+#include <wasi/core.h>
+#include <wasi/libc.h>
+#include <stdlib.h>
+#include <sysexits.h>
+
+// The user's `main` function, expecting arguments.
+int main(int argc, char *argv[]);
+
+// If the user's `main` function expects arguments, the compiler won't emit
+// an `__original_main` function so this version will get linked in, which
+// initializes the argument data and calls `main`.
+int __original_main(void) {
+ __wasi_errno_t err;
+
+ // Get the sizes of the arrays we'll have to create to copy in the args.
+ size_t argv_buf_size;
+ size_t argc;
+ err = __wasi_args_sizes_get(&argc, &argv_buf_size);
+ if (err != __WASI_ESUCCESS) {
+ _Exit(EX_OSERR);
+ }
+
+ // Add 1 for the NULL pointer to mark the end, and check for overflow.
+ size_t num_ptrs = argc + 1;
+ if (num_ptrs == 0) {
+ _Exit(EX_SOFTWARE);
+ }
+
+ // Allocate memory for storing the argument chars.
+ char *argv_buf = malloc(argv_buf_size);
+ if (argv_buf == NULL) {
+ _Exit(EX_SOFTWARE);
+ }
+
+ // Allocate memory for the array of pointers. This uses `calloc` both to
+ // handle overflow and to initialize the NULL pointer at the end.
+ char **argv = calloc(num_ptrs, sizeof(char *));
+ if (argv == NULL) {
+ free(argv_buf);
+ _Exit(EX_SOFTWARE);
+ }
+
+ // Fill the argument chars, and the argv array with pointers into those chars.
+ err = __wasi_args_get(argv, argv_buf);
+ if (err != __WASI_ESUCCESS) {
+ free(argv_buf);
+ free(argv);
+ _Exit(EX_OSERR);
+ }
+
+ // Call main with the arguments!
+ return main(argc, argv);
+}