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From: campbell@maynard.BSW.COM (Larry Campbell)
Newsgroups: comp.lang.c
Subject: Re: structure function returns -- how?
Message-ID: <773@maynard.BSW.COM>
Date: Sat, 6-Dec-86 18:33:59 EST
Article-I.D.: maynard.773
Posted: Sat Dec  6 18:33:59 1986
Date-Received: Sun, 7-Dec-86 04:35:03 EST
References: <131@hcx1.UUCP>
Reply-To: campbell@maynard.UUCP (Larry Campbell)
Organization: The Boston Software Works, Inc.
Lines: 17

In article <131@hcx1.UUCP> notes@hcx1.UUCP writes:
>Suppose   a   is declared as a structure and   b   is a function which 
>returns a structure.  In the statement:
>                       a = b () ;
>when and how should the copying into   a   take place?

The compiler on my system (which is pcc based) allocates static unnamed
storage in b.  It puts the result there and returns a pointer to the
storage.  The routine containing the assignment then copies the result
into a, using the pointer returned by b.  It seems to me that this is
also signal-unsafe -- if a signal occurs just before the copy, and the
signal handler calls b -- whammo.
-- 
Larry Campbell				     The Boston Software Works, Inc.
Internet: campbell@maynard.bsw.com	    120 Fulton Street, Boston MA 02109
uucp: {alliant,wjh12}!maynard!campbell  	    +1 617 367 6846
ARPA: campbell%maynard.uucp@harvisr.harvard.edu      MCI: LCAMPBELL