RE: lseek() on entries in /proc/device-tree returns EINVAL

["Joakim Tjernlund" <Joakim.Tjernlund@transmode.se>]

> -----Original Message-----
> From: linuxppc-dev-bounces+joakim.tjernlund=transmode.se@ozlabs.org [mailto:linuxppc-dev-
> bounces+joakim.tjernlund=transmode.se@ozlabs.org] On Behalf Of Timur Tabi
> Sent: den 16 april 2008 22:58
> To: linuxppc-dev@ozlabs.org
> Subject: lseek() on entries in /proc/device-tree returns EINVAL
> 
> I'm writing a utility that parses the device tree in /proc/device-tree, and in
> order to read a property into memory, I have to first find out how large it is.
>  So I have the following code:
> 
> 	off_t off;
> 	int f;
> 
> 	f = open(filename, O_RDONLY);
> 	if (f == -1) {
> 		perror(__func__);
> 		return NULL;
> 	}
> 
> 	off = lseek(f, 0, SEEK_END);
> 	if (off == -1) {
> 		perror(__func__);
> 		goto fail;
> 	}
> 
> The lseek() call returns -1, and errno is set to EINVAL.  According to the man
> page, this means:
> 
>        EINVAL The  whence  argument  is  not a proper value, or the resulting
>               file offset would be negative for a regular file, block special
>               file, or directory.
> 
> Is there a limitation for the implementation of /proc/device-tree that prevents
> lseek() from working?  If so, how do I determine the size of a property?

Yeah, just reported a similar problem at LKML. busybox start-stop-daemon broke
between 2.6.23 and current tree. The change was intentional but the borkage
was not. Al Viro has been informed, lets see what comes of it.

 Jocke