Is there a standard prototype for `execvp'?

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3 total messages Started by Ron Guilmette Wed, 30 Jan 1991 01:54

#723

Author: Ron Guilmette
Date: Wed, 30 Jan 1991 01:54

49 lines
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Submitted-by: rfg@lupine.uucp (Ron Guilmette)

It is somewhat dated now, but the only book I have about POSIX is
copyright 1988.

Reading that book, it seems that the POSIX committee didn't want to
use ANSI C function prototypes for their specification of the C language
binding because prototypes were too "new-fangled".  Specifically, they
apparently choose not to express the binding in terms of prototypes because:

	"... the Working Group was aware that some vendors would wish
	to implement POSIX in terms of a binding to an historical
	variant of the C language..."

So in effect, it seems that the bindings given in the book I'm looking
at are for "traditional C" (rather than ANSI C).

In addition to avoiding prototypes, the POSIX folks also (apparently)
decided to avoid the use of ANSI C type qualifiers (i.e. "const" and
"volatile") in the C binding.

Now even thought I don't really keep up on such things, I assume that
some progress has been made since 1988.  Is there now also an ANSI C
binding for POSIX?  If so, please tell me the exact name of *that*
document so that I can go buy a copy.

The thing that I most want to know at the moment is the "correct" (or
"standard") prototype for the `execvp' function.  The POSIX book I have
here doesn't use any ANSI C type qualifiers at all, and so I have no
idea what (if any) type qualifiers should be used to declare the types
of the formal parameters for execvp.

For example, my intuition tells me that a "proper" prototype for `execvp'
should look like:

	extern int execvp (const char *, const char *const *);

But somebody else disagrees with me.

It seems that this sort of thing could be an important "standards" issue
because many variants of UN*X operating systems are now shipping with fully
prototyped system include files.  Are they "POSIX-conformant" with respect
to the qualifiers used to declare the types of their formals?  How would
one be able know one way or the other?

Please excuse me if this has all been resolved long ago (and if my nearly
total ignorance is showing).

Volume-Number: Volume 22, Number 87

Re: Is there a standard prototype for `execvp'?

#742

Author: Doug Gwyn
Date: Thu, 31 Jan 1991 19:03

20 lines
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Submitted-by: gwyn@smoke.brl.mil (Doug Gwyn)

In article <17501@cs.utexas.edu> rfg@lupine.uucp (Ron Guilmette) writes:
>Are they "POSIX-conformant" with respect to the qualifiers used to
>declare the types of their formals?

Since "POSIX" did not specify the qualifiers, a conforming implementation
need not provide them in any prototypes in the standard/POSIX headers.
If the implementor wants to be "helpful", he could through judicious use
of "const*" improve the compile-time error checking, but that is not
required.  In a related note in another newsgroup I observe that
"const*const*" is not only not helpful, it is actually harmful and
should not be used in place of "**" in such prototypes.

Basically P1003 didn't have enough qualified people-time to revise the
1003.1 draft to convert it to give genuine prototypes.  However, I would
recommends that all future C bindings do so; it's much cleaner than the
hybrid "UNIX man page SYNOPSIS" format that has been traditionally used.

Volume-Number: Volume 22, Number 94

Re: Is there a standard prototype for `execvp'?

#731

Author: David A Willcox
Date: Fri, 01 Feb 1991 15:08

27 lines
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Submitted-by: willcox@urbana.mcd.mot.com (David A Willcox)

rfg@lupine.uucp (Ron Guilmette) writes:

>It is somewhat dated now, but the only book I have about POSIX is
>copyright 1988.

The new version of POSIX.1, IEEE Std 1003.1-1990, came out last
December.  You can get it from the IEEE; their number is 1-800-678-IEEE,
and I think that the order number is SH13680.  It uses ANSI C prototypes.
execvp(), for example, is:

	int execvp(const char *file, char *const argv[]);

It also has quite a number of other "bug fixes".

>Reading that book, it seems that the POSIX committee didn't want to
>use ANSI C function prototypes for their specification of the C language
>binding because prototypes were too "new-fangled".  Specifically, they
>apparently choose not to express the binding in terms of prototypes because:

ANSI C "wasn't" when the 1988 version of POSIX was written.  There were
drafts of the C standard around, but it wasn't approved, and there was no
guarantee that it wouldn't change.  That was the main reason for staying
with the traditional syntax. 

Volume-Number: Volume 22, Number 97

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