Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!tut.cis.ohio-state.edu!bloom-beacon!apple!versatc!mips!prls!philabs!linus!nixbur!nixpbe!mboen
From: mboen@nixpbe.UUCP (Martin Boening)
Newsgroups: comp.os.minix
Subject: Minimal version of C-Library in MINIX-ST??
Keywords: fopen dumb
Message-ID: <284@nixpbe.UUCP>
Date: 2 May 89 08:21:11 GMT
Organization: Nixdorf Computer AG, Paderborn, Germany
Lines: 49

Last week I tried porting zoo to MINIX-ST and noticed something strange:
I achieved compression ratios of 100 - 101 percent. The debug-output gave
a first clue: lzc wrote 0 bytes to output. So I looked at the zoo sources
closely and noticed that for **NIX-like systems the following opening modes
for files are defined:

> #define Z_READ  "r"
> #define Z_WRITE "r+"
> #define Z_RDWR  "r+"
> #define Z_NEW   "w"

In the Minix sources the fopen-Routine doesn't scan the whole modestring
though. It just looks at the first character. As a result, only three modes
are supported:

 'w' -> create file
 'r' -> read file
 'a' -> write to file (append)

i.e with mode 'w', creat is called, with 'r' an 'open (fn, 0)' and with 'w'
an 'open (fn, 1)'.

All, open does is a 'callm3(FS,OPEN,mode,name)'. Looking at do_open I saw
that 3 modes are supported:

  0    read file
  1    write file
  2    read and write file <--!!!

So, why can't fopen do an 'open (fn, 2)' to open a file for reading and
writing when the modestring contains "r+" or "w+". I tried this and now
zoo seems to work alright (some problems with the time settings remain
[did you know that yesterday was may 1st, 1997?:-)])

My question: is the library supplied with MINIX-ST a minimal version? Has
this been fixed? Does anybody know what GCC does and if it handles this
better? Does anybody know of problems that might occur when opening a file
for reading and writing using fopen (buffer problems, etc.) Does anybody
even care to comment ? :-)

Martin

Email:

in Europe: ...!unido!nixpbe!mboening.pad
elsewhere: ...!uunet!philabs!linus!nixbur!mboening.pad
-- 
Email: in the   USA ->  ...!uunet!philabs!linus!nixbur!mboening.pad
       outside  USA ->  {...!mcvax}!unido!nixpbe!mboening.pad