GNU bug report logs - #13054
Assume POSIX 1003.1-1988 or later for execve.

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Message #5 received at submit <at> debbugs.gnu.org (full text, mbox):

From: Paul Eggert <eggert <at> cs.ucla.edu>
To: bug-gnu-emacs <at> gnu.org
Cc: Eli Zaretskii <eliz <at> gnu.org>
Subject: Assume POSIX 1003.1-1988 or later for execve.
Date: Sat, 01 Dec 2012 22:37:39 -0600

[Message part 1 (text/plain, inline)]

Attached is a patch to simplify Emacs that I discovered while looking
into the putenv/setenv problem.  It affects the NT port so I'm
CC'ing this to Eli to give him a heads-up.

[execve.txt (text/plain, attachment)]

Message #8 received at 13054 <at> debbugs.gnu.org (full text, mbox):

From: Andreas Schwab <schwab <at> linux-m68k.org>
To: Paul Eggert <eggert <at> cs.ucla.edu>
Cc: 13054 <at> debbugs.gnu.org
Subject: Re: bug#13054: Assume POSIX 1003.1-1988 or later for execve.
Date: Sun, 02 Dec 2012 09:27:53 +0100

Paul Eggert <eggert <at> cs.ucla.edu> writes:

> +	Assume POSIX 1003.1-1988 or later for execve.
> +	* callproc.c (Fcall_process):
> +	* process.c (create_process):
> +	Don't save and restore environ;	no longer needed.
> +	* callproc.c (child_setup):
> +	Use execve, not execvp, to preserve environ.

How does this have anything to do with POSIX?

Andreas.

-- 
Andreas Schwab, schwab <at> linux-m68k.org
GPG Key fingerprint = 58CA 54C7 6D53 942B 1756  01D3 44D5 214B 8276 4ED5
"And now for something completely different."

Message #11 received at 13054 <at> debbugs.gnu.org (full text, mbox):

From: Eli Zaretskii <eliz <at> gnu.org>
To: Paul Eggert <eggert <at> cs.ucla.edu>
Cc: 13054 <at> debbugs.gnu.org
Subject: Re: Assume POSIX 1003.1-1988 or later for execve.
Date: Sun, 02 Dec 2012 19:03:39 +0200

> Date: Sat, 01 Dec 2012 22:37:39 -0600
> From: Paul Eggert <eggert <at> cs.ucla.edu>
> CC: Eli Zaretskii <eliz <at> gnu.org>
> 
> Attached is a patch to simplify Emacs that I discovered while looking
> into the putenv/setenv problem.  It affects the NT port so I'm
> CC'ing this to Eli to give him a heads-up.

Thanks.  You can go ahead and commit this, these changes don't affect
MS-Windows at all (except in trivial "a = b; b = a;" way, without
changing a or b in between).

However, please omit these changes from the changeset:

> === modified file 'lib-src/ntlib.h'
> --- lib-src/ntlib.h	2012-01-19 07:21:25 +0000
> +++ lib-src/ntlib.h	2012-12-02 04:32:26 +0000
> @@ -79,6 +79,7 @@
>  
>  /* map to MSVC names */
>  #define execlp    _execlp
> +#define execve    _execve
>  #define execvp    _execvp
>  #define fdopen	  _fdopen
>  #ifndef fileno
> @@ -104,4 +105,3 @@
>  #undef _WINSOCK_H
>  
>  /* end of ntlib.h */
> -
> 
> === modified file 'nt/ChangeLog'
> --- nt/ChangeLog	2012-12-01 20:09:30 +0000
> +++ nt/ChangeLog	2012-12-02 04:32:26 +0000
> @@ -1,3 +1,8 @@
> +2012-12-02  Paul Eggert  <eggert <at> cs.ucla.edu>
> +
> +	Assume POSIX 1003.1-1988 or later for execve.
> +	* inc/ms-w32.h (execve): New macro.
> +
>  2012-12-01  Juanma Barranquero  <lekktu <at> gmail.com>
>  
>  	* config.nt: Sync with autogen/config.in.
> 
> === modified file 'nt/inc/ms-w32.h'
> --- nt/inc/ms-w32.h	2012-11-27 03:10:32 +0000
> +++ nt/inc/ms-w32.h	2012-12-02 04:32:26 +0000
> @@ -204,6 +204,7 @@
>  
>  /* Map to MSVC names.  */
>  #define execlp    _execlp
> +#define execve    _execve
>  #define execvp    _execvp
>  #define fdopen	  _fdopen
>  #ifndef fileno
> 

They are not needed.  (The Windows build of Emacs doesn't use any
functions of the exec* family, because they are fundamentally broken
on Windows.  I will look into removing the other exec* macros from
Windows-specific files.)

