Imports - Wasi — ContextQMD

<h1><a id="imports"></a>World imports</h1> <ul> <li>Imports: <ul> <li>interface <a href="#wasi_io_error_0_2_11"><code>wasi:io/[email protected]</code></a></li> <li>interface <a href="#wasi_io_poll_0_2_11"><code>wasi:io/[email protected]</code></a></li> <li>interface <a href="#wasi_io_streams_0_2_11"><code>wasi:io/[email protected]</code></a></li> <li>interface <a href="#wasi_clocks_wall_clock_0_2_11"><code>wasi:clocks/[email protected]</code></a></li> <li>interface <a href="#wasi_filesystem_types_0_2_11"><code>wasi:filesystem/[email protected]</code></a></li> <li>interface <a href="#wasi_filesystem_preopens_0_2_11"><code>wasi:filesystem/[email protected]</code></a></li> </ul> </li> </ul> <h2><a id="wasi_io_error_0_2_11"></a>Import interface wasi:io/[email protected]</h2> <hr /> <h3>Types</h3> <h4><a id="error"></a><code>resource error</code></h4> <p>A resource which represents some error information.</p> <p>The only method provided by this resource is <code>to-debug-string</code>, which provides some human-readable information about the error.</p> <p>In the <code>wasi:io</code> package, this resource is returned through the <code>wasi:io/streams.stream-error</code> type.</p> <p>To provide more specific error information, other interfaces may offer functions to "downcast" this error into more specific types. For example, errors returned from streams derived from filesystem types can be described using the filesystem's own error-code type. This is done using the function <code>wasi:filesystem/types.filesystem-error-code</code>, which takes a <code>borrow<error></code> parameter and returns an <code>option<wasi:filesystem/types.error-code></code>.</p> <h2>The set of functions which can "downcast" an <a href="#error"><code>error</code></a> into a more concrete type is open.</h2> <h3>Functions</h3> <h4><a id="method_error_to_debug_string"></a><code>[method]error.to-debug-string: func</code></h4> <p>Returns a string that is suitable to assist humans in debugging this error.</p> <p>WARNING: The returned string should not be consumed mechanically! It may change across platforms, hosts, or other implementation details. Parsing this string is a major platform-compatibility hazard.</p> <h5>Params</h5> <ul> <li><a id="method_error_to_debug_string.self"></a><code>self</code>: borrow<<a href="#error"><a href="#error"><code>error</code></a></a>></li> </ul> <h5>Return values</h5> <ul> <li><a id="method_error_to_debug_string.0"></a> <code>string</code></li> </ul> <h2><a id="wasi_io_poll_0_2_11"></a>Import interface wasi:io/[email protected]</h2> <p>A poll API intended to let users wait for I/O events on multiple handles at once.</p> <hr /> <h3>Types</h3> <h4><a id="pollable"></a><code>resource pollable</code></h4> <h2><a href="#pollable"><code>pollable</code></a> represents a single I/O event which may be ready, or not.</h2> <h3>Functions</h3> <h4><a id="method_pollable_ready"></a><code>[method]pollable.ready: func</code></h4> <p>Return the readiness of a pollable. This function never blocks.</p> <p>Returns <code>true</code> when the pollable is ready, and <code>false</code> otherwise.</p> <h5>Params</h5> <ul> <li><a id="method_pollable_ready.self"></a><code>self</code>: borrow<<a href="#pollable"><a href="#pollable"><code>pollable</code></a></a>></li> </ul> <h5>Return values</h5> <ul> <li><a id="method_pollable_ready.0"></a> <code>bool</code></li> </ul> <h4><a id="method_pollable_block"></a><code>[method]pollable.block: func</code></h4> <p><code>block</code> returns immediately if the pollable is ready, and otherwise blocks until ready.</p> <p>This function is equivalent to calling <code>poll.poll</code> on a list containing only this pollable.</p> <h5>Params</h5> <ul> <li><a id="method_pollable_block.self"></a><code>self</code>: borrow<<a href="#pollable"><a href="#pollable"><code>pollable</code></a></a>></li> </ul> <h4><a id="poll"></a><code>poll: func</code></h4> <p>Poll for completion on a set of pollables.</p> <p>This function takes a list of pollables, which identify I/O sources of interest, and waits until one or more of the events is ready for I/O.</p> <p>The result <code>list<u32></code> contains one or more indices of handles in the argument list that is ready for I/O.</p> <p>This function traps if either:</p> <ul> <li>the list is empty, or:</li> <li>the list contains more elements than can be indexed with a <code>u32</code> value.</li> </ul> <p>A timeout can be implemented by adding a pollable from the wasi-clocks API to the list.</p> <p>This function does not return a <code>result</code>; polling in itself does not do any I/O so it doesn't fail. If any of the I/O sources identified by the pollables has an error, it is indicated by marking the source as being ready for I/O.</p> <h5>Params</h5> <ul> <li><a id="poll.in"></a><code>in</code>: list<borrow<<a href="#pollable"><a href="#pollable"><code>pollable</code></a></a>>></li> </ul> <h5>Return values</h5> <ul> <li><a id="poll.0"></a> list<<code>u32</code>></li> </ul> <h2><a id="wasi_io_streams_0_2_11"></a>Import interface wasi:io/[email protected]</h2> <p>WASI I/O is an I/O abstraction API which is currently focused on providing stream types.</p> <p>In the future, the component model is expected to add built-in stream types; when it does, they are expected to subsume this API.</p> <hr /> <h3>Types</h3> <h4><a id="error"></a><code>type error</code></h4> <p><a href="#error"><a href="#error"><code>error</code></a></a></p> <p> <h4><a id="pollable"></a><code>type pollable</code></h4> <p><a href="#pollable"><a href="#pollable"><code>pollable</code></a></a></p> <p> <h4><a id="stream_error"></a><code>variant stream-error</code></h4> <p>An error for input-stream and output-stream operations.</p> <h5>Variant Cases</h5> <ul> <li> <p><a id="stream_error.last_operation_failed"></a><code>last-operation-failed</code>: own<<a href="#error"><a href="#error"><code>error</code></a></a>></p> <p>The last operation (a write or flush) failed before completion. <p>More information is available in the <a href="#error"><code>error</code></a> payload.</p> <p>After this, the stream will be closed. All future operations return <a href="#stream_error.closed"><code>stream-error::closed</code></a>.</p> </li> <li> <p><a id="stream_error.closed"></a><code>closed</code></p> <p>The stream is closed: no more input will be accepted by the stream. A closed output-stream will return this error on all future operations. </li> </ul> <h4><a id="input_stream"></a><code>resource input-stream</code></h4> <p>An input bytestream.</p> <p><a href="#input_stream"><code>input-stream</code></a>s are <em>non-blocking</em> to the extent practical on underlying platforms. I/O operations always return promptly; if fewer bytes are promptly available than requested, they return the number of bytes promptly available, which could even be zero. To wait for data to be available, use the <code>subscribe</code> function to obtain a <a href="#pollable"><code>pollable</code></a> which can be polled for using <code>wasi:io/poll</code>.</p> <h4><a id="output_stream"></a><code>resource output-stream</code></h4> <p>An output bytestream.</p> <p><a href="#output_stream"><code>output-stream</code></a>s are <em>non-blocking</em> to the extent practical on underlying platforms. Except where specified otherwise, I/O operations also always return promptly, after the number of bytes that can be written promptly, which could even be zero. To wait for the stream to be ready to accept data, the <code>subscribe</code> function to obtain a <a href="#pollable"><code>pollable</code></a> which can be polled for using <code>wasi:io/poll</code>.</p> <h2>Dropping an <a href="#output_stream"><code>output-stream</code></a> while there's still an active write in progress may result in the data being lost. Before dropping the stream, be sure to fully flush your writes.</h2> <h3>Functions</h3> <h4><a id="method_input_stream_read"></a><code>[method]input-stream.read: func</code></h4> <p>Perform a non-blocking read from the stream.</p> <p>When the source of a <code>read</code> is binary data, the bytes from the source are returned verbatim. When the source of a <code>read</code> is known to the implementation to be text, bytes containing the UTF-8 encoding of the text are returned.</p> <p>This function returns a list of bytes containing the read data, when successful. The returned list will contain up to <code>len</code> bytes; it may return fewer than requested, but not more. The list is empty when no bytes are available for reading at this time. The pollable given by <code>subscribe</code> will be ready when more bytes are available.</p> <p>This function fails with a <a href="#stream_error"><code>stream-error</code></a> when the operation encounters an error, giving <code>last-operation-failed</code>, or when the stream is closed, giving <code>closed</code>.</p> <p>When the caller gives a <code>len</code> of 0, it represents a request to read 0 bytes. If the stream is still open, this call should succeed and return an empty list, or otherwise fail with <code>closed</code>.