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.
This was causing some games (most notably Pokemon Quest) to softlock due to an event being fired when not supposed to. This also removes a hack wherein we were firing the state changed event when the game retrieves it, which is incorrect.
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).
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.
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.
This allows the array to be constexpr. std::function is also allowed to
allocate memory, which makes its constructor non-trivial, we definitely
don't want to have all of these execute at runtime, taking up time
before the application can actually load.
While partially correct, this service call allows the retrieved event to
be null, as it also uses the same handle to check if it was referring to
a Process instance. The previous two changes put the necessary machinery
in place to allow for this, so we can simply call those member functions
here and be done with it.
Process instances can be waited upon for state changes. This is also
utilized by svcResetSignal, which will be modified in an upcoming
change. This simply puts all of the WaitObject related machinery in
place.
svcResetSignal relies on the event instance to have already been
signaled before attempting to reset it. If this isn't the case, then an
error code has to be returned.
This function simply does a handle table lookup for a writable event
instance identified by the given handle value. If a writable event
cannot be found for the given handle, then an invalid handle error is
returned. If a writable event is found, then it simply signals the
event, as one would expect.
svcCreateEvent operates by creating both a readable and writable event
and then attempts to add both to the current process' handle table.
If adding either of the events to the handle table fails, then the
relevant error from the handle table is returned.
If adding the readable event after the writable event to the table
fails, then the writable event is removed from the handle table and the
relevant error from the handle table is returned.
Note that since we do not currently test resource limits, we don't check
the resource limit table yet.
Two kernel object should absolutely never have the same handle ID type.
This can cause incorrect behavior when it comes to retrieving object
types from the handle table. In this case it allows converting a
WritableEvent into a ReadableEvent and vice-versa, which is undefined
behavior, since the object types are not the same.
This also corrects ClearEvent() to check both kernel types like the
kernel itself does.
Previously, ILibraryAppletAccessor would signal upon creation of any applet, but this is incorrect. A flag inside of the applet code determines whether or not creation should signal state change and swkbd happens to be one of these applets.
Load() is already given the process instance as a parameter, so instead
of coupling the class to the System class, we can just forward that
parameter to LoadNro()
The kernel uses the handle table of the current process to retrieve the
process that should be used to retrieve certain information. To someone
not familiar with the kernel, this might raise the question of "Ok,
sounds nice, but doesn't this make it impossible to retrieve information
about the current process?".
No, it doesn't, because HandleTable instances in the kernel have the
notion of a "pseudo-handle", where certain values allow the kernel to
lookup objects outside of a given handle table. Currently, there's only
a pseudo-handle for the current process (0xFFFF8001) and a pseudo-handle
for the current thread (0xFFFF8000), so to retrieve the current process,
one would just pass 0xFFFF8001 into svcGetInfo.
The lookup itself in the handle table would be something like:
template <typename T>
T* Lookup(Handle handle) {
if (handle == PSEUDO_HANDLE_CURRENT_PROCESS) {
return CurrentProcess();
}
if (handle == PSUEDO_HANDLE_CURRENT_THREAD) {
return CurrentThread();
}
return static_cast<T*>(&objects[handle]);
}
which, as is shown, allows accessing the current process or current
thread, even if those two objects aren't actually within the HandleTable
instance.
Our implementation of svcGetInfo was slightly incorrect in that we
weren't doing proper error checking everywhere. Instead, reorganize it
to be similar to how the kernel seems to do it.
We can just return a new instance of this when it's requested. This only
ever holds pointers to the existing registed caches, so it's not a large
object. Plus, this also gets rid of the need to keep around a separate
member function just to properly clear out the union.
Gets rid of one of five globals in the filesystem code.
This is the same behavior-wise as DeleteDirectoryRecursively, with the
only difference being that it doesn't delete the top level directory in
the hierarchy, so given:
root_dir/
- some_dir/
- File.txt
- OtherFile.txt
The end result is just:
root_dir/
More hardware accurate. On the actual system, there is a differentiation between the signaler and signalee, they form a client/server relationship much like ServerPort and ClientPort.
