Path Manipulation

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Author: turnec2 (talk, contrib)


WARNING: Strings longer than ${NSIS_MAX_STRLEN} will get truncated/corrupted. Do NOT use this function to update %PATH%, use the EnVar_plug-in instead. (See below for a link to an alternative implementation.)


Description

Version: 1.0

Append, prepend or remove a pathname from the PATH environmental variable in either the "all users" (HKLM) or the "current user" (HKCU) section of the registry.

Duplicates entries, leading and trailing spaces around each entry, and duplicate semicolons are removed from the contents of PATH before performing the requested operation. This step prevents the corruption of the variable's contents (e.g., when removing a target pathname that is a subset of another pathname).

Usage

See Environmental Variables: append, prepend, and remove entries for more details.

Warning

Warning : this code will replace paths rather than append if the existing path exceeds the maximum string length in the NSIS build you are using. Some setup crash can also occurs.

Default maximum string length is 1024, see Special Builds for a 8192 max length.

The problem occurs because the function ReadRegStr returns the same result if 'value is too long' and if 'value is not set'.

This could be fixed by using the native Win32 function RegQueryValueEx() instead. See this alternative implementation for a working example.

Syntax

 ${EnvVarUpdate} "ResultVar" "EnvVarName" "Action" "RegLoc" "Pathname"

or 

 Push "EnvVarName" 
 Push "Action"
 Push "RegLoc"
 Push "Pathname"
 Call EnvVarUpdate
 Pop  "ResultVar"

Parameters

ResultVar
Updated contents PATH returned by the function
EnvVarName
"PATH"
Action
"A" = Append
"P" = Prepend
"R" = Remove
RegLoc
"HKLM" = the "all users" section of the registry
"HKCU" = the "current user" section
Pathname
Pathname to add to or remove from the contents of PATH (e.g., "C:\MyApp")

Examples

 ${EnvVarUpdate} $0 "PATH" "A" "HKLM" "C:\Program Files\Windows Resource Kits\Tools"  
 ${EnvVarUpdate} $0 "PATH" "P" "HKCU" "%WinDir%\System32"  
 ${EnvVarUpdate} $0 "PATH" "R" "HKLM" "C:\Program Files\MyApp-v1.0"
 ${EnvVarUpdate} $0 "PATH" "A" "HKLM" "C:\Program Files\MyApp-v2.0"
 
 ${un.EnvVarUpdate} $0 "PATH" "R" "HKLM" "C:\MyLib-v1.0"   
 ${un.EnvVarUpdate} $0 "PATH" "R" "HKLM" "C:\MyLib-v2.0"

Dependencies


Credits

  • Version 1.0: Cal Turney (turnec2)
  • Amir Szekely (KiCHiK) and e-circ for developing the forerunners of this function: AddToPath, un.RemoveFromPath, AddToEnvVar, un.RemoveFromEnvVar, WriteEnvStr, and un.DeleteEnvStr
  • Diego Pedroso (deguix) for StrTok
  • Kevin English (kenglish_hi)for StrContains
  • Hendri Adriaens (Smile2Me), Diego Pedroso (deguix), and Dan Fuhry (dandaman32) for StrReplace


Function Code

EnvVarUpdate function code

Functions for Windows 95, 98, and ME

Author: KiCHiK (talk, contrib)


The following routines, AddToPath, un.RemoveFromPath, AddToEnvVar, and un.RemoveFromEnvVar are provided for Windows 95, 98, or ME in that they support the update of the PATH variable within the autoexec.bat file.

NOTE: These routines can corrupt the contents of the PATH variable if the path being removed happens to be a subset of another path. For example, if PATH contains "C:\Windows\system32\wbem" and you remove "C:\Windows\system32" the result is "\wbem". They also do not prevent duplication of entries if the user runs the installer multiple times.

