Jan Blunck wrote:
Also, how is lseek + readdir supposed to work in general?
This is how libc is reading directories (at least on arch s390x):
getdents() != 0
lseek() to d_off of last dirent
getdents() != 0
lseek() to d_off of last dirent
getdents() == 0
return
Therefore I really need values that make sense for d_off. Therefore I
really need values that make (some kind of) sense for i_size.
Please be aware that not all filesystems treat directories as sequential
files, filled with with odd sized records. Some directories are distributed
across the entire file system and the d_off fields really contain the
address on disk of the next entry in the directory. The d_off field is
really
just a cookie and is not meant to be interpreted as an offset into the
directory. The lseek() system call is used, but only because that was a
handy way of positioning the pointer into the directory. It is unfortunate
that the getdents(2) system call was not defined with a cookie as one of
its arguments to indicate where to start fetching entries from. This would
have reduced the confusion about treating directories as files or not.
Thanx...
ps
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