> On Tuesday 25 January 2011 18:45:15 Roland McGrath wrote: > > I know of no reason to > > think that the current treatment of the empty string was ever intended at > > the creation of the *at interfaces. > > I always assumed that this was done so that the *at syscalls can replace > both the ones that take a file descriptor (e.g. fstat) and the ones that > take a pathname (e.g. stat), which is sensible for the non-AT_FDCWD case, > although not documented in the man pages. I see your point. That is, having the empty string relative to a file descriptor work means it can replace f* calls on non-directories, whereas the standard method of passing "." for descriptor-relative resolution can only work on a file descriptor open on a directory. Is that what you mean? I don't think this was part of the original intent when the calls were added, but I suppose it makes sense. > Treating the empty string special for AT_FDCWD is rather pointless, but > at least consistent. I agree about the consistency point. However, one could also call it consistent if the empty string fails to resolve when operating on either a directory file descriptor or AT_FDCWD but works on a non-directory file descriptor. POSIX does not mandate that *at calls fail with ENOTDIR when passed a non-directory file descriptor (it's a "may fail" error, not a "shall fail" error). So that behavior would be consistent both with the POSIX requirements as I read them, and with the desire you mentioned to let the fblahat system call serve to implement fblah as well as blah. Then libc would not have to wrap the *at calls with any special check to conform to POSIX. Thanks, Roland -- To unsubscribe from this list: send the line "unsubscribe linux-api" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
