Fix #292: Check for Homebrew's OpenSSL libraries correctly

This change improves the way we check for OpenSSL libraries that must be
installed on the user's macOS system before PowerShell Editor Services can
be loaded successfully.  Previously we were looking for a path that
required a symbolic link to be created after installing OpenSSL.  It turns
out that PowerShell on macOS has built-in library paths which target
Homebrew's installation path for OpenSSL.  We now check primarily for this
path before looking at the system-wide installation path.

Author: daviwil

docs/troubleshooting.md

@@ -9,7 +9,16 @@ PowerShell extension for Visual Studio Code.
 
 The most common problem when the PowerShell extension doesn't work on Mac OS X is that
 OpenSSL is not installed.  You can check for the installation of OpenSSL by looking for
-the following two files:
+the following files:
+
+If installed using Homebrew:
+
+```
+/usr/local/opt/openssl/lib/libcrypto.1.0.0.dylib
+/usr/local/opt/openssl/lib/libssl.1.0.0.dylib
+```
+
+If installed by some other means:
 
 ```
 /usr/local/lib/libcrypto.1.0.0.dylib
@@ -21,17 +30,15 @@ do not have OpenSSL installed.
 
 #### Installing OpenSSL via Homebrew
 
-You can use [Homebrew](http://brew.sh) to easily install OpenSSL.  First, install Homebrew and then run the following command:
+We **highly recommend** that you use [Homebrew](http://brew.sh) to install OpenSSL.  The PowerShell distribution for OS X
+has built-in support for Homebrew's OpenSSL library paths.  If you install with Homebrew, you will avoid
+[security concerns](https://github.com/PowerShell/PowerShell/blob/master/docs/installation/linux.md#openssl)
+around creating symbolic links in your `/usr/local/lib` path which are needed when using other means of installation.
 
-```
-brew install openssl
-```
-
-After installation, the libraries of interest must be symlinked to `/usr/local/lib`; e.g. (note that /usr/local/lib may not already exist and may need to be created before symlinking):
+First, install Homebrew and then run the following command:
 
 ```
-ln -s /usr/local/opt/openssl/lib/libcrypto.1.0.0.dylib /usr/local/lib/libcrypto.1.0.0.dylib
-ln -s /usr/local/opt/openssl/lib/libssl.1.0.0.dylib /usr/local/lib/libssl.1.0.0.dylib
+brew install openssl
 ```
 
 Restart VS Code after completing the installation and verify that the extension is working correctly.
@@ -47,8 +54,8 @@ sudo port install openssl
 You will need to take an additional step once installation completes:
 
 ```
-sudo ln -s /opt/local/lib/libcrypto.1.0.0.dylib /usr/local/lib/
-sudo ln -s /opt/local/lib/libssl.1.0.0.dylib /usr/local/lib/
+sudo ln -s /opt/local/lib/libcrypto.1.0.0.dylib /usr/local/lib/libcrypto.1.0.0.dylib
+sudo ln -s /opt/local/lib/libssl.1.0.0.dylib /usr/local/lib/libssl.1.0.0.dylib
 ```
 
 Thanks to [@MarlonRodriguez](https://github.com/MarlonRodriguez) for the tip!

src/session.ts

@@ -454,9 +454,12 @@ export class SessionManager {
         else if (os.platform() == "darwin") {
             powerShellExePath = "/usr/local/bin/powershell";
 
-            // Check for OpenSSL dependency on OS X
-            if (!utils.checkIfFileExists("/usr/local/lib/libcrypto.1.0.0.dylib") ||
-                !utils.checkIfFileExists("/usr/local/lib/libssl.1.0.0.dylib")) {
+            // Check for OpenSSL dependency on OS X.  Look for the default Homebrew installation
+            // path and if that fails check the system-wide library path.
+            if (!(utils.checkIfFileExists("/usr/local/opt/openssl/lib/libcrypto.1.0.0.dylib") &&
+                  utils.checkIfFileExists("/usr/local/opt/openssl/lib/libssl.1.0.0.dylib")) &&
+                !(utils.checkIfFileExists("/usr/local/lib/libcrypto.1.0.0.dylib") &&
+                  utils.checkIfFileExists("/usr/local/lib/libssl.1.0.0.dylib"))) {
                     var thenable =
                         vscode.window.showWarningMessage(
                             "The PowerShell extension will not work without OpenSSL on Mac OS X",