Allow inspection and revocation of permissions (#1875)

9 files changed, 249 insertions, 0 deletions

diff --git a/BUILD.gn b/BUILD.gn
index 756d0e9cf..91abcc80d 100644
--- a/BUILD.gn
+++ b/BUILD.gn
@@ -91,6 +91,7 @@ ts_sources = [
   "js/mock_builtin.js",
   "js/net.ts",
   "js/os.ts",
+  "js/permissions.ts",
   "js/platform.ts",
   "js/plugins.d.ts",
   "js/process.ts",
diff --git a/js/deno.ts b/js/deno.ts
index 66d7d796c..d13ca81dd 100644
--- a/js/deno.ts
+++ b/js/deno.ts
@@ -50,6 +50,12 @@ export { symlinkSync, symlink } from "./symlink";
 export { writeFileSync, writeFile, WriteFileOptions } from "./write_file";
 export { ErrorKind, DenoError } from "./errors";
 export { libdeno } from "./libdeno";
+export {
+  permissions,
+  revokePermission,
+  Permission,
+  Permissions
+} from "./permissions";
 export { platform } from "./platform";
 export { truncateSync, truncate } from "./truncate";
 export { FileInfo } from "./file_info";
diff --git a/js/permissions.ts b/js/permissions.ts
new file mode 100644
index 000000000..6acb80b1f
--- /dev/null
+++ b/js/permissions.ts
@@ -0,0 +1,74 @@
+// Copyright 2018-2019 the Deno authors. All rights reserved. MIT license.
+import * as msg from "gen/msg_generated";
+import * as flatbuffers from "./flatbuffers";
+import * as dispatch from "./dispatch";
+import { assert } from "./util";
+
+/** Permissions as granted by the caller */
+export type Permissions = {
+  read: boolean;
+  write: boolean;
+  net: boolean;
+  env: boolean;
+  run: boolean;
+
+  // NOTE: Keep in sync with src/permissions.rs
+};
+
+export type Permission = keyof Permissions;
+
+/** Inspect granted permissions for the current program.
+ *
+ *       if (Deno.permissions().read) {
+ *         const file = await Deno.readFile("example.test");
+ *         // ...
+ *       }
+ */
+export function permissions(): Permissions {
+  const baseRes = dispatch.sendSync(...getReq())!;
+  assert(msg.Any.PermissionsRes === baseRes.innerType());
+  const res = new msg.PermissionsRes();
+  assert(baseRes.inner(res) != null);
+  // TypeScript cannot track assertion above, therefore not null assertion
+  return createPermissions(res);
+}
+
+/** Revoke a permission. When the permission was already revoked nothing changes
+ *
+ *       if (Deno.permissions().read) {
+ *         const file = await Deno.readFile("example.test");
+ *         Deno.revokePermission('read');
+ *       }
+ *       Deno.readFile("example.test"); // -> error or permission prompt
+ */
+export function revokePermission(permission: Permission): void {
+  dispatch.sendSync(...revokeReq(permission));
+}
+
+function createPermissions(inner: msg.PermissionsRes): Permissions {
+  return {
+    read: inner.read(),
+    write: inner.write(),
+    net: inner.net(),
+    env: inner.env(),
+    run: inner.run()
+  };
+}
+
+function getReq(): [flatbuffers.Builder, msg.Any, flatbuffers.Offset] {
+  const builder = flatbuffers.createBuilder();
+  msg.Permissions.startPermissions(builder);
+  const inner = msg.Permissions.endPermissions(builder);
+  return [builder, msg.Any.Permissions, inner];
+}
+
+function revokeReq(
+  permission: string
+): [flatbuffers.Builder, msg.Any, flatbuffers.Offset] {
+  const builder = flatbuffers.createBuilder();
+  const permission_ = builder.createString(permission);
+  msg.PermissionRevoke.startPermissionRevoke(builder);
+  msg.PermissionRevoke.addPermission(builder, permission_);
+  const inner = msg.PermissionRevoke.endPermissionRevoke(builder);
+  return [builder, msg.Any.PermissionRevoke, inner];
+}
diff --git a/js/permissions_test.ts b/js/permissions_test.ts
new file mode 100644
index 000000000..f4245c03b
--- /dev/null
+++ b/js/permissions_test.ts
@@ -0,0 +1,22 @@
+// Copyright 2018-2019 the Deno authors. All rights reserved. MIT license.
+import { testPerm, assert, assertEqual } from "./test_util.ts";
+import { Permission } from "deno";
+
+const knownPermissions: Permission[] = ["run", "read", "write", "net", "env"];
+
+for (let grant of knownPermissions) {
+  testPerm({ [grant]: true }, function envGranted() {
+    const perms = Deno.permissions();
+    assert(perms !== null);
+    for (const perm in perms) {
+      assertEqual(perms[perm], perm === grant);
+    }
+
+    Deno.revokePermission(grant);
+
+    const revoked = Deno.permissions();
+    for (const perm in revoked) {
+      assertEqual(revoked[perm], false);
+    }
+  });
+}
diff --git a/js/unit_tests.ts b/js/unit_tests.ts
index 91c1745b6..5085deb5c 100644
--- a/js/unit_tests.ts
+++ b/js/unit_tests.ts
@@ -45,6 +45,7 @@ import "./url_test.ts";
 import "./url_search_params_test.ts";
 import "./write_file_test.ts";
 import "./performance_test.ts";
+import "./permissions_test.ts";
 import "./version_test.ts";
 
