malloc's and signals -- a dangerous mixture?

[Charles Noren]

While reading the C standards group I came across the comment
that malloc's are dangerous to use in combination with signal
handlers.  I can see the potential problem if the malloc
library uses static storage and an malloc is interrupted with
another malloc in a signal handler.  Could someone shed some
light on the subject and possibly provide some rules when
malloc's are safe (and portable) to use with signals. 
Information specific to Sun 3 with SunOS 4.0 along with issues
dealing with other systems in general is desired.

Thanks in advance.
-- 
Chuck Noren
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