578645 - DR. WILY WINS BECAUSE THE GAME OPENS THE LEVEL FILE TWICE TWICE - Created by Divverent
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Recorded times for : 578645 - DR. WILY WINS BECAUSE THE GAME OPENS THE LEVEL FILE TWICE TWICE
| Runner | Runner PB | Total play time | Total deaths | Minimum clear deaths | |
| divverent | 22s696 | 2 |
Description of that level
Level demonstrates game bug. Please skip.
Comments
Posted by : divverent -
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Sorry, adding one more: there is likely also a way to do it without a debugger as follows:
In a bash shell (probably can also do something similar in powershell on Windows), write a loop like:
while :; do
ln -snf win.mmlv upload.mmlv
ln -snf lose.mmlv upload.mmlv
done
and have that running while trying to upload "upload.mmlv".
It'll basically make it random which of the file open calls gets which actual file, so after a bunch of attempts you should succeed at this same result as well (but sometimes you may actually upload the "good" version as well.
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Sorry, adding one more: there is likely also a way to do it without a debugger as follows:
In a bash shell (probably can also do something similar in powershell on Windows), write a loop like:
while :; do
ln -snf win.mmlv upload.mmlv
ln -snf lose.mmlv upload.mmlv
done
and have that running while trying to upload "upload.mmlv".
It'll basically make it random which of the file open calls gets which actual file, so after a bunch of attempts you should succeed at this same result as well (but sometimes you may actually upload the "good" version as well.
Posted by : divverent -
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I should add: the fact that it opens the level file eight times for loading it (maybe even 12, not sure if anything from the first 4 times before the "you have to test it first" dialog is used) is also super suspicious, as it could imply that the level data the comparison is made to and the level actually loaded are different (so even if you fix the issue at the end, it could still be done by replacing one of the first eight calls).
Thus I would suggest that the real and proper fix is to remove all cases where the same file is opened more than once for one action. It may take some refactoring, but given you pass the file name along, why not just replace that by passing the file content along instead... and if you do that, you can even use the exact same byte string for playtesting and uploading, so you won't even need to compare at all.
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I should add: the fact that it opens the level file eight times for loading it (maybe even 12, not sure if anything from the first 4 times before the "you have to test it first" dialog is used) is also super suspicious, as it could imply that the level data the comparison is made to and the level actually loaded are different (so even if you fix the issue at the end, it could still be done by replacing one of the first eight calls).
Thus I would suggest that the real and proper fix is to remove all cases where the same file is opened more than once for one action. It may take some refactoring, but given you pass the file name along, why not just replace that by passing the file content along instead... and if you do that, you can even use the exact same byte string for playtesting and uploading, so you won't even need to compare at all.
Posted by : divverent -
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Thanks for the quick response, and for being able to remove the level while keeping this message thread open.
The way I did it was actually using a debugger not on the game itself (that kinda didn't work, but might be because I'm running in WINE on Linux, although strace shows the full paths, I couldn't get them in gdb but gdb only showed directory paths - probably was me doing something wrong, not successful anti-debugging tech), but instead, I ran a FUSE file system in the debugger:
$ cd /tmp
$ apt-get source bindfs
$ cd bindfs
$ CFLAGS=-g3 LDFLAGS=-g3 ./configure
$ make
$ mkdir /tmp/mm
$ sudo gdb --args /tmp/bindfs-1.14.7/src/bindfs -o nonempty /tmp/mm ~/.wine/drive_c/users/rpolzer/AppData/Local/MegaMaker/Levels
(gdb) break bindfs_open
(gdb) break bindfs_create
(gdb) set follow-fork-mode child
(gdb) run
Now whenever the game tries to open a file in the Levels directory, the debugger interrupts the game and I can continue using
(gdb) c
I observed the game opening the level file twice for displaying the level list, then four times after selecting it, and eight times from the "you need to test it first to show it is beatable" dialog to actually showing the level. Then after the "do you want to upload" dialog, it opened the file twice.
And IIRC the first time, the level file has to be unchanged, but after running "c" once after the dialog, I replaced the level file by the unbeatable version and hit "c" again. Mega Man Maker then uploaded the unbeatable version after me having beaten the beatable one.
To test the same on Windows, I guess the best way is to run it in Visual Studio and have a breakpoint on whatever system function you use to opening a file. Although I guess you can use the same approach with a FUSE file system on Windows too: https://github.com/billziss-gh/winfuse.
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Thanks for the quick response, and for being able to remove the level while keeping this message thread open.
The way I did it was actually using a debugger not on the game itself (that kinda didn't work, but might be because I'm running in WINE on Linux, although strace shows the full paths, I couldn't get them in gdb but gdb only showed directory paths - probably was me doing something wrong, not successful anti-debugging tech), but instead, I ran a FUSE file system in the debugger:
$ cd /tmp
$ apt-get source bindfs
$ cd bindfs
$ CFLAGS=-g3 LDFLAGS=-g3 ./configure
$ make
$ mkdir /tmp/mm
$ sudo gdb --args /tmp/bindfs-1.14.7/src/bindfs -o nonempty /tmp/mm ~/.wine/drive_c/users/rpolzer/AppData/Local/MegaMaker/Levels
(gdb) break bindfs_open
(gdb) break bindfs_create
(gdb) set follow-fork-mode child
(gdb) run
Now whenever the game tries to open a file in the Levels directory, the debugger interrupts the game and I can continue using
(gdb) c
I observed the game opening the level file twice for displaying the level list, then four times after selecting it, and eight times from the "you need to test it first to show it is beatable" dialog to actually showing the level. Then after the "do you want to upload" dialog, it opened the file twice.
And IIRC the first time, the level file has to be unchanged, but after running "c" once after the dialog, I replaced the level file by the unbeatable version and hit "c" again. Mega Man Maker then uploaded the unbeatable version after me having beaten the beatable one.
To test the same on Windows, I guess the best way is to run it in Visual Studio and have a breakpoint on whatever system function you use to opening a file. Although I guess you can use the same approach with a FUSE file system on Windows too: https://github.com/billziss-gh/winfuse.
Posted by : goldstorm -
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Noted. Is this possible to do without a debugger? Seems like a fast / frame perfect trick. I appreciate your report, and we will investigate alternatives to the method you described above.
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Noted. Is this possible to do without a debugger? Seems like a fast / frame perfect trick. I appreciate your report, and we will investigate alternatives to the method you described above.
Posted by : divverent -
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To moderators: please write down the issue internally so a next release can fix it, and then take down this level. You can contact me for further details at divVerent@gmail.com.
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To moderators: please write down the issue internally so a next release can fix it, and then take down this level. You can contact me for further details at divVerent@gmail.com.
Posted by : divverent -
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When tracing the game, I found that after the upload confirmation message, the level file is opened twice. So I used a debugger to halt the game between the two calls, and replaced the file in between.
Please fix the game so it only opens and reads the level file once, and uses that file content both for comparing or uploading.
Or actually, rather only open it once (and not EIGHT! times) when loading initially, and remember that content also for uploading. Much simpler anyway.
2
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When tracing the game, I found that after the upload confirmation message, the level file is opened twice. So I used a debugger to halt the game between the two calls, and replaced the file in between.
Please fix the game so it only opens and reads the level file once, and uses that file content both for comparing or uploading.
Or actually, rather only open it once (and not EIGHT! times) when loading initially, and remember that content also for uploading. Much simpler anyway.
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