nsis.pathupdate.nsh

!include "WinMessages.nsh"

; see https://support.microsoft.com/en-us/kb/104011
!define Environ 'HKLM "SYSTEM\CurrentControlSet\Control\Session Manager\Environment"'
; HKEY_LOCAL_MACHINE = 0x80000002

; 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_LOCAL_MACHINE, "SYSTEM\CurrentControlSet\Control\Session Manager\Environment", &$3)
  System::Call "advapi32::RegOpenKey(i 0x80000002, t'SYSTEM\CurrentControlSet\Control\Session Manager\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


; 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

  ; NSIS ReadRegStr returns empty string on string overflow
  ; Native calls are used here to check actual length of PATH
  ; $4 = RegOpenKey(HKEY_LOCAL_MACHINE, "SYSTEM\CurrentControlSet\Control\Session Manager\Environment", &$3)
  System::Call "advapi32::RegOpenKey(i 0x80000002, t'SYSTEM\CurrentControlSet\Control\Session Manager\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 "RemoveFromPath: 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 "RemoveFromPath: unexpected error code $4"
      Goto done
    StrCpy $1 ""

  ; length < ${NSIS_MAX_STRLEN} -> ReadRegStr can be used
  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