ByteBuffer previously had a flag that determined whether it owned the
bytes inside it or not (m_owned.) Owned ByteBuffers would free() on
destruction and non-owned ones would not.
This was a huge source of confusion and made it hard to reason about
lifetimes since there were no compile-time clues about whether a buffer
was owned or non-owned.
The adopt mode was used at some point to take over ownership of a
random malloc'ed buffer, but nothing was using it so this patch removes
that as well.
When a process crashes, we generate a coredump file and write it in
/tmp/coredumps/.
The coredump file is an ELF file of type ET_CORE.
It contains a segment for every userspace memory region of the process,
and an additional PT_NOTE segment that contains the registers state for
each thread, and a additional data about memory regions
(e.g their name).
Thankfully, this hasn't happened in any other code yet, but it happened
while I was trying something out. Using '==' on two ByteBuffers to check
whether they're equal seemed straight-forward, so I ran into the trap.
I originally defined the bytes() method for the String class, because it
made it obvious that it's a span of bytes instead of span of characters.
This commit makes this more consistent by defining a bytes() method when
the type of the span is known to be u8.
Additionaly, the cast operator to Bytes is overloaded for ByteBuffer and
such.
This function did a const_cast internally which made the call side look
"safe". This method is removed completely and call sites are replaced
with ByteBuffer::wrap(const_cast<void*>(data), size) which makes the
behaviour obvious.
Prior to this, we wrote to the log every time the << operator
was used, which meant that only these parts of the log statement
were serialized. If the thread was preempted, or especially with
multiple CPUs the debug output was hard to decipher. Instead, we
buffer up the log statements. To avoid allocations we'll attempt
to use stack space, which covers most log statements.
Since ByteBuffer is a Buffer, it should allow us to overwrite parts of
it that we have allocated.
This comes in useful in handling unsequenced writes like handling
fragmented ip packets :^)
We can use __builtin_memset() without including <string.h>.
This is pretty neat, as it will allow us to reduce the header deps
of AK templates a bit, if applied consistently.
Note that this is an enabling change for an upcoming #include removal.
As suggested by Joshua, this commit adds the 2-clause BSD license as a
comment block to the top of every source file.
For the first pass, I've just added myself for simplicity. I encourage
everyone to add themselves as copyright holders of any file they've
added or modified in some significant way. If I've added myself in
error somewhere, feel free to replace it with the appropriate copyright
holder instead.
Going forward, all new source files should include a license header.
So we already have ByteBuffer::wrap() which is like a StringView for random
data. This might not be the best abstraction actually, but this will be
immediately useful so let's add it.
Also run it across the whole tree to get everything using the One True Style.
We don't yet run this in an automated fashion as it's a little slow, but
there is a snippet to do so in makeall.sh.
This way you can spam small write()s on a file without the kernel writing
to disk every single time. Flushes are included in the FS::sync() operation
and will get triggered regularly by syncd. :^)
I also added a generator cache to FileHandle. This way, multiple
reads to a generated file (i.e in a synthfs) can transparently
handle multiple calls to read() without the contents changing
between calls.
The cache is discarded at EOF (or when the FileHandle is destroyed.)
