write works to close tabs!

extension/background.js

@@ -198,6 +198,17 @@ const router = {
               throw new UnixError(unix.ENOENT);
             }
           }
+        },
+
+        "control": {
+          async write(path, buf) {
+            const tabId = parseInt(pathComponent(path, -2));
+            if (buf.trim() === 'close') {
+              await new Promise(resolve => chrome.tabs.remove(tabId, resolve));
+            } else {
+              throw new UnixError(unix.EIO);
+            }
+          }
         }
       }
     }
@@ -223,10 +234,10 @@ async function getattr(path) {
   let route = findRoute(path);
   if (route.getattr) {
     return route.getattr(path);
-  } else if (route.read) {
+  } else if (route.read || route.write) {
     // default file attrs
     return {
-      st_mode: unix.S_IFREG | 0444,
+      st_mode: unix.S_IFREG | ((route.read && 0444) || (route.write && 0222)),
       st_nlink: 1,
       st_size: 100 // FIXME
     };
@@ -249,16 +260,20 @@ async function read(path, fh, size, offset) {
   let route = findRoute(path);
   if (route.read) return route.read(path, fh, size, offset);
 }
-async function readlink(path) {
+async function write(path, buf, offset) {
   let route = findRoute(path);
-  if (route.readlink) return route.readlink(path);
+  if (route.write) return route.write(path, buf, offset);
 }
-
 async function release(path, fh) {
   let route = findRoute(path);
   if (route.release) return route.release(path, fh);
 }
 
+async function readlink(path) {
+  let route = findRoute(path);
+  if (route.readlink) return route.readlink(path);
+}
+
 async function opendir(path) {
   let route = findRoute(path);
   if (route.opendir) return route.opendir(path);
@@ -305,6 +320,14 @@ async function onmessage(event) {
       };
       if (ret.base64Encoded) response.base64Encoded = ret.base64Encoded;
 
+    } else if (req.op === 'write') {
+      // FIXME: decide whether base64 should be handled here
+      // or in a higher layer?
+      const ret = await write(req.path, atob(req.buf), req.offset)
+      response = {
+        op: 'write'
+      };
+
     } else if (req.op === 'release') {
       await release(req.path, req.fh);
       response = {

fs/tabfs.c

@@ -32,6 +32,22 @@ static cJSON *send_request_then_await_response(cJSON *req) {
     return resp;
 }
 
+// This helper macro is used to implement all the FUSE fs operations.
+//
+// It constructs a JSON object to represent the incoming request, then
+// dispatches it to the WebSocket server in ws.c (which then
+// dispatches it to our browser extension). It then awaits the
+// response from the browser and lets us pull that apart to ultimately
+// return the data to FUSE.
+//
+// OP is an opcode string which the extension handles in JS.
+// REQ_BUILDER_BODY is a block which should add whatever request
+// properties you want to send to the browser to the `req` cJSON
+// object.  RESP_HANDLER_BODY should handle whatever response
+// properties are on the `resp` cJSON object and pass them back to the
+// kernel.  It should also set the value of `ret` to the desired
+// return value.  (MAKE_REQ takes over return from the containing
+// function so it can automatically return error values.)
 #define MAKE_REQ(OP, REQ_BUILDER_BODY, RESP_HANDLER_BODY)       \
     do {                                              \
         int ret = -1;                                 \
@@ -135,6 +151,22 @@ tabfs_read(const char *path, char *buf, size_t size, off_t offset,
     });
 }
 
+static int
+tabfs_write(const char *path, const char *buf, size_t size, off_t offset,
+            struct fuse_file_info *fi) {
+    MAKE_REQ("write", {
+        cJSON_AddStringToObject(req, "path", path);
+
+        char base64_buf[size + 1]; // ughh.
+        base64_encode((const unsigned char *) buf, size, base64_buf);
+
+        cJSON_AddStringToObject(req, "buf", base64_buf);
+        cJSON_AddNumberToObject(req, "offset", offset);
+    }, {
+        ret = size;
+    });
+}
+
 static int tabfs_release(const char *path, struct fuse_file_info *fi) {
     MAKE_REQ("release", {
         cJSON_AddStringToObject(req, "path", path);
@@ -187,6 +219,7 @@ static struct fuse_operations tabfs_filesystem_operations = {
     .readlink = tabfs_readlink,
     .open     = tabfs_open,    /* To enforce read-only access.       */
     .read     = tabfs_read,    /* To provide file content.           */
+    .write    = tabfs_write,
     .release  = tabfs_release,
 
     .opendir  = tabfs_opendir,