asprintf.h

   1 /* https://git.datadissipation.net */
   2 #ifndef ASPRINTF_H_
   3  #define ASPRINTF_H_ 1
   4
   5  #ifdef ASPRINTF_INCLUDE_LIBC_
   6   #include <stdarg.h>
   7   #include <stdio.h>
   8   #include <stdlib.h>
   9  #endif
  10
  11  #ifndef HAVE_ASPRINTF
  12   int vasprintf_(char **strp, const char *fmt, va_list ap);
  13   int asprintf_(char **strp, const char *fmt, ...);
  14   /*
  15    * Credit for a big part of the macro madness:
  16    * Jens Gustedt
  17    * https://gustedt.wordpress.com/2010/06/08/detect-empty-macro-arguments/
  18    */
  19   #define vasprintf(s, f, a)   vasprintf_(s, f, a)
  20   #define I_COND_COMMA_(...) ,
  21   #define I_PICK_ARG_(_1, _2, ARG, ...) ARG
  22   #define I_HAS_COMMA_(...) I_PICK_ARG_(__VA_ARGS__, 1, 0)
  23
  24   #define I_ISEMPTY_(...)                                                      \
  25   II_ISEMPTY_(                                                                 \
  26           /* test if there is just one argument, eventually an empty           \
  27           one */                                                               \
  28           I_HAS_COMMA_(__VA_ARGS__),                                           \
  29           /* test if I_COND_COMMA_ together with the argument                  \
  30           adds a comma */                                                      \
  31           I_HAS_COMMA_(I_COND_COMMA_ __VA_ARGS__),                             \
  32           /* test if the argument together with a parenthesis                  \
  33           adds a comma */                                                      \
  34           I_HAS_COMMA_(__VA_ARGS__ (/*empty*/)),                               \
  35           /* test if placing it between I_COND_COMMA_ and the                  \
  36           parenthesis adds a comma */                                          \
  37           I_HAS_COMMA_(I_COND_COMMA_ __VA_ARGS__ (/*empty*/))                  \
  38           )
  39
  40   #define I_PASTE5_(_0, _1, _2, _3, _4) _0 ## _1 ## _2 ## _3 ## _4
  41   #define II_ISEMPTY_(_0, _1, _2, _3)\
  42   I_HAS_COMMA_(I_PASTE5_(I_IS_EMPTY_CASE_, _0, _1, _2, _3))
  43   #define I_IS_EMPTY_CASE_0001 ,
  44
  45   #define II_PASTE_(a) I_EMPTY_##a
  46   #define I_PASTE_(a) II_PASTE_(a)
  47
  48   #define I_GET_ARG_(...) I_PICK_ARG_(__VA_ARGS__)
  49   #define asprintf(s, f, ...)\
  50   asprintf_(s, f I_PASTE_(I_ISEMPTY_(I_GET_ARG_(, , __VA_ARGS__))) __VA_ARGS__)
  51   #define I_EMPTY_1
  52   #define I_EMPTY_0 I_COND_COMMA_()
  53  #endif
  54
  55  #ifdef ASPRINTF_IMPLEMENTATION_
  56  int vasprintf_(char **strp, const char *fmt, va_list ap) {
  57          int size, ret;
  58          va_list tp;
  59
  60          va_copy(tp, ap);
  61          size = vsnprintf(NULL, 0, fmt, tp);
  62          va_end(tp);
  63
  64          if (size < 0) {
  65                  return -1;
  66          }
  67          *strp = malloc(size + 1);
  68          if (*strp == NULL) {
  69                  return -1;
  70          }
  71
  72          ret = vsnprintf(*strp, size + 1, fmt, ap);
  73          if (ret < 0) {
  74                  free(*strp);
  75                  return -1;
  76          }
  77
  78          return ret;
  79  }
  80
  81  int asprintf_(char **strp, const char *fmt, ...) {
  82          int ret;
  83          va_list ap;
  84
  85          va_start(ap, fmt);
  86          ret = vasprintf(strp, fmt, ap);
  87          va_end(ap);
  88
  89          return ret;
  90  }
  91  #endif
  92 #endif