</p> <p>The <code>len</code> parameter is a <code>u64</code>, which could represent a list of u8 which is not possible to allocate in wasm32, or not desirable to allocate as as a return value by the callee. The callee may return a list of bytes less than <code>len</code> in size while more bytes are available for reading.</p> <h5>Params</h5> <ul> <li><a id="method_input_stream_read.self"></a><code>self</code>: borrow<<a href="#input_stream"><a href="#input_stream"><code>input-stream</code></a></a>></li> <li><a id="method_input_stream_read.len"></a><code>len</code>: <code>u64</code></li> </ul> <h5>Return values</h5> <ul> <li><a id="method_input_stream_read.0"></a> result<list<<code>u8</code>>, <a href="#stream_error"><a href="#stream_error"><code>stream-error</code></a></a>></li> </ul> <h4><a id="method_input_stream_blocking_read"></a><code>[method]input-stream.blocking-read: func</code></h4> <p>Read bytes from a stream, after blocking until at least one byte can be read. Except for blocking, behavior is identical to <code>read</code>.</p> <h5>Params</h5> <ul> <li><a id="method_input_stream_blocking_read.self"></a><code>self</code>: borrow<<a href="#input_stream"><a href="#input_stream"><code>input-stream</code></a></a>></li> <li><a id="method_input_stream_blocking_read.len"></a><code>len</code>: <code>u64</code></li> </ul> <h5>Return values</h5> <ul> <li><a id="method_input_stream_blocking_read.0"></a> result<list<<code>u8</code>>, <a href="#stream_error"><a href="#stream_error"><code>stream-error</code></a></a>></li> </ul> <h4><a id="method_input_stream_skip"></a><code>[method]input-stream.skip: func</code></h4> <p>Skip bytes from a stream. Returns number of bytes skipped.</p> <p>Behaves identical to <code>read</code>, except instead of returning a list of bytes, returns the number of bytes consumed from the stream.</p> <h5>Params</h5> <ul> <li><a id="method_input_stream_skip.self"></a><code>self</code>: borrow<<a href="#input_stream"><a href="#input_stream"><code>input-stream</code></a></a>></li> <li><a id="method_input_stream_skip.len"></a><code>len</code>: <code>u64</code></li> </ul> <h5>Return values</h5> <ul> <li><a id="method_input_stream_skip.0"></a> result<<code>u64</code>, <a href="#stream_error"><a href="#stream_error"><code>stream-error</code></a></a>></li> </ul> <h4><a id="method_input_stream_blocking_skip"></a><code>[method]input-stream.blocking-skip: func</code></h4> <p>Skip bytes from a stream, after blocking until at least one byte can be skipped. Except for blocking behavior, identical to <code>skip</code>.</p> <h5>Params</h5> <ul> <li><a id="method_input_stream_blocking_skip.self"></a><code>self</code>: borrow<<a href="#input_stream"><a href="#input_stream"><code>input-stream</code></a></a>></li> <li><a id="method_input_stream_blocking_skip.len"></a><code>len</code>: <code>u64</code></li> </ul> <h5>Return values</h5> <ul> <li><a id="method_input_stream_blocking_skip.0"></a> result<<code>u64</code>, <a href="#stream_error"><a href="#stream_error"><code>stream-error</code></a></a>></li> </ul> <h4><a id="method_input_stream_subscribe"></a><code>[method]input-stream.subscribe: func</code></h4> <p>Create a <a href="#pollable"><code>pollable</code></a> which will resolve once either the specified stream has bytes available to read or the other end of the stream has been closed. The created <a href="#pollable"><code>pollable</code></a> is a child resource of the <a href="#input_stream"><code>input-stream</code></a>. Implementations may trap if the <a href="#input_stream"><code>input-stream</code></a> is dropped before all derived <a href="#pollable"><code>pollable</code></a>s created with this function are dropped.</p> <h5>Params</h5> <ul> <li><a id="method_input_stream_subscribe.self"></a><code>self</code>: borrow<<a href="#input_stream"><a href="#input_stream"><code>input-stream</code></a></a>></li> </ul> <h5>Return values</h5> <ul> <li><a id="method_input_stream_subscribe.0"></a> own<<a href="#pollable"><a href="#pollable"><code>pollable</code></a></a>></li> </ul> <h4><a id="method_output_stream_check_write"></a><code>[method]output-stream.check-write: func</code></h4> <p>Check readiness for writing. This function never blocks.</p> <p>Returns the number of bytes permitted for the next call to <code>write</code>, or an error. Calling <code>write</code> with more bytes than this function has permitted will trap.</p> <p>When this function returns 0 bytes, the <code>subscribe</code> pollable will become ready when this function will report at least 1 byte, or an error.</p> <h5>Params</h5> <ul> <li><a id="method_output_stream_check_write.self"></a><code>self</code>: borrow<<a href="#output_stream"><a href="#output_stream"><code>output-stream</code></a></a>></li> </ul> <h5>Return values</h5> <ul> <li><a id="method_output_stream_check_write.0"></a> result<<code>u64</code>, <a href="#stream_error"><a href="#stream_error"><code>stream-error</code></a></a>></li> </ul> <h4><a id="method_output_stream_write"></a><code>[method]output-stream.write: func</code></h4> <p>Perform a write. This function never blocks.</p> <p>When the destination of a <code>write</code> is binary data, the bytes from <code>contents</code> are written verbatim. When the destination of a <code>write</code> is known to the implementation to be text, the bytes of <code>contents</code> are transcoded from UTF-8 into the encoding of the destination and then written.</p> <p>Precondition: check-write gave permit of Ok(n) and contents has a length of less than or equal to n. Otherwise, this function will trap.</p> <p>returns Err(closed) without writing if the stream has closed since the last call to check-write provided a permit.</p> <h5>Params</h5> <ul> <li><a id="method_output_stream_write.self"></a><code>self</code>: borrow<<a href="#output_stream"><a href="#output_stream"><code>output-stream</code></a></a>></li> <li><a id="method_output_stream_write.contents"></a><code>contents</code>: list<<code>u8</code>></li> </ul> <h5>Return values</h5> <ul> <li><a id="method_output_stream_write.0"></a> result<_, <a href="#stream_error"><a href="#stream_error"><code>stream-error</code></a></a>></li> </ul> <h4><a id="method_output_stream_blocking_write_and_flush"></a><code>[method]output-stream.blocking-write-and-flush: func</code></h4> <p>Perform a write of up to 4096 bytes, and then flush the stream. Block until all of these operations are complete, or an error occurs.</p> <p>Returns success when all of the contents written are successfully flushed to output. If an error occurs at any point before all contents are successfully flushed, that error is returned as soon as possible. If writing and flushing the complete contents causes the stream to become closed, this call should return success, and subsequent calls to check-write or other interfaces should return stream-error::closed.</p> <h5>Params</h5> <ul> <li><a id="method_output_stream_blocking_write_and_flush.self"></a><code>self</code>: borrow<<a href="#output_stream"><a href="#output_stream"><code>output-stream</code></a></a>></li> <li><a id="method_output_stream_blocking_write_and_flush.contents"></a><code>contents</code>: list<<code>u8</code>></li> </ul> <h5>Return values</h5> <ul> <li><a id="method_output_stream_blocking_write_and_flush.0"></a> result<_, <a href="#stream_error"><a href="#stream_error"><code>stream-error</code></a></a>></li> </ul> <h4><a id="method_output_stream_flush"></a><code>[method]output-stream.flush: func</code></h4> <p>Request to flush buffered output. This function never blocks.</p> <p>This tells the output-stream that the caller intends any buffered output to be flushed. the output which is expected to be flushed is all that has been passed to <code>write</code> prior to this call.</p> <p>Upon calling this function, the <a href="#output_stream"><code>output-stream</code></a> will not accept any writes (<code>check-write</code> will return <code>ok(0)</code>) until the flush has completed. The <code>subscribe</code> pollable will become ready when the flush has completed and the stream can accept more writes.</p> <h5>Params</h5> <ul> <li><a id="method_output_stream_flush.self"></a><code>self</code>: borrow<<a href="#output_stream"><a href="#output_stream"><code>output-stream</code></a></a>></li> </ul> <h5>Return values</h5> <ul> <li><a id="method_output_stream_flush.0"></a> result<_, <a href="#stream_error"><a href="#stream_error"><code>stream-error</code></a></a>></li> </ul> <h4><a id="method_output_stream_blocking_flush"></a><code>[method]output-stream.blocking-flush: func</code></h4> <p>Request to flush buffered output, and block until flush completes and stream is ready for writing again.</p> <h5>Params</h5> <ul> <li><a id="method_output_stream_blocking_flush.self"></a><code>self</code>: borrow<<a href="#output_stream"><a href="#output_stream"><code>output-stream</code></a></a>></li> </ul> <h5>Return values</h5> <ul> <li><a id="method_output_stream_blocking_flush.0"></a> result<_, <a href="#stream_error"><a href="#stream_error"><code>stream-error</code></a></a>></li> </ul> <h4><a id="method_output_stream_subscribe"></a><code>[method]output-stream.subscribe: func</code></h4> <p>Create a <a href="#pollable"><code>pollable</code></a> which will resolve once the output-stream is ready for more writing, or an error has occurred. When this pollable is ready, <code>check-write</code> will return <code>ok(n)</code> with n>0, or an error.