Merge pull request #14693 from Budibase/js-stack-traces

Pull the error object out of isolated-vm when a user script throws an error.

packages/builder/src/components/common/bindings/BindingPanel.svelte

@@ -66,6 +66,7 @@
   let insertAtPos
   let targetMode = null
   let expressionResult
+  let expressionError
   let evaluating = false
 
   $: useSnippets = allowSnippets && !$licensing.isFreePlan
@@ -142,10 +143,16 @@
   }
 
   const debouncedEval = Utils.debounce((expression, context, snippets) => {
+    try {
+      expressionError = null
       expressionResult = processStringSync(expression || "", {
         ...context,
         snippets,
       })
+    } catch (err) {
+      expressionResult = null
+      expressionError = err
+    }
     evaluating = false
   }, 260)
 
@@ -370,6 +377,7 @@
       {:else if sidePanel === SidePanels.Evaluation}
         <EvaluationSidePanel
           {expressionResult}
+          {expressionError}
           {evaluating}
           expression={editorValue}
         />

packages/builder/src/components/common/bindings/EvaluationSidePanel.svelte

@@ -3,26 +3,37 @@
   import { Icon, ProgressCircle, notifications } from "@budibase/bbui"
   import { copyToClipboard } from "@budibase/bbui/helpers"
   import { fade } from "svelte/transition"
+  import { UserScriptError } from "@budibase/string-templates"
 
   export let expressionResult
+  export let expressionError
   export let evaluating = false
   export let expression = null
 
-  $: error = expressionResult === "Error while executing JS"
+  $: error = expressionError != null
   $: empty = expression == null || expression?.trim() === ""
   $: success = !error && !empty
   $: highlightedResult = highlight(expressionResult)
 
+  const formatError = err => {
+    if (err.code === UserScriptError.code) {
+      return err.userScriptError.toString()
+    }
+    return err.toString()
+  }
+
   const highlight = json => {
     if (json == null) {
       return ""
     }
-    // Attempt to parse and then stringify, in case this is valid JSON
+
+    // Attempt to parse and then stringify, in case this is valid result
     try {
       json = JSON.stringify(JSON.parse(json), null, 2)
     } catch (err) {
       // Ignore
     }
+
     return formatHighlight(json, {
       keyColor: "#e06c75",
       numberColor: "#e5c07b",
@@ -34,7 +45,7 @@
   }
 
   const copy = () => {
-    let clipboardVal = expressionResult
+    let clipboardVal = expressionResult.result
     if (typeof clipboardVal === "object") {
       clipboardVal = JSON.stringify(clipboardVal, null, 2)
     }
@@ -73,6 +84,8 @@
   <div class="body">
     {#if empty}
       Your expression will be evaluated here
+    {:else if error}
+      {formatError(expressionError)}
     {:else}
       <!-- eslint-disable-next-line svelte/no-at-html-tags-->
       {@html highlightedResult}

packages/server/src/api/controllers/script.ts

@@ -1,11 +1,18 @@
 import { Ctx } from "@budibase/types"
 import { IsolatedVM } from "../../jsRunner/vm"
-import { iifeWrapper } from "@budibase/string-templates"
+import { iifeWrapper, UserScriptError } from "@budibase/string-templates"
 
 export async function execute(ctx: Ctx) {
   const { script, context } = ctx.request.body
   const vm = new IsolatedVM()
+  try {
     ctx.body = vm.withContext(context, () => vm.execute(iifeWrapper(script)))
+  } catch (err: any) {
+    if (err.code === UserScriptError.code) {
+      throw err.userScriptError
+    }
+    throw err
+  }
 }
 
 export async function save(ctx: Ctx) {

packages/server/src/api/routes/tests/row.spec.ts

@@ -49,6 +49,7 @@ import * as uuid from "uuid"
 import { Knex } from "knex"
 import { InternalTables } from "../../../db/utils"
 import { withEnv } from "../../../environment"
+import { JsTimeoutError } from "@budibase/string-templates"
 
 const timestamp = new Date("2023-01-26T11:48:57.597Z").toISOString()
 tk.freeze(timestamp)
@@ -3013,7 +3014,7 @@ describe.each([
             let i = 0
             for (; i < 10; i++) {
               const row = rows[i]
-              if (row.formula !== "Timed out while executing JS") {
+              if (row.formula !== JsTimeoutError.message) {
                 break
               }
             }
@@ -3027,7 +3028,7 @@ describe.each([
             for (; i < 10; i++) {
               const row = rows[i]
               expect(row.text).toBe("foo")
-              expect(row.formula).toBe("Request JS execution limit hit")
+              expect(row.formula).toStartWith("CPU time limit exceeded ")
             }
           }
         }

