Subject: Important! Bug in /usr/include/ctypes.h Date: Fri, 15 Nov 1991 18:42:58 -0500 From: tytso@ATHENA.MIT.EDU (Theodore Ts'o)
I found the problem which caused "mcopy a:*.c ." to files with
unreadable filenames. The problem was that it was trying to convert the
uppercase MS-DOS filenames to lowercase, and this was failing because
tolower() is incorrectly defined in ctype.h: the plus sign should be a
minus sign.
diff -r1.1 ctype.h
31c31
< #define tolower(c) (_ctmp=c,isupper(_ctmp)?_ctmp+('a'+'A'):_ctmp)
---
> #define tolower(c) (_ctmp=c,isupper(_ctmp)?_ctmp+('a'-'A'):_ctmp)
If you are trying to port programs to Linux, you should apply this patch
to your ctype.h --- it could save you a lot of aggravation. (I know
that it will cause problems with flex at the very least, and probably
many other programs.)
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I agree with Peter McDonald's observation that it is extremely nice to
have only compiler for Linux, and it would be a shame if one needed to
have both compilers around, depending on which compiler was used by a
developer. At the very least, it would make the code uglier as people
put in porting #ifdef's. gcc has a lot to recommend it, especially
since version 2.0 gives you g++ and Objective C basically for free.
I note that once Linux has paging, gcc will be able to work with 2 meg
machines, although granted, it will be slower than normal. I don't know
what kind of speed hit gcc on a 2 meg machine with paging would take,
but perhaps this would be sufficient that we can just have one main
compiler for Linux.
Also, memory is getting relatively cheap these days --- we're talking
maybe US$30 to US$40 per megabyte if your machine can take SIMMS.
Upgrading a machine from 2 meg to 4 meg doesn't cost *that* much money.
As long as the system will run gcc (albeit slowly), would this alleviate
concerns about insufficient support of 2 meg machines?
----------------------------------------
Along the lines of having only one compiler for Linux, I am currently
looking into how it might be possible to assmeble the 16-bit binary
portions of Linux, so that we could just use gas to compile the boot
sector and setup code. There are a bunch of issues to deal with,
including modifying gas to emit 16-bit object files, which doesn't look
that hard.
Another problem is that the gas format is using a "source, destination"
convention, while the as86 assembler seems to be using a "destination,
source" convention. If absolutely necessary, I can figure some of the
unclear translations by looking at the object code in the boot sector
and the matching it up against the opcodes in the gas sources, but this
seems rather crude and unpleasant. Does someone have a quick conversion
chart between the two assemblers which they could send to me? This
would save me a lot of dirty work. Thanks!
- Ted