libc-bottom-half/sources/environ.c

   1 #include <unistd.h>
   2 #include <stdlib.h>
   3 #include <sysexits.h>
   4 #include <wasi/api.h>
   5 #include <wasi/libc.h>
   6 #include <wasi/libc-environ.h>
   7
   8 // If the program does use `environ`, it'll get this version of
   9 // `__wasilibc_environ`, which is initialized with a constructor function, so
  10 // that it's initialized whenever user code might want to access it.
  11 char **__wasilibc_environ;
  12 extern __typeof(__wasilibc_environ) _environ
  13     __attribute__((weak, alias("__wasilibc_environ")));
  14 extern __typeof(__wasilibc_environ) environ
  15     __attribute__((weak, alias("__wasilibc_environ")));
  16
  17 // We define this function here in the same source file as
  18 // `__wasilibc_environ`, so that this function is called in iff environment
  19 // variable support is used.
  20 // Concerning the 50 -- levels up to 100 are reserved for the implementation,
  21 // so we an arbitrary number in the middle of the range to allow other
  22 // reserved things to go before or after.
  23 __attribute__((constructor(50)))
  24 static void __wasilibc_initialize_environ_eagerly(void) {
  25     __wasilibc_initialize_environ();
  26 }