Option for environment variable for git + errors

"Git bash" recommended method of working is *not* putting git in path.
This commits adds the possiblity to use an environment variable pointing
to the git executable.
Also, the non-silent installation now shows clearer errors.

README.md

@@ -1,32 +1 @@
-# Windows Credential Store for Git
-This application is a small helper app designed to follow the git credentials API as defined by the [Git Documentation](https://github.com/gitster/git-htmldocs/blob/master/technical/api-credentials.txt).
-## Installation
-
-1. Download the git-credential-winstore.exe file from the downloads section
-2. Run it (make sure you have git in your PATH)
-
-## FAQs
-
-### Why doesn't it work?
-Make sure you're running the latest version of msysgit. The credential API is fairly new. I've tested this on version 1.7.10.
-
-### Why doesn't it install?
-Make sure you're running with GIT on your PATH (perhaps by running from the GIT bash shell)
-
-### Where are you storing my credentials?
-This app just uses the existing Windows Credential Store to hold your credentials. You can see the stored credentials by going to Control Panel > User Accounts > Credential Manager and choosing "Windows Credentials". The entries starting "git:" are from git-credential-winstore.
-
-### I have another question?
-That's not a question.
-
-### But I actually have another question...
-Ok, you can email me at [andrew@andrewnurse.net](mailto:andrew@andrewnurse.net).
-
-## Special Thanks
-* [Paul Betts](http://paulbetts.org/) for creating our handy-dandy installer.
-* [Matt Wrock](https://github.com/mwrock) for adding a silent option to the installer.
-* [mattn](https://github.com/mattn) for adding support for Windows XP.
-* [Marc Brooks](https://github.com/IDisposable) for some readme tweaks.
-
-## License
-This code is Copyright Andrew Nurse and other contributors 2012. You are hereby granted a license to use the software and code under the terms of the Apache License, Version 2.0 (http://www.apache.org/licenses/LICENSE-2.0.html)
+# Windows Credential Store for GitThis application is a small helper app designed to follow the git credentials API as defined by the [Git Documentation](https://github.com/gitster/git-htmldocs/blob/master/technical/api-credentials.txt).## Installation1. Download the git-credential-winstore.exe file from the downloads section2. Run it (make sure you have git in your PATH)## FAQs### Why doesn't it work?Make sure you're running the latest version of msysgit. The credential API is fairly new. I've tested this on version 1.7.10.### Why doesn't it install?Make sure one of the following is correct:* running with GIT on your PATH (perhaps by running from the GIT bash shell)+ Environment variable GIT_EXECUTABLE points to the git executable (if you don't want git on your path)### Where are you storing my credentials?This app just uses the existing Windows Credential Store to hold your credentials. You can see the stored credentials by going to Control Panel > User Accounts > Credential Manager and choosing "Windows Credentials". The entries starting "git:" are from git-credential-winstore.### I have another question?That's not a question.### But I actually have another question...Ok, you can email me at [andrew@andrewnurse.net](mailto:andrew@andrewnurse.net).## Special Thanks* [Paul Betts](http://paulbetts.org/) for creating our handy-dandy installer.* [Matt Wrock](https://github.com/mwrock) for adding a silent option to the installer.* [mattn](https://github.com/mattn) for adding support for Windows XP.* [Marc Brooks](https://github.com/IDisposable) for some readme tweaks.## LicenseThis code is Copyright Andrew Nurse and other contributors 2012. You are hereby granted a license to use the software and code under the terms of the Apache License, Version 2.0 (http://www.apache.org/licenses/LICENSE-2.0.html)

git-credential-winstore/Program.cs

@@ -22,6 +22,8 @@ class Program
             { "erase", EraseCommand }
         };
 
+        static String GIT_EXECUTABLE_ENVIRONMENT_VARIABLE = "GIT_EXECUTABLE";
+
         static void Main(string[] args)
         {
             TryLaunchDebugger(ref args);
@@ -130,7 +132,28 @@ private static void InstallTheApp(bool silent)
             var dest = new FileInfo(Environment.ExpandEnvironmentVariables(@"%AppData%\GitCredStore\git-credential-winstore.exe"));
             File.Copy(Assembly.GetExecutingAssembly().Location, dest.FullName, true);
 
-            Process.Start("git", string.Format("config --global credential.helper \"!'{0}'\"", dest.FullName));
+            var gitArguments = string.Format("config --global credential.helper \"!'{0}'\"", dest.FullName);
+
+            try {
+                Process.Start("git", gitArguments);
+            } catch (System.ComponentModel.Win32Exception e) {
+                // Running git failed - try the environment variable (sometimes git will not be in the path - 
+                // e.g. when running git bash in recommended setting
+                var gitExecutablePath = System.Environment.GetEnvironmentVariable(GIT_EXECUTABLE_ENVIRONMENT_VARIABLE);
+                if (string.IsNullOrEmpty(gitExecutablePath)) {
+                    MessageBox.Show("Git is not in path and environment variable " + GIT_EXECUTABLE_ENVIRONMENT_VARIABLE +
+                        " is not set.", "No git executable found", MessageBoxButtons.OK);
+                } else {
+                    try {
+                        Process.Start(gitExecutablePath, gitArguments);
+                    } catch (Exception e1) {
+                        MessageBox.Show("Git is not in path and environment variable " + GIT_EXECUTABLE_ENVIRONMENT_VARIABLE +
+                            " doesn't point to a correct git executable.", "No git executable found", MessageBoxButtons.OK);
+                    }
+                }
+
+            }
+
         }
 
         static IEnumerable<Tuple<string, string>> GetCommand(IDictionary<string, string> args)