Debugging other folks’ code

September 17, 2005 @ 2:57 am · Filed under Uncategorized

I love debugging things, but I think I’m spoiled most of the time because for nearly everything I work on I can grab the source code, build a debug version, and debug that. Tonight I had the pleasure of debugging something that I originally thought was a bug in the OS but which turned out to be in a third-party application and, because I didn’t have the application’s source code, I tracked it down to the instruction that went wrong instead of the line. (Actually, two instructions, since the code had two bugs.)

Of course, I’ve reported this to the developer. I wonder what they’ll think when they get a bug report saying “you have a bug in the instruction at offset 156 of this function, where you’re reading a series of two shorts as an int, and another one at offset 188, where you’re reading the short at offset 4 instead of the short at offset 6″. I could give them diffs with the fixes, but I suspect diffs to their assembly code probably wouldn’t be very useful.

1 Comment

  1. Marshall Clow Said,

    December 20, 2005 @ 9:58 pm

    Been there, done that ;-)
    I used to develop printer drivers, so I spent a lot of time looking at disassemblies of other people’s printing code, trying to figure out why their code worked with (say) the Laserwriter driver, but not mine.

    When you call developers (or email them) about bugs like this, most are deeply suspicious. The good one say “Cool! Thanks for hunting this down!!”

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