Do not resolve symbolic links in posix locator if they exceed the cou…

…nt limit (#21658)

Closes #21310

Fixes interpreter discovery running forever for non-Windows OS

src/client/pythonEnvironments/base/locators/lowLevel/posixKnownPathsLocator.ts

@@ -33,6 +33,7 @@ export class PosixKnownPathsLocator extends Locator<BasicEnvInfo> {
                 // those binaries as environments.
                 const knownDirs = (await commonPosixBinPaths()).filter((dirname) => !isPyenvShimDir(dirname));
                 let pythonBinaries = await getPythonBinFromPosixPaths(knownDirs);
+                traceVerbose(`Found ${pythonBinaries.length} python binaries in posix paths`);
 
                 // Filter out MacOS system installs of Python 2 if necessary.
                 if (isMacPython2Deprecated) {

src/client/pythonEnvironments/common/externalDependencies.ts

@@ -10,7 +10,7 @@ import { IDisposable, IConfigurationService } from '../../common/types';
 import { chain, iterable } from '../../common/utils/async';
 import { getOSType, OSType } from '../../common/utils/platform';
 import { IServiceContainer } from '../../ioc/types';
-import { traceVerbose } from '../../logging';
+import { traceError, traceVerbose } from '../../logging';
 
 let internalServiceContainer: IServiceContainer;
 export function initializeExternalDependencies(serviceContainer: IServiceContainer): void {
@@ -93,16 +93,21 @@ export function arePathsSame(path1: string, path2: string): boolean {
     return normCasePath(path1) === normCasePath(path2);
 }
 
-export async function resolveSymbolicLink(absPath: string, stats?: fsapi.Stats): Promise<string> {
+export async function resolveSymbolicLink(absPath: string, stats?: fsapi.Stats, count?: number): Promise<string> {
     stats = stats ?? (await fsapi.lstat(absPath));
     if (stats.isSymbolicLink()) {
+        if (count && count > 5) {
+            traceError(`Detected a potential symbolic link loop at ${absPath}, terminating resolution.`);
+            return absPath;
+        }
         const link = await fsapi.readlink(absPath);
         // Result from readlink is not guaranteed to be an absolute path. For eg. on Mac it resolves
         // /usr/local/bin/python3.9 -> ../../../Library/Frameworks/Python.framework/Versions/3.9/bin/python3.9
         //
         // The resultant path is reported relative to the symlink directory we resolve. Convert that to absolute path.
         const absLinkPath = path.isAbsolute(link) ? link : path.resolve(path.dirname(absPath), link);
-        return resolveSymbolicLink(absLinkPath);
+        count = count ? count + 1 : 1;
+        return resolveSymbolicLink(absLinkPath, undefined, count);
     }
     return absPath;
 }

src/client/pythonEnvironments/common/posixUtils.ts

@@ -7,7 +7,7 @@ import * as path from 'path';
 import { uniq } from 'lodash';
 import { getSearchPathEntries } from '../../common/utils/exec';
 import { resolveSymbolicLink } from './externalDependencies';
-import { traceError, traceInfo } from '../../logging';
+import { traceError, traceInfo, traceVerbose } from '../../logging';
 
 /**
  * Determine if the given filename looks like the simplest Python executable.
@@ -123,6 +123,7 @@ export async function getPythonBinFromPosixPaths(searchDirs: string[]): Promise<
             // Ensure that we have a collection of unique global binaries by
             // resolving all symlinks to the target binaries.
             try {
+                traceVerbose(`Attempting to resolve symbolic link: ${filepath}`);
                 const resolvedBin = await resolveSymbolicLink(filepath);
                 if (binToLinkMap.has(resolvedBin)) {
                     binToLinkMap.get(resolvedBin)?.push(filepath);