Date: Thu, 03 Oct 2002 10:33:35 +1000 From: Gregory Bond <gnb@itga.com.au> To: "Jin Guojun [DSD]" <j_guojun@lbl.gov> Cc: freebsd-bugs@FreeBSD.ORG Subject: Re: kern/43599: Balloc did not check mallocated pointer in libc/stdlib/strtod.c Message-ID: <200210030033.KAA01121@lightning.itga.com.au> In-Reply-To: Your message of Wed, 02 Oct 2002 16:10:04 -0700.
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> "man stdio" does not say this. Is this BSD specific?
No, signal handlers have always had very limited capability. IIUC, under the
broader ANSI C standards, all they can reliably and portably do is set a
variable of type "volatile sig_atomic_t" and return. Most real systems are
more forgiving, but not limitless.
[One of the real pains in the first ANSI C standardisation process was dealing
with the then-common practice of calling longjmp() from a signal handler.
There is simply no way to make this work anything like reliably or portably, so
it is not required by the standard, even tho many C libraries jump through ugly
hoops to try and make it work.]
For FreeBSD, signal(3) contains the sentence:
See sigaction(2) for a list of functions that are considered safe for use
in signal handlers.
And sigaction(2) has a list of 40-50 system calls and functions [notably _not_
including any STDIO ones, or longjmp()] and the comment:
All functions not in the above lists are considered to be unsafe with
respect to signals. That is to say, the behaviour of such functions when
called from a signal handler is undefined.
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