</p> <p>If the stream is closed, this pollable is always ready immediately.</p> <p>The created <a href="#pollable"><code>pollable</code></a> is a child resource of the <a href="#output_stream"><code>output-stream</code></a>. Implementations may trap if the <a href="#output_stream"><code>output-stream</code></a> is dropped before all derived <a href="#pollable"><code>pollable</code></a>s created with this function are dropped.</p> <h5>Params</h5> <ul> <li><a id="method_output_stream_subscribe.self"></a><code>self</code>: borrow<<a href="#output_stream"><a href="#output_stream"><code>output-stream</code></a></a>></li> </ul> <h5>Return values</h5> <ul> <li><a id="method_output_stream_subscribe.0"></a> own<<a href="#pollable"><a href="#pollable"><code>pollable</code></a></a>></li> </ul> <h4><a id="method_output_stream_write_zeroes"></a><code>[method]output-stream.write-zeroes: func</code></h4> <p>Write zeroes to a stream.</p> <p>This should be used precisely like <code>write</code> with the exact same preconditions (must use check-write first), but instead of passing a list of bytes, you simply pass the number of zero-bytes that should be written.</p> <h5>Params</h5> <ul> <li><a id="method_output_stream_write_zeroes.self"></a><code>self</code>: borrow<<a href="#output_stream"><a href="#output_stream"><code>output-stream</code></a></a>></li> <li><a id="method_output_stream_write_zeroes.len"></a><code>len</code>: <code>u64</code></li> </ul> <h5>Return values</h5> <ul> <li><a id="method_output_stream_write_zeroes.0"></a> result<_, <a href="#stream_error"><a href="#stream_error"><code>stream-error</code></a></a>></li> </ul> <h4><a id="method_output_stream_blocking_write_zeroes_and_flush"></a><code>[method]output-stream.blocking-write-zeroes-and-flush: func</code></h4> <p>Perform a write of up to 4096 zeroes, and then flush the stream. Block until all of these operations are complete, or an error occurs.</p> <p>Functionality is equivelant to <code>blocking-write-and-flush</code> with contents given as a list of len containing only zeroes.</p> <h5>Params</h5> <ul> <li><a id="method_output_stream_blocking_write_zeroes_and_flush.self"></a><code>self</code>: borrow<<a href="#output_stream"><a href="#output_stream"><code>output-stream</code></a></a>></li> <li><a id="method_output_stream_blocking_write_zeroes_and_flush.len"></a><code>len</code>: <code>u64</code></li> </ul> <h5>Return values</h5> <ul> <li><a id="method_output_stream_blocking_write_zeroes_and_flush.0"></a> result<_, <a href="#stream_error"><a href="#stream_error"><code>stream-error</code></a></a>></li> </ul> <h4><a id="method_output_stream_splice"></a><code>[method]output-stream.splice: func</code></h4> <p>Read from one stream and write to another.</p> <p>The behavior of splice is equivalent to:</p> <ol> <li>calling <code>check-write</code> on the <a href="#output_stream"><code>output-stream</code></a></li> <li>calling <code>read</code> on the <a href="#input_stream"><code>input-stream</code></a> with the smaller of the <code>check-write</code> permitted length and the <code>len</code> provided to <code>splice</code></li> <li>calling <code>write</code> on the <a href="#output_stream"><code>output-stream</code></a> with that read data.</li> </ol> <p>Any error reported by the call to <code>check-write</code>, <code>read</code>, or <code>write</code> ends the splice and reports that error.</p> <p>This function returns the number of bytes transferred; it may be less than <code>len</code>.</p> <h5>Params</h5> <ul> <li><a id="method_output_stream_splice.self"></a><code>self</code>: borrow<<a href="#output_stream"><a href="#output_stream"><code>output-stream</code></a></a>></li> <li><a id="method_output_stream_splice.src"></a><code>src</code>: borrow<<a href="#input_stream"><a href="#input_stream"><code>input-stream</code></a></a>></li> <li><a id="method_output_stream_splice.len"></a><code>len</code>: <code>u64</code></li> </ul> <h5>Return values</h5> <ul> <li><a id="method_output_stream_splice.0"></a> result<<code>u64</code>, <a href="#stream_error"><a href="#stream_error"><code>stream-error</code></a></a>></li> </ul> <h4><a id="method_output_stream_blocking_splice"></a><code>[method]output-stream.blocking-splice: func</code></h4> <p>Read from one stream and write to another, with blocking.</p> <p>This is similar to <code>splice</code>, except that it blocks until the <a href="#output_stream"><code>output-stream</code></a> is ready for writing, and the <a href="#input_stream"><code>input-stream</code></a> is ready for reading, before performing the <code>splice</code>.</p> <h5>Params</h5> <ul> <li><a id="method_output_stream_blocking_splice.self"></a><code>self</code>: borrow<<a href="#output_stream"><a href="#output_stream"><code>output-stream</code></a></a>></li> <li><a id="method_output_stream_blocking_splice.src"></a><code>src</code>: borrow<<a href="#input_stream"><a href="#input_stream"><code>input-stream</code></a></a>></li> <li><a id="method_output_stream_blocking_splice.len"></a><code>len</code>: <code>u64</code></li> </ul> <h5>Return values</h5> <ul> <li><a id="method_output_stream_blocking_splice.0"></a> result<<code>u64</code>, <a href="#stream_error"><a href="#stream_error"><code>stream-error</code></a></a>></li> </ul> <h2><a id="wasi_clocks_wall_clock_0_2_11"></a>Import interface wasi:clocks/[email protected]</h2> <p>WASI Wall Clock is a clock API intended to let users query the current time. The name "wall" makes an analogy to a "clock on the wall", which is not necessarily monotonic as it may be reset.</p> <p>It is intended to be portable at least between Unix-family platforms and Windows.</p> <p>A wall clock is a clock which measures the date and time according to some external reference.</p> <p>External references may be reset, so this clock is not necessarily monotonic, making it unsuitable for measuring elapsed time.</p> <p>It is intended for reporting the current date and time for humans.</p> <hr /> <h3>Types</h3> <h4><a id="datetime"></a><code>record datetime</code></h4> <p>A time and date in seconds plus nanoseconds.</p> <h5>Record Fields</h5> <ul> <li><a id="datetime.seconds"></a><code>seconds</code>: <code>u64</code></li> <li><a id="datetime.nanoseconds"></a><code>nanoseconds</code>: <code>u32</code></li> </ul> <hr /> <h3>Functions</h3> <h4><a id="now"></a><code>now: func</code></h4> <p>Read the current value of the clock.</p> <p>This clock is not monotonic, therefore calling this function repeatedly will not necessarily produce a sequence of non-decreasing values.</p> <p>The returned timestamps represent the number of seconds since 1970-01-01T00:00:00Z, also known as <a href="https://pubs.opengroup.org/onlinepubs/9699919799/xrat/V4_xbd_chap04.html#tag_21_04_16">POSIX's Seconds Since the Epoch</a>, also known as <a href="https://en.wikipedia.org/wiki/Unix_time">Unix Time</a>.</p> <p>The nanoseconds field of the output is always less than 1000000000.</p> <h5>Return values</h5> <ul> <li><a id="now.0"></a> <a href="#datetime"><a href="#datetime"><code>datetime</code></a></a></li> </ul> <h4><a id="resolution"></a><code>resolution: func</code></h4> <p>Query the resolution of the clock.</p> <p>The nanoseconds field of the output is always less than 1000000000.</p> <h5>Return values</h5> <ul> <li><a id="resolution.0"></a> <a href="#datetime"><a href="#datetime"><code>datetime</code></a></a></li> </ul> <h2><a id="wasi_filesystem_types_0_2_11"></a>Import interface wasi:filesystem/[email protected]</h2> <p>WASI filesystem is a filesystem API primarily intended to let users run WASI programs that access their files on their existing filesystems, without significant overhead.</p> <p>It is intended to be roughly portable between Unix-family platforms and Windows, though it does not hide many of the major differences.</p> <p>Paths are passed as interface-type <code>string</code>s, meaning they must consist of a sequence of Unicode Scalar Values (USVs). Some filesystems may contain paths which are not accessible by this API.</p> <p>The directory separator in WASI is always the forward-slash (<code>/</code>).</p> <p>All paths in WASI are relative paths, and are interpreted relative to a <a href="#descriptor"><code>descriptor</code></a> referring to a base directory. If a <code>path</code> argument to any WASI function starts with <code>/</code>, or if any step of resolving a <code>path</code>, including <code>..</code> and symbolic link steps, reaches a directory outside of the base directory, or reaches a symlink to an absolute or rooted path in the underlying filesystem, the function fails with <a href="#error_code.not_permitted"><code>error-code::not-permitted</code></a>.</p> <p>For more information about WASI path resolution and sandboxing, see <a href="https://github.com/WebAssembly/wasi-filesystem/blob/main/path-resolution.md">WASI filesystem path resolution</a>.