Read a file header into a record ?

[m. e.l.]

Hi all,

I have a

TMyFileheader = Record

  ...

end;

And I would like to read the header of the file into it:

procedure GetMyFileHeader(const Filename: string);

var FileHeader: TMyFileHeader;

       FileStream: TFileStream;

begin

  FileStream := TFileStream.Create(Filename, fmOpenRead or fmShareDenyNone);

  try

    if FileStream.Read(FileHeader, SizeOf(FileHeader)) = SizeOf(FileHeader)  then begin

      ...

    end;

  finally

    FileStream.Free;

  end;

But the TFileStream.Read method only accepts a string (ReadBuffer as well)... !

How can I read the file header into the record ?

Or, if I read it into a string, how to copy the string content into the FileHeader record  ?

Thanks for any help !

Mel

[Bill Stewart]

Are you sure this is the solution you need to pursue? It might help if you describe the overall problem you're trying to solve.

[m. e.l.]

If I could read that file header, I could perform different actions, which depend on which version has the file I want to read. And this is to be found in the file header.

This would be the simplest solution.

If it is not possible, then I will look for another way.

[Gavin Lambert]

On Wednesday, April 30, 2025 at 7:13:05 AM UTC+12 m. e.l. wrote:

If I could read that file header, I could perform different actions, which depend on which version has the file I want to read. And this is to be found in the file header.

This would be the simplest solution.

Once you get to a certain level of complexity, it's usually easier to package your code into an EXE or DLL that's called from the installer rather than trying to translate it into direct [Code]. 

[Bill Stewart]

On Tuesday, April 29, 2025 at 1:13:05 PM UTC-6 m. e.l. wrote:

If I could read that file header, I could perform different actions, which depend on which version has the file I want to read. And this is to be found in the file header.

This would be the simplest solution.

If it is not possible, then I will look for another way.

To me this sounds like a possible XY problem[1].

This is why I was asking what is the actual problem you're trying to solve. (I wasn't asking how you think it might be possible to solve it.)

[1] https://xyproblem.info/

[m. e.l.]

:) no it is not an XY problem. Just believe me.

One way or the other, I need to get the file version of some files.

Reading the file header was in my eyes the simplest solution.

As it seems Inno cannot do that, I will find another way.

Writing a dll just for that task is a possiblity.

[Bill Stewart]

On Thursday, May 1, 2025 at 5:14:53 AM UTC-6 m. e.l. wrote:

:) no it is not an XY problem. Just believe me.

One way or the other, I need to get the file version of some files.

Reading the file header was in my eyes the simplest solution.

Inno Setup has a number of functions related to file versions. See the documentation:

https://jrsoftware.org/ishelp/index.php?topic=scriptfunctions

Scroll down to the section "File Version functions". Here what's there as I write this:

function GetVersionNumbers(const Filename: String; var VersionMS, VersionLS: Cardinal): Boolean;
function GetVersionComponents(const Filename: String; var Major, Minor, Revision, Build: Word): Boolean;
function GetVersionNumbersString(const Filename: String; var Version: String): Boolean;
function GetPackedVersion(const Filename: String; var Version: Int64): Boolean;

function PackVersionNumbers(const VersionMS, VersionLS: Cardinal): Int64;
function PackVersionComponents(const Major, Minor, Revision, Build: Word): Int64;

function ComparePackedVersion(const Version1, Version2: Int64): Integer;
function SamePackedVersion(const Version1, Version2: Int64): Boolean;

procedure UnpackVersionNumbers(const Version: Int64; var VersionMS, VersionLS: Cardinal);
procedure UnpackVersionComponents(const Version: Int64; var Major, Minor, Revision, Build: Word);

function VersionToStr(const Version: Int64): String;
function StrToVersion(const Version: String; var Version: Int64): Boolean;

[m. e.l.]

Thanks. I am aware about those functions.
They are working for exes or dlls, but not for proprietary data files, which is my case.

[Eivind Bakkestuen]

The inno setup script isn't really intended for low level file manipulation. Make a DLL. :)

--
You received this message because you are subscribed to the Google Groups "innosetup" group.
To unsubscribe from this group and stop receiving emails from it, send an email to innosetup+...@googlegroups.com.
To view this discussion visit https://groups.google.com/d/msgid/innosetup/84e78ae9-e6c3-4689-a268-2c590c481e37n%40googlegroups.com.