support actually setting the home directory selected by the user in the installer

getting this working right was suprisingly messy and I'm still not happy with
any of it.  For now I'm just happy that it appears to work, and will find a
cleaner way later.

Author: embray

Diff for: SageMath.iss

@@ -100,7 +100,7 @@ Name: desktop; Description: "Create &desktop icons"; GroupDescription: "Addition
 [Files]
 Source: "dot_sage\*"; DestDir: "{#SageRootWin}\dot_sage"; Flags: recursesubdirs ignoreversion
 Source: "{#Source}\*"; DestDir: "{#Runtime}"; Excludes: "{#SageExcludes}"; Flags: recursesubdirs ignoreversion
-Source: "resources\sagemath.ico"; DestDir: "{app}"; Flags: ignoreversion; AfterInstall: FixupSymlinks
+Source: "resources\sagemath.ico"; DestDir: "{app}"; Flags: ignoreversion; AfterInstall: PostInstall
 
 ; InnoSetup will not create empty directories found when including files
 ; recursively in the [Files] section, so any directories that must exist
@@ -232,7 +232,7 @@ var
 begin
     Page := CreateInputDirPage(InstallModeSelectPageID, 'Select Sage home directory',
     'Select the default directory that Sage will start in', '', False, '');
-    Page.Add('');
+    Page.Add('Sage will start with this folder as your working directory by default; you can also change this after installation using the sage-sethome command:');
     UserHomeDirSelectPageID := Page.ID;
     with Page do
     begin
@@ -284,7 +284,44 @@ begin
         WizardForm.FilenameLabel.Caption := Copy(filenam, 2, Length(filenam));
         WizardForm.ProgressGauge.Position := i;
         Exec(ExpandConstant('{sys}\attrib.exe'), '+S ' + filenam,
-                            ExpandConstant('{#Runtime}'), SW_HIDE,
-                            ewNoWait, resultCode);
+             ExpandConstant('{#Runtime}'), SW_HIDE, ewNoWait, resultCode);
     end;
 end;
+
+
+// In principle we should be able to run the sage-sethome script with the
+// just-installed bash.exe, but this seems to encounter insurmountable
+// problems with quoting or I'm not sure what else, so we essentially
+// reimplement that script here to write the appropriate /etc/fstab.d file.
+procedure SetHome();
+var
+    resultCode: Integer;
+    userHome: String;
+    fstabdFile: String;
+    fstabLine: String;
+    fstabLines: TArrayOfString;
+begin
+    fstabdFile := ExpandConstant('{#Runtime}\etc\fstab.d\') + GetUserNameString();
+    userHome := Copy(UserHomeDir, 1, Length(UserHomeDir));
+    StringChangeEx(userHome, ' ', '\040', True)
+    fstabLine := userHome + ' /home/sage ntfs binary,posix=1,user,acl 0 0';
+    SetArrayLength(fstabLines, 1);
+    fstabLines[0] := fstabLine;
+    SaveStringsToUTF8File(fstabdFile, fstabLines, False);
+    // The above nevertheless writes the file with a bunch of stupid
+    // ideosyncracies (most notably, a useless UTF-8 BOM) which confuse
+    // Cygwin; we run this final cleanup script to fix everything, ugh.
+    Exec(ExpandConstant('{#Bin}\dash.exe'),
+         '/usr/local/bin/_sage-complete-install.sh',
+         ExpandConstant('{#Runtime}'), 
+         SW_HIDE, ewNoWait, resultCode);
+    MsgBox(IntToStr(resultCode), mbInformation, MB_OK);
+end;
+
+
+procedure PostInstall();
+begin
+    FixupSymlinks();
+    if UserInstall then
+        SetHome();
+end;

Diff for: cygwin-sage-runtime.list

@@ -2,6 +2,7 @@ base-files    	4.2-3
 bash          	4.3.42-4
 cygutils      	1.4.15-2
 cygwin        	2.6.0-1
+dos2unix        7.4.0-1
 gcc-core      	5.3.0-5
 gcc-fortran   	5.3.0-5
 gcc-g++       	5.3.0-5

Diff for: cygwin_extras/usr/local/bin/_sage-complete-install.sh

@@ -0,0 +1,8 @@
+#!/bin/sh
+export PATH=/usr/bin:/bin
+for filename in /etc/fstab.d/*; do
+    dos2unix "$filename"
+    chmod 600 "$filename"
+done
+
+rm -f /usr/local/bin/_sage-complete-install.sh