1#ifdef _REENTRANT
 2#include <stdatomic.h>
 3extern void __wasi_init_tp(void);
 4#endif
 5#ifdef __wasilibc_use_wasip2
 6#include <wasi/wasip2.h>
 7#else
 8#include <wasi/api.h>
 9#endif
10extern void __wasm_call_ctors(void);
11extern int __main_void(void);
12extern void __wasm_call_dtors(void);
13
14__attribute__((export_name("_start")))
15void _start(void) {
16    // Commands should only be called once per instance. This simple check
17    // ensures that the `_start` function isn't started more than once.
18    //
19    // We use `volatile` here to prevent the store to `started` from being
20    // sunk past any subsequent code, and to prevent any compiler from
21    // optimizing based on the knowledge that `_start` is the program
22    // entrypoint.
23#ifdef _REENTRANT
24    static volatile _Atomic int started = 0;
25    int expected = 0;
26    if (!atomic_compare_exchange_strong(&started, &expected, 1)) {
27        __builtin_trap();
28    }
29#else
30    static volatile int started = 0;
31    if (started != 0) {
32        __builtin_trap();
33    }
34    started = 1;
35#endif
36
37#ifdef _REENTRANT
38    __wasi_init_tp();
39#endif
40
41    // The linker synthesizes this to call constructors.
42    __wasm_call_ctors();
43
44    // Call `__main_void` which will either be the application's zero-argument
45    // `__main_void` function or a libc routine which obtains the command-line
46    // arguments and calls `__main_argv_argc`.
47    int r = __main_void();
48
49    // Call atexit functions, destructors, stdio cleanup, etc.
50    __wasm_call_dtors();
51
52    // If main exited successfully, just return, otherwise call
53    // `__wasi_proc_exit`.
54#ifdef __wasilibc_use_wasip2
55    if (r != 0) {
56        exit_result_void_void_t status = { .is_err = true };
57        exit_exit(&status);
58    }
59#else
60    if (r != 0) {
61        __wasi_proc_exit(r);
62    }
63#endif
64}