mirror of
https://github.com/fluencelabs/wasmer
synced 2024-12-14 22:55:40 +00:00
43 lines
1.6 KiB
Rust
43 lines
1.6 KiB
Rust
use super::env::get_emscripten_data;
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use libc::{c_int, c_void};
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use std::cell::UnsafeCell;
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use wasmer_runtime_core::vm::Ctx;
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/// setjmp
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pub extern "C" fn __setjmp(env_addr: u32, ctx: &mut Ctx) -> c_int {
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debug!("emscripten::__setjmp (setjmp)");
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unsafe {
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// Rather than using the env as the holder of the jump buffer pointer,
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// we use the environment address to store the index relative to jumps
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// so the address of the jump it's outside the wasm memory itself.
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let jump_index = ctx.memory(0)[env_addr as usize] as *mut i8;
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// We create the jump buffer outside of the wasm memory
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let jump_buf: UnsafeCell<[c_int; 27]> = UnsafeCell::new([0; 27]);
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let jumps = &mut get_emscripten_data(ctx).jumps;
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let result = setjmp(jump_buf.get() as _);
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// We set the jump index to be the last value of jumps
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*jump_index = jumps.len() as _;
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// We hold the reference of the jump buffer
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jumps.push(jump_buf);
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result
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}
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}
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/// longjmp
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pub extern "C" fn __longjmp(env_addr: u32, val: c_int, ctx: &mut Ctx) -> ! {
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debug!("emscripten::__longjmp (longmp)");
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unsafe {
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// We retrieve the jump index from the env address
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let jump_index = ctx.memory(0)[env_addr as usize] as *mut i8;
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let jumps = &mut get_emscripten_data(ctx).jumps;
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// We get the real jump buffer from the jumps vector, using the retrieved index
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let jump_buf = &jumps[*jump_index as usize];
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longjmp(jump_buf.get() as _, val)
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};
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}
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extern "C" {
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fn setjmp(env: *mut c_void) -> c_int;
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fn longjmp(env: *mut c_void, val: c_int) -> !;
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}
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