Question

I have a requirement to bundle a zip file to my installer. I need nsis code such that it checks the available free space on installdir and copy that to a variable.

Answer 1

NSIS has a section attribute that sort of helps you do this: AddSize.

If you really need the amount in a variable you must use the system plugin:

System::Call 'kernel32::GetDiskFreeSpaceEx(t"$instdir",*l.r1,*l,*l)'
DetailPrint $1

or if you need Win9x/NT4 support:

!include LogicLib.nsh

Function GetDiskFree
Exch $0
Push $1
System::Call 'kernel32::GetDiskFreeSpaceEx(tr0,*l0s,*l,*l)i.r1'
${If} $1 < 1
    Exch $2 ;Throw away result from Ex
    System::Call 'kernel32::SetCurrentDirectory(tr0)'
    System::Call 'kernel32::GetDiskFreeSpace(i0,*i0r1,*i0r0,*i0r2,*i)'
    System::Call 'kernel32::SetCurrentDirectory(to)'
    IntOp $1 $1 * $0
    System::Int64Op $1 * $2
    Exch
    Pop $2
${EndIf}
Exch 2
Pop $0
Pop $1
FunctionEnd


Section
Push $instdir
Call GetDiskFree
Pop $0
System::Int64Op $0 / 1024 ;to kb
Pop $1
DetailPrint "$1 KiB ($0)"
SectionEnd