</p> <hr /> <h3>Types</h3> <h4><a id="input_stream"></a><code>type input-stream</code></h4> <p><a href="#input_stream"><a href="#input_stream"><code>input-stream</code></a></a></p> <p> <h4><a id="output_stream"></a><code>type output-stream</code></h4> <p><a href="#output_stream"><a href="#output_stream"><code>output-stream</code></a></a></p> <p> <h4><a id="error"></a><code>type error</code></h4> <p><a href="#error"><a href="#error"><code>error</code></a></a></p> <p> <h4><a id="datetime"></a><code>type datetime</code></h4> <p><a href="#datetime"><a href="#datetime"><code>datetime</code></a></a></p> <p> <h4><a id="filesize"></a><code>type filesize</code></h4> <p><code>u64</code></p> <p>File size or length of a region within a file. <h4><a id="descriptor_type"></a><code>enum descriptor-type</code></h4> <p>The type of a filesystem object referenced by a descriptor.</p> <p>Note: This was called <code>filetype</code> in earlier versions of WASI.</p> <h5>Enum Cases</h5> <ul> <li> <p><a id="descriptor_type.unknown"></a><code>unknown</code></p> <p>The type of the descriptor or file is unknown or is different from any of the other types specified. </li> <li> <p><a id="descriptor_type.block_device"></a><code>block-device</code></p> <p>The descriptor refers to a block device inode. </li> <li> <p><a id="descriptor_type.character_device"></a><code>character-device</code></p> <p>The descriptor refers to a character device inode. </li> <li> <p><a id="descriptor_type.directory"></a><code>directory</code></p> <p>The descriptor refers to a directory inode. </li> <li> <p><a id="descriptor_type.fifo"></a><code>fifo</code></p> <p>The descriptor refers to a named pipe. </li> <li> <p><a id="descriptor_type.symbolic_link"></a><code>symbolic-link</code></p> <p>The file refers to a symbolic link inode. </li> <li> <p><a id="descriptor_type.regular_file"></a><code>regular-file</code></p> <p>The descriptor refers to a regular file inode. </li> <li> <p><a id="descriptor_type.socket"></a><code>socket</code></p> <p>The descriptor refers to a socket. </li> </ul> <h4><a id="descriptor_flags"></a><code>flags descriptor-flags</code></h4> <p>Descriptor flags.</p> <p>Note: This was called <code>fdflags</code> in earlier versions of WASI.</p> <h5>Flags members</h5> <ul> <li> <p><a id="descriptor_flags.read"></a><code>read</code>: </p> <p>Read mode: Data can be read. </li> <li> <p><a id="descriptor_flags.write"></a><code>write</code>: </p> <p>Write mode: Data can be written to. </li> <li> <p><a id="descriptor_flags.file_integrity_sync"></a><code>file-integrity-sync</code>: </p> <p>Request that writes be performed according to synchronized I/O file integrity completion. The data stored in the file and the file's metadata are synchronized. This is similar to `O_SYNC` in POSIX. <p>The precise semantics of this operation have not yet been defined for WASI. At this time, it should be interpreted as a request, and not a requirement.</p> </li> <li> <p><a id="descriptor_flags.data_integrity_sync"></a><code>data-integrity-sync</code>: </p> <p>Request that writes be performed according to synchronized I/O data integrity completion. Only the data stored in the file is synchronized. This is similar to `O_DSYNC` in POSIX. <p>The precise semantics of this operation have not yet been defined for WASI. At this time, it should be interpreted as a request, and not a requirement.</p> </li> <li> <p><a id="descriptor_flags.requested_write_sync"></a><code>requested-write-sync</code>: </p> <p>Requests that reads be performed at the same level of integrity requested for writes. This is similar to `O_RSYNC` in POSIX. <p>The precise semantics of this operation have not yet been defined for WASI. At this time, it should be interpreted as a request, and not a requirement.</p> </li> <li> <p><a id="descriptor_flags.mutate_directory"></a><code>mutate-directory</code>: </p> <p>Mutating directories mode: Directory contents may be mutated. <p>When this flag is unset on a descriptor, operations using the descriptor which would create, rename, delete, modify the data or metadata of filesystem objects, or obtain another handle which would permit any of those, shall fail with <a href="#error_code.read_only"><code>error-code::read-only</code></a> if they would otherwise succeed.</p> <p>This may only be set on directories.</p> </li> </ul> <h4><a id="path_flags"></a><code>flags path-flags</code></h4> <p>Flags determining the method of how paths are resolved.</p> <h5>Flags members</h5> <ul> <li><a id="path_flags.symlink_follow"></a><code>symlink-follow</code>: <p>As long as the resolved path corresponds to a symbolic link, it is expanded. </li> </ul> <h4><a id="open_flags"></a><code>flags open-flags</code></h4> <p>Open flags used by <code>open-at</code>.</p> <h5>Flags members</h5> <ul> <li> <p><a id="open_flags.create"></a><code>create</code>: </p> <p>Create file if it does not exist, similar to `O_CREAT` in POSIX. </li> <li> <p><a id="open_flags.directory"></a><code>directory</code>: </p> <p>Fail if not a directory, similar to `O_DIRECTORY` in POSIX. </li> <li> <p><a id="open_flags.exclusive"></a><code>exclusive</code>: </p> <p>Fail if file already exists, similar to `O_EXCL` in POSIX. </li> <li> <p><a id="open_flags.truncate"></a><code>truncate</code>: </p> <p>Truncate file to size 0, similar to `O_TRUNC` in POSIX. </li> </ul> <h4><a id="link_count"></a><code>type link-count</code></h4> <p><code>u64</code></p> <p>Number of hard links to an inode. <h4><a id="descriptor_stat"></a><code>record descriptor-stat</code></h4> <p>File attributes.</p> <p>Note: This was called <code>filestat</code> in earlier versions of WASI.</p> <h5>Record Fields</h5> <ul> <li> <p><a id="descriptor_stat.type"></a><code>type</code>: <a href="#descriptor_type"><a href="#descriptor_type"><code>descriptor-type</code></a></a></p> <p>File type. </li> <li> <p><a id="descriptor_stat.link_count"></a><a href="#link_count"><code>link-count</code></a>: <a href="#link_count"><a href="#link_count"><code>link-count</code></a></a></p> <p>Number of hard links to the file. </li> <li> <p><a id="descriptor_stat.size"></a><code>size</code>: <a href="#filesize"><a href="#filesize"><code>filesize</code></a></a></p> <p>For regular files, the file size in bytes. For symbolic links, the length in bytes of the pathname contained in the symbolic link. </li> <li> <p><a id="descriptor_stat.data_access_timestamp"></a><code>data-access-timestamp</code>: option<<a href="#datetime"><a href="#datetime"><code>datetime</code></a></a>></p> <p>Last data access timestamp. <p>If the <code>option</code> is none, the platform doesn't maintain an access timestamp for this file.</p> </li> <li> <p><a id="descriptor_stat.data_modification_timestamp"></a><code>data-modification-timestamp</code>: option<<a href="#datetime"><a href="#datetime"><code>datetime</code></a></a>></p> <p>Last data modification timestamp. <p>If the <code>option</code> is none, the platform doesn't maintain a modification timestamp for this file.</p> </li> <li> <p><a id="descriptor_stat.status_change_timestamp"></a><code>status-change-timestamp</code>: option<<a href="#datetime"><a href="#datetime"><code>datetime</code></a></a>></p> <p>Last file status-change timestamp. <p>If the <code>option</code> is none, the platform doesn't maintain a status-change timestamp for this file.</p> </li> </ul> <h4><a id="new_timestamp"></a><code>variant new-timestamp</code></h4> <p>When setting a timestamp, this gives the value to set it to.</p> <h5>Variant Cases</h5> <ul> <li> <p><a id="new_timestamp.no_change"></a><code>no-change</code></p> <p>Leave the timestamp set to its previous value. </li> <li> <p><a id="new_timestamp.now"></a><a href="#now"><code>now</code></a></p> <p>Set the timestamp to the current time of the system clock associated with the filesystem. </li> <li> <p><a id="new_timestamp.timestamp"></a><code>timestamp</code>: <a href="#datetime"><a href="#datetime"><code>datetime</code></a></a></p> <p>Set the timestamp to the given value. </li> </ul> <h4><a id="directory_entry"></a><code>record directory-entry</code></h4> <p>A directory entry.</p> <h5>Record Fields</h5> <ul> <li> <p><a id="directory_entry.type"></a><code>type</code>: <a href="#descriptor_type"><a href="#descriptor_type"><code>descriptor-type</code></a></a></p> <p>The type of the file referred to by this directory entry. </li> <li> <p><a id="directory_entry.name"></a><code>name</code>: <code>string</code></p> <p>The name of the object. </li> </ul> <h4><a id="error_code"></a><code>enum error-code</code></h4> <p>Error codes returned by functions, similar to <code>errno</code> in POSIX. Not all of these error codes are returned by the functions provided by this API; some are used in higher-level library layers, and others are provided merely for alignment with POSIX.