From 9014a20c658496a498f98fabf9bf00381fc2d450 Mon Sep 17 00:00:00 2001
From: James Bowman <jamesb@excamera.com>
Date: Sun, 26 Jan 2020 11:54:37 -0800
Subject: [PATCH] Adds to PATH on install, removes on uninstall Using
 recommended functions at https://nsis.sourceforge.io/Path_Manipulation

[#29]
---
 nsis/i2cdriver.nsi | 184 +++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 184 insertions(+)

diff --git a/nsis/i2cdriver.nsi b/nsis/i2cdriver.nsi
index 3b3451c..fd0eb1e 100644
--- a/nsis/i2cdriver.nsi
+++ b/nsis/i2cdriver.nsi
@@ -91,6 +91,9 @@ section "install"
 	WriteRegDWORD HKLM "Software\Microsoft\Windows\CurrentVersion\Uninstall\${COMPANYNAME} ${APPNAME}" "NoRepair" 1
 	# Set the INSTALLSIZE constant (!defined at the top of this script) so Add/Remove Programs can accurately report the size
 	WriteRegDWORD HKLM "Software\Microsoft\Windows\CurrentVersion\Uninstall\${COMPANYNAME} ${APPNAME}" "EstimatedSize" ${INSTALLSIZE}
+
+        Push "$INSTDIR"
+        Call AddToPath
 sectionEnd
  