These parameters don't need to utilize a shared lifecycle directly in
the interface. Instead, the caller should provide a regular reference
for the function to use. This also allows the type system to flag
attempts to pass nullptr and makes it more generic, since it can now be
used in contexts where a shared_ptr isn't being used (in other words, we
don't constrain the usage of the interface to a particular mode of
memory management).
While we're at it, organize the array linearly, since clang formats the
array elements quite wide length-wise with the addition of the missing
'u'.
Technically also fixes patch lookup and icon lookup with Portuguese,
though I doubt anyone has actually run into this issue.
The opposite of the getter functions, this function sets the limit value
for a particular ResourceLimit resource category, with the restriction
that the new limit value must be equal to or greater than the current
resource value. If this is violated, then ERR_INVALID_STATE is returned.
e.g.
Assume:
current[Events] = 10;
limit[Events] = 20;
a call to this service function lowering the limit value to 10 would be
fine, however, attempting to lower it to 9 in this case would cause an
invalid state error.
This kernel service function is essentially the exact same as
svcGetResourceLimitLimitValue(), with the only difference being that it
retrieves the current value for a given resource category using the
provided resource limit handle, rather than retrieving the limiting
value of that resource limit instance.
Given these are exactly the same and only differ on returned values, we
can extract the existing code for svcGetResourceLimitLimitValue() to
handle both values.
This kernel service function retrieves the maximum allowable value for
a provided resource category for a given resource limit instance. Given
we already have the functionality added to the resource limit instance
itself, it's sufficient to just hook it up.
The error scenarios for this are:
1. If an invalid resource category type is provided, then ERR_INVALID_ENUM is returned.
2. If an invalid handle is provided, then ERR_INVALID_HANDLE is returned (bad thing goes in, bad thing goes out, as one would expect).
If neither of the above error cases occur, then the out parameter is
provided with the maximum limit value for the given category and success
is returned.
This function simply creates a ResourceLimit instance and attempts to
create a handle for it within the current process' handle table. If the
kernal fails to either create the ResourceLimit instance or create a
handle for the ResourceLimit instance, it returns a failure code
(OUT_OF_RESOURCE, and HANDLE_TABLE_FULL respectively). Finally, it exits
by providing the output parameter with the handle value for the
ResourceLimit instance and returning that it was successful.
Note: We do not return OUT_OF_RESOURCE because, if yuzu runs out of
available memory, then new will currently throw. We *could* allocate the
kernel instance with std::nothrow, however this would be inconsistent
with how all other kernel objects are currently allocated.
Avoids the need to create a copy of the std::string instance
(potentially allocating).
The only reason RegisterService takes its argument by value is because
it's std::moved internally.
Keeps the CPU-specific behavior from being spread throughout the main
System class. This will also act as the home to contain member functions
that perform operations on all cores. The reason for this being that the
following pattern is sort of prevalent throughout sections of the
codebase:
If clearing the instruction cache for all 4 cores is necessary:
Core::System::GetInstance().ArmInterface(0).ClearInstructionCache();
Core::System::GetInstance().ArmInterface(1).ClearInstructionCache();
Core::System::GetInstance().ArmInterface(2).ClearInstructionCache();
Core::System::GetInstance().ArmInterface(3).ClearInstructionCache();
This is kind of... well, silly to copy around whenever it's needed.
especially when it can be reduced down to a single line.
This change also puts the basics in place to begin "ungrafting" all of the
forwarding member functions from the System class that are used to
access CPU state or invoke CPU-specific behavior. As such, this change
itself makes no changes to the direct external interface of System. This
will be covered by another changeset.
The interface for shared memory was changed, but another commit was
merged that relied on the (previously public) internals of SharedMemory.
This amends that discrepancy.
The decision was made to name them LayeredExeFS instead of just LayeredFS to differentiate from normal RomFS-based mods. The name may be long/unweildy, but conveys the meaning well.
