Force usage of a worker thread for stdin on all platforms #7058
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This commit is a follow-up to bytecodealliance#6833 to remove the `unix` module for handling stdio which sets stdin to nonblocking mode. I've just now discovered that on macOS at least configuring `O_NONBLOCK` for stdin affects the stdout/stderr descriptors too. This program for example will panic: fn main() { unsafe { let r = libc::fcntl( libc::STDIN_FILENO, libc::F_SETFL, libc::fcntl(libc::STDIN_FILENO, libc::F_GETFL) | libc::O_NONBLOCK, ); assert_eq!(r, 0); } loop { println!("hello"); } } It was originally assumed that updating the flags for stdin wouldn't affect anything else except Wasmtime, but because this looks to not be the case this commit removes the logic of registering stdin raw with Tokio and instead unconditionally using the worker thread solution which should work in all situations.
pchickey
approved these changes
Sep 18, 2023
|
Weird behavior by MacOS but nothing we can do about it. Worker thread solution ought to be good enough. Thanks for tracking this one down, its a weird one. |
eduardomourar
pushed a commit
to eduardomourar/wasmtime
that referenced
this pull request
Sep 22, 2023
…liance#7058) This commit is a follow-up to bytecodealliance#6833 to remove the `unix` module for handling stdio which sets stdin to nonblocking mode. I've just now discovered that on macOS at least configuring `O_NONBLOCK` for stdin affects the stdout/stderr descriptors too. This program for example will panic: fn main() { unsafe { let r = libc::fcntl( libc::STDIN_FILENO, libc::F_SETFL, libc::fcntl(libc::STDIN_FILENO, libc::F_GETFL) | libc::O_NONBLOCK, ); assert_eq!(r, 0); } loop { println!("hello"); } } It was originally assumed that updating the flags for stdin wouldn't affect anything else except Wasmtime, but because this looks to not be the case this commit removes the logic of registering stdin raw with Tokio and instead unconditionally using the worker thread solution which should work in all situations.
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This commit is a follow-up to #6833 to remove the
unixmodule for handling stdio which sets stdin to nonblocking mode. I've just now discovered that on macOS at least configuringO_NONBLOCKfor stdin affects the stdout/stderr descriptors too. This program for example will panic:It was originally assumed that updating the flags for stdin wouldn't affect anything else except Wasmtime, but because this looks to not be the case this commit removes the logic of registering stdin raw with Tokio and instead unconditionally using the worker thread solution which should work in all situations.