 # Uninstaller
@@ -127,4 +130,185 @@ section "uninstall"
 
 	# Remove the desktop shortcut
 	delete "$DESKTOP\I2CDriver.lnk"
+
+        # Remove install dir from PATH
+        Push "$INSTDIR"
+        Call un.RemoveFromPath
 sectionEnd
+
+;--------------------------------------------------------------------
+; Path functions
+;
+; Based on example from:
+; http://nsis.sourceforge.net/Path_Manipulation
+;
+
+
+!include "WinMessages.nsh"
+
+; Registry Entry for environment (NT4,2000,XP)
+; All users:
+;!define Environ 'HKLM "SYSTEM\CurrentControlSet\Control\Session Manager\Environment"'
+; Current user only:
+!define Environ 'HKCU "Environment"'
+
+; AddToPath - Appends dir to PATH
+;   (does not work on Win9x/ME)
+;
+; Usage:
+;   Push "dir"
+;   Call AddToPath
+
+Function AddToPath
+  Exch $0
+  Push $1
+  Push $2
+  Push $3
+  Push $4
+
+  ; NSIS ReadRegStr returns empty string on string overflow
+  ; Native calls are used here to check actual length of PATH
+
+  ; $4 = RegOpenKey(HKEY_CURRENT_USER, "Environment", &$3)
+  System::Call "advapi32::RegOpenKey(i 0x80000001, t'Environment', *i.r3) i.r4"
+  IntCmp $4 0 0 done done
+  ; $4 = RegQueryValueEx($3, "PATH", (DWORD*)0, (DWORD*)0, &$1, ($2=NSIS_MAX_STRLEN, &$2))
+  ; RegCloseKey($3)
+  System::Call "advapi32::RegQueryValueEx(i $3, t'PATH', i 0, i 0, t.r1, *i ${NSIS_MAX_STRLEN} r2) i.r4"
+  System::Call "advapi32::RegCloseKey(i $3)"
+
+  IntCmp $4 234 0 +4 +4 ; $4 == ERROR_MORE_DATA
+    DetailPrint "AddToPath: original length $2 > ${NSIS_MAX_STRLEN}"
+    MessageBox MB_OK "PATH not updated, original length $2 > ${NSIS_MAX_STRLEN}"
+    Goto done
+
+  IntCmp $4 0 +5 ; $4 != NO_ERROR
+    IntCmp $4 2 +3 ; $4 != ERROR_FILE_NOT_FOUND
+      DetailPrint "AddToPath: unexpected error code $4"
+      Goto done
+    StrCpy $1 ""
+
+  ; Check if already in PATH
+  Push "$1;"
+  Push "$0;"
+  Call StrStr
+  Pop $2
+  StrCmp $2 "" 0 done
+  Push "$1;"
+  Push "$0\;"
+  Call StrStr
+  Pop $2
+  StrCmp $2 "" 0 done
+
+  ; Prevent NSIS string overflow
+  StrLen $2 $0
+  StrLen $3 $1
+  IntOp $2 $2 + $3
+  IntOp $2 $2 + 2 ; $2 = strlen(dir) + strlen(PATH) + sizeof(";")
+  IntCmp $2 ${NSIS_MAX_STRLEN} +4 +4 0
+    DetailPrint "AddToPath: new length $2 > ${NSIS_MAX_STRLEN}"
+    MessageBox MB_OK "PATH not updated, new length $2 > ${NSIS_MAX_STRLEN}."
+    Goto done
+
+  ; Append dir to PATH
+  DetailPrint "Add to PATH: $0"
+  StrCpy $2 $1 1 -1
+  StrCmp $2 ";" 0 +2
+    StrCpy $1 $1 -1 ; remove trailing ';'
+  StrCmp $1 "" +2   ; no leading ';'
+    StrCpy $0 "$1;$0"
+  WriteRegExpandStr ${Environ} "PATH" $0
+  SendMessage ${HWND_BROADCAST} ${WM_WININICHANGE} 0 "STR:Environment" /TIMEOUT=5000
+
+done:
+  Pop $4
+  Pop $3
+  Pop $2
+  Pop $1
+  Pop $0
+FunctionEnd
+
+; StrStr - find substring in a string
+;
+; Usage:
+;   Push "this is some string"
+;   Push "some"
+;   Call StrStr
+;   Pop $0 ; "some string"
+
+!macro StrStr un
+Function ${un}StrStr
+  Exch $R1 ; $R1=substring, stack=[old$R1,string,...]
+  Exch     ;                stack=[string,old$R1,...]
+  Exch $R2 ; $R2=string,    stack=[old$R2,old$R1,...]
+  Push $R3
+  Push $R4
+  Push $R5
+  StrLen $R3 $R1
+  StrCpy $R4 0
+  ; $R1=substring, $R2=string, $R3=strlen(substring)
+  ; $R4=count, $R5=tmp
+  loop:
+    StrCpy $R5 $R2 $R3 $R4
+    StrCmp $R5 $R1 done
+    StrCmp $R5 "" done
+    IntOp $R4 $R4 + 1
+    Goto loop
+done:
+  StrCpy $R1 $R2 "" $R4
+  Pop $R5
+  Pop $R4
+  Pop $R3
+  Pop $R2
+  Exch $R1 ; $R1=old$R1, stack=[result,...]
+FunctionEnd
+!macroend
+!insertmacro StrStr ""
+!insertmacro StrStr "un."
+
+; RemoveFromPath - Removes dir from PATH
+;
+; Usage:
+;   Push "dir"
+;   Call RemoveFromPath
+
+Function un.RemoveFromPath
+  Exch $0
+  Push $1
+  Push $2
+  Push $3
+  Push $4
+  Push $5
+  Push $6
+
+  ReadRegStr $1 ${Environ} "PATH"
+  StrCpy $5 $1 1 -1
+  StrCmp $5 ";" +2
+    StrCpy $1 "$1;" ; ensure trailing ';'
+  Push $1
+  Push "$0;"
+  Call un.StrStr
+  Pop $2 ; pos of our dir
+  StrCmp $2 "" done
+
+  DetailPrint "Remove from PATH: $0"
+  StrLen $3 "$0;"
+  StrLen $4 $2
+  StrCpy $5 $1 -$4 ; $5 is now the part before the path to remove
+  StrCpy $6 $2 "" $3 ; $6 is now the part after the path to remove
+  StrCpy $3 "$5$6"
+  StrCpy $5 $3 1 -1
+  StrCmp $5 ";" 0 +2
+    StrCpy $3 $3 -1 ; remove trailing ';'
+  WriteRegExpandStr ${Environ} "PATH" $3
+  SendMessage ${HWND_BROADCAST} ${WM_WININICHANGE} 0 "STR:Environment" /TIMEOUT=5000
+
+done:
+  Pop $6
+  Pop $5
+  Pop $4
+  Pop $3
+  Pop $2
+  Pop $1
+  Pop $0
+FunctionEnd