In the previous change, the memory writing was moved into the service
function itself, however it still had a problem, in that the entire
MemoryInfo structure wasn't being written out, only the first 32 bytes
of it were being written out. We still need to write out the trailing
two reference count members and zero out the padding bits.
Not doing this can result in wrong behavior in userland code in the following
scenario:
MemoryInfo info; // Put on the stack, not quaranteed to be zeroed out.
svcQueryMemory(&info, ...);
if (info.device_refcount == ...) // Whoops, uninitialized read.
This can also cause the wrong thing to happen if the user code uses
std::memcmp to compare the struct, with another one (questionable, but
allowed), as the padding bits are not guaranteed to be a deterministic
value. Note that the kernel itself also fully zeroes out the structure
before writing it out including the padding bits.
Moves the memory writes directly into QueryProcessMemory instead of
letting the wrapper function do it. It would be inaccurate to allow the
handler to do it because there's cases where memory shouldn't even be
written to. For example, if the given process handle is invalid.
HOWEVER, if the memory writing is within the wrapper, then we have no
control over if these memory writes occur, meaning in an error case, 68
bytes of memory randomly get trashed with zeroes, 64 of those being
written to wherever the memory info address points to, and the remaining
4 being written wherever the page info address points to.
One solution in this case would be to just conditionally check within
the handler itself, but this is kind of smelly, given the handler
shouldn't be performing conditional behavior itself, it's a behavior of
the managed function. In other words, if you remove the handler from the
equation entirely, does the function still retain its proper behavior?
In this case, no.
Now, we don't potentially trash memory from this function if an invalid
query is performed.
The kernel returns a memory info instance with the base address set to
the end of the address space, and the size of said block as
0 - address_space_end, it doesn't set both of said members to zero.
Gets the two structures out of an unrelated header and places them with
the rest of the memory management code.
This also corrects the structures. PageInfo appears to only contain a
32-bit flags member, and the extra padding word in MemoryInfo isn't
necessary.
Amends the MemoryState enum to use the same values like the actual
kernel does. Also provides the necessary operators to operate on them.
This will be necessary in the future for implementing
svcSetMemoryAttribute, as memory block state is checked before applying
the attribute.
Based off RE, the backing code only ever seems to use 0-2 as the range
of values 1 being a generic log enable, with 2 indicating logging should
go to the SD card. These are used as a set of flags internally.
Given we only care about receiving the log in general, we can just
always signify that we want logging in general.
Amends it with missing values deduced from RE (ProperSystem being from
SwitchBrew for naming)
(SdCardUser wasn't that difficult to discern given it's used alongside
SdCardSystem when creating the save data indexer, based off the usage of
the string "saveDataIxrDbSd" nearby).
Original reason:
As Windows multi-byte character codec is unspecified while we always assume std::string uses UTF-8 in our code base, this can output gibberish when the string contains non-ASCII characters. ::OutputDebugStringW combined with Common::UTF8ToUTF16W is preferred here.
This was only ever public so that code could check whether or not a
handle was valid or not. Instead of exposing the object directly and
allowing external code to potentially mess with the map contents, we
just provide a member function that allows checking whether or not a
handle is valid.
This makes all member variables of the VMManager class private except
for the page table.
These auto-deduce the result based off its arguments, so there's no need
to do that work for the compiler, plus, the function return value itself
already indicates what we're returning.
Similarly, here we can avoid doing unnecessary work twice by retrieving
the file type only once and comparing it against relevant operands,
avoiding potential unnecessary object construction/destruction.
While GetFileType() is indeed a getter function, that doesn't mean it's
a trivial function, given some case require reading from the data or
constructing other objects in the background. Instead, only do necessary
work once.
No implementations actually modify instance state (and it would be
questionable to do that in the first place given the name), so we can
make this a const member function.
Lioncash