[Solved] Error allocating memory for a 6 MB file

[water]

46 minutes ago, LarsJ said:

If you need the footer only, then read the file from the end.

This only works for text files which you can read line by line. I'm not sure this is possible in this case. Not enough info provided by the OP.

[jchd]

Open the file in suitable read mode (binary or text). FileSetPos at FileGetSize - <suitable footer length> then read to end.

[TheDcoder]

10 hours ago, jchd said:

<suitable footer length>

The footer length is variable, that is why I iterate.

 

I would be happy to provide more info, don't hesitate to ask

[water]

Which application creates this files? Doesn't this application provide an API something similar to extract the needed information?

[TheDcoder]

@water I made the application which creates the files

 

It basically uses 7zip to create a archive and then appends a footer to it.

[water]

As the problem is already solved what are you after now? Performance, reliability of your code?

[TheDcoder]

Just now, water said:

As the problem is already solved what are you after now?

Nothing. I am just answering your question

 

lol

[water]

No, in post #9 you asked

Quote

Any suggestions?

 

[TheDcoder]

Yes, I did ask but I also quoted:

Quote

lot of overhead to check a 6MB file

You recommend to:

Quote

read the file in one go.

Then I said:

Quote

I normally process larger files, this was tiny compared to them

Then you said:

Quote

Ah, new information.

 

Then I thought that it was over (as reading a big file in one go would cause problems). Clear now?

[water]

Fine. I'm out now

[jchd]

IIRC 7zip header contains the archive size.

[TheDcoder]

@jchd Oh , That is some valuable information, Thanks

[LarsJ]

To read the file from the end use similar code as in first post. To start from the end the calculations of the file position must be a little different but the principle is the same.

If you'll post a test file, I'll post some code.

[water]

The code from post #1 is quite fine (except from a few modifications I would make as I posted above). What I really would change is the number of bytes to read with FileRead.
When the code steps backward in chunks of 1024 Bytes then I would read 1024 Byte + (length of the word to search for) - 1 ("Test" in this case). So you would find the word even when it spreads over two chunks.

[TheDcoder]

14 hours ago, LarsJ said:

If you'll post a test file, I'll post some code.

I am not sure if it is a good idea... it violates one of the forum's rules (but it is not related to computer virus)

[guinness]

4 minutes ago, TheDcoder said:

I am not sure if it is a good idea... it violates one of the forum's rules (but it is not related to computer virus)

Then why create unethical applications?

[TheDcoder]

@guinness Its not unethical, it just violates one of the rules... a rule which is not common on all other forums. I am not willing to say it out loud, unless someone can guarantee that this thread won't get locked if I point out the rule.

[TheDcoder]

Alright, I got permission from M23

The "rule" I was referring to was interaction with games. Since my script does not directly interact with the game, Melba gave me the permission to post

@LarsJ Here is a sample file to parse: https://www.dropjiffy.com/f/1WBYNWWO (expires in 24 hours)

The footer's beginning is marked with "MCMap!" & ending with "MCEnd."

 

TD

[jchd]

I rarely answer post related to games but this thread has gone a bit far for what it's worth.

#include <FileConstants.au3>

Local Const $7zHeaderSize = 32
Local $filename = "C:\Users\jc\Downloads\testing.mcmap"
Local $filehdl = FileOpen($filename, $FO_BINARY)
Local $fileheader = FileRead($filehdl, $7zHeaderSize)
If BinaryMid($fileheader, 1, 6) <> Binary('0x377ABCAF271C') Then
    MsgBox(0, '', 'File is not a 7z archive')
    Exit
EndIf
Local $blockheader = DllStructCreate("byte[" & $7zHeaderSize & "]")
DllStructSetData($blockheader, 1, $fileheader)
Local $header = DllStructCreate("align 1;byte tag[6];byte major;byte minor;uint crc1;uint64 offset;uint64 size;uint crc2", DllStructGetPtr($blockheader))
FileSetPos($filehdl, DllStructGetData($header, 'offset') + DllStructGetData($header, 'size'), $FILE_CURRENT)
Local $sTrailer = BinaryToString(FileRead($filehdl))
ConsoleWrite($sTrailer)

Details taken from http://cpansearch.perl.org/src/BJOERN/Compress-Deflate7-1.0/7zip/DOC/7zFormat.txt

[TheDcoder]

@jchd Marvelous! You made my day!

But that is too complicated for me to understand ... it works though

Edited February 16, 2016 by TheDcoder