[PATCH] Fix readdir_r with long file names

[Florian Weimer]

On 03/01/2016 09:14 PM, Michael Kerrisk (man-pages) wrote:

> What happens with readdir() when it gets a filename that is larger 
> than 255 characters?

Good question.  Ugh.

readdir will return a pointer to a struct dirent whose d_name member
will not be null-terminated, but the memory following the struct dirent
object will contain the rest of the name, and will eventually be
null-terminated.

This will work perfectly fine if you don't copy struct dirent objects
using memcpy, and the compiler does not optimize things too much.  We
should implement compiler support for this wart: inhibit optimizations
(I think there are already special cases for length-0 and length-1
arrays at the end, so it's not totally without precedent), and warn
about sizeof (struct dirent) and using it as a (non-pointer) declarator.
 The second part is likely generally useful for structs whose size is
not intended to be part of the ABI.

Florian