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gh-124621: Emscripten: Fix regression in use-after-close error handling #136837

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merged 1 commit into from
Jul 19, 2025
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gh-124621: Emscripten: Fix regression in use-after-close error handling #136837

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gh-124621: Emscripten: Fix regression in use-after-close error handling 
Introduced in GH-136822. If the fd is already closed,
`SYSCALLS.getStreamFromFD()` throws an error. We need to catch it and
discard it. The `__wasi_fd_read_orig()` fallback will use it to set errno.
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@hoodmane
hoodmane committed Jul 19, 2025
commit eea3a6084930f965d9e4e583d80f55bb064fd01c
9 changes: 8 additions & 1 deletion Python/emscripten_syscalls.c
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Original file line number Diff line number Diff line change
Expand Up @@ -148,10 +148,17 @@ EM_JS_MACROS(__externref_t, __maybe_fd_read_async, (
size_t iovcnt,
__wasi_size_t *nread
), {
var stream = SYSCALLS.getStreamFromFD(fd);
if (!WebAssembly.promising) {
return null;
}
var stream;
try {
stream = SYSCALLS.getStreamFromFD(fd);
} catch (e) {
// If the fd was already closed or never existed, getStreamFromFD()
// raises. We'll let fd_read_orig() handle setting errno.
return null;
}
if (!stream.stream_ops.readAsync) {
// Not an async device. Fall back to __wasi_fd_read_orig().
return null;
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