 import "../website/app_test.js";
diff --git a/src/msg.fbs b/src/msg.fbs
index da03e00a4..1b57e72ef 100644
--- a/src/msg.fbs
+++ b/src/msg.fbs
@@ -12,6 +12,9 @@ union Any {
   Exit,
   Environ,
   EnvironRes,
+  Permissions,
+  PermissionRevoke,
+  PermissionsRes,
   Fetch,
   FetchRes,
   MakeTempDir,
@@ -231,6 +234,20 @@ table KeyValue {
   value: string;
 }
 
+table Permissions {}
+
+table PermissionRevoke {
+  permission: string;
+}
+
+table PermissionsRes {
+  run: bool;
+  read: bool;
+  write: bool;
+  net: bool;
+  env: bool;
+}
+
 // Note this represents The WHOLE header of an http message, not just the key
 // value pairs. That means it includes method and url for Requests and status
 // for responses. This is why it is singular "Header" instead of "Headers".
diff --git a/src/ops.rs b/src/ops.rs
index 5535ca1b9..ba309ca7a 100644
--- a/src/ops.rs
+++ b/src/ops.rs
@@ -130,6 +130,8 @@ pub fn dispatch(
       msg::Any::Now => op_now,
       msg::Any::IsTTY => op_is_tty,
       msg::Any::Seek => op_seek,
+      msg::Any::Permissions => op_permissions,
+      msg::Any::PermissionRevoke => op_revoke_permission,
       _ => panic!(format!(
         "Unhandled message {}",
         msg::enum_name_any(inner_type)
@@ -503,6 +505,57 @@ fn op_env(
   ))
 }
 
