Date: Wed, 22 Jan 1997 13:17:03 +0200 (IST)
From: Eli Zaretskii <eliz AT is DOT elta DOT co DOT il>
To: djgpp-workers AT delorie DOT com
Subject: Re: `access' function and `prn' etc.
In-Reply-To: <5c2fls$a3s@sun3.uni-essen.de>
Message-ID: <Pine.SUN.3.91.970122131152.101B-100000@is>
MIME-Version: 1.0
Content-Type: TEXT/PLAIN; charset=US-ASCII


On 21 Jan 1997, Peter Gerwinski wrote:

> when applying the `access' function to DOS device files like `prn'
> or `lpt1', it returns "not writeable":

I replied to the poster, but I'm unsure whether we need to fix this and 
if so, how exactly.  The problem is that DOS fails the `_chmod' call.  
This can be remedied with `findfirst', as the patch below shows, but then 
all devices come out both readable and writeable, since there is no way 
to tell if a device can be written to or read from without opening it 
first (which will make `access' much slower).

Please tell me whether you think the patch below is a Good Thing.

*** src/libc/posix/unistd/access.c~0	Wed Jan 22 10:12:40 1997
--- src/libc/posix/unistd/access.c	Wed Jan 22 10:28:02 1997
*************** int access(const char *fn, int flags)
*** 32,37 ****
--- 32,44 ----
            return 0;
        }
  
+     /* Devices also fail `_chmod'; some programs won't write to
+        a device unless `access' tells them they are writeable.  */
+     if (findfirst(fn, &ff, FA_RDONLY | FA_ARCH) == 0
+ 	&& (ff.ff_attrib & 0x40) == 0x40
+ 	&& (flags & (X_OK | D_OK)) == 0)
+       return 0;
+ 
      errno = ENOENT;
      return -1;
    }