packages/server/src/jsRunner/index.ts

@@ -1,7 +1,7 @@
 import { serializeError } from "serialize-error"
 import env from "../environment"
 import {
-  JsErrorTimeout,
+  JsTimeoutError,
   setJSRunner,
   setOnErrorLog,
 } from "@budibase/string-templates"
@@ -40,7 +40,7 @@ export function init() {
         return vm.withContext(rest, () => vm.execute(js))
       } catch (error: any) {
         if (error.message === "Script execution timed out.") {
-          throw new JsErrorTimeout()
+          throw new JsTimeoutError()
         }
         throw error
       }

packages/server/src/jsRunner/tests/jsRunner.spec.ts

@@ -41,10 +41,11 @@ describe("jsRunner (using isolated-vm)", () => {
   })
 
   it("should prevent sandbox escape", async () => {
-    const output = await processJS(
+    await expect(
-      `return this.constructor.constructor("return process.env")()`
+      processJS(`return this.constructor.constructor("return process.env")()`)
+    ).rejects.toThrow(
+      "error while running user-supplied JavaScript: ReferenceError: process is not defined"
     )
-    expect(output).toBe("Error while executing JS")
   })
 
   describe("helpers", () => {

packages/server/src/jsRunner/vm/isolated-vm.ts

@@ -7,14 +7,12 @@ import querystring from "querystring"
 
 import { BundleType, loadBundle } from "../bundles"
 import { Snippet, VM } from "@budibase/types"
-import { iifeWrapper } from "@budibase/string-templates"
+import { iifeWrapper, UserScriptError } from "@budibase/string-templates"
 import environment from "../../environment"
 
-class ExecutionTimeoutError extends Error {
+export class JsRequestTimeoutError extends Error {
-  constructor(message: string) {
+  static code = "JS_REQUEST_TIMEOUT_ERROR"
-    super(message)
+  code = JsRequestTimeoutError.code
-    this.name = "ExecutionTimeoutError"
-  }
 }
 
 export class IsolatedVM implements VM {
@@ -29,6 +27,7 @@ export class IsolatedVM implements VM {
 
   private readonly resultKey = "results"
   private runResultKey: string
+  private runErrorKey: string
 
   constructor({
     memoryLimit,
@@ -47,6 +46,7 @@ export class IsolatedVM implements VM {
     this.jail.setSync("global", this.jail.derefInto())
 
     this.runResultKey = crypto.randomUUID()
+    this.runErrorKey = crypto.randomUUID()
     this.addToContext({
       [this.resultKey]: { [this.runResultKey]: "" },
     })
@@ -210,13 +210,19 @@ export class IsolatedVM implements VM {
     if (this.isolateAccumulatedTimeout) {
       const cpuMs = Number(this.isolate.cpuTime) / 1e6
       if (cpuMs > this.isolateAccumulatedTimeout) {
-        throw new ExecutionTimeoutError(
+        throw new JsRequestTimeoutError(
           `CPU time limit exceeded (${cpuMs}ms > ${this.isolateAccumulatedTimeout}ms)`
         )
       }
     }
 
-    code = `results['${this.runResultKey}']=${this.codeWrapper(code)}`
+    code = `
+      try {
+        results['${this.runResultKey}']=${this.codeWrapper(code)}
+      } catch (e) {
+        results['${this.runErrorKey}']=e
+      }
+    `
 
     const script = this.isolate.compileScriptSync(code)
 
@@ -227,6 +233,9 @@ export class IsolatedVM implements VM {
 
     // We can't rely on the script run result as it will not work for non-transferable values
     const result = this.getFromContext(this.resultKey)
+    if (result[this.runErrorKey]) {
+      throw new UserScriptError(result[this.runErrorKey])
+    }
     return result[this.runResultKey]
   }
 

packages/server/src/utilities/rowProcessor/utils.ts

@@ -1,5 +1,5 @@
 import { AutoFieldDefaultNames } from "../../constants"
-import { processStringSync } from "@budibase/string-templates"
+import { processStringSync, UserScriptError } from "@budibase/string-templates"
 import {
   AutoColumnFieldMetadata,
   FieldSchema,
@@ -81,7 +81,14 @@ export async function processFormulas<T extends Row | Row[]>(
             ...row,
             [column]: tracer.trace("processStringSync", {}, span => {
               span?.addTags({ table_id: table._id, column, static: isStatic })
+              try {
                 return processStringSync(formula, context)
+              } catch (err: any) {
+                if (err.code === UserScriptError.code) {
+                  return err.userScriptError.toString()
+                }
+                throw err
+              }
             }),
           }
         }

