Add error handling for parser

Author: marcnjaramillo

extensions/ql-vscode/src/cli.ts

@@ -3,8 +3,10 @@ import * as child_process from 'child_process';
 import * as fs from 'fs-extra';
 import * as path from 'path';
 import { parser } from 'stream-json';
-import { chain } from 'stream-chain';
+import { pick } from 'stream-json/filters/Pick';
+import { verifier } from 'stream-json/utils/Verifier';
 import Assembler = require('stream-json/Assembler');
+import { chain } from 'stream-chain';
 import * as sarif from 'sarif';
 import { SemVer } from 'semver';
 import { Readable } from 'stream';
@@ -20,9 +22,6 @@ import { assertNever } from './pure/helpers-pure';
 import { QueryMetadata, SortDirection } from './pure/interface-types';
 import { Logger, ProgressReporter } from './logging';
 import { CompilationMessage } from './pure/messages';
-// import Chain = require('stream-chain');
-import { pick } from 'stream-json/filters/Pick';
-// import { filter } from 'stream-json/filters/Filter';
 
 
 /**
@@ -676,39 +675,56 @@ export class CodeQLCliServer implements Disposable {
 
   async interpretBqrs(metadata: QueryMetadata, resultsPath: string, interpretedResultsPath: string, sourceInfo?: SourceInfo): Promise<sarif.Log> {
     await this.runInterpretCommand(SARIF_FORMAT, metadata, resultsPath, interpretedResultsPath, sourceInfo);
-    const fakeSarifPath = '/Users/marcjaramillo/MLH/jdk11-taintedpath-large-ungrouped.sarif';
+
     try {
+      // Parse the SARIF file into token streams, filtering out only the results array.
       const p = parser();
-      //TODO: see if there is a way to create a parser that will return the count of codeFlow
-      // paths first and then parse the SARIF based on whether it exceeds a certain threshhold.
-      // Also, see if it's possible to parse only the first 5 or so codeFlows right up front
-      // rather than parsing everything and then getting rid of the paths we don't want.
-      // Update 11-10-2021: with the new test file, everything works much better so this may not be necessary.
       const pipeline = chain([
-        fs.createReadStream(fakeSarifPath),
+        fs.createReadStream(interpretedResultsPath),
         p,
-        pick({filter: 'runs.0.results'})
+        pick({filter: 'runs.0.results'}),
+        verifier()
       ]);
 
+      // Creates JavaScript objects from the token stream
       const asm = Assembler.connectTo(pipeline);
-      //TODO: figure out error handling for Assembler
-      return await new Promise((resolve) => {
-        asm.on('done', (asm) => {
-          const dummyTool : sarif.Tool = {driver: {name: ''}};
-
-          const log : sarif.Log = {
-            version: '2.1.0', 
-            runs: [
-              { 
-                tool: dummyTool, 
-                results: asm.current
-              }
-            ]
-          };
-
-          console.log('Log completed');
-          resolve(log);
+
+      // Returns a constructed Log object with the results or an empty array if no results were found.
+      // If the parser fails for any reason, it will reject the promise.
+      return await new Promise((resolve, reject) => {
+        pipeline.on('error', (error) => {
+          reject(error);
         });
+
+          asm.on('done', (asm) => {
+            const dummyTool : sarif.Tool = {driver: {name: ''}};
+            if (asm.current) {
+              const log : sarif.Log = {
+                version: '2.1.0', 
+                runs: [
+                  { 
+                    tool: dummyTool, 
+                    results: asm.current
+                  }
+                ]
+              };
+
+              resolve(log);
+            } else {
+              const log : sarif.Log = {
+                version: '2.1.0', 
+                runs: [
+                  { 
+                    tool: dummyTool, 
+                    results: []
+                  }
+                ]
+              };
+
+              resolve(log);
+            }
+  
+          });
       });
     } catch (err) {
       throw new Error(`Parsing output of interpretation failed: ${err.stderr || err}`);