"broken savefile" - WHAT THE HELL'S WRONG?! How do I recover my char?!

[takkaria]

Originally Posted by PowerDiver

Would changing the procedure to (1) write to a temporary savefile and then (2) rename the tmp to replace the original be good enough? I'd think that ought to be fairly robust.

We already write to savefile.new, then move savefile to savefile.old, then move savefile.new to savefile, then delete savefile.(old|new), checking for errors and issues at each step. Windows is just an arse.

[LostTemplar]

Without use of fsync() this did not help, atleast with ext4 filesystem, allmost any system crash or power down results in broken savefile. I never had any problems under windows.

[d_m]

Originally Posted by LostTemplar

Without use of fsync() this did not help, atleast with ext4 filesystem, allmost any system crash or power down results in broken savefile. I never had any problems under windows.

Check out the "Disadvantages" section of this article on ext4:

http://en.wikipedia.org/wiki/Ext4

[Tiburon Silverflame]

The 2-tier approach I'm suggesting would use 2 completely separate *files*. So if I'm using Tiburon as my character, the level-switched save might be Tiburon.level, while the user-invoked or game-exit save might be Tiburon. That way, no matter what happens, you have 1 file that is no more than a single level old, which is safe.

[Pete Mack]

Originally Posted by LostTemplar

Without use of fsync() this did not help, atleast with ext4 filesystem, allmost any system crash or power down results in broken savefile. I never had any problems under windows.

This is correct.
Before renaming the file, force a disk sync--standard practice for editor apps and databases. For a panic save file, it's a good idea to reopen it and verifying that it is valid before renaming.

[Nemesis]

Originally Posted by ramela

What you consider questionable might differ from what others see as questionable and you shouldn't snap at other people for voicing their opinions.

Everyone gets to have their own opinion on what is a legimate win and what is not, even if you were hurt by your computer crash.

Try not to snap yourself when in this situation!

[Derakon]

Originally Posted by Pete Mack

This is correct.
Before renaming the file, force a disk sync--standard practice for editor apps and databases. For a panic save file, it's a good idea to reopen it and verifying that it is valid before renaming.

This sounds basically like what I suggested, right? Validate save, if it's good, replace old save with it, otherwise, use old save.

[Tiburon Silverflame]

I still see some issues...

First, some of this tends to be OS-specific, or at least the calls to implement the disk sync, are likely to be OS-specific.

Second, it still feels like the process that Pete/Derakon are mentioning, is potentially subject to crashes at the wrong time. It might be *safer*...but it's not safe.

[ramela]

Originally Posted by Nemesis

Try not to snap yourself when in this situation!

Well, this has happened to me twice. Both times I did snap, but in private.

Then I just started over.

[Derakon]

Tiburon: to my knowledge, moving a file is an atomic operation on all filesystems -- that is to say, it either succeeds, or it doesn't happen at all. So if you have two files "goodsave" and "panicsave" and you try to move panicsave over goodsave (having previously validated panicsave is a valid savefile), then there's nothing, that will corrupt panicsave that wouldn't also screw over your entire hard drive (i.e. catastrophic hardware failure).

Writing a file isn't an atomic operation, which is why panicsaves are not reliable in the first place.