+fn op_permissions(
+  isolate: &Isolate,
+  base: &msg::Base<'_>,
+  data: libdeno::deno_buf,
+) -> Box<Op> {
+  assert_eq!(data.len(), 0);
+  let cmd_id = base.cmd_id();
+  let builder = &mut FlatBufferBuilder::new();
+  let inner = msg::PermissionsRes::create(
+    builder,
+    &msg::PermissionsResArgs {
+      run: isolate.permissions.allows_run(),
+      read: isolate.permissions.allows_read(),
+      write: isolate.permissions.allows_write(),
+      net: isolate.permissions.allows_net(),
+      env: isolate.permissions.allows_env(),
+    },
+  );
+  ok_future(serialize_response(
+    cmd_id,
+    builder,
+    msg::BaseArgs {
+      inner: Some(inner.as_union_value()),
+      inner_type: msg::Any::PermissionsRes,
+      ..Default::default()
+    },
+  ))
+}
+
+fn op_revoke_permission(
+  isolate: &Isolate,
+  base: &msg::Base<'_>,
+  data: libdeno::deno_buf,
+) -> Box<Op> {
+  assert_eq!(data.len(), 0);
+  let inner = base.inner_as_permission_revoke().unwrap();
+  let permission = inner.permission().unwrap();
+  let result = match permission {
+    "run" => isolate.permissions.revoke_run(),
+    "read" => isolate.permissions.revoke_read(),
+    "write" => isolate.permissions.revoke_write(),
+    "net" => isolate.permissions.revoke_net(),
+    "env" => isolate.permissions.revoke_env(),
+    _ => Ok(()),
+  };
+  if let Err(e) = result {
+    return odd_future(e);
+  }
+  ok_future(empty_buf())
+}
+
 fn op_fetch(
   isolate: &Isolate,
   base: &msg::Base<'_>,
diff --git a/src/permissions.rs b/src/permissions.rs
index b40afb64e..03ffd20cb 100644
--- a/src/permissions.rs
+++ b/src/permissions.rs
@@ -12,6 +12,7 @@ use std::sync::atomic::{AtomicBool, Ordering};
 #[cfg_attr(feature = "cargo-clippy", allow(stutter))]
 #[derive(Debug, Default)]
 pub struct DenoPermissions {
+  // Keep in sync with src/permissions.ts
   pub allow_read: AtomicBool,
   pub allow_write: AtomicBool,
   pub allow_net: AtomicBool,
@@ -91,6 +92,51 @@ impl DenoPermissions {
     r
   }
 
+  pub fn allows_run(&self) -> bool {
+    return self.allow_run.load(Ordering::SeqCst);
+  }
+
+  pub fn allows_read(&self) -> bool {
+    return self.allow_read.load(Ordering::SeqCst);
+  }
+
+  pub fn allows_write(&self) -> bool {
+    return self.allow_write.load(Ordering::SeqCst);
+  }
+
+  pub fn allows_net(&self) -> bool {
+    return self.allow_net.load(Ordering::SeqCst);
+  }
+
+  pub fn allows_env(&self) -> bool {
+    return self.allow_env.load(Ordering::SeqCst);
+  }
+
+  pub fn revoke_run(&self) -> DenoResult<()> {
+    self.allow_run.store(false, Ordering::SeqCst);
+    return Ok(());
+  }
+
+  pub fn revoke_read(&self) -> DenoResult<()> {
+    self.allow_read.store(false, Ordering::SeqCst);
+    return Ok(());
+  }
+
+  pub fn revoke_write(&self) -> DenoResult<()> {
+    self.allow_write.store(false, Ordering::SeqCst);
+    return Ok(());
+  }
+
+  pub fn revoke_net(&self) -> DenoResult<()> {
+    self.allow_net.store(false, Ordering::SeqCst);
+    return Ok(());
+  }
+
+  pub fn revoke_env(&self) -> DenoResult<()> {
+    self.allow_env.store(false, Ordering::SeqCst);
+    return Ok(());
+  }
+
   pub fn default() -> Self {
     Self {
       allow_read: AtomicBool::new(false),
diff --git a/website/manual.md b/website/manual.md
index 9081637a1..43b79d003 100644
--- a/website/manual.md
+++ b/website/manual.md
@@ -286,6 +286,35 @@ It's worth noting that like the `cat.ts` example, the `copy()` function here
 also does not make unnecessary memory copies. It receives a packet from the
 kernel and sends back, without further complexity.
 
+### Inspecting and revoking permissions
+
+Sometimes a program may want to revoke previously granted permissions. When a
+program, at a later stage, needs those permissions, a new prompt will be
+presented to the user.
+
+```ts
+const { permissions, revokePermission, open, remove } = Deno;
+
+(async () => {
+  // lookup a permission
+  if (!permissions().write) {
+    throw new Error("need write permission");
+  }
+
+  const log = await open("request.log", "a+");
+
+  // revoke some permissions
+  revokePermission("read");
+  revokePermission("write");
+
+  // use the log file
+  await log.write(encoder.encode("hello\n"));
+
+  // this will prompt for the write permission or fail.
+  await remove("request.log");
+})();
+```
+
 ### File server
 
 This one serves a local directory in HTTP.