Path Manipulation

Author: KiCHiK (talk, contrib)

Description

Here are two functions, one for adding directories to the search path of Windows and the other to remove them. These functions should work on every version of Windows including 95, 98, ME, NT, 2000, and XP.

For Windows NT/2000/XP they will write to HKEY_CURRENT_USER\Environment\PATH. For 9x/ME they will write to the autoexec.bat file.

Changes on 9x machines will take place after a reboot. These functions set the reboot flag if the path variable was changed on 9x.

These functions require NSIS 2.0b0 and above due to the usage of SendMessage with /TIMEOUT. It is possible to use it with earlier versions of NSIS with a little application I have created called RefreshEnv. It does exactly the same as SendMessage with /TIMEOUT. You can find it at this forum thread.

Usage Example

Section "Add to path"
  Push $INSTDIR
  Call AddToPath
SectionEnd
 
# ...
 
Section "uninstall"
  # ...
  Push $INSTDIR
  Call un.RemoveFromPath
  # ...
SectionEnd

The Functions

The functions in the flesh:

!ifndef _AddToPath_nsh
!define _AddToPath_nsh
 
!verbose 3
!include "WinMessages.NSH"
!verbose 4
 
!ifndef WriteEnvStr_RegKey
  !ifdef ALL_USERS
    !define WriteEnvStr_RegKey \
       'HKLM "SYSTEM\CurrentControlSet\Control\Session Manager\Environment"'
  !else
    !define WriteEnvStr_RegKey 'HKCU "Environment"'
  !endif
!endif
 
; AddToPath - Adds the given dir to the search path.
;        Input - head of the stack
;        Note - Win9x systems requires reboot
 
Function AddToPath
  Exch $0
  Push $1
  Push $2
  Push $3
 
  # don't add if the path doesn't exist
  IfFileExists "$0\*.*" "" AddToPath_done
 
  ReadEnvStr $1 PATH
  Push "$1;"
  Push "$0;"
  Call StrStr
  Pop $2
  StrCmp $2 "" "" AddToPath_done
  Push "$1;"
  Push "$0\;"
  Call StrStr
  Pop $2
  StrCmp $2 "" "" AddToPath_done
  GetFullPathName /SHORT $3 $0
  Push "$1;"
  Push "$3;"
  Call StrStr
  Pop $2
  StrCmp $2 "" "" AddToPath_done
  Push "$1;"
  Push "$3\;"
  Call StrStr
  Pop $2
  StrCmp $2 "" "" AddToPath_done
 
  Call IsNT
  Pop $1
  StrCmp $1 1 AddToPath_NT
    ; Not on NT
    StrCpy $1 $WINDIR 2
    FileOpen $1 "$1\autoexec.bat" a
    FileSeek $1 -1 END
    FileReadByte $1 $2
    IntCmp $2 26 0 +2 +2 # DOS EOF
      FileSeek $1 -1 END # write over EOF
    FileWrite $1 "$\r$\nSET PATH=%PATH%;$3$\r$\n"
    FileClose $1
    SetRebootFlag true
    Goto AddToPath_done
 
  AddToPath_NT:
    ReadRegStr $1 ${WriteEnvStr_RegKey} "PATH"
    StrCpy $2 $1 1 -1 # copy last char
    StrCmp $2 ";" 0 +2 # if last char == ;
      StrCpy $1 $1 -1 # remove last char
    StrCmp $1 "" AddToPath_NTdoIt
      StrCpy $0 "$1;$0"
    AddToPath_NTdoIt:
      WriteRegExpandStr ${WriteEnvStr_RegKey} "PATH" $0
      SendMessage ${HWND_BROADCAST} ${WM_WININICHANGE} 0 "STR:Environment" /TIMEOUT=5000
 
  AddToPath_done:
    Pop $3
    Pop $2
    Pop $1
    Pop $0
FunctionEnd
 
; RemoveFromPath - Remove a given dir from the path
;     Input: head of the stack
 
Function un.RemoveFromPath
  Exch $0
  Push $1
  Push $2
  Push $3
  Push $4
  Push $5
  Push $6
 
