After a short correspondence with Otto Moerbeek it turned out
mallocarray() is only in the OpenBSD-Kernel, because the kernel-
malloc doesn't have realloc.
Userspace applications should rather use reallocarray with an
explicit NULL-pointer.
Assuming reallocarray() will become available in c-stdlibs in the
next few years, we nip mallocarray() in the bud to allow an easy
transition to a system-provided version when the day comes.
A function used only in the OpenBSD-Kernel as of now, but it surely
provides a helpful interface when you just don't want to make sure
the incoming pointer to erealloc() is really NULL so it behaves
like malloc, making it a bit more safer.
Talking about *allocarray(): It's definitely a major step in code-
hardening. Especially as a system administrator, you should be
able to trust your core tools without having to worry about segfaults
like this, which can easily lead to privilege escalation.
How do the GNU coreutils handle this?
$ strings -n 4611686018427387903
strings: invalid minimum string length -1
$ strings -n 4611686018427387904
strings: invalid minimum string length 0
They silently overflow...
In comparison, sbase:
$ strings -n 4611686018427387903
mallocarray: out of memory
$ strings -n 4611686018427387904
mallocarray: out of memory
The first out of memory is actually a true OOM returned by malloc,
whereas the second one is a detected overflow, which is not marked
in a special way.
Now tell me which diagnostic error-messages are easier to understand.
Stateless and I stumbled upon this issue while discussing the
semantics of read, accepting a size_t but only being able to return
ssize_t, effectively lacking the ability to report successful
reads > SSIZE_MAX.
The discussion went along and we came to the topic of input-based
memory allocations. Basically, it was possible for the argument
to a memory-allocation-function to overflow, leading to a segfault
later.
The OpenBSD-guys came up with the ingenious reallocarray-function,
and I implemented it as ereallocarray, which automatically returns
on error.
Read more about it here[0].
A simple testcase is this (courtesy to stateless):
$ sbase-strings -n (2^(32|64) / 4)
This will segfault before this patch and properly return an OOM-
situation afterwards (thanks to the overflow-check in reallocarray).
[0]: http://www.openbsd.org/cgi-bin/man.cgi/OpenBSD-current/man3/calloc.3
Be stricter while resolving escapes in the delimiter-string and
error out when it has length 0 or contains an invalid escape.
Thanks to Hiltjo Posthuma's sharp eagle eyes this bug was spotted.
Having multibyte delimiters is not enough. For full flexibility,
the possiblity of cutting input lines with arbitrary length delimiters
is the real deal.
Given this functionality, it only sounds reasonable to also add support
to resolve escapes.
Thanks to Truls Becken for making the suggestion and designing such a
flexible cut(1)-implementation!
Now you can specify a multibyte-delimiter to cut, which should
definitely be possible for the end-user (Fuck POSIX).
Looking at GNU/coreutils' cut(1)[0], which basically ignores the difference
between characters and bytes, the -n-option and which is bloated as hell,
one has to wonder why they are still default. This is insane!
Things like this personally keep me motivated to make sbase better
every day.
[0]: http://git.savannah.gnu.org/gitweb/?p=coreutils.git;a=blob;f=src/cut.c;hb=HEAD
NSFW! You have been warned.
There's no point free-ing memory when the kernel can do it for us.
Just reuse the already allocated memory to hold lines.
Thanks Truls Becken for pointing this out.
It actually makes the binaries smaller, the code easier to read
(gems like "val == true", "val == false" are gone) and actually
predictable in the sense of that we actually know what we're
working with (one bitwise operator was quite adventurous and
should now be fixed).
This is also more consistent with the other suckless projects
around which don't use boolean types.
FRIGN
Truls Becken
sin
Evan Gates
Hiltjo Posthuma