Re: permissions not honoured by /bin/pwd aka getcwd

From: Harald Kirsch (
Date: Thu Feb 24 2000 - 12:17:18 EST

On Thu, Feb 24, 2000 at 11:31:43AM -0500, Alan Curry wrote:
> Harald Kirsch writes the following:
> >The point is that on all other *nixes (as reported in the Tcl-newsgroup)
> >the behaviour is different. getcwd does return `permission denied' if
> >the x-flag of the current dir or any of its parents is not present.
> >
> >But maybe all other systems are not POSIX and Linux is or Linux knows
> >better than POSIX?
> You might get a better response if you can point to the POSIX requirement
> that getcwd() behave specifically as you describe, or that the system is not
> allowed to have additional syscalls that provide slightly more information
> than is available through opendir/readdir/etc.

Ok, a fair request and I can not currently cite the part of POSIX requiring
the behaviour I describe.

On the other hand, as explained:
> To be more precise, read permission controls whether you can readdir(),
> and execute permission controls whether you can lookup entries e.g. to
> stat(), open(), readlink() or follow subdirectory etc.

Your reasoning would mean that we can implement `additional syscalls'
linuxstat(), linuxopen() and linuxreadlink() which `provide slightly
more information', e.g. by not at all looking at permissions.

Of course we can, but should we?

Harald Kirsch

Harald Kirsch,, +49 721 6091 369 |
FhG/IITB,      Fraunhoferstr.1, 76131 Karlsruhe  |

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