This will scan the <mod>/exefs dir for all files and then layer those on top of the game's exefs and use this as the new exefs. This allows for overriding of the compressed NSOs or adding new files. This does use the same dir as IPS/IPSwitch patch, but since the loader will not look for those they are ignored.
<random> isn't necesary directly within the header and can be placed in
the cpp file where its needed. Avoids propagating random generation
utilities via a header file.
Cleans out the citra/3DS-specific implementation details that don't
apply to the Switch. Sets the stage for implementing ResourceLimit
instances properly.
While we're at it, remove the erroneous checks within CreateThread() and
SetThreadPriority(). While these are indeed checked in some capacity,
they are not checked via a ResourceLimit instance.
In the process of moving out Citra-specifics, this also replaces the
system ResourceLimit instance's values with ones from the Switch.
This service function was likely intended to be a way to redirect where
the output of a log went. e.g. Firing a log over a network, dumping over
a tunneling session, etc.
Given we always want to see the log and not change its output. It's one
of the lucky service functions where the easiest implementation is to
just do nothing at all and return success.
Both member functions assume the passed in target process will not be
null. Instead of making this assumption implicit, we can change the
functions to be references and enforce this at the type-system level.
Makes the interface nicer to use in terms of 64-bit code, as it makes it
less likely for one to get truncation warnings (and also makes sense in
the context of the rest of the interface where 64-bit types are used for
sizes and offsets
The separate enum isn't particularly necessary here, and the values can
just be directly put into the ResultCode instances, given the names are
also self-documenting here.
Used by developers to test games, not present on retail systems. Some games are known to respond to DebugPad input though, for example Kirby Star Allies.
Default implementation will return "yuzu" for any string. GUI clients (or CLI) can implement the Frontend::SoftwareKeyboardApplet class and register an instance to provide functionality.
Similar to PR 1706, which cleans up the error codes for the filesystem
code, but done for the kernel error codes. This removes the ErrCodes
namespace and specifies the errors directly. This also fixes up any
straggling lines of code that weren't using the named error codes where
applicable.
It seems palma is done through bluetooth, we need this for pokemon go however more research needs to be done when we actually get palma working. This is presumably used for transfering data between the controller and the console, it does not seem for actual input as far as I know.
There's no real point to keeping the separate enum around, especially
given the name of the error code itself is supposed to document what the
value actually represents.
empty() in this case will always return false, since the returned
container is a std::array. Instead, check if all given users are invalid
before returning the error code.
The previous expression would copy sizeof(size_t) amount of bytes (8 on
a 64-bit platform) rather than the full 10 bytes comprising the uuid
member.
Given the source and destination types are the same, we can just use an
assignment here instead.
When yuzu is compiled in release mode this function is unused, however,
when compiled in debug mode, it's used within a LOG_TRACE statement.
This prevents erroneous compilation warnings about an unused function
(that isn't actually totally unused).
* svcBreak now dumps information from the debug buffer passed
info1 and info2 seem to somtimes hold an address to a buffer, this is usually 4 bytes or the size of the int and contains an error code. There's other circumstances where it can be something different so we hexdump these to examine them at a later date.
* Addressed comments
Started implementation of the AM message queue mainly used in state getters. Added the ability to switch docked mode whilst in game without stopping emulation. Also removed some things which shouldn't be labelled as stubs as they're implemented correctly
These are needed by Edizon to boot. They are used to see if a user is using SX OS, as SX OS registers a custom service called 'tx' and attempting to register a service of the same name lets the application know if it is present.
Allows resuing a common KeyManager when a large amount of NCAs are handled by the same class. Should the parameter not be provided, a new KeyManager will be constructed, as was the default behavior prior to this.
Previously, we would let a user enter an unbounded name and then
silently truncate away characters that went over the 32-character limit.
This is kind of bad from the UX point of view, because we're essentially
not doing what the user intended in certain scenarios.
