GNU bug report logs - #21309
libtool should not use the dangerous, undocumented AC_TRY_EVAL macro, currently broken

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Message #8 received at 21309 <at> debbugs.gnu.org (full text, mbox):

From: Vincent Lefevre <vincent <at> vinc17.net>
To: 21309 <at> debbugs.gnu.org
Subject: Re: libtool generates binary data in config.log due to buggy escaping
Date: Mon, 8 Feb 2016 17:44:39 +0100

I actually get these binary data with dash (when setting
CONFIG_SHELL=/bin/sh in my environment, where /bin/sh is dash).

On 2015-08-20 03:56:02 +0200, Vincent Lefevre wrote:
> The generated "libtool" script contains:
> 
> global_symbol_pipe="sed -n -e 's/^.*[    ]\\([ABCDGIRSTW][ABCDGIRSTW]*\\)[       ][      ]*\\([_A-Za-z][_A-Za-z0-9]*\\)\$/\\1 \\2 \\2/p' | sed '/ __gnu_lto/d'"
> 
> So, I suppose that the binary data come from the \\1 and \\2.

The problem is that it yields, for instance:

+ echo configure:10030: /usr/bin/nm -B conftest.o \| sed -n -e 's/^.*[ ]\([ABCDGIRSTW][ABCDGIRSTW]*\)[ ][ ]*\([_A-Za-z][_A-Za-z0-9]*\)$/\1 \2 \2/p' | sed '/ __gnu_lto/d' \> conftest.nm

With bash:

$ echo '\1' | hd
00000000  5c 31 0a                                          |\1.|
00000003

With dash:

$ echo '\1' | hd
00000000  01 0a                                             |..|
00000002

POSIX[*] says:

  if any of the operands contain a <backslash> character, the results
  are implementation-defined.

So, the above code is not portable.

[*] http://pubs.opengroup.org/onlinepubs/9699919799/utilities/echo.html

-- 
Vincent Lefèvre <vincent <at> vinc17.net> - Web: <https://www.vinc17.net/>
100% accessible validated (X)HTML - Blog: <https://www.vinc17.net/blog/>
Work: CR INRIA - computer arithmetic / AriC project (LIP, ENS-Lyon)

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