54 lines
1.5 KiB
C
54 lines
1.5 KiB
C
#ifdef _REENTRANT
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#include <stdatomic.h>
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extern void __wasi_init_tp(void);
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#endif
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#include <wasi/api.h>
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extern void __wasm_call_ctors(void);
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extern int __main_void(void);
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extern void __wasm_call_dtors(void);
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__attribute__((export_name("_start")))
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void _start(void) {
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// Commands should only be called once per instance. This simple check
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// ensures that the `_start` function isn't started more than once.
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//
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// We use `volatile` here to prevent the store to `started` from being
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// sunk past any subsequent code, and to prevent any compiler from
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// optimizing based on the knowledge that `_start` is the program
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// entrypoint.
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#ifdef _REENTRANT
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static volatile _Atomic int started = 0;
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int expected = 0;
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if (!atomic_compare_exchange_strong(&started, &expected, 1)) {
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__builtin_trap();
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}
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#else
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static volatile int started = 0;
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if (started != 0) {
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__builtin_trap();
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}
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started = 1;
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#endif
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#ifdef _REENTRANT
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__wasi_init_tp();
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#endif
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// The linker synthesizes this to call constructors.
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__wasm_call_ctors();
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// Call `__main_void` which will either be the application's zero-argument
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// `__main_void` function or a libc routine which obtains the command-line
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// arguments and calls `__main_argv_argc`.
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int r = __main_void();
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// Call atexit functions, destructors, stdio cleanup, etc.
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__wasm_call_dtors();
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// If main exited successfully, just return, otherwise call
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// `__wasi_proc_exit`.
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if (r != 0) {
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__wasi_proc_exit(r);
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}
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}
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