Creates a pipe that feeds data between two file handles.
fd_pipe() function is used to create a pipe, which is a unidirectional communication channel that allows data to be transferred between two file handles. It creates a pair of file descriptors representing the read and write ends of the pipe.
;;; Pipes are bidirectional ;;; ;;; Opens a pipe with two file handles (@interface func (export "fd_pipe") (result $error (expected (tuple $fd $fd) (error $errno))) ) ```### Parameters - `ctx`: A mutable reference to the function environment. - `ro_fd1`: A wasm pointer to a `WasiFd` where the first file descriptor representing one end of the pipe will be written. - `ro_fd2`: A wasm pointer to a `WasiFd` where the second file descriptor representing the other end of the pipe will be written. ### Return Value The function returns an `Errno` value indicating the success or failure of the operation. If the operation is successful, it returns `Errno::Success`. Otherwise, it returns an appropriate `Errno` value. ### Logging This function has been instrumented with trace-level logging. It will log the following information: - `fd1`: The first file descriptor representing one end of the pipe. - `fd2`: The second file descriptor representing the other end of the pipe. ### Description The `fd_pipe()` function creates a pipe by performing the following steps: 1. It retrieves the memory view, file system state, and inodes from the WASI environment using the function context. 2. It creates a new `Pipe` using the `Pipe::channel()` function, which returns two objects representing the read and write ends of the pipe. 3. It creates two inodes for the pipe using the `create_inode_with_default_stat()` method of the file system state. Each inode is associated with one end of the pipe and has the type `Kind::Pipe`. 4. It creates two file descriptors for the pipe using the `create_fd()` method of the file system state. The file descriptors have the necessary rights and flags for reading and writing to the pipe. 5. It records the created file descriptors in the current span for logging purposes. 6. It writes the file descriptors to the memory locations specified by the `ro_fd1` and `ro_fd2` wasm pointers using the `write()` method. 7. It returns `Errno::Success` to indicate the successful creation of the pipe.