From 96f0c0f9e6a4afbe7455b5c4567d40a25270a3a2 Mon Sep 17 00:00:00 2001
From: Sebastian Schuberth <sschuberth@gmail.com>
Date: Sat, 14 May 2011 19:34:32 +0200
Subject: [PATCH] Installer: Early check whether the installation directory is
 writable

This avoids the user from going through all the settings again in case
a directory was chosen that cannot be written to in setup's very last
copy step.

Signed-off-by: Sebastian Schuberth <sschuberth@gmail.com>
---
 share/WinGit/helpers.inc.iss | 22 ++++++++++++++++++++++
 share/WinGit/install.iss     | 21 +++++++++++++++++++++
 2 files changed, 43 insertions(+)

diff --git a/share/WinGit/helpers.inc.iss b/share/WinGit/helpers.inc.iss
index ff187bf5..0377dc52 100644
--- a/share/WinGit/helpers.inc.iss
+++ b/share/WinGit/helpers.inc.iss
@@ -60,3 +60,25 @@ begin
         Result:=(Pos(Component,Value)>0);
     end;
 end;
+
+// Checks whether the specified directory can be created and written to.
+// Note that the created dummy file is not explicitly deleted here, so that
+// needs to be done as part of the uninstall process.
+function IsDirWritable(DirName:String):Boolean;
+var
+    FileName:String;
+begin
+    Result:=False;
+
+    if not ForceDirectories(DirName) then begin
+        Exit;
+    end;
+
+    FileName:=DirName+'\setup.ini';
+
+    if not SetIniBool('Dummy','Writable',true,FileName) then begin
+        Exit;
+    end;
+
+    Result:=GetIniBool('Dummy','Writable',false,FileName);
+end;
diff --git a/share/WinGit/install.iss b/share/WinGit/install.iss
index b5d1de30..1abcd13f 100644
--- a/share/WinGit/install.iss
+++ b/share/WinGit/install.iss
@@ -698,6 +698,14 @@ procedure CurPageChanged(CurPageID:Integer);
 var
     i:Integer;
 begin
+    if CurPageID=wpSelectDir then begin
+        if not IsDirWritable(WizardDirValue) then begin
+            // If the default directory is not writable, choose another default that most likely is.
+            // This will be checked later again when the user clicks "Next".
+            WizardForm.DirEdit.Text:=ExpandConstant('{localappdata}\{#APP_NAME}');
+        end;
+    end;
+
     // Uncheck the console font option by default.
     if CurPageID=wpSelectComponents then begin
         for i:=0 to WizardForm.ComponentsList.Items.Count-1 do begin
@@ -723,6 +731,19 @@ var
 begin
     Result:=True;
 
+    if CurPageID=wpSelectDir then begin
+        if not IsDirWritable(WizardDirValue) then begin
+            MsgBox(
+                'The specified installation directory does not seem to be writable. ' +
+            +   'Please choose another directory or restart setup as a user with sufficient permissions.'
+            ,   mbCriticalError
+            ,   MB_OK
+            );
+            Result:=False;
+            Exit;
+        end;
+    end;
+
     if (PuTTYPage<>NIL) and (CurPageID=PuTTYPage.ID) then begin
         Result:=RdbSSH[GS_OpenSSH].Checked or
             (RdbSSH[GS_Plink].Checked and FileExists(EdtPlink.Text));
-- 
2.11.4.GIT