Message #14 received at 13054 <at> debbugs.gnu.org (full text, mbox):

From: Paul Eggert <eggert <at> cs.ucla.edu>
To: Andreas Schwab <schwab <at> linux-m68k.org>
Cc: 13054 <at> debbugs.gnu.org
Subject: Re: bug#13054: Assume POSIX 1003.1-1988 or later for execve.
Date: Sun, 02 Dec 2012 10:17:11 -0800

On 12/02/2012 12:27 AM, Andreas Schwab wrote:
> How does this have anything to do with POSIX?

The patched version uses execve, the unpatched version doesn't.
Long ago, it made sense to avoid execve, because some pre-POSIX
platforms lacked execve.  (The FreeBSD man pages say that
execve was introduced in 4.2BSD, so I assume 4.1BSD lacked it.)
execve was standardized in POSIX 1003.1-1988, though.  It's
safe to assume execve now on all POSIXish platforms, and doing
so simplifies Emacs a bit.

Message #17 received at 13054 <at> debbugs.gnu.org (full text, mbox):

From: Andreas Schwab <schwab <at> linux-m68k.org>
To: Paul Eggert <eggert <at> cs.ucla.edu>
Cc: 13054 <at> debbugs.gnu.org
Subject: Re: bug#13054: Assume POSIX 1003.1-1988 or later for execve.
Date: Sun, 02 Dec 2012 19:48:02 +0100

Paul Eggert <eggert <at> cs.ucla.edu> writes:

> The patched version uses execve, the unpatched version doesn't.
> Long ago, it made sense to avoid execve, because some pre-POSIX
> platforms lacked execve.

execvp is just a wrapper around execve, so avoiding the latter doesn't
make sense.  There must be some other reason why execvp is used.

Andreas.

-- 
Andreas Schwab, schwab <at> linux-m68k.org
GPG Key fingerprint = 58CA 54C7 6D53 942B 1756  01D3 44D5 214B 8276 4ED5
"And now for something completely different."

Message #22 received at 13054-done <at> debbugs.gnu.org (full text, mbox):

From: Paul Eggert <eggert <at> cs.ucla.edu>
To: Andreas Schwab <schwab <at> linux-m68k.org>
Cc: 13054-done <at> debbugs.gnu.org
Subject: Re: bug#13054: Assume POSIX 1003.1-1988 or later for execve.
Date: Sun, 02 Dec 2012 11:19:50 -0800

On 12/02/2012 10:48 AM, Andreas Schwab wrote:
> execvp is just a wrapper around execve
> There must be some other reason why execvp is used.

Perhaps the author of that part of Emacs simply
didn't know about execve.  That would explain things.

It sounds like the main issue here is about mentioning
POSIX in the ChangeLog, so I removed that, along with
removing the other stuff Eli asked to remove, and
installed it as trunk bzr 111064.

Message #25 received at 13054-done <at> debbugs.gnu.org (full text, mbox):

From: Andreas Schwab <schwab <at> linux-m68k.org>
To: Paul Eggert <eggert <at> cs.ucla.edu>
Cc: 13054-done <at> debbugs.gnu.org
Subject: Re: bug#13054: Assume POSIX 1003.1-1988 or later for execve.
Date: Sun, 02 Dec 2012 22:10:16 +0100

Paul Eggert <eggert <at> cs.ucla.edu> writes:

> Perhaps the author of that part of Emacs simply
> didn't know about execve.  That would explain things.

I think the original author just wanted child_setup to search PATH.  The
change logs don't give any indication whether that was ever necessary.

Andreas.

-- 
Andreas Schwab, schwab <at> linux-m68k.org
GPG Key fingerprint = 58CA 54C7 6D53 942B 1756  01D3 44D5 214B 8276 4ED5
"And now for something completely different."

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