  IntFmt $6 "%c" 26 # DOS EOF
 
  Call un.IsNT
  Pop $1
  StrCmp $1 1 unRemoveFromPath_NT
    ; Not on NT
    StrCpy $1 $WINDIR 2
    FileOpen $1 "$1\autoexec.bat" r
    GetTempFileName $4
    FileOpen $2 $4 w
    GetFullPathName /SHORT $0 $0
    StrCpy $0 "SET PATH=%PATH%;$0"
    Goto unRemoveFromPath_dosLoop
 
    unRemoveFromPath_dosLoop:
      FileRead $1 $3
      StrCpy $5 $3 1 -1 # read last char
      StrCmp $5 $6 0 +2 # if DOS EOF
        StrCpy $3 $3 -1 # remove DOS EOF so we can compare
      StrCmp $3 "$0$\r$\n" unRemoveFromPath_dosLoopRemoveLine
      StrCmp $3 "$0$\n" unRemoveFromPath_dosLoopRemoveLine
      StrCmp $3 "$0" unRemoveFromPath_dosLoopRemoveLine
      StrCmp $3 "" unRemoveFromPath_dosLoopEnd
      FileWrite $2 $3
      Goto unRemoveFromPath_dosLoop
      unRemoveFromPath_dosLoopRemoveLine:
        SetRebootFlag true
        Goto unRemoveFromPath_dosLoop
 
    unRemoveFromPath_dosLoopEnd:
      FileClose $2
      FileClose $1
      StrCpy $1 $WINDIR 2
      Delete "$1\autoexec.bat"
      CopyFiles /SILENT $4 "$1\autoexec.bat"
      Delete $4
      Goto unRemoveFromPath_done
 
  unRemoveFromPath_NT:
    ReadRegStr $1 ${WriteEnvStr_RegKey} "PATH"
    StrCpy $5 $1 1 -1 # copy last char
    StrCmp $5 ";" +2 # if last char != ;
      StrCpy $1 "$1;" # append ;
    Push $1
    Push "$0;"
    Call un.StrStr ; Find `$0;` in $1
    Pop $2 ; pos of our dir
    StrCmp $2 "" unRemoveFromPath_done
      ; else, it is in path
      # $0 - path to add
      # $1 - path var
      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 # copy last char
      StrCmp $5 ";" 0 +2 # if last char == ;
        StrCpy $3 $3 -1 # remove last char
 
      WriteRegExpandStr ${WriteEnvStr_RegKey} "PATH" $3
      SendMessage ${HWND_BROADCAST} ${WM_WININICHANGE} 0 "STR:Environment" /TIMEOUT=5000
 
  unRemoveFromPath_done:
    Pop $6
    Pop $5
    Pop $4
    Pop $3
    Pop $2
    Pop $1
    Pop $0
FunctionEnd
 
!ifndef IsNT_KiCHiK
!define IsNT_KiCHiK
 
###########################################
#            Utility Functions            #
###########################################
 
; IsNT
; no input
; output, top of the stack = 1 if NT or 0 if not
;
; Usage:
;   Call IsNT
;   Pop $R0
;  ($R0 at this point is 1 or 0)
 
!macro IsNT un
Function ${un}IsNT
  Push $0
  ReadRegStr $0 HKLM "SOFTWARE\Microsoft\Windows NT\CurrentVersion" CurrentVersion
  StrCmp $0 "" 0 IsNT_yes
  ; we are not NT.
  Pop $0
  Push 0
  Return
 
  IsNT_yes:
    ; NT!!!
    Pop $0
    Push 1
FunctionEnd
!macroend
!insertmacro IsNT ""
!insertmacro IsNT "un."
 
!endif ; IsNT_KiCHiK
 
; StrStr
; input, top of stack = string to search for
;        top of stack-1 = string to search in
; output, top of stack (replaces with the portion of the string remaining)
; modifies no other variables.
;
; Usage:
;   Push "this is a long ass string"
;   Push "ass"
;   Call StrStr
;   Pop $R0
;  ($R0 at this point is "ass string")
 
!macro StrStr un
Function ${un}StrStr
Exch $R1 ; st=haystack,old$R1, $R1=needle
  Exch    ; st=old$R1,haystack
  Exch $R2 ; st=old$R1,old$R2, $R2=haystack
  Push $R3
  Push $R4
  Push $R5
  StrLen $R3 $R1
  StrCpy $R4 0
  ; $R1=needle
  ; $R2=haystack
  ; $R3=len(needle)
  ; $R4=cnt
  ; $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
FunctionEnd
!macroend
!insertmacro StrStr ""
!insertmacro StrStr "un."
 
!endif ; _AddToPath_nsh