wasi-libc/libc-bottom-half/crt/crt1.c

#include <stdlib.h>
#include <sysexits.h>
#include <wasi/core.h>
#include <wasi/libc.h>
#include <wasi/libc-internal.h>

__wasi_errno_t __wasilibc_populate_environ(void) __attribute__((weak));
extern void __wasm_call_ctors(void);
extern int __original_main(void);
extern void __prepare_for_exit(void);
void _Exit(int) __attribute__((noreturn));
__wasi_errno_t __wasilibc_populate_libpreopen(void) __attribute__((weak));

void _start(void) {
    // Record the preopened resources, if needed.
    if (&__wasilibc_populate_libpreopen != NULL &&
        __wasilibc_populate_libpreopen() != __WASI_ESUCCESS)
    {
        _Exit(EX_OSERR);
    }

    // Fill in the environment from WASI syscalls, if needed.
    if (&__wasilibc_populate_environ != NULL &&
        __wasilibc_populate_environ() != __WASI_ESUCCESS)
    {
        _Exit(EX_OSERR);
    }

    // The linker synthesizes this to call constructors.
    __wasm_call_ctors();

    // Call `__original_main` which will either be the application's
    // zero-argument `main` function (renamed by the compiler) or a libc
    // routine which populates `argv` and `argc` and calls the application's
    // two-argument `main`.
    int r = __original_main();

    // Call atexit functions, destructors, stdio cleanup, etc.
    __prepare_for_exit();

    // If main exited successfully, just return, otherwise call _Exit.
    if (r != 0) {
        _Exit(r);
    }
}