #define I_PICK_ARG_(_1, _2, ARG, ...) ARG
  56   #define I_HAS_COMMA_(...) I_PICK_ARG_(__VA_ARGS__, 1, 0)
  57
  58   #define I_ISEMPTY_(...)                                                      \
  59   II_ISEMPTY_(                                                                 \
  60           /* test if there is just one argument, eventually an empty           \
  61           one */                                                               \
  62           I_HAS_COMMA_(__VA_ARGS__),                                           \
  63           /* test if I_COND_COMMA_ together with the argument                  \
  64           adds a comma */                                                      \
  65           I_HAS_COMMA_(I_COND_COMMA_ __VA_ARGS__),                             \
  66           /* test if the argument together with a parenthesis                  \
  67           adds a comma */                                                      \
  68           I_HAS_COMMA_(__VA_ARGS__ (/*empty*/)),                               \
  69           /* test if placing it between I_COND_COMMA_ and the                  \
  70           parenthesis adds a comma */                                          \
  71           I_HAS_COMMA_(I_COND_COMMA_ __VA_ARGS__ (/*empty*/))                  \
  72           )
  73
  74   #define I_PASTE5_(_0, _1, _2, _3, _4) _0 ## _1 ## _2 ## _3 ## _4
  75   #define II_ISEMPTY_(_0, _1, _2, _3)\
  76   I_HAS_COMMA_(I_PASTE5_(I_IS_EMPTY_CASE_, _0, _1, _2, _3))
  77   #define I_IS_EMPTY_CASE_0001 ,
  78
  79   #define II_PASTE_(a) I_EMPTY_##a
  80   #define I_PASTE_(a) II_PASTE_(a)
  81
  82   #define I_GET_ARG_(...) I_PICK_ARG_(__VA_ARGS__)
  83   #define asprintf(s, f, ...)\
  84   i_asprintf_(s, f I_PASTE_(I_ISEMPTY_(I_GET_ARG_(, , __VA_ARGS__))) __VA_ARGS__)
  85   #define I_EMPTY_1
  86   #define I_EMPTY_0 I_COND_COMMA_()
  87  #endif /* !HAVE_ASPRINTF */
  88
  89  #ifdef ASPRINTF_IMPLEMENTATION
  90  int
  91  i_vasprintf_(char **restrict strp, const char *restrict fmt, va_list ap)
  92  {
  93          int size, ret;
  94          va_list tp;
  95
  96          va_copy(tp, ap);
  97          size = vsnprintf(NULL, 0, fmt, tp);
  98          va_end(tp);
  99
 100          if (size < 0) {
 101                  return -1;
 102          }
 103          *strp = malloc(size + 1);
 104          if (*strp == NULL) {
 105                  return -1;
 106          }
 107
 108          ret = vsnprintf(*strp, size + 1, fmt, ap);
 109          if (ret < 0) {
 110                  free(*strp);
 111                  return -1;
 112          }
 113
 114          return ret;
 115  }
 116
 117  int
 118  i_asprintf_(char **restrict strp, const char *restrict fmt, ...)
 119  {
 120          int ret;
 121          va_list ap;
 122
 123          va_start(ap, fmt);
 124          ret = i_vasprintf_(strp, fmt, ap);
 125          va_end(ap);
 126
 127          return ret;
 128  }
 129  #endif /* ASPRINTF_IMPLEMENTATION */
 130 #endif /* !ASPRINTF_H_ */