packages/string-templates/src/errors.ts

@@ -1,3 +1,20 @@
-export class JsErrorTimeout extends Error {
+export class JsTimeoutError extends Error {
-  code = "ERR_SCRIPT_EXECUTION_TIMEOUT"
+  static message = "Timed out while executing JS"
+  static code = "JS_TIMEOUT_ERROR"
+  code: string = JsTimeoutError.code
+
+  constructor() {
+    super(JsTimeoutError.message)
+  }
+}
+
+export class UserScriptError extends Error {
+  static code = "USER_SCRIPT_ERROR"
+  code: string = UserScriptError.code
+
+  constructor(readonly userScriptError: Error) {
+    super(
+      `error while running user-supplied JavaScript: ${userScriptError.toString()}`
+    )
+  }
 }

packages/string-templates/src/helpers/javascript.ts

@@ -3,6 +3,7 @@ import cloneDeep from "lodash/fp/cloneDeep"
 import { LITERAL_MARKER } from "../helpers/constants"
 import { getJsHelperList } from "./list"
 import { iifeWrapper } from "../iife"
+import { JsTimeoutError, UserScriptError } from "../errors"
 
 // The method of executing JS scripts depends on the bundle being built.
 // This setter is used in the entrypoint (either index.js or index.mjs).
@@ -94,12 +95,41 @@ export function processJS(handlebars: string, context: any) {
   } catch (error: any) {
     onErrorLog && onErrorLog(error)
 
+    // The error handling below is quite messy, because it has fallen to
+    // string-templates to handle a variety of types of error specific to usages
+    // above it in the stack. It would be nice some day to refactor this to
+    // allow each user of processStringSync to handle errors in the way they see
+    // fit.
+
+    // This is to catch the error vm.runInNewContext() throws when the timeout
+    // is exceeded.
     if (error.code === "ERR_SCRIPT_EXECUTION_TIMEOUT") {
       return "Timed out while executing JS"
     }
-    if (error.name === "ExecutionTimeoutError") {
+
-      return "Request JS execution limit hit"
+    // This is to catch the JsRequestTimeoutError we throw when we detect a
+    // timeout across an entire request in the backend. We use a magic string
+    // because we can't import from the backend into string-templates.
+    if (error.code === "JS_REQUEST_TIMEOUT_ERROR") {
+      return error.message
     }
+
+    // This is to catch the JsTimeoutError we throw when we detect a timeout in
+    // a single JS execution.
+    if (error.code === JsTimeoutError.code) {
+      return JsTimeoutError.message
+    }
+
+    // This is to catch the error that happens if a user-supplied JS script
+    // throws for reasons introduced by the user.
+    if (error.code === UserScriptError.code) {
+      throw error
+    }
+
+    if (error.name === "SyntaxError") {
+      return error.toString()
+    }
+
     return "Error while executing JS"
   }
 }

packages/string-templates/src/index.ts

@@ -16,6 +16,7 @@ import { removeJSRunner, setJSRunner } from "./helpers/javascript"
 
 import manifest from "./manifest.json"
 import { ProcessOptions } from "./types"
+import { UserScriptError } from "./errors"
 
 export { helpersToRemoveForJs, getJsHelperList } from "./helpers/list"
 export { FIND_ANY_HBS_REGEX } from "./utilities"
@@ -229,7 +230,10 @@ export function processStringSync(
     } else {
       return process(string)
     }
-  } catch (err) {
+  } catch (err: any) {
+    if (err.code === UserScriptError.code) {
+      throw err
+    }
     return input
   }
 }
@@ -448,7 +452,7 @@ export function convertToJS(hbs: string) {
   return `${varBlock}${js}`
 }
 
-export { JsErrorTimeout } from "./errors"
+export { JsTimeoutError, UserScriptError } from "./errors"
 
 export function defaultJSSetup() {
   if (!isBackendService()) {
@@ -463,7 +467,27 @@ export function defaultJSSetup() {
         setTimeout: undefined,
       }
       createContext(context)
-      return runInNewContext(js, context, { timeout: 1000 })
+
+      const wrappedJs = `
+        result = {
+          result: null,
+          error: null,
+        };
+
+        try {
+          result.result = ${js};
+        } catch (e) {
+          result.error = e;
+        }
+
+        result;
+      `
+
+      const result = runInNewContext(wrappedJs, context, { timeout: 1000 })
+      if (result.error) {
+        throw new UserScriptError(result.error)
+      }
+      return result.result
     })
   } else {
     removeJSRunner()