</p> <h5>Enum Cases</h5> <ul> <li> <p><a id="error_code.access"></a><code>access</code></p> <p>Permission denied, similar to `EACCES` in POSIX. </li> <li> <p><a id="error_code.would_block"></a><code>would-block</code></p> <p>Resource unavailable, or operation would block, similar to `EAGAIN` and `EWOULDBLOCK` in POSIX. </li> <li> <p><a id="error_code.already"></a><code>already</code></p> <p>Connection already in progress, similar to `EALREADY` in POSIX. </li> <li> <p><a id="error_code.bad_descriptor"></a><code>bad-descriptor</code></p> <p>Bad descriptor, similar to `EBADF` in POSIX. </li> <li> <p><a id="error_code.busy"></a><code>busy</code></p> <p>Device or resource busy, similar to `EBUSY` in POSIX. </li> <li> <p><a id="error_code.deadlock"></a><code>deadlock</code></p> <p>Resource deadlock would occur, similar to `EDEADLK` in POSIX. </li> <li> <p><a id="error_code.quota"></a><code>quota</code></p> <p>Storage quota exceeded, similar to `EDQUOT` in POSIX. </li> <li> <p><a id="error_code.exist"></a><code>exist</code></p> <p>File exists, similar to `EEXIST` in POSIX. </li> <li> <p><a id="error_code.file_too_large"></a><code>file-too-large</code></p> <p>File too large, similar to `EFBIG` in POSIX. </li> <li> <p><a id="error_code.illegal_byte_sequence"></a><code>illegal-byte-sequence</code></p> <p>Illegal byte sequence, similar to `EILSEQ` in POSIX. </li> <li> <p><a id="error_code.in_progress"></a><code>in-progress</code></p> <p>Operation in progress, similar to `EINPROGRESS` in POSIX. </li> <li> <p><a id="error_code.interrupted"></a><code>interrupted</code></p> <p>Interrupted function, similar to `EINTR` in POSIX. </li> <li> <p><a id="error_code.invalid"></a><code>invalid</code></p> <p>Invalid argument, similar to `EINVAL` in POSIX. </li> <li> <p><a id="error_code.io"></a><code>io</code></p> <p>I/O error, similar to `EIO` in POSIX. </li> <li> <p><a id="error_code.is_directory"></a><code>is-directory</code></p> <p>Is a directory, similar to `EISDIR` in POSIX. </li> <li> <p><a id="error_code.loop"></a><code>loop</code></p> <p>Too many levels of symbolic links, similar to `ELOOP` in POSIX. </li> <li> <p><a id="error_code.too_many_links"></a><code>too-many-links</code></p> <p>Too many links, similar to `EMLINK` in POSIX. </li> <li> <p><a id="error_code.message_size"></a><code>message-size</code></p> <p>Message too large, similar to `EMSGSIZE` in POSIX. </li> <li> <p><a id="error_code.name_too_long"></a><code>name-too-long</code></p> <p>Filename too long, similar to `ENAMETOOLONG` in POSIX. </li> <li> <p><a id="error_code.no_device"></a><code>no-device</code></p> <p>No such device, similar to `ENODEV` in POSIX. </li> <li> <p><a id="error_code.no_entry"></a><code>no-entry</code></p> <p>No such file or directory, similar to `ENOENT` in POSIX. </li> <li> <p><a id="error_code.no_lock"></a><code>no-lock</code></p> <p>No locks available, similar to `ENOLCK` in POSIX. </li> <li> <p><a id="error_code.insufficient_memory"></a><code>insufficient-memory</code></p> <p>Not enough space, similar to `ENOMEM` in POSIX. </li> <li> <p><a id="error_code.insufficient_space"></a><code>insufficient-space</code></p> <p>No space left on device, similar to `ENOSPC` in POSIX. </li> <li> <p><a id="error_code.not_directory"></a><code>not-directory</code></p> <p>Not a directory or a symbolic link to a directory, similar to `ENOTDIR` in POSIX. </li> <li> <p><a id="error_code.not_empty"></a><code>not-empty</code></p> <p>Directory not empty, similar to `ENOTEMPTY` in POSIX. </li> <li> <p><a id="error_code.not_recoverable"></a><code>not-recoverable</code></p> <p>State not recoverable, similar to `ENOTRECOVERABLE` in POSIX. </li> <li> <p><a id="error_code.unsupported"></a><code>unsupported</code></p> <p>Not supported, similar to `ENOTSUP` and `ENOSYS` in POSIX. </li> <li> <p><a id="error_code.no_tty"></a><code>no-tty</code></p> <p>Inappropriate I/O control operation, similar to `ENOTTY` in POSIX. </li> <li> <p><a id="error_code.no_such_device"></a><code>no-such-device</code></p> <p>No such device or address, similar to `ENXIO` in POSIX. </li> <li> <p><a id="error_code.overflow"></a><code>overflow</code></p> <p>Value too large to be stored in data type, similar to `EOVERFLOW` in POSIX. </li> <li> <p><a id="error_code.not_permitted"></a><code>not-permitted</code></p> <p>Operation not permitted, similar to `EPERM` in POSIX. </li> <li> <p><a id="error_code.pipe"></a><code>pipe</code></p> <p>Broken pipe, similar to `EPIPE` in POSIX. </li> <li> <p><a id="error_code.read_only"></a><code>read-only</code></p> <p>Read-only file system, similar to `EROFS` in POSIX. </li> <li> <p><a id="error_code.invalid_seek"></a><code>invalid-seek</code></p> <p>Invalid seek, similar to `ESPIPE` in POSIX. </li> <li> <p><a id="error_code.text_file_busy"></a><code>text-file-busy</code></p> <p>Text file busy, similar to `ETXTBSY` in POSIX. </li> <li> <p><a id="error_code.cross_device"></a><code>cross-device</code></p> <p>Cross-device link, similar to `EXDEV` in POSIX. </li> </ul> <h4><a id="advice"></a><code>enum advice</code></h4> <p>File or memory access pattern advisory information.</p> <h5>Enum Cases</h5> <ul> <li> <p><a id="advice.normal"></a><code>normal</code></p> <p>The application has no advice to give on its behavior with respect to the specified data. </li> <li> <p><a id="advice.sequential"></a><code>sequential</code></p> <p>The application expects to access the specified data sequentially from lower offsets to higher offsets. </li> <li> <p><a id="advice.random"></a><code>random</code></p> <p>The application expects to access the specified data in a random order. </li> <li> <p><a id="advice.will_need"></a><code>will-need</code></p> <p>The application expects to access the specified data in the near future. </li> <li> <p><a id="advice.dont_need"></a><code>dont-need</code></p> <p>The application expects that it will not access the specified data in the near future. </li> <li> <p><a id="advice.no_reuse"></a><code>no-reuse</code></p> <p>The application expects to access the specified data once and then not reuse it thereafter. </li> </ul> <h4><a id="metadata_hash_value"></a><code>record metadata-hash-value</code></h4> <p>A 128-bit hash value, split into parts because wasm doesn't have a 128-bit integer type.</p> <h5>Record Fields</h5> <ul> <li> <p><a id="metadata_hash_value.lower"></a><code>lower</code>: <code>u64</code></p> <p>64 bits of a 128-bit hash value. </li> <li> <p><a id="metadata_hash_value.upper"></a><code>upper</code>: <code>u64</code></p> <p>Another 64 bits of a 128-bit hash value. </li> </ul> <h4><a id="descriptor"></a><code>resource descriptor</code></h4> <p>A descriptor is a reference to a filesystem object, which may be a file, directory, named pipe, special file, or other object on which filesystem calls may be made.</p> <h4><a id="directory_entry_stream"></a><code>resource directory-entry-stream</code></h4> <h2>A stream of directory entries.</h2> <h3>Functions</h3> <h4><a id="method_descriptor_read_via_stream"></a><code>[method]descriptor.read-via-stream: func</code></h4> <p>Return a stream for reading from a file, if available.</p> <p>May fail with an error-code describing why the file cannot be read.</p> <p>Multiple read, write, and append streams may be active on the same open file and they do not interfere with each other.</p> <p>Note: This allows using <code>read-stream</code>, which is similar to <code>read</code> in POSIX.</p> <h5>Params</h5> <ul> <li><a id="method_descriptor_read_via_stream.self"></a><code>self</code>: borrow<<a href="#descriptor"><a href="#descriptor"><code>descriptor</code></a></a>></li> <li><a id="method_descriptor_read_via_stream.offset"></a><code>offset</code>: <a href="#filesize"><a href="#filesize"><code>filesize</code></a></a></li> </ul> <h5>Return values</h5> <ul> <li><a id="method_descriptor_read_via_stream.0"></a> result<own<<a href="#input_stream"><a href="#input_stream"><code>input-stream</code></a></a>>, <a href="#error_code"><a href="#error_code"><code>error-code</code></a></a>></li> </ul> <h4><a id="method_descriptor_write_via_stream"></a><code>[method]descriptor.write-via-stream: func</code></h4> <p>Return a stream for writing to a file, if available.</p> <p>May fail with an error-code describing why the file cannot be written.</p> <p>Note: This allows using <code>write-stream</code>, which is similar to <code>write</code> in POSIX.</p> <h5>Params</h5> <ul> <li><a id="method_descriptor_write_via_stream.self"></a><code>self</code>: borrow<<a href="#descriptor"><a href="#descriptor"><code>descriptor</code></a></a>></li> <li><a id="method_descriptor_write_via_stream.offset"></a><code>offset</code>: <a href="#filesize"><a href="#filesize"><code>filesize</code></a></a></li> </ul> <h5>Return values</h5> <ul> <li><a id="method_descriptor_write_via_stream.0"></a> result<own<<a href="#output_stream"><a href="#output_stream"><code>output-stream</code></a></a>>, <a href="#error_code"><a href="#error_code"><code>error-code</code></a></a>></li> </ul> <h4><a id="method_descriptor_append_via_stream"></a><code>[method]descriptor.append-via-stream: func</code></h4> <p>Return a stream for appending to a file, if available.</p> <p>May fail with an error-code describing why the file cannot be appended.</p> <p>Note: This allows using <code>write-stream</code>, which is similar to <code>write</code> with <code>O_APPEND</code> in POSIX.</p> <h5>Params</h5> <ul> <li><a id="method_descriptor_append_via_stream.self"></a><code>self</code>: borrow<<a href="#descriptor"><a href="#descriptor"><code>descriptor</code></a></a>></li> </ul> <h5>Return values</h5> <ul> <li><a id="method_descriptor_append_via_stream.0"></a> result<own<<a href="#output_stream"><a href="#output_stream"><code>output-stream</code></a></a>>, <a href="#error_code"><a href="#error_code"><code>error-code</code></a></a>></li> </ul> <h4><a id="method_descriptor_advise"></a><code>[method]descriptor.advise: func</code></h4> <p>Provide file advisory information on a descriptor.