[PHP.wasm] Support non-blocking read streams

packages/php-wasm/compile/php/php_wasm.c

@@ -344,6 +344,8 @@ EM_JS(__wasi_errno_t, js_fd_read, (__wasi_fd_t fd, const __wasi_iovec_t *iov, si
             }
 
             const success = returnCode === 0;
+            // @TODO: Do not reason about child_proc_by_fd. Just use pipes and detect
+            //        when the other end of the pipe is closed.
             const failure = (
                 ++retries > maxRetries ||
                 !(fd in PHPWASM.child_proc_by_fd) ||
@@ -360,7 +362,16 @@ EM_JS(__wasi_errno_t, js_fd_read, (__wasi_fd_t fd, const __wasi_iovec_t *iov, si
                 // If the failure is due to a timeout, return 0 to indicate that we
                 // reached EOF. Otherwise, propagate the error code.
                 wakeUp(returnCode === 6 ? 0 : returnCode);
+            } else if (
+                returnCode === ERRNO_CODES.EWOULDBLOCK &&
+                stream.flags & locking.O_NONBLOCK
+            ) {
+                // Non-blocking stream with no data available yet – return immediately.
+                HEAPU32[pnum >> 2] = 0;
+                wakeUp(returnCode);
             } else {
+                // It's a blocking stream and we Blocking stream with no data available yet.
+                // Let's poll up to a timeout.
                 setTimeout(poll, interval);
             }
         }

packages/php-wasm/compile/php/phpwasm-emscripten-library-file-locking-for-node.js

@@ -23,6 +23,20 @@ const LibraryForFileLocking = {
 		F_RDLCK: 0,
 		F_WRLCK: 1,
 		F_UNLCK: 2,
+		/**
+		 * @see fcntl.c:
+		 * https://github.com/torvalds/linux/blob/a79a588fc1761dc12a3064fc2f648ae66cea3c5a/fs/fcntl.c#L37
+		 */
+		O_APPEND: Number('{{{cDefs.O_APPEND}}}'),
+		O_NONBLOCK: Number('{{{cDefs.O_NONBLOCK}}}'),
+		SETFL_MASK:
+			Number('{{{cDefs.O_APPEND}}}') |
+			Number('{{{cDefs.O_NONBLOCK}}}')
+			// These macros are not defined in Emscripten at the time of writing:
+			// emscripten_O_NDELAY |
+			// emscripten_O_DIRECT |
+			// emscripten_O_NOATIME
+		,
 		lockStateToFcntl: {
 			shared: 0,
 			exclusive: 1,
@@ -40,7 +54,10 @@ const LibraryForFileLocking = {
 			}
 
 			// Handle PROXYFS nodes which wrap other nodes.
-			if (!node?.mount?.opts?.fs?.lookupPath || !node?.mount?.type?.realPath) {
+			if (
+				!node?.mount?.opts?.fs?.lookupPath ||
+				!node?.mount?.type?.realPath
+			) {
 				return false;
 			}
 
@@ -50,7 +67,8 @@ const LibraryForFileLocking = {
 			}
 			const vfsPath = node.mount.type.realPath(node);
 			try {
-				const underlyingNode = node.mount.opts.fs.lookupPath(vfsPath)?.node;
+				const underlyingNode =
+					node.mount.opts.fs.lookupPath(vfsPath)?.node;
 				return !!underlyingNode?.isSharedFS;
 			} catch (e) {
 				return false;
@@ -116,11 +134,14 @@ const LibraryForFileLocking = {
 		SYSCALLS.varargs = varargs;
 
 		// These constants are replaced by Emscripten during the build process
+		const emscripten_F_SETFL = Number('{{{cDefs.F_SETFL}}}');
 		const emscripten_F_GETLK = Number('{{{cDefs.F_GETLK}}}');
 		const emscripten_F_SETLK = Number('{{{cDefs.F_SETLK}}}');
 		const emscripten_F_SETLKW = Number('{{{cDefs.F_SETLKW}}}');
 		const emscripten_SEEK_SET = Number('{{{cDefs.SEEK_SET}}}');
 
+
+
 		// NOTE: With the exception of l_type, these offsets are not exposed to
 		// JS by Emscripten, so we hardcode them here.
 		const emscripten_flock_l_type_offset = 0;
@@ -511,6 +532,38 @@ const LibraryForFileLocking = {
 				// because it is a known errno for a failed F_SETLKW command.
 				return -ERRNO_CODES.EDEADLK;
 			}
+			case emscripten_F_SETFL: {
+				/**
+				 * Overrides the core Emscripten implementation to reflect what
+				 * fcntl does in linux kernel. This implementation is still missing
+				 * a bunch of nuance, but, unlike the core Emscripten implementation,
+				 * it overrides the stream flags while preserving non-stream flags.
+				 * 
+				 * @see fcntl.c:
+				 * https://github.com/torvalds/linux/blob/a79a588fc1761dc12a3064fc2f648ae66cea3c5a/fs/fcntl.c#L39
+				 */
+				const arg = SYSCALLS.get();
+				const stream = SYSCALLS.getStreamFromFD(fd);
+
+				// Get current flags
+				const currentFlags = stream.flags;
+
+				// Required for strict SunOS emulation
+				if (emscripten_O_NONBLOCK !== emscripten_O_NDELAY) {
+					if (arg & emscripten_O_NDELAY) {
+						arg |= emscripten_O_NONBLOCK;
+					}
+				}
+
+				// Pipe packetized mode is controlled by O_DIRECT flag
+				// We don't have S_ISFIFO or FMODE_CAN_ODIRECT checks in our implementation
+				// so we skip this validation
+
+				// Update the stream flags
+				stream.flags = (arg & locking.SETFL_MASK) | (currentFlags & ~locking.SETFL_MASK);
+
+				return 0;
+			}
 			default:
 				return _builtin_fcntl64(fd, cmd, varargs);
 		}
@@ -683,17 +736,14 @@ const LibraryForFileLocking = {
 	js_release_file_locks: async function js_release_file_locks() {
 		_js_wasm_trace('js_release_file_locks()');
 		const pid = PHPLoader.processId;
-		if(pid && PHPLoader.fileLockManager)
-		{
-			return await PHPLoader.fileLockManager
-				.releaseLocksForProcess(pid)
-				.then(() => {
-					_js_wasm_trace('js_release_file_locks succeeded');
-				})
-				.catch((e) => {
-					_js_wasm_trace('js_release_file_locks error %s', e);
-				});
-		}
+		return await PHPLoader.fileLockManager
+			.releaseLocksForProcess(pid)
+			.then(() => {
+				_js_wasm_trace('js_release_file_locks succeeded');
+			})
+			.catch((e) => {
+				_js_wasm_trace('js_release_file_locks error %s', e);
+			});
 	},
 };