From 22aaeaa9e139e960c7b8c819962e7ff0de95ff71 Mon Sep 17 00:00:00 2001
From: Omar Rizwan <omar.rizwan@gmail.com>
Date: Wed, 2 Dec 2020 20:24:20 -0800
Subject: [PATCH] base64 reads. start working on screenshot stuff.

---
 README.md               | 24 ++++++++++++++----------
 extension/background.js | 13 +++++++++++++
 extension/manifest.json |  6 +++---
 fs/tabfs.c              | 13 +++++++------
 4 files changed, 37 insertions(+), 19 deletions(-)

diff --git a/README.md b/README.md
index 52a6de9..c855795 100644
--- a/README.md
+++ b/README.md
@@ -51,14 +51,17 @@ $ cat mnt/tabs/by-id/*/text > text.txt
 
 ## Setup
 
+**disclaimer**: security, functionality
+
 First, install the browser extension.
 
 Then, install the C filesystem.
 
 ### 1. Install the browser extension
 
-(I think it will work on Edge or Opera or whatever, too. You'll need to
-change the native messaging path in install.sh in those cases.)
+(I think it will work on Edge or Opera or whatever, too. You'll need
+to change the native messaging path in install.sh in those cases. Not
+sure about Safari.)
 
 #### in Chrome
 
@@ -67,7 +70,7 @@ Developer mode (top-right corner).
 
 Load-unpacked the `extension/` folder in this repo.
 
-Make a note of the extension ID. Mine is
+**Make a note of the extension ID Chrome assigns.** Mine is
 `jimpolemfaeckpjijgapgkmolankohgj`. We'll use this later.
 
 #### in Firefox
@@ -134,11 +137,12 @@ operations, even when I don't feel like I'm actually doing anything.)
 
 ## Design
 
-- `extension/`: Browser extension, written in JS
-  - [`background.js`](extension/background.js): **The most interesting file**. Defines all the
-    synthetic files and what browser operations they map to.
 - `fs/`: Native FUSE filesystem, written in C
   - [`tabfs.c`](fs/tabfs.c): Talks to FUSE, implements fs operations, talks to extension.
+- `extension/`: Browser extension, written in JS
+  - [`background.js`](extension/background.js): **The most interesting
+    file**. Defines all the synthetic files and what browser
+    operations they invoke behind the scenes.
 
 <!-- TODO: concretize this -->
 
@@ -172,6 +176,10 @@ GPLv3
 
 ## hmm
 
+processes as files. the real process is the browser. 
+
+browser and Unix
+
 it's way too hard to make an extension. even 'make an extension' is
 a bad framing. lightness
 
@@ -186,9 +194,5 @@ fake filesystems talk
 
 Screenotate
 
-processes as files. the real process is the browser. 
-
-browser and Unix
-
 rmdir a non-empty directory
 
diff --git a/extension/background.js b/extension/background.js
index 759bd0d..3132f48 100644
--- a/extension/background.js
+++ b/extension/background.js
@@ -138,6 +138,18 @@ router["/tabs/by-id"] = {
 router["/tabs/by-id/*/url"] = withTab(tab => tab.url + "\n");
 router["/tabs/by-id/*/title"] = withTab(tab => tab.title + "\n");
 router["/tabs/by-id/*/text"] = fromScript(`document.body.innerText`);
+router["/tabs/by-id/*/screenshot.png"] = {
+  async read({path, fh, size, offset}) {
+    const tabId = parseInt(pathComponent(path, -2));
+    await debugTab(tabId);
+    await sendDebuggerCommand(tabId, "Page.enable", {});
+
+    const {data} = await sendDebuggerCommand(tabId, "Page.captureScreenshot");
+    const arr = Uint8Array.from(atob(data), c => c.charCodeAt(0));
+    const slice = arr.slice(offset, offset + size);
+    return { buf: String.fromCharCode(...slice) };
+  }
+};
 router["/tabs/by-id/*/resources"] = {
   async opendir({path}) {
     const tabId = parseInt(pathComponent(path, -2));
@@ -367,6 +379,7 @@ async function onMessage(req) {
   try {
     response = await findRoute(req.path)[req.op](req);
     response.op = req.op;
+    if (response.buf) response.buf = btoa(response.buf);
 
   } catch (e) {
     console.error(e);
diff --git a/extension/manifest.json b/extension/manifest.json
index 614a6ac..5b742d7 100644
--- a/extension/manifest.json
+++ b/extension/manifest.json
@@ -1,12 +1,12 @@
 {
   "manifest_version": 2,
 
-  "name": "TabFS Extension",
-  "description": "Connects to TabFS filesystem",
+  "name": "TabFS",
+  "description": "Mount your browser tabs as a filesystem",
   "version": "1.0",
 
   "permissions": [
-    "tabs", "debugger", "nativeMessaging",
+    "tabs", "tabCapture", "debugger", "nativeMessaging",
     "unlimitedStorage",
     "*://*/*"
   ],
diff --git a/fs/tabfs.c b/fs/tabfs.c
index 3e3f1db..f52a143 100644
--- a/fs/tabfs.c
+++ b/fs/tabfs.c
@@ -79,8 +79,9 @@ static int tabfs_getattr(const char *path, struct stat *stbuf) {
 static int tabfs_readlink(const char *path, char *buf, size_t size) {
     send_request("{op: %Q, path: %Q}", "readlink", path);
 
-    char *scan_buf; receive_response("{buf: %Q}", &scan_buf);
-    snprintf(buf, size, "%s", scan_buf); free(scan_buf);
+    char *scan_buf; int scan_len;
+    receive_response("{buf: %V}", &scan_buf, &scan_len);
+    memcpy(buf, scan_buf, scan_len < size ? scan_len : size); free(scan_buf);
 
     return 0;
 }
@@ -99,11 +100,11 @@ tabfs_read(const char *path, char *buf, size_t size, off_t offset,
     send_request("{op: %Q, path: %Q, size: %d, offset: %d, fh: %d, flags: %d}",
                  "read", path, size, offset, fi->fh, fi->flags);
 
-    // FIXME: base64
-    char *scan_buf; receive_response("{buf: %Q}", &scan_buf);
-    snprintf(buf, size, "%s", scan_buf); free(scan_buf);
+    char *scan_buf; int scan_len;
+    receive_response("{buf: %V}", &scan_buf, &scan_len);
+    memcpy(buf, scan_buf, scan_len < size ? scan_len : size); free(scan_buf);
 
-    return strlen(scan_buf);
+    return scan_len;
 
     /* MAKE_REQ("read", { */
     /*     cJSON_AddStringToObject(req, "path", path); */