Nuno Lopes wrote:
Hi,
In the last days I've exchanged some e-mails with PCRE's author because
of one more bug that appeared in our database about segfaults in PCRE
(related to stack overflows).
PCRE can consume a lot of stack, because of backtracking (thus
segfaulting PHP). Yesterday I've discovered that when using the
setrlimit() function, most segfaults can be avoided
(http://mega.ist.utl.pt/~ncpl/php_pcre_stack_limits.txt) :)
But I was thinking why we can't fail more silently from segfaults. A
recursive PHP function can easily segfault PHP. Why can't we catch the
signal and recover from the error? (and print a "stack overflow"
message, like java does).
Because catching these kinds of signals is a nightmare. In this
particular instance it may work because your stack hasn't been trashed,
but in many other cases it simply isn't safe to try to execute further
code. I don't know how many times I have had to go through and get rid
of some programmer's misguided idea that trying to catch and handle a
SEGV nicely was a good idea. An infinitely chain of segfaults in your
segfault handler is impossible to avoid and is much much worse than just
dropping a core as fast as possible and exiting. Any such handler also
tends to obscure the actual problem making it much more difficult to
examine the core file later.
-Rasmus
--
PHP Internals - PHP Runtime Development Mailing List
To unsubscribe, visit: http://www.php.net/unsub.php
