NSIS section sizes doubled due to use of SetOverwrite - nsis

Question

I've inherited an installer script, and I'm annoyed by it claiming to require twice as much space as it actually needs.
I found that this was due to how each section is using SetOverwrite (because they're re-used for a repair install?). I understand that it's necessary to keep the duplicated File commands in each of the If/Else blocks because of how SetOverwrite works (see below), but I have confirmed that it results in a doubling of the automatic section size calculations.
${MementoSection} $(APP_Section_SecHelp) SecHelp
SetDetailsPrint textonly
DetailPrint $(APP_DetailPrint_SecHelp)
SetDetailsPrint listonly
SetOutPath $INSTDIR
SectionIn 1 2
${If} $SetOverwriteOn == TRUE
SetOverwrite ifnewer
File /r "${APP_SOURCE_DIR}\Help"
${Else}
SetOverwrite off
File /r "${APP_SOURCE_DIR}\Help"
${EndIf}
SectionGetFlags ${SecHelp} $SecHelp_GetFlag
${MementoSectionEnd}
Is this a bad design pattern that I should change? Do I need to add a hack to call SectionGetSize, divide by 2 and call SectionSetSize?

Answer 1

Personally I would just use SetOverwrite ifnewer for both but if you absolutely want to do it your way then using SectionSetSize is one option.
Another thing you could do is to put the repair File /r instruction in a separate function that you call from the section. The downside of a function is that the progressbar does not move much during the extraction.
A third alternative is to put some of the repair tasks in a separate section that is unchecked by default and you enable it when you are in repair mode.
Edit: Here is a example that uses SectionSetSize:
!include LogicLib.nsh
InstallDir $Temp
Page Components InitComponentsPage
Page Directory
Page InstFiles
!macro ModifySectionHack SID TEMPVAR
SectionGetSize ${SID} ${TEMPVAR}
IntOp ${TEMPVAR} ${TEMPVAR} / 2
SectionSetSize ${SID} ${TEMPVAR}
!macroend
Function InitComponentsPage
StrCpy $0 0
loop:
ClearErrors
SectionGetFlags $0 $1 ; The error flag is set if we try to access a section that does not exist
IfErrors done
!insertmacro ModifySectionHack $0 $1
IntOp $0 $0 + 1
Goto loop
done:
FunctionEnd
Section "Foo"
InitPluginsDir ; Need a place to extract to for this example
SetOutPath $PluginsDir
${If} 1 <> 2 ; Don't really care about the result
SetOverwrite ifnewer
File "${NSISDIR}\bin\makensis.exe" ; ~400kb
${Else}
SetOverwrite off
File "${NSISDIR}\bin\makensis.exe"
${EndIf}
SectionEnd
Section "Bar"
InitPluginsDir ; Need a place to extract to for this example
SetOutPath $PluginsDir
${If} 1 <> 2 ; Don't really care about the result
SetOverwrite ifnewer
File "${NSISDIR}\nsis.exe" ; ~700kb
${Else}
SetOverwrite off
File "${NSISDIR}\nsis.exe"
${EndIf}
SectionEnd
This loops through all the sections and adjusts all of them but I'm not sure if that is such a good idea. If this was my script then I would manually call ModifySectionHack on each section that has the SetOverwrite problem:
!include LogicLib.nsh
InstallDir $Temp
Page Components
Page Directory
Page InstFiles
!macro ModifySectionHack SID TEMPVAR
SectionGetSize ${SID} ${TEMPVAR}
IntOp ${TEMPVAR} ${TEMPVAR} / 2
SectionSetSize ${SID} ${TEMPVAR}
!macroend
Section "Foo" SID_FOO
InitPluginsDir ; Need a place to extract to for this example
SetOutPath $PluginsDir
${If} 1 <> 2 ; Don't really care about the result
SetOverwrite ifnewer
File "${NSISDIR}\bin\makensis.exe" ; ~400kb
${Else}
SetOverwrite off
File "${NSISDIR}\bin\makensis.exe"
${EndIf}
SectionEnd
Section "Bar"
${If} 1 = 2
File /r "${NSISDIR}\stubs"
${EndIf}
SectionEnd
Section "Baz" SID_BAZ
InitPluginsDir ; Need a place to extract to for this example
SetOutPath $PluginsDir
${If} 1 <> 2 ; Don't really care about the result
SetOverwrite ifnewer
File "${NSISDIR}\nsis.exe" ; ~700kb
${Else}
SetOverwrite off
File "${NSISDIR}\nsis.exe"
${EndIf}
SectionEnd
Function .onInit
; Adjust the section size for the sections that use SetOverwrite:
!insertmacro ModifySectionHack ${SID_FOO} $1
!insertmacro ModifySectionHack ${SID_BAZ} $1
FunctionEnd