On Thu, Jun 05, 2014 at 06:50:31PM +0200, Bert Freudenberg wrote:
>  
> 
> On 04.06.2014, at 18:19, Douglas McPherson <djm1329 at san.rr.com> wrote:
> 
> > Hi All, 
> > 
> > I've tested a fix for this on OS X and Linux. The fix simply adds an extra attempt to open the file after the "w+b" attempt using this code:
> > 
> >          if (getFile(f) == NULL) {
> >             setFile(f, fopen(cFileName, "wb"));
> >          }
> > 
> > If the previous attempts to open the file failed (because the file exists with write-only permission, no read permission) then the above will actually open the file write-only. Adding the extra attempt preserves existing behaviour for the success paths, so the change should be transparent to existing code.
> > 
> > BTW, AFAICT the same issue exists in Pharo.
> > 
> > Thoughts?
> > 
> > Doug
> 
> Sounds reasonable to me.
> 
> - Bert -

I have not tested it yet, but I think that this would truncate an existing file,
so that if the write-only file exists and contains data, the data would be lost.

Doug, could you check this with your patched VM?

Thanks,
Dave

> 
> 
> > 
> > 
> > On Jun 1, 2014, at 19:44 , Douglas McPherson wrote:
> > 
> >> It turns out #forceNewFileNamed: does not work either.
> >> 
> >> I believe the immediate cause of the problem is in the function you pointed me at: sqFileOpen() in platforms/Cross/plugins/FilePlugin/sqFilePluginBasicPrims.c:
> >> 
> >> 	if (writeFlag) {
> >> 		/* First try to open an existing file read/write: */
> >> 		setFile(f, fopen(cFileName, "r+b"));
> >> 		if (getFile(f) == NULL) {
> >> 			/* Previous call fails if file does not exist. In that case,
> >> 			   try opening it in write mode to create a new, empty file.
> >> 			*/
> >> 			setFile(f, fopen(cFileName, "w+b"));
> >> 			if (getFile(f) != NULL) {
> >> 			    char type[4],creator[4];
> >> 				dir_GetMacFileTypeAndCreator(sqFileName, sqFileNameSize, type, creator);
> >> 				if (strncmp(type,"BINA",4) == 0 || strncmp(type,"????",4) == 0 || *(int *)type == 0 ) 
> >> 				    dir_SetMacFileTypeAndCreator(sqFileName, sqFileNameSize,"TEXT","R*ch");	
> >> 			}
> >> 		}
> >> 
> >> The first call to fopen() indeed fails if the file does not exist. But it also fails if the file exists but does not have both read and write "r+b" permission. So in that case the intent, as you mentioned, is to try to open in write-only but "w+b" is not the write-only mode, it is also a read and write mode, see [1]. So this fopen() attempt also fails if the file has write-only permission. A fix may be to use mode "wb" instead of "w+b", but I'm not sure if there are unintended consequences to doing this.
> >> 
> >> [1] http://en.wikibooks.org/wiki/C_Programming/C_Reference/stdio.h/fopen   
> >> 
> >> On May 31, 2014, at 14:45 , Douglas McPherson wrote:
> >> 
> >>> Ahh, thanks. I'll try it out when back in front of my machine.
> >>> 
> >>> Thanks,
> >>> Doug
> >>> 
> >>> Sent from my iPhone
> >>> 
> >>> On May 31, 2014, at 14:23, Eliot Miranda <eliot.miranda at gmail.com> wrote:
> >>> 
> >>>> Hi Doug,
> >>>> 
> >>>> 
> >>>> On Sat, May 31, 2014 at 10:00 AM, Douglas McPherson <djm1329 at san.rr.com> wrote:
> >>>> Is there a way to open a write-only file in Squeak? On both Mac and Linux attempting to open such a file fails.
> >>>> 
> >>>> Squeak has forceNewFileNamed: & forceNewFileNamed:do:.  If you look at sqFileOpen in platforms/Cross/plugins/FilePlugin/sqFilePluginBasicPrims.c you'll see it first attempts to open read-write and if that fails, opens write-only.  So it should work.
> >>>> 
> >>>> HTH
> >>>> 
> >>>> For example, if you create a write-only file, i.e. in a shell, after cd to default directory
> >>>> 
> >>>> echo nada > foo
> >>>> chmod 200 foo
> >>>> 
> >>>> Then from Squeak
> >>>> 
> >>>> StandardFileStream fileNamed: 'foo'
> >>>> 
> >>>> returns nil.
> >>>> 
> >>>> If the file is given read permission (i.e. chmod 600 foo) then Squeak can open it.
> >>>> 
> >>>> Anyone know a workaround?
> >>>> 
> >>>> Thanks,
> >>>> Doug
> >>>> 
> >>>> 
> >>>> -- 
> >>>> best,
> >>>> Eliot
> >>>> 
> >>> 
> >> 
> >> 
> > 
> > 
> 
> 
>