Re: [PATCH] git tag --contains : avoid stack overflow

From: Jean-Jacques Lafay <jeanjacques.lafay@gmail.com>
Date: Nov 10, 2012, 21:13 UTC
Message-ID: <d9843c09-3ca9-406e-9df8-78603235d985@googlegroups.com>
In-Reply-To: <03ED9D50D1F64467863C051959CFC433@PhilipOakley>

Le samedi 10 novembre 2012 21:00:10 UTC+1, Philip Oakley a écrit :

Show 22 quoted lines

> From: "Jean-Jacques Lafay" <jeanjacq...@gmail.com <javascript:>> Sent: 
> Saturday, 
> November 10, 2012 5:36 PM 
> > In large repos, the recursion implementation of contains(commit, 
> > commit_list) 
> > may result in a stack overflow. Replace the recursion with a loop to 
> > fix it. 
> > 
> > Signed-off-by: Jean-Jacques Lafay <jeanjacq...@gmail.com <javascript:>> 
>
> This is a change to the main git code so it is better to submit it to 
> the main git list at g...@vger.kernel.org <javascript:> (plain text, no 
> HTML, first 
> post usually has a delay ;-) 
>
> It sounds reasonable but others may have opinions and comments. 
>
> Have you actually suffered from the stack overflow issue? You only 
> suggest it as a possibility, rather than a real problem. 
>
> Philip 
>

Yes, it actually crashed on me, and since the call is made by GitExtension while browsing the commit history, it was quickly annoying to have windows popping a "git.exe stopped working" message box at my face every time I clicked on a line of the history ;-) (well, you can sort of work around it by having the "file tree" or "diff" tab active)

Coincidentally, as I was having a glance at the recent topics, I saw that someone else experienced it.

However, I couldn't reproduce it on Linux : where the windows 
implementations crashes at a ~32000 depth (*not* exactly 32768, mind you), 
on linux it happily went through 100000 commits. I didn't take time to look 
much further, but maybe on my 64 bit Linux VM, the process can afford to 
reserve a much bigger address range for the stack of each thread than the 
1Mb given to 32 bit processes on windows.
 
Jean-Jacques.

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