From: Bruno Haible <haible AT ilog DOT fr>
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Message-ID: <15025.20732.410053.828022@honolulu.ilog.fr>
Date: Fri, 16 Mar 2001 00:32:12 +0100 (CET)
To: "Juan Manuel Guerrero" <ST001906 AT HRZ1 DOT HRZ DOT TU-Darmstadt DOT De>
Cc: recode-bugs AT IRO DOT UMontreal DOT CA, djgpp-workers AT delorie DOT com
Subject: Re: OS/DJGPP specific difficulties with recode 3.6
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Juan Manuel Guerrero writes:
> While trying to compile recode 3.6 out-of-the-box
> on MSDOS using DJGPP I have found two difficulties:
> 
> a) An OS specific issue.

> I will only show the output that diff produces for the first test:
> 7. ./dumps.m4:3         --- -	Thu Mar 15 15:38:49 2001
> +++ stdout	Thu Mar 15 15:38:48 2001
> @@ -1,21 +1,23 @@
> - 10
> - 97,  10
> - 97,  98,  10
> - 97,  98,  99,  10
> - 97,  98,  99, 100,  10
> - 97,  98,  99, 100, 101, 102, 103, 104, 105,  10
> + 13,  10
> + 97,  13,  10
> + 97,  98,  13,  10
> + 97,  98,  99,  13,  10
> + 97,  98,  99, 100,  13,  10
> + 97,  98,  99, 100, 101, 102, 103, 104, 105,  13,  10

CR/LF. The tests apparently expect a Unix compatible 'echo' command.

> It is *not* worth to reproduce diff's output for all the other failing tests.

Yes, it's obvious.

> 1) The file ./m4/microsoft.m4 has been completely removed. This means that not
> only the file has been removed, the functionality proveded by it has also been
> removed and has **not** been substituted by some other appropiate code. As the
> name suggests, microsoft.m4 supplied code needed to detect if DOS/windows is
> used as OS.

There are other ways to do it. #if, or looking at config.guess output.

> The script configure.in contained code that defined the macro
> DEFAULT_CHARSET to IBM-PC or latin-1 based on the result returned by microsoft.m4.

The assumption that all non-Microsoft-OS users are in a Latin1 locale
is broken. The assumption that all DOS users use the IBM-PC = CP437
character set is broken as well. You made a list of all character
encodings used in DOS for config.charset, a few weeks ago, didn't you?

> 2) Now, the same snippet from recode 3.6, function disambiguate_name()
> from file ./src/names.c:
>   /* Look for a match.  */
> 
>   if (!name || !*name)
>     switch (find_type)
>       {
>       case ALIAS_FIND_AS_CHARSET:
>       case ALIAS_FIND_AS_EITHER:
> 	name = getenv ("DEFAULT_CHARSET");
> 	if (!name)
> 	  name = "char"; /* locale dependent */
> 	break;
> 
>       default:
> 	return NULL;
> 
> The important issue is to notice the use and function of the
> macro DEFAULT_CHARSET. With this macro, an OS specific (and appropiate)
> charset ****and**** surface (CRLF or LF)

The point about the surface escaped me and François, when we discussed
it.

Would you mind changing in your port

	  name = "char"; /* locale dependent */

into

<usual prologue for getting O_BINARY defined>
#if O_BINARY
	  name = "char/crlf"; /* locale dependent but with CR-LF surface */
#else
	  name = "char"; /* locale dependent */
#endif

> it will evaluate the environment variable DEFAULT_CHARSET for
> getting the appropiate charset. This character set always implies
> the used surface. Of course, the average MSDOS/DJGPP user will never
> set this value at all.

Which is exactly why we went through the config.charset horror. Once
for all applications, including recode.

> By inspection of the recode 3.6 code it can be seen that it will default to "char"
> and this selection implies always LF as surface, making recode 3.6 almost useless
> for the mayority of the non-POSIX platform users like the MSDOS/DJGPP ones.

OK, I've understood. Do *you* always think at everything and never make
bugs?

> This means, I will simply replace the following code:
> 	if (!name)
> 	  name = "char"; /* locale dependent */
> 	break;
> 
> by this one:
> 	if (!name)
> 	  name = "IBM-PC";
> 	break;

Please use the change above. Not everyone uses CP437.

Bruno