Instead, we clamp it to 32 characters and make that visually apparent in
the dialog box to provide a name for a user.
* get rid of boost::optional
* Remove optional references
* Use std::reference_wrapper for optional references
* Fix clang format
* Fix clang format part 2
* Adressed feedback
* Fix clang format and MacOS build
Returns the raw NACP bytes and the raw icon bytes into a title-provided buffer. Pulls from Registration Cache for control data, returning all zeros should it not exist.
When enabled in settings, PatchNSO will dump the unmodified NSO that it was passed to a file named <build id>.nso in the dump root for the current title ID.
Also adds UI option in Debug > Dump section, with the idea later things to be dumped (i.e. other game data or textures, etc) will use the same group box.
An object to read SaveDataInfo objects, which describe a unique save on the system. This implementation iterates through all the directories in the save data space and uses the paths to reconstruct the metadata.
Many of the Current<Thing> getters (as well as a few others) were
missing const qualified variants, which makes it a pain to retrieve
certain things from const qualified references to System.
This is just flat data, so it doesn't really need to be in the function
itself. This also allows deduplicating the constant for the backup size
in GetImageSize().
Now that we've gotten the innaccurate error codes out of the way, we can
finally toss away a bunch of these, trimming down the error codes to
ones that are actually used and knocking out two TODO comments.
All priority checks are supposed to occur before checking the validity
of the thread handle, we're also not supposed to return
ERR_NOT_AUTHORIZED here.
We can just call the function instead of duplicating the code here. This
also prevents an unused function warning.
We also don't need to take the lambda capture by reference. It's just a
u64 value, so by value is fine here.
* Fixed conflict with nfp
* Few fixups for nfc
* Conflict 2
* Fixed AttachAvailabilityChangeEvent
* Conflict 3
* Fixed byte padding
* Refactored amiibo to not reside in "System"
* Removed remaining references of nfc from system
* used enum for Nfc GetStateOld
* Added missing newline
* Moved file operations to front end
* Conflict 4
* Amiibos now use structs and added mutexes
* Removed amiibo_path
In the kernel, there isn't a singular handle table that everything gets
tossed into or used, rather, each process gets its own handle table that
it uses. This currently isn't an issue for us, since we only execute one
process at the moment, but we may as well get this out of the way so
it's not a headache later on.
This should be comparing against the queried process' vma_map, not the
current process'. The only reason this hasn't become an issue yet is we
currently only handle one process being active at any time.
This is a subset of the better-hid-2 changes, this fixes input in various games which don't support dual joycons. This pr will search for the next best controller which is supported by the current game
This event signals the game when new DLC is purchased from the eShop while the game is running. Since, for the forseeable future, yuzu will not have this ability, it seems safe to stub with a dummy event that will never fire. This is needed to boot Sonic Mania Plus (update v1.04).
When writing VFS, it initally seemed useful to include a function to in-place convert container files into directories in one homogenous directory structure, but re-evaluating it now there have been plenty of chances to use it and there has always been a better way. Removing as it is unused and likely will not be used.
Now that the changes clarifying the address spaces has been merged, we
can wrap the checks that the kernel performs when mapping shared memory
(and other forms of memory) into its own helper function and then use
those within MapSharedMemory and UnmapSharedMemory to complete the
sanitizing checks that are supposed to be done.
swap.h only needs to be present in the header for the type aliases and
definitions, it's not actually needed in the cpp files though. input.h
is just unused entirely in xpad.h
These classes are non-trivial and are definitely going to be changed in
the future, so we default these to prevent issues with forward
declarations, and to keep the compiler from inlining tear-down code.
The constructor alone is pretty large, the reading code should be split
into its consistuent parts to make it easier to understand it without
having to build a mental model of a 300+ line function.
The only reason the getter existed was to check whether or not the
program NCA was null. Instead, we can just provide a function to query
for the existence of it, instead of exposing it entirely.
