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From: culberts@hplwbc.hpl.hp.com (Bruce Culbertson)
Newsgroups: comp.sys.nsc.32k
Subject: Minix comments
Message-ID: <9009041816.AA16986@hplwbc.hpl.hp.com>
Date: 4 Sep 90 18:16:15 GMT
Sender: news@daver.bungi.com
Lines: 54
Approved: news@daver.bungi.com

Hi gang,

I am delighted to see so much recent pc532 activity.  Several people are
pounding on Minix in ways I haven't and are consequently seeing weird
behavior I haven't experienced.  Keep it up -- eventually this will
result in a better OS.

Several people have reported that the passwd command is broken.  You're
right.  I set my password and then I updated the standard IO library.
Since I didn't need to change my password, I didn't notice that the new
library broke passwd.

Passwd uses a light-weight printf called prints.  Prints does not do a
flush after each call, which is why you do not see the passwd prompts.
Worse, the prompts can wind up in your /etc/passwd file, making login's
impossible.  Passwd uses the cute trick of close'ing (not fclose'ing)
stdout and then opening /etc/passwd as stdout.  When the flush finally
occurs, the prompts go into /etc/passwd.

Do not try to fix this by putting something like

	#define prints printf

into passwd.c.  Because the library routine getpass calls prints,
passwd will still fail with this fix.

Instead put this at the end of passwd.c and recompile:

	prints (f, a, b, c)
	char *f, *a, *b, *c;
	{printf (f, a, b, c);}

That will probably get the portability police on my back -- use VARARGS
if you prefer.  Next, I will criticize other people's poor quality code.

Several people have reported that code like this will not work:

	foo()
	{
	  char bar[] = "Hello";

	  strcpy (bar, "Bye");
	}

This has never been legal C, although it worked on some computers.
(Well, maybe K&R were vague on the subject, but it sure is illegal now.)
GCC puts the string "Hello" into the text segment, which is write
protected in my Minix implementation.  Hence, the strcpy() gets a bus
error when it tries to write it.  Since there is some of this kind of
code still around, GCC provides a "-fwritable-strings" option to put the
"constant" strings into the data segment.

Have fun,
Bruce