WinXP - hanging when opening big rar file

[PascalT]

Windows XP 32 bit SP3
TC11.55 RC4 32 bit

I tried to open a 30.4 Gb rar file (containing only one packed file) by double-clicking it.
Total Commander seemed to hang forever with the disk access light of the PC on ; I had to kill the process.

This rar file immediately opens and unpacks normally in WinRAR 6.02 32 bit on the same computer.
It also opens normally and immediately in Windows 10 64 bit and TC11.55 RC4 64 bit.

If this is due to limits with XP and detectable by TC, maybe a warning could be better than a hanging.

[PascalT]

I give you some informations from WinRAR about the rar file:
version to extract : 5.0
OS host : Unix
Total folders : 0
Total files : 1
Total size : 32 753 093 113
Packed size : 32 642 627 544
Ratio : 99%
Dictionary size : 32 MB

[ghisler(Author)]

TC 11.55 uses the 7zip dll on Windows Vista, XP and older, because the new unrar.dll only works on Windows 7 and newer. If your Unix host only supports XP functions, TC will have to use 7zip dll. Can you try how long it takes to open the file with 7zip?
https://www.7-zip.org

In general, opening a big RAR file can take a long time, because the headers with the file names and attributes are spread across the entire file. I guess that WinRAR sees that the first file takes the entire rest of the file, and doesn't continue reading the file.

[PascalT]

7Zip (24.09 32 bit) opens the rar file immediately. So why not TC ?
Also TC 64 bit on windows 10 opens it immediately (on a faster PC but through network so I'm sure the whole file is not read).

[ghisler(Author)]

I don't know, I use the 7zip dll. I will try to find out in the debugger what 7zfm does differently.

[PascalT]

Some more informations :

1 - The rar file is finally opened after 12 mn (on a core2 duo) ; So the file seems to be entirely scanned.

2 - For this rar file 7Zip gives these infos (maybe the "Locator QuickOpen" is important) :
Début : 15h52
fin : 16h04
-> 12 mn

Taille: 32 753 093 113
Taille compressée: 32 642 627 544
Dossiers: 0
Fichiers: 1
CRC: 3C81096B
------------------------:
Chemin: D:\T\toto.rar
Type: Rar5
Taille physique: 32 642 627 812
Caractéristiques: Locator QuickOpen:32642627665
Chiffrer: -
Solide: -
Blocs: 1
Méthode: v6:32M:m1
Multi-volume: -
Volumes: 1

3 - Strangely enough a 46GB multipart (93 parts) rar containing 1 file is opened by TC (32bit on Windows XP) in 4 s. It seems multipart rar are treated better !

[PascalT]

Typo :
Forget the :
"Début : 15h52
fin : 16h04
-> 12 mn"

[ghisler(Author)]

I found the problem! The 7z "open" function has a parameter "maxCheckStartPosition" which tells the library how far it should look for the start of the archive, for opening self-extracting archives with a small executable in front of the data. This was set to 0 in my library, making 7z search the entire archive. Setting this to 1MB fixes the issue.

[MaxX]

2ghisler(Author)
AFAIK, 7zip uses first 8 MBytes of file to search archive headers.
Some 7z installers (like Opera GX setup) use that big binaries the 7z archive's beginning.
Please, consider this.

[ghisler(Author)]

Interesting, I never saw any SFX modules larger than about 400 kBytes. But increasing the maximum from 1MB to 8MB doesn't have a big penalty, so I will change it.

[browny]

Will this improve timing for installers?

[ghisler(Author)]

No, the Total7zip author would have to check whether he has set the max SFTP module size, and to which value.

[ghisler(Author)]

This should be fixed in RC5, please test it!

01.06.25 Fixed: Opening big RAR files with 7zip dll when unrar.dll not available could take a long time (32)

The problem only affected the 32-bit version, and only when unrar.dll wasn't available (Vista or older) or when it was deleted or renamed.

[PascalT]

Fixed for me with TC 11.55rc5.
All big rar files open in seconds in Win XP !

[ghisler(Author)]

Great, thanks for testing!

Moderator message from: ghisler(Author) » 2025-06-08, 07:56 UTC

Moved to fixed bugs