My advice on implementing stuff in C: [LWN.net]

My advice on implementing stuff in C:

Posted Oct 25, 2010 10:05 UTC (Mon) by hppnq (guest, #14462)
In reply to: My advice on implementing stuff in C: by nix
Parent article: Russell: On C Library Implementation

The only way to avoid *that* [stack-OOM] is to do a deep recursion first, and then ensure that you never call functions further down in the call stack than you have already allocated, neither in your code nor in any library you may call.

You would have to know in advance how deep you can recurse, or you should be able to handle SIGSEGV. The maximum stack size can be tuned through rlimits, and that should solve wahern's problem of some other process draining out all available memory. This problem is not the result of bad programming, but of bad systems management.

(That said, rlimits are horribly broken. Just add more memory. ;-)

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My advice on implementing stuff in C:

Posted Oct 25, 2010 22:28 UTC (Mon) by paulj (subscriber, #341) [Link]

FWIW, it's not defined what happens if you overflow the stack. You can't rely on getting a SEGV (isn't that a very recent addition to Linux, thanks to that Xorg security hole)?

My advice on implementing stuff in C:

Posted Oct 25, 2010 22:36 UTC (Mon) by nix (subscriber, #2304) [Link]

Even if you do get SIGSEGV from a stack-OOM, well, you'd better hope the system supports sigaltstack() as well, or you'll not be able to call the signal handler... oh, and, btw, it is (even now) easier to make a list of the systems on which sigaltstack() works properly than the systems on which it does not :(

My advice on implementing stuff in C:

Posted Oct 26, 2010 7:55 UTC (Tue) by hppnq (guest, #14462) [Link]

The point is, you can't safely expand the stack by recursing deeply in order to prevent running out of stack.