Manipulating the string produced by EXEDIR

I am sure this is a well documented feature, but I'm not sure what I'm looking for.

I would like to set an output directory using the EXEDIR path, but am not sure how to manipulate path strings to move up directories.

I would like to achieve the following:

1. Installer detects path to itself, then saves part of the path to $R0, and another part to $R1

Eg

Installer is in C:\Program Files\my app\my folder\target folder\installer.exe

Thus

EXEDIR = C:\Program Files\my app\my folder\target folder\

$R0 = C:\Program Files\my app
$R1 = C:\Program Files\my app\my folder

How is this done?

Thank you.

Edit: Something like this, but with one function for each output above?

from http://nsis.sourceforge.net/Get_first_part_of_a_string

Push $EXEDIR ; Input string
Call GetFirstStrPart
Pop "$R0"

Where $R0 will now be "C:\Program Files\my app"

The Function

Function GetFirstStrPart
Exch $R0
Push $R1
Push $R2
StrLen $R1 $R0
IntOp $R1 $R1 + 1
loop:
IntOp $R1 $R1 - 1
StrCpy $R2 $R0 1 -$R1
StrCmp $R2 "" exit2
StrCmp $R2 "my folder\target folder\" exit1 ;the directories to cut off
Goto loop
exit1:
StrCpy $R0 $R0 -$R1
exit2:
Pop $R2
Pop $R1
Exch $R0
FunctionEnd

E.1.15 GetParent does what you are asking for.

The section intro even shows a short example:

Include header:



!include "FileFunc.nsh"



Call functions:



Section Install

     ${GetFileExt} "C:\My Downloads\Index.html" $R0

     ; $R0="html"

SectionEnd



Section un.Install

     ${GetParent} "C:\My Downloads\Index.html" $R0

     ; $R0="C:\My Downloads"

SectionEnd

Edit: did not see the reply above before I posted. That sounds much better, though this works too:

Edit2: Actually the post above does not do what I want, but this does:

StrStrip seems to do the job...

If you start with

EXEDIR = C:\Program Files\my app\my folder\target folder\

then call this when you need it

${StrStrip} "$\my folder$\target folder" "$EXEDIR" $R0

this is the result:

$R0 = C:\Program Files\my app


Seems like a ropey way to do things, but I can't see a better way, unless someone can suggest something.

Your use of StrStrip requires that you know exactly what the path components are that have to be removed. Perhaps in your situation that is a constant and it will work for you. If that is the case, then just a simple string copy to remove X characters from the end is the easiest solution:

StrCpy $0 "C:\Program Files\my app\my folder\target folder\" -24

  ; $0 = "C:\Program Files\my app\"

In general, GetParent is the better way. Your example requires calling it twice since you want to move up two levels in the path:

${GetParent} "C:\Program Files\my app\my folder\target folder" $0

${GetParent} $0 $0

  ; $0 = "C:\Program Files\my app"

Ah, okay. Many thanks.

I've ended up in fact with ${GetParent} $EXEDIR $0, as I do know the nearby path components, but not the whole string, so it really depends on the installer being in the right place.

Actually you can even do "C:\NonExistingDirectory\.." and you'd get "C:\" again. I just can't remember whether or not this also works on win9x.