Description

Here are four functions, two for adding to and removing directories from the search path (i.e. PATH environment variable) of Windows and two more for adding to and removing directories from a user defined environment variable such as INCLUDE or LIB etc. 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.

The directory added to the path must exist prior to calling this function.

Usage Example

!include "LogicLib.nsh"
!include "EnvVarUpdate.nsh" #download http://nsis.sourceforge.net/mediawiki/images/a/ad/EnvVarUpdate.7z
 
 
Section "Add to path"
  Push $INSTDIR
  Call AddToPath
 
  Push "LIB"
  Push "c:\Mylibrary\lib"
  Call AddToEnvVar
 
  ;likewise AddToPath could be
  Push "PATH"
  Push $INSTDIR
  Call AddToEnvVar
 
SectionEnd
 
# ...
 
Section "uninstall"
  # ...
  Push $INSTDIR
  Call un.RemoveFromPath
  # ...
  Push "LIB"
  Push "c:\Mylibrary\lib"
  Call un.RemoveFromEnvVar
 
  ;Likewise RemoveFromPath could be
  Push "PATH"
  Push $INSTDIR
  Call un.RemoveFromEnvVar
 
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"
    StrCmp $1 "" AddToPath_NTdoIt
      Push $1
      Call Trim
      Pop $1
      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
 
 
 
; AddToEnvVar - Adds the given value to the given environment var
;        Input - head of the stack $0 environement variable $1=value to add
;        Note - Win9x systems requires reboot
 
Function AddToEnvVar
 
  Exch $1 ; $1 has environment variable value
  Exch
  Exch $0 ; $0 has environment variable name
 
  DetailPrint "Adding $1 to $0"
  Push $2
  Push $3
  Push $4
 
 
  ReadEnvStr $2 $0
  Push "$2;"
  Push "$1;"
  Call StrStr
  Pop $3
  StrCmp $3 "" "" AddToEnvVar_done
 
  Push "$2;"
  Push "$1\;"
  Call StrStr
  Pop $3
  StrCmp $3 "" "" AddToEnvVar_done
 
 
  Call IsNT
  Pop $2
  StrCmp $2 1 AddToEnvVar_NT
    ; Not on NT
    StrCpy $2 $WINDIR 2
    FileOpen $2 "$2\autoexec.bat" a
    FileSeek $2 -1 END
    FileReadByte $2 $3
    IntCmp $3 26 0 +2 +2 # DOS EOF
      FileSeek $2 -1 END # write over EOF
    FileWrite $2 "$\r$\nSET $0=%$0%;$4$\r$\n"
    FileClose $2
    SetRebootFlag true
    Goto AddToEnvVar_done
 
  AddToEnvVar_NT:
    ReadRegStr $2 ${WriteEnvStr_RegKey} $0
    StrCpy $3 $2 1 -1 # copy last char
    StrCmp $3 ";" 0 +2 # if last char == ;
      StrCpy $2 $2 -1 # remove last char
    StrCmp $2 "" AddToEnvVar_NTdoIt
      StrCpy $1 "$2;$1"
    AddToEnvVar_NTdoIt:
      WriteRegExpandStr ${WriteEnvStr_RegKey} $0 $1
      SendMessage ${HWND_BROADCAST} ${WM_WININICHANGE} 0 "STR:Environment" /TIMEOUT=5000
 
  AddToEnvVar_done:
    Pop $4
    Pop $3
    Pop $2
    Pop $0
    Pop $1
 
FunctionEnd
 
; RemoveFromEnvVar - Remove a given value from a environment var
;     Input: head of the stack
 
Function un.RemoveFromEnvVar
 
  Exch $1 ; $1 has environment variable value
  Exch
  Exch $0 ; $0 has environment variable name
 
  DetailPrint "Removing $1 from $0"
  Push $2
  Push $3
  Push $4
  Push $5
  Push $6
  Push $7
 
