When working with FixedMemoryStreams, and especially MappedFiles, you
may don't want to copy the underlying data when you read from the
stream. Pointing into that data is perfectly fine as long as you know
the lifetime of it is long enough.
This commit adds a couple of methods for reading either a single value,
or a span of them, in this way. As noted, for single values you sadly
get a raw pointer instead of a reference, but that's the only option
right now.
These methods are slightly more convenient than storing the Bytes
separately. However, it it feels unsanitary to reach in and access this
data directly. Both of the users of these already have the
[Readonly]Bytes available in their constructors, and can easily avoid
using these methods, so let's remove them entirely.
Due to overload resolutions rules, this simple code provokes a crash:
ReadonlyBytes readonly_bytes{};
FixedMemoryStream stream{readonly_bytes};
ReadonlyBytes give_them_back{stream.bytes()};
// -> Panics on VERIFY(m_writing_enabled);
// but this is fine:
auto bytes = static_cast<FixedMemoryStream const&>(*stream).bytes()
If we need to be explicit about it, let's rename the overload instead of
adding that `static_cast`.
Similar to POSIX read, the basic read and write functions of AK::Stream
do not have a lower limit of how much data they read or write (apart
from "none at all").
Rename the functions to "read some [data]" and "write some [data]" (with
"data" being omitted, since everything here is reading and writing data)
to make them sufficiently distinct from the functions that ensure to
use the entire buffer (which should be the go-to function for most
usages).
No functional changes, just a lot of new FIXMEs.
Similar to the return values earlier, a signed value doesn't really make
sense here. Relying on the much more standard `size_t` makes it easier
to use Stream in all contexts.
This patch adds the `USING_AK_GLOBALLY` macro which is enabled by
default, but can be overridden by build flags.
This is a step towards integrating Jakt and AK types.
Apologies for the enormous commit, but I don't see a way to split this
up nicely. In the vast majority of cases it's a simple change. A few
extra places can use TRY instead of manual error checking though. :^)
On i686, reading integers larger than `2^32 - 1` would fail as the
32-bit `size_t` parameter would overflow. This caused us to read too few
bytes in LibDebug's DWARF parser. Making this method templated solves
this issue, as we now can call this API with a `u64` parameter.
The get_dir_entries syscall failed if the serialized form of all the
directory entries together was too large to fit in its temporary buffer.
Now the kernel uses a fixed size buffer, that is flushed to an output
buffer when it is full. If this flushing operation fails because there
is not enough space available, the syscall will return -EINVAL. That
error code is then used in userspace as a signal to allocate a larger
buffer and retry the syscall.
SPDX License Identifiers are a more compact / standardized
way of representing file license information.
See: https://spdx.dev/resources/use/#identifiers
This was done with the `ambr` search and replace tool.
ambr --no-parent-ignore --key-from-file --rep-from-file key.txt rep.txt *
(...and ASSERT_NOT_REACHED => VERIFY_NOT_REACHED)
Since all of these checks are done in release builds as well,
let's rename them to VERIFY to prevent confusion, as everyone is
used to assertions being compiled out in release.
We can introduce a new ASSERT macro that is specifically for debug
checks, but I'm doing this wholesale conversion first since we've
accumulated thousands of these already, and it's not immediately
obvious which ones are suitable for ASSERT.
This fixes an OOB access when the last read/written chunk is empty (as we _just_
started on a new chunk).
Also adds a test case to TestMemoryStream.
Found via human fuzzing in the shell:
```sh
for $(cat /dev/urandom) {
clear
match $it {
?* as (x) {
echo $x
sleep 1
}
}
}
```
would assert at some point.
OutputMemoryStream was originally a proxy for DuplexMemoryStream that
did not expose any reading API.
Now I need to add another class that is like OutputMemoryStream but only
for static buffers. My first idea was to make OutputMemoryStream do that
too, but I think it's much better to have a distinct class for that.
I originally wanted to call that class FixedOutputMemoryStream but that
name is really cumbersome and it's a bit unintuitive because
InputMemoryStream is already reading from a fixed buffer.
So let's just use DuplexMemoryStream instead of OutputMemoryStream for
any dynamic stuff and create a new OutputMemoryStream for static
buffers.
Consider the following snippet:
void foo(InputStream& stream) {
if(!stream.eof()) {
u8 byte;
stream >> byte;
}
}
There is a very subtle bug in this snippet, for some input streams eof()
might return false even if no more data can be read. In this case an
error flag would be set on the stream.
Until now I've always ensured that this is not the case, but this made
the implementation of eof() unnecessarily complicated.
InputFileStream::eof had to keep a ByteBuffer around just to make this
possible. That meant a ton of unnecessary copies just to get a reliable
eof().
In most cases it isn't actually necessary to have a reliable eof()
implementation.
In most other cases a reliable eof() is avaliable anyways because in
some cases like InputMemoryStream it is very easy to implement.
The streaming operator doesn't short-circuit, consider the following
snippet:
void foo(InputStream& stream) {
int a, b;
stream >> a >> b;
}
If the first read fails, the second is called regardless. It should be
well defined what happens in this case: nothing.
