c1fc1a00ea
[wasm] Fix Asyncify loop exit condition for normal return
Stop calling `asyncify_stop_unwind` when the main function returns
without any unwinding. In the era when Asyncify buffers were allocated
on the stack, the `top` and `end` fields were remained in the stack
space even after the main function returned, so buffer-overflow check in
the `asyncify_stop_unwind` function passed. But now, the `top` and `end`
fields are part of the jump buffer allocated on the heap and they are
deallocated with `free` when the corresponding VM tag is popped. So, the
buffer-overflow check in the `asyncify_stop_unwind` function failed when
the main fuction returned without any unwinding, and we have to break
the asyncify loop before calling `asyncify_stop_unwind`.
Related commit: bc46b12b12
55 lines
1.6 KiB
C
55 lines
1.6 KiB
C
#include "wasm/machine.h"
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#include "wasm/setjmp.h"
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#include "wasm/fiber.h"
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#include "wasm/asyncify.h"
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#include <stdlib.h>
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int rb_wasm_rt_start(int (main)(int argc, char **argv), int argc, char **argv) {
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int result;
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void *asyncify_buf;
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bool new_fiber_started = false;
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void *arg0 = NULL, *arg1 = NULL;
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void (*fiber_entry_point)(void *, void *) = NULL;
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while (1) {
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if (fiber_entry_point) {
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fiber_entry_point(arg0, arg1);
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} else {
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result = main(argc, argv);
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}
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extern void *rb_asyncify_unwind_buf;
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// Exit Asyncify loop if there is no unwound buffer, which
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// means that main function has returned normally.
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if (rb_asyncify_unwind_buf == NULL) {
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break;
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}
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// NOTE: it's important to call 'asyncify_stop_unwind' here instead in rb_wasm_handle_jmp_unwind
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// because unless that, Asyncify inserts another unwind check here and it unwinds to the root frame.
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asyncify_stop_unwind();
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if ((asyncify_buf = rb_wasm_handle_jmp_unwind()) != NULL) {
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asyncify_start_rewind(asyncify_buf);
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continue;
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}
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if ((asyncify_buf = rb_wasm_handle_scan_unwind()) != NULL) {
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asyncify_start_rewind(asyncify_buf);
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continue;
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}
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asyncify_buf = rb_wasm_handle_fiber_unwind(&fiber_entry_point, &arg0, &arg1, &new_fiber_started);
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// Newly starting fiber doesn't have asyncify buffer yet, so don't rewind it for the first time entry
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if (asyncify_buf) {
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asyncify_start_rewind(asyncify_buf);
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continue;
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} else if (new_fiber_started) {
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continue;
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}
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break;
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}
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return result;
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}
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