</p> <p>This is similar to <code>posix_fadvise</code> in POSIX.</p> <h5>Params</h5> <ul> <li><a id="method_descriptor_advise.self"></a><code>self</code>: borrow<<a href="#descriptor"><a href="#descriptor"><code>descriptor</code></a></a>></li> <li><a id="method_descriptor_advise.offset"></a><code>offset</code>: <a href="#filesize"><a href="#filesize"><code>filesize</code></a></a></li> <li><a id="method_descriptor_advise.length"></a><code>length</code>: <a href="#filesize"><a href="#filesize"><code>filesize</code></a></a></li> <li><a id="method_descriptor_advise.advice"></a><a href="#advice"><code>advice</code></a>: <a href="#advice"><a href="#advice"><code>advice</code></a></a></li> </ul> <h5>Return values</h5> <ul> <li><a id="method_descriptor_advise.0"></a> result<_, <a href="#error_code"><a href="#error_code"><code>error-code</code></a></a>></li> </ul> <h4><a id="method_descriptor_sync_data"></a><code>[method]descriptor.sync-data: func</code></h4> <p>Synchronize the data of a file to disk.</p> <p>This function succeeds with no effect if the file descriptor is not opened for writing.</p> <p>Note: This is similar to <code>fdatasync</code> in POSIX.</p> <h5>Params</h5> <ul> <li><a id="method_descriptor_sync_data.self"></a><code>self</code>: borrow<<a href="#descriptor"><a href="#descriptor"><code>descriptor</code></a></a>></li> </ul> <h5>Return values</h5> <ul> <li><a id="method_descriptor_sync_data.0"></a> result<_, <a href="#error_code"><a href="#error_code"><code>error-code</code></a></a>></li> </ul> <h4><a id="method_descriptor_get_flags"></a><code>[method]descriptor.get-flags: func</code></h4> <p>Get flags associated with a descriptor.</p> <p>Note: This returns similar flags to <code>fcntl(fd, F_GETFL)</code> in POSIX.</p> <p>Note: This returns the value that was the <code>fs_flags</code> value returned from <code>fdstat_get</code> in earlier versions of WASI.</p> <h5>Params</h5> <ul> <li><a id="method_descriptor_get_flags.self"></a><code>self</code>: borrow<<a href="#descriptor"><a href="#descriptor"><code>descriptor</code></a></a>></li> </ul> <h5>Return values</h5> <ul> <li><a id="method_descriptor_get_flags.0"></a> result<<a href="#descriptor_flags"><a href="#descriptor_flags"><code>descriptor-flags</code></a></a>, <a href="#error_code"><a href="#error_code"><code>error-code</code></a></a>></li> </ul> <h4><a id="method_descriptor_get_type"></a><code>[method]descriptor.get-type: func</code></h4> <p>Get the dynamic type of a descriptor.</p> <p>Note: This returns the same value as the <code>type</code> field of the <code>fd-stat</code> returned by <code>stat</code>, <code>stat-at</code> and similar.</p> <p>Note: This returns similar flags to the <code>st_mode & S_IFMT</code> value provided by <code>fstat</code> in POSIX.</p> <p>Note: This returns the value that was the <code>fs_filetype</code> value returned from <code>fdstat_get</code> in earlier versions of WASI.</p> <h5>Params</h5> <ul> <li><a id="method_descriptor_get_type.self"></a><code>self</code>: borrow<<a href="#descriptor"><a href="#descriptor"><code>descriptor</code></a></a>></li> </ul> <h5>Return values</h5> <ul> <li><a id="method_descriptor_get_type.0"></a> result<<a href="#descriptor_type"><a href="#descriptor_type"><code>descriptor-type</code></a></a>, <a href="#error_code"><a href="#error_code"><code>error-code</code></a></a>></li> </ul> <h4><a id="method_descriptor_set_size"></a><code>[method]descriptor.set-size: func</code></h4> <p>Adjust the size of an open file. If this increases the file's size, the extra bytes are filled with zeros.</p> <p>Note: This was called <code>fd_filestat_set_size</code> in earlier versions of WASI.</p> <h5>Params</h5> <ul> <li><a id="method_descriptor_set_size.self"></a><code>self</code>: borrow<<a href="#descriptor"><a href="#descriptor"><code>descriptor</code></a></a>></li> <li><a id="method_descriptor_set_size.size"></a><code>size</code>: <a href="#filesize"><a href="#filesize"><code>filesize</code></a></a></li> </ul> <h5>Return values</h5> <ul> <li><a id="method_descriptor_set_size.0"></a> result<_, <a href="#error_code"><a href="#error_code"><code>error-code</code></a></a>></li> </ul> <h4><a id="method_descriptor_set_times"></a><code>[method]descriptor.set-times: func</code></h4> <p>Adjust the timestamps of an open file or directory.</p> <p>Note: This is similar to <code>futimens</code> in POSIX.</p> <p>Note: This was called <code>fd_filestat_set_times</code> in earlier versions of WASI.</p> <h5>Params</h5> <ul> <li><a id="method_descriptor_set_times.self"></a><code>self</code>: borrow<<a href="#descriptor"><a href="#descriptor"><code>descriptor</code></a></a>></li> <li><a id="method_descriptor_set_times.data_access_timestamp"></a><code>data-access-timestamp</code>: <a href="#new_timestamp"><a href="#new_timestamp"><code>new-timestamp</code></a></a></li> <li><a id="method_descriptor_set_times.data_modification_timestamp"></a><code>data-modification-timestamp</code>: <a href="#new_timestamp"><a href="#new_timestamp"><code>new-timestamp</code></a></a></li> </ul> <h5>Return values</h5> <ul> <li><a id="method_descriptor_set_times.0"></a> result<_, <a href="#error_code"><a href="#error_code"><code>error-code</code></a></a>></li> </ul> <h4><a id="method_descriptor_read"></a><code>[method]descriptor.read: func</code></h4> <p>Read from a descriptor, without using and updating the descriptor's offset.</p> <p>This function returns a list of bytes containing the data that was read, along with a bool which, when true, indicates that the end of the file was reached. The returned list will contain up to <code>length</code> bytes; it may return fewer than requested, if the end of the file is reached or if the I/O operation is interrupted.</p> <p>In the future, this may change to return a <code>stream<u8, error-code></code>.</p> <p>Note: This is similar to <code>pread</code> in POSIX.</p> <h5>Params</h5> <ul> <li><a id="method_descriptor_read.self"></a><code>self</code>: borrow<<a href="#descriptor"><a href="#descriptor"><code>descriptor</code></a></a>></li> <li><a id="method_descriptor_read.length"></a><code>length</code>: <a href="#filesize"><a href="#filesize"><code>filesize</code></a></a></li> <li><a id="method_descriptor_read.offset"></a><code>offset</code>: <a href="#filesize"><a href="#filesize"><code>filesize</code></a></a></li> </ul> <h5>Return values</h5> <ul> <li><a id="method_descriptor_read.0"></a> result<(list<<code>u8</code>>, <code>bool</code>), <a href="#error_code"><a href="#error_code"><code>error-code</code></a></a>></li> </ul> <h4><a id="method_descriptor_write"></a><code>[method]descriptor.write: func</code></h4> <p>Write to a descriptor, without using and updating the descriptor's offset.</p> <p>It is valid to write past the end of a file; the file is extended to the extent of the write, with bytes between the previous end and the start of the write set to zero.</p> <p>In the future, this may change to take a <code>stream<u8, error-code></code>.</p> <p>Note: This is similar to <code>pwrite</code> in POSIX.</p> <h5>Params</h5> <ul> <li><a id="method_descriptor_write.self"></a><code>self</code>: borrow<<a href="#descriptor"><a href="#descriptor"><code>descriptor</code></a></a>></li> <li><a id="method_descriptor_write.buffer"></a><code>buffer</code>: list<<code>u8</code>></li> <li><a id="method_descriptor_write.offset"></a><code>offset</code>: <a href="#filesize"><a href="#filesize"><code>filesize</code></a></a></li> </ul> <h5>Return values</h5> <ul> <li><a id="method_descriptor_write.0"></a> result<<a href="#filesize"><a href="#filesize"><code>filesize</code></a></a>, <a href="#error_code"><a href="#error_code"><code>error-code</code></a></a>></li> </ul> <h4><a id="method_descriptor_read_directory"></a><code>[method]descriptor.read-directory: func</code></h4> <p>Read directory entries from a directory.</p> <p>On filesystems where directories contain entries referring to themselves and their parents, often named <code>.</code> and <code>..</code> respectively, these entries are omitted.</p> <p>This always returns a new stream which starts at the beginning of the directory. Multiple streams may be active on the same directory, and they do not interfere with each other.</p> <h5>Params</h5> <ul> <li><a id="method_descriptor_read_directory.self"></a><code>self</code>: borrow<<a href="#descriptor"><a href="#descriptor"><code>descriptor</code></a></a>></li> </ul> <h5>Return values</h5> <ul> <li><a id="method_descriptor_read_directory.0"></a> result<own<<a href="#directory_entry_stream"><a href="#directory_entry_stream"><code>directory-entry-stream</code></a></a>>, <a href="#error_code"><a href="#error_code"><code>error-code</code></a></a>></li> </ul> <h4><a id="method_descriptor_sync"></a><code>[method]descriptor.sync: func</code></h4> <p>Synchronize the data and metadata of a file to disk.</p> <p>This function succeeds with no effect if the file descriptor is not opened for writing.