Subject: Re: BUG: open() O_ flags one bit too high
From: [email-masked] (John R Hanson)
To: "Victor Szel" <[email-masked]>
Cc: [email-masked]
Date: Sun, 05 Sep 1999 10:27:53 GMT

Cygwin uses win32 calls, not crtdll or msvcrt(XX)
calls, so the only way you can tell which flags
do what is to USE THE SOURCE LUKE ;-)
if you have had problems with open, you may
be using the wrong headers, DO NOT use vc++
or mingw32 headers when building cygwin apps.

On Sun, 5 Sep 1999 12:00:26 +0200, you wrote:

>Chris,
>
>> > >#ifdef __CYGWIN__
>> > >/* TODO: Get Cygwin fixed so that this bug fix won't be needed */
>> > >static inline int FixCygwinIOflags( int flags )
>> > >{
>> > >   /* Starting with O_CREAT, the Cygwin I/O flags are 1 bit too high */
>> > >   return ( ( flags & 0x1FF00 ) >> 1 ) | ( flags & 0xFF );
>> > >}
>> > >#endif
>> > 
>> > System O_CREAT (octal) O_CREAT (hex)
>> > ----------------------------------------------------
>> > Cygwin 01000 0x200
>> > Digital UNIX 01000 0x200
>> > FreeBSD 01000 0x200
>> > Irix 00400 0x100
>> > Linux 00100 0x040
>> > SCO UNIX 3.2 00400 0x100
>> > Solaris 00400 0x100
>> > Ultrix 01000 0x200
>> > 
>> > What was the bug again?
>> 
>> It could be that it's some sort of feature/bug in WinNT and not in Cygwin then, 
>> since the O_CREAT flag passed to open() was 0x200, but open always 
>> returned -1 in this case. WinNT 4.0 SP5 and Win2000 Build 2072 is the 
>> same in this respect. If this is the case, a workaround in Cygwin could be 
>> worth considering.
>
>After digging a bit more here's a snippet from 
>the FCNTL.H supplied with MS VC++ 4:
>
>#define _O_CREAT 0x0100 /* create and open file */
>#define _O_TRUNC 0x0200 /* open and truncate */
>#define _O_EXCL  0x0400 /* open only if file doesn't already exist */
>
>#define O_CREAT  _O_CREAT
>#define O_TRUNC  _O_TRUNC
>#define O_EXCL  _O_EXCL
>
>Victor Szel

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