Stander
11th November 2010 10:37 UTC

IfFileExists and quotes
Hi!

Recently I was trying to read the "UninstallString" from the system registry and check if the uninstaller file exists.

  ReadRegStr $R0 HKLM \
  "Software\Microsoft\Windows\CurrentVersion\Uninstall\My_App" \
  "UninstallString"

  IfFileExists $R0 +1 done

The problem is that if the file path stored in the registry includes quotes, the IfFileExists function always returns false.

Example
if $R0 = C:\Program files\MyApp\uninstall.exe then IfFileExists returns true (file exists)
but
if $R0 = "C:\Program files\MyApp\uninstall.exe" then IfFileExists returns false (file doesn't exist)

Is there any way to make it work or to exclude quotes from the received value (path)?

Regards,
Stander

MSG
11th November 2010 11:27 UTC

To remove a " from the beginning of the string:

StrCpy $R1 $R0 1
${If} $R1 == '"'
StrCpy $R0 $R0 "" 1
${EndIf}

I'll leave the removal of a trailing " character as an exercise to you.

(Hint: http://nsis.sourceforge.net/Docs/Chapter4.html#4.9.8 )

Stander
11th November 2010 17:16 UTC

Thanks a lot MSG!

Homework done! :)

StrCpy $R1 $R0 "" -1
${If} $R1 == '"'
  StrCpy $R0 $R0 -1
${EndIf}

But... I'm wondering why the IfFileExists function doesn't respect quotes.
Many other functions have no problems with paths with quotes.
For instance ExecWait accepts all paths, no matter if they include quotes or not.

Moreover, according to this guide it is even recommended to use quotes in paths saved to the registry.

Anders
11th November 2010 18:51 UTC

Any instruction that executes a new process should be quoted, for everything else, quotes are probably not required. IfFileExists probably ends up calling the win32 api GetFileAttributes, and it does not want quoted paths (Like most win32 functions)

Stander
11th November 2010 22:06 UTC

Originally posted by Anders
Any instruction that executes a new process should be quoted, for everything else, quotes are probably not required. IfFileExists probably ends up calling the win32 api GetFileAttributes, and it does not want quoted paths (Like most win32 functions)

Thanks for the explanation.

Regards,
Stander