</p> <p>Note: This is similar to <code>fsync</code> in POSIX.</p> <h5>Params</h5> <ul> <li><a id="method_descriptor_sync.self"></a><code>self</code>: borrow<<a href="#descriptor"><a href="#descriptor"><code>descriptor</code></a></a>></li> </ul> <h5>Return values</h5> <ul> <li><a id="method_descriptor_sync.0"></a> result<_, <a href="#error_code"><a href="#error_code"><code>error-code</code></a></a>></li> </ul> <h4><a id="method_descriptor_create_directory_at"></a><code>[method]descriptor.create-directory-at: func</code></h4> <p>Create a directory.</p> <p>Note: This is similar to <code>mkdirat</code> in POSIX.</p> <h5>Params</h5> <ul> <li><a id="method_descriptor_create_directory_at.self"></a><code>self</code>: borrow<<a href="#descriptor"><a href="#descriptor"><code>descriptor</code></a></a>></li> <li><a id="method_descriptor_create_directory_at.path"></a><code>path</code>: <code>string</code></li> </ul> <h5>Return values</h5> <ul> <li><a id="method_descriptor_create_directory_at.0"></a> result<_, <a href="#error_code"><a href="#error_code"><code>error-code</code></a></a>></li> </ul> <h4><a id="method_descriptor_stat"></a><code>[method]descriptor.stat: func</code></h4> <p>Return the attributes of an open file or directory.</p> <p>Note: This is similar to <code>fstat</code> in POSIX, except that it does not return device and inode information. For testing whether two descriptors refer to the same underlying filesystem object, use <code>is-same-object</code>. To obtain additional data that can be used do determine whether a file has been modified, use <code>metadata-hash</code>.</p> <p>Note: This was called <code>fd_filestat_get</code> in earlier versions of WASI.</p> <h5>Params</h5> <ul> <li><a id="method_descriptor_stat.self"></a><code>self</code>: borrow<<a href="#descriptor"><a href="#descriptor"><code>descriptor</code></a></a>></li> </ul> <h5>Return values</h5> <ul> <li><a id="method_descriptor_stat.0"></a> result<<a href="#descriptor_stat"><a href="#descriptor_stat"><code>descriptor-stat</code></a></a>, <a href="#error_code"><a href="#error_code"><code>error-code</code></a></a>></li> </ul> <h4><a id="method_descriptor_stat_at"></a><code>[method]descriptor.stat-at: func</code></h4> <p>Return the attributes of a file or directory.</p> <p>Note: This is similar to <code>fstatat</code> in POSIX, except that it does not return device and inode information. See the <code>stat</code> description for a discussion of alternatives.</p> <p>Note: This was called <code>path_filestat_get</code> in earlier versions of WASI.</p> <h5>Params</h5> <ul> <li><a id="method_descriptor_stat_at.self"></a><code>self</code>: borrow<<a href="#descriptor"><a href="#descriptor"><code>descriptor</code></a></a>></li> <li><a id="method_descriptor_stat_at.path_flags"></a><a href="#path_flags"><code>path-flags</code></a>: <a href="#path_flags"><a href="#path_flags"><code>path-flags</code></a></a></li> <li><a id="method_descriptor_stat_at.path"></a><code>path</code>: <code>string</code></li> </ul> <h5>Return values</h5> <ul> <li><a id="method_descriptor_stat_at.0"></a> result<<a href="#descriptor_stat"><a href="#descriptor_stat"><code>descriptor-stat</code></a></a>, <a href="#error_code"><a href="#error_code"><code>error-code</code></a></a>></li> </ul> <h4><a id="method_descriptor_set_times_at"></a><code>[method]descriptor.set-times-at: func</code></h4> <p>Adjust the timestamps of a file or directory.</p> <p>Note: This is similar to <code>utimensat</code> in POSIX.</p> <p>Note: This was called <code>path_filestat_set_times</code> in earlier versions of WASI.</p> <h5>Params</h5> <ul> <li><a id="method_descriptor_set_times_at.self"></a><code>self</code>: borrow<<a href="#descriptor"><a href="#descriptor"><code>descriptor</code></a></a>></li> <li><a id="method_descriptor_set_times_at.path_flags"></a><a href="#path_flags"><code>path-flags</code></a>: <a href="#path_flags"><a href="#path_flags"><code>path-flags</code></a></a></li> <li><a id="method_descriptor_set_times_at.path"></a><code>path</code>: <code>string</code></li> <li><a id="method_descriptor_set_times_at.data_access_timestamp"></a><code>data-access-timestamp</code>: <a href="#new_timestamp"><a href="#new_timestamp"><code>new-timestamp</code></a></a></li> <li><a id="method_descriptor_set_times_at.data_modification_timestamp"></a><code>data-modification-timestamp</code>: <a href="#new_timestamp"><a href="#new_timestamp"><code>new-timestamp</code></a></a></li> </ul> <h5>Return values</h5> <ul> <li><a id="method_descriptor_set_times_at.0"></a> result<_, <a href="#error_code"><a href="#error_code"><code>error-code</code></a></a>></li> </ul> <h4><a id="method_descriptor_link_at"></a><code>[method]descriptor.link-at: func</code></h4> <p>Create a hard link.</p> <p>Fails with <a href="#error_code.no_entry"><code>error-code::no-entry</code></a> if the old path does not exist, with <a href="#error_code.exist"><code>error-code::exist</code></a> if the new path already exists, and <a href="#error_code.not_permitted"><code>error-code::not-permitted</code></a> if the old path is not a file.</p> <p>Note: This is similar to <code>linkat</code> in POSIX.</p> <h5>Params</h5> <ul> <li><a id="method_descriptor_link_at.self"></a><code>self</code>: borrow<<a href="#descriptor"><a href="#descriptor"><code>descriptor</code></a></a>></li> <li><a id="method_descriptor_link_at.old_path_flags"></a><code>old-path-flags</code>: <a href="#path_flags"><a href="#path_flags"><code>path-flags</code></a></a></li> <li><a id="method_descriptor_link_at.old_path"></a><code>old-path</code>: <code>string</code></li> <li><a id="method_descriptor_link_at.new_descriptor"></a><code>new-descriptor</code>: borrow<<a href="#descriptor"><a href="#descriptor"><code>descriptor</code></a></a>></li> <li><a id="method_descriptor_link_at.new_path"></a><code>new-path</code>: <code>string</code></li> </ul> <h5>Return values</h5> <ul> <li><a id="method_descriptor_link_at.0"></a> result<_, <a href="#error_code"><a href="#error_code"><code>error-code</code></a></a>></li> </ul> <h4><a id="method_descriptor_open_at"></a><code>[method]descriptor.open-at: func</code></h4> <p>Open a file or directory.</p> <p>If <code>flags</code> contains <a href="#descriptor_flags.mutate_directory"><code>descriptor-flags::mutate-directory</code></a>, and the base descriptor doesn't have <a href="#descriptor_flags.mutate_directory"><code>descriptor-flags::mutate-directory</code></a> set, <code>open-at</code> fails with <a href="#error_code.read_only"><code>error-code::read-only</code></a>.</p> <p>If <code>flags</code> contains <code>write</code> or <code>mutate-directory</code>, or <a href="#open_flags"><code>open-flags</code></a> contains <code>truncate</code> or <code>create</code>, and the base descriptor doesn't have <a href="#descriptor_flags.mutate_directory"><code>descriptor-flags::mutate-directory</code></a> set, <code>open-at</code> fails with <a href="#error_code.read_only"><code>error-code::read-only</code></a>.</p> <p>Note: This is similar to <code>openat</code> in POSIX.</p> <h5>Params</h5> <ul> <li><a id="method_descriptor_open_at.self"></a><code>self</code>: borrow<<a href="#descriptor"><a href="#descriptor"><code>descriptor</code></a></a>></li> <li><a id="method_descriptor_open_at.path_flags"></a><a href="#path_flags"><code>path-flags</code></a>: <a href="#path_flags"><a href="#path_flags"><code>path-flags</code></a></a></li> <li><a id="method_descriptor_open_at.path"></a><code>path</code>: <code>string</code></li> <li><a id="method_descriptor_open_at.open_flags"></a><a href="#open_flags"><code>open-flags</code></a>: <a href="#open_flags"><a href="#open_flags"><code>open-flags</code></a></a></li> <li><a id="method_descriptor_open_at.flags"></a><code>flags</code>: <a href="#descriptor_flags"><a href="#descriptor_flags"><code>descriptor-flags</code></a></a></li> </ul> <h5>Return values</h5> <ul> <li><a id="method_descriptor_open_at.0"></a> result<own<<a href="#descriptor"><a href="#descriptor"><code>descriptor</code></a></a>>, <a href="#error_code"><a href="#error_code"><code>error-code</code></a></a>></li> </ul> <h4><a id="method_descriptor_readlink_at"></a><code>[method]descriptor.readlink-at: func</code></h4> <p>Read the contents of a symbolic link.</p> <p>If the contents contain an absolute or rooted path in the underlying filesystem, this function fails with <a href="#error_code.not_permitted"><code>error-code::not-permitted</code></a>.</p> <p>Note: This is similar to <code>readlinkat</code> in POSIX.</p> <h5>Params</h5> <ul> <li><a id="method_descriptor_readlink_at.self"></a><code>self</code>: borrow<<a href="#descriptor"><a href="#descriptor"><code>descriptor</code></a></a>></li> <li><a id="method_descriptor_readlink_at.path"></a><code>path</code>: <code>string</code></li> </ul> <h5>Return values</h5> <ul> <li><a id="method_descriptor_readlink_at.0"></a> result<<code>string</code>, <a href="#error_code"><a href="#error_code"><code>error-code</code></a></a>></li> </ul> <h4><a id="method_descriptor_remove_directory_at"></a><code>[method]descriptor.remove-directory-at: func</code></h4> <p>Remove a directory.