WAMR enable file system access

[m1cha1s]

Has anybody attempted to allow WASI file access when embedding WAMR in C/C++ code? Because when i try to run a simple Rust program that opens a file and reads its contents compiled with: cargo build --target wasm32-wasi. Error message when trying to run it: thread 'main' panicked at 'couldn't open test.txt: failed to find a pre-opened file descriptor through which "test.txt" could be opened', src/main.rs:10:21 note: run with RUST_BACKTRACE=1 environment variable to display a backtrace

Source files:

• test.cpp
• main.rs

[loganek]

@m1cha1s unfortunately your test.cpp only contains Hello world text.
Answering your question: your WASM code runs in sandboxing environment, therefore any I/O access must be explicitly granted. To enable access to specific directories, you can use the wasm_runtime_set_wasi_args (second argument in that function is a list of directories that should be allowed, and the third one is the size of the list).

[m1cha1s]

@loganek thank you for the answer. I didn't find that function. It would be nice if there was a file access example, or the wasm_runtime_set_wasi_args description had some file access part or something.

[wenyongh]

@m1cha1s WASI is built using capability-based security principles, to access the file under the folder, normally we should grant the acess privileges for the folder. For the iwasm built under product-mini/platforms/linux/build, we can use iwasm --dir=<dir1> --dir=<dir2> ... <wasm file>. For the usage of wasm_runtime_set_wasi_args, please refer to:
https://github.com/bytecodealliance/wasm-micro-runtime/blob/main/product-mini/platforms/posix/main.c#L554-L555
Thanks.