  IntFmt $7 "%c" 26 # DOS EOF
 
  Call un.IsNT
  Pop $2
  StrCmp $2 1 unRemoveFromEnvVar_NT
    ; Not on NT
    StrCpy $2 $WINDIR 2
    FileOpen $2 "$2\autoexec.bat" r
    GetTempFileName $5
    FileOpen $3 $5 w
    GetFullPathName /SHORT $1 $1
    StrCpy $1 "SET $0=%$0%;$1"
    Goto unRemoveFromEnvVar_dosLoop
 
    unRemoveFromEnvVar_dosLoop:
      FileRead $2 $4
      StrCpy $6 $4 1 -1 # read last char
      StrCmp $6 $7 0 +2 # if DOS EOF
        StrCpy $4 $4 -1 # remove DOS EOF so we can compare
      StrCmp $4 "$1$\r$\n" unRemoveFromEnvVar_dosLoopRemoveLine
      StrCmp $4 "$1$\n" unRemoveFromEnvVar_dosLoopRemoveLine
      StrCmp $4 "$1" unRemoveFromEnvVar_dosLoopRemoveLine
      StrCmp $4 "" unRemoveFromEnvVar_dosLoopEnd
      FileWrite $3 $4
      Goto unRemoveFromEnvVar_dosLoop
      unRemoveFromEnvVar_dosLoopRemoveLine:
        SetRebootFlag true
        Goto unRemoveFromEnvVar_dosLoop
 
    unRemoveFromEnvVar_dosLoopEnd:
      FileClose $3
      FileClose $2
      StrCpy $2 $WINDIR 2
      Delete "$2\autoexec.bat"
      CopyFiles /SILENT $5 "$2\autoexec.bat"
      Delete $5
      Goto unRemoveFromEnvVar_done
 
  unRemoveFromEnvVar_NT:
    ReadRegStr $2 ${WriteEnvStr_RegKey} $0
    StrCpy $6 $2 1 -1 # copy last char
    StrCmp $6 ";" +2 # if last char != ;
      StrCpy $2 "$2;" # append ;
    Push $2
    Push "$1;"
    Call un.StrStr ; Find `$1;` in $2
    Pop $3 ; pos of our dir
    StrCmp $3 "" unRemoveFromEnvVar_done
      ; else, it is in path
      # $1 - path to add
      # $2 - path var
      StrLen $4 "$1;"
      StrLen $5 $3
      StrCpy $6 $2 -$5 # $6 is now the part before the path to remove
      StrCpy $7 $3 "" $4 # $7 is now the part after the path to remove
      StrCpy $4 $6$7
 
      StrCpy $6 $4 1 -1 # copy last char
      StrCmp $6 ";" 0 +2 # if last char == ;
      StrCpy $4 $4 -1 # remove last char
 
      WriteRegExpandStr ${WriteEnvStr_RegKey} $0 $4
 
      ; delete reg value if null
      StrCmp $4 "" 0 +2 # if null delete reg
      DeleteRegValue ${WriteEnvStr_RegKey} $0
 
      SendMessage ${HWND_BROADCAST} ${WM_WININICHANGE} 0 "STR:Environment" /TIMEOUT=5000
 
  unRemoveFromEnvVar_done:
    Pop $7
    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."
 
Function Trim ; Added by Pelaca
	Exch $R1
	Push $R2
Loop:
	StrCpy $R2 "$R1" 1 -1
	StrCmp "$R2" " " RTrim
	StrCmp "$R2" "$\n" RTrim
	StrCmp "$R2" "$\r" RTrim
	StrCmp "$R2" ";" RTrim
	GoTo Done
RTrim:	
	StrCpy $R1 "$R1" -1
	Goto Loop
Done:
	Pop $R2
	Exch $R1
FunctionEnd
 
!endif ; _AddToPath_nsh
Retrieved from "https://nsis.sourceforge.io/mediawiki/index.php?title=Path_Manipulation&oldid=25839"