</p> <p>Return <a href="#error_code.not_empty"><code>error-code::not-empty</code></a> if the directory is not empty.</p> <p>Note: This is similar to <code>unlinkat(fd, path, AT_REMOVEDIR)</code> in POSIX.</p> <h5>Params</h5> <ul> <li><a id="method_descriptor_remove_directory_at.self"></a><code>self</code>: borrow<<a href="#descriptor"><a href="#descriptor"><code>descriptor</code></a></a>></li> <li><a id="method_descriptor_remove_directory_at.path"></a><code>path</code>: <code>string</code></li> </ul> <h5>Return values</h5> <ul> <li><a id="method_descriptor_remove_directory_at.0"></a> result<_, <a href="#error_code"><a href="#error_code"><code>error-code</code></a></a>></li> </ul> <h4><a id="method_descriptor_rename_at"></a><code>[method]descriptor.rename-at: func</code></h4> <p>Rename a filesystem object.</p> <p>Note: This is similar to <code>renameat</code> in POSIX.</p> <h5>Params</h5> <ul> <li><a id="method_descriptor_rename_at.self"></a><code>self</code>: borrow<<a href="#descriptor"><a href="#descriptor"><code>descriptor</code></a></a>></li> <li><a id="method_descriptor_rename_at.old_path"></a><code>old-path</code>: <code>string</code></li> <li><a id="method_descriptor_rename_at.new_descriptor"></a><code>new-descriptor</code>: borrow<<a href="#descriptor"><a href="#descriptor"><code>descriptor</code></a></a>></li> <li><a id="method_descriptor_rename_at.new_path"></a><code>new-path</code>: <code>string</code></li> </ul> <h5>Return values</h5> <ul> <li><a id="method_descriptor_rename_at.0"></a> result<_, <a href="#error_code"><a href="#error_code"><code>error-code</code></a></a>></li> </ul> <h4><a id="method_descriptor_symlink_at"></a><code>[method]descriptor.symlink-at: func</code></h4> <p>Create a symbolic link (also known as a "symlink").</p> <p>If <code>old-path</code> starts with <code>/</code>, the function fails with <a href="#error_code.not_permitted"><code>error-code::not-permitted</code></a>.</p> <p>Note: This is similar to <code>symlinkat</code> in POSIX.</p> <h5>Params</h5> <ul> <li><a id="method_descriptor_symlink_at.self"></a><code>self</code>: borrow<<a href="#descriptor"><a href="#descriptor"><code>descriptor</code></a></a>></li> <li><a id="method_descriptor_symlink_at.old_path"></a><code>old-path</code>: <code>string</code></li> <li><a id="method_descriptor_symlink_at.new_path"></a><code>new-path</code>: <code>string</code></li> </ul> <h5>Return values</h5> <ul> <li><a id="method_descriptor_symlink_at.0"></a> result<_, <a href="#error_code"><a href="#error_code"><code>error-code</code></a></a>></li> </ul> <h4><a id="method_descriptor_unlink_file_at"></a><code>[method]descriptor.unlink-file-at: func</code></h4> <p>Unlink a filesystem object that is not a directory.</p> <p>Return <a href="#error_code.is_directory"><code>error-code::is-directory</code></a> if the path refers to a directory. Note: This is similar to <code>unlinkat(fd, path, 0)</code> in POSIX.</p> <h5>Params</h5> <ul> <li><a id="method_descriptor_unlink_file_at.self"></a><code>self</code>: borrow<<a href="#descriptor"><a href="#descriptor"><code>descriptor</code></a></a>></li> <li><a id="method_descriptor_unlink_file_at.path"></a><code>path</code>: <code>string</code></li> </ul> <h5>Return values</h5> <ul> <li><a id="method_descriptor_unlink_file_at.0"></a> result<_, <a href="#error_code"><a href="#error_code"><code>error-code</code></a></a>></li> </ul> <h4><a id="method_descriptor_is_same_object"></a><code>[method]descriptor.is-same-object: func</code></h4> <p>Test whether two descriptors refer to the same filesystem object.</p> <p>In POSIX, this corresponds to testing whether the two descriptors have the same device (<code>st_dev</code>) and inode (<code>st_ino</code> or <code>d_ino</code>) numbers. wasi-filesystem does not expose device and inode numbers, so this function may be used instead.</p> <h5>Params</h5> <ul> <li><a id="method_descriptor_is_same_object.self"></a><code>self</code>: borrow<<a href="#descriptor"><a href="#descriptor"><code>descriptor</code></a></a>></li> <li><a id="method_descriptor_is_same_object.other"></a><code>other</code>: borrow<<a href="#descriptor"><a href="#descriptor"><code>descriptor</code></a></a>></li> </ul> <h5>Return values</h5> <ul> <li><a id="method_descriptor_is_same_object.0"></a> <code>bool</code></li> </ul> <h4><a id="method_descriptor_metadata_hash"></a><code>[method]descriptor.metadata-hash: func</code></h4> <p>Return a hash of the metadata associated with a filesystem object referred to by a descriptor.</p> <p>This returns a hash of the last-modification timestamp and file size, and may also include the inode number, device number, birth timestamp, and other metadata fields that may change when the file is modified or replaced. It may also include a secret value chosen by the implementation and not otherwise exposed.</p> <p>Implementations are encouraged to provide the following properties:</p> <ul> <li>If the file is not modified or replaced, the computed hash value should usually not change.</li> <li>If the object is modified or replaced, the computed hash value should usually change.</li> <li>The inputs to the hash should not be easily computable from the computed hash.</li> </ul> <p>However, none of these is required.</p> <h5>Params</h5> <ul> <li><a id="method_descriptor_metadata_hash.self"></a><code>self</code>: borrow<<a href="#descriptor"><a href="#descriptor"><code>descriptor</code></a></a>></li> </ul> <h5>Return values</h5> <ul> <li><a id="method_descriptor_metadata_hash.0"></a> result<<a href="#metadata_hash_value"><a href="#metadata_hash_value"><code>metadata-hash-value</code></a></a>, <a href="#error_code"><a href="#error_code"><code>error-code</code></a></a>></li> </ul> <h4><a id="method_descriptor_metadata_hash_at"></a><code>[method]descriptor.metadata-hash-at: func</code></h4> <p>Return a hash of the metadata associated with a filesystem object referred to by a directory descriptor and a relative path.</p> <p>This performs the same hash computation as <code>metadata-hash</code>.</p> <h5>Params</h5> <ul> <li><a id="method_descriptor_metadata_hash_at.self"></a><code>self</code>: borrow<<a href="#descriptor"><a href="#descriptor"><code>descriptor</code></a></a>></li> <li><a id="method_descriptor_metadata_hash_at.path_flags"></a><a href="#path_flags"><code>path-flags</code></a>: <a href="#path_flags"><a href="#path_flags"><code>path-flags</code></a></a></li> <li><a id="method_descriptor_metadata_hash_at.path"></a><code>path</code>: <code>string</code></li> </ul> <h5>Return values</h5> <ul> <li><a id="method_descriptor_metadata_hash_at.0"></a> result<<a href="#metadata_hash_value"><a href="#metadata_hash_value"><code>metadata-hash-value</code></a></a>, <a href="#error_code"><a href="#error_code"><code>error-code</code></a></a>></li> </ul> <h4><a id="method_directory_entry_stream_read_directory_entry"></a><code>[method]directory-entry-stream.read-directory-entry: func</code></h4> <p>Read a single directory entry from a <a href="#directory_entry_stream"><code>directory-entry-stream</code></a>.</p> <h5>Params</h5> <ul> <li><a id="method_directory_entry_stream_read_directory_entry.self"></a><code>self</code>: borrow<<a href="#directory_entry_stream"><a href="#directory_entry_stream"><code>directory-entry-stream</code></a></a>></li> </ul> <h5>Return values</h5> <ul> <li><a id="method_directory_entry_stream_read_directory_entry.0"></a> result<option<<a href="#directory_entry"><a href="#directory_entry"><code>directory-entry</code></a></a>>, <a href="#error_code"><a href="#error_code"><code>error-code</code></a></a>></li> </ul> <h4><a id="filesystem_error_code"></a><code>filesystem-error-code: func</code></h4> <p>Attempts to extract a filesystem-related <a href="#error_code"><code>error-code</code></a> from the stream <a href="#error"><code>error</code></a> provided.</p> <p>Stream operations which return <a href="#stream_error.last_operation_failed"><code>stream-error::last-operation-failed</code></a> have a payload with more information about the operation that failed. This payload can be passed through to this function to see if there's filesystem-related information about the error to return.</p> <p>Note that this function is fallible because not all stream-related errors are filesystem-related errors.</p> <h5>Params</h5> <ul> <li><a id="filesystem_error_code.err"></a><code>err</code>: borrow<<a href="#error"><a href="#error"><code>error</code></a></a>></li> </ul> <h5>Return values</h5> <ul> <li><a id="filesystem_error_code.0"></a> option<<a href="#error_code"><a href="#error_code"><code>error-code</code></a></a>></li> </ul> <h2><a id="wasi_filesystem_preopens_0_2_11"></a>Import interface wasi:filesystem/[email protected]</h2> <hr /> <h3>Types</h3> <h4><a id="descriptor"></a><code>type descriptor</code></h4> <p><a href="#descriptor"><a href="#descriptor"><code>descriptor</code></a></a></p> <p> <hr /> <h3>Functions</h3> <h4><a id="get_directories"></a><code>get-directories: func</code></h4> <p>Return the set of preopened directories, and their paths.</p> <h5>Return values</h5> <ul> <li><a id="get_directories.0"></a> list<(own<<a href="#descriptor"><a href="#descriptor"><code>descriptor</code></a></a>>, <code>string</code>)></li> </ul>