Now that the changes to the dirname(3) function had some time to settle,
let's go ahead and use the same approach for replacing basename(3) by a
simple implementation that modifies the input string, thereby making it
thread-safe and guaranteed to succeed.
Unlike dirname(3), this function already had a thread-safe variant
basename_r(3). This function had its own set of problems, like having an
upper bound on the pathname length. Keep this function around for
compatibility, but remove most references from the man page. Make the
man page more similar to that of dirname(3).
As the basename_r(3) function is only provided by FreeBSD (and Bionic),
depending on its use is even more implementation defined than assuming
that basename(3) is thread-safe.
Reviewed by: emaste
Differential Revision: https://reviews.freebsd.org/D8382
Update the existing manual pages for basename(3) and dirname(3) to
mention that in future versions of FreeBSD, these functions will no
longer use internal buffers for storing the results.
MFC after: 1 week
Differential Revision: https://reviews.freebsd.org/D7356
POSIX allows these functions to be implemented in a way that the
resulting string is stored in the input buffer. Though some may find
this annoying, this has the advantage that it makes it possible to
implement this function in a thread-safe way. It also means that they
can be implemented in a way that they work for paths of arbitrary
length, as the output string of these functions is never longer than
max(1, len(input)).
Portable code already needs to be written with this in mind, so in my
opinion it makes very little sense to allow the existing behaviour.
Prevent the base system from falling back to this by switching over to
POSIX prototypes.
I'm not going to bump the __FreeBSD_version for this. The reason is that
it's possible to account for this change in a portable way, without
depending on a specific version of FreeBSD. An exp-run was done some
time ago. As far as I know, all regressions as a result of this have
already been fixed.
I'll give this change some time to settle. In the long run I want to
replace our copies by ones that are thread-safe and don't depend on
PATH_MAX/MAXPATHLEN.