The data retrieved in these cases are ultimately chiefly owned by either
the RegisteredCache instance itself, or the filesystem factories. Both
these should live throughout the use of their contained data. If they
don't, it should be considered an interface/design issue, and using
shared_ptr instances here would mask that, as the data would always be
prolonged after the main owner's lifetime ended.
This makes the lifetime of the data explicit and makes it harder to
accidentally create cyclic references. It also makes the interface
slightly more flexible than the previous API, as a shared_ptr can be
created from a unique_ptr, but not the other way around, so this allows
for that use-case if it ever becomes necessary in some form.
There's no need for shared ownership here, as the only owning class
instance of those Cpu instances is the System class itself. We can also
make the thread_to_cpu map use regular pointers instead of shared_ptrs,
given that the Cpu instances will always outlive the cases where they're
used with that map.
Like the barrier, this is owned entirely by the System and will always
outlive the encompassing state, so shared ownership semantics aren't
necessary here.
This will always outlive the Cpu instances, since it's destroyed after
we destroy the Cpu instances on shutdown, so there's no need for shared
ownership semantics here.
This function doesn't need to care about ownership semantics, so we can
just pass it a reference to the file itself, rather than a
std::shared_ptr alias.
So, one thing that's puzzled me is why the kernel seemed to *not* use
the direct code address ranges in some cases for some service functions.
For example, in svcMapMemory, the full address space width is compared
against for validity, but for svcMapSharedMemory, it compares against
0xFFE00000, 0xFF8000000, and 0x7FF8000000 as upper bounds, and uses
either 0x200000 or 0x8000000 as the lower-bounds as the beginning of the
compared range. Coincidentally, these exact same values are also used in
svcGetInfo, and also when initializing the user address space, so this
is actually retrieving the ASLR extents, not the extents of the address
space in general.
This should help diagnose crashes easier and prevent many users thinking that a game is still running when in fact it's just an audio thread still running(this is typically not killed when svcBreak is hit since the game expects us to do this)
A fairly basic service function, which only appears to currently support
retrieving the process state. This also alters the ProcessStatus enum to
contain all of the values that a kernel process seems to be able of
reporting with regards to state.
Neither of these functions alter the ownership of the provided pointer,
so we can simply make the parameters a reference rather than a direct
shared pointer alias. This way we also disallow passing incorrect memory values like
nullptr.
We can just reserve the memory then perform successive insertions
instead of needing to use memcpy. This also avoids the need to zero out
the output vector's memory before performing the insertions.
We can also std::move the output std::vector into the destination so
that we don't need to make a completely new copy of the vector, getting
rid of an unnecessary allocation.
Additionally, we can use iterators to determine the beginning and end
ranges of the std::vector instances that comprise the output vector, as
the end of one range just becomes the beginning for the next successive
range, and since std::vector's iterator constructor copies data within
the range [begin, end), this is more straightforward and gets rid of the
need to have an offset variable that keeps getting incremented to
determine where to do the next std::memcpy.
Given it's only used in one spot and has a fairly generic name, we can
just specify it directly in the function call. This also the benefit of
automatically moving it.
Instead, we can make it part of the type and make named variables for
them, so they only require one definition (and if they ever change for
whatever reason, they only need to be changed in one spot).
Given the VirtualFile instance isn't stored into the class as a data
member, or written to, this can just be turned into a const reference,
as the constructor doesn't need to make a copy of it.
If the data is unconditionally being appended to the back of a
std::vector, we can just directly insert it there without the need to
insert all of the elements one-by-one with a std::back_inserter.
Given the filesystem should always be assumed to be volatile, we should
check and bail out if a seek operation isn't successful. This'll prevent
potentially writing/returning garbage data from the function in rare
cases.
This also allows removing a check to see if an offset is within the
bounds of a file before perfoming a seek operation. If a seek is
attempted beyond the end of a file, it will fail, so this essentially
combines two checks into one in one place.
Given the file is opened a few lines above and no operations are done,
other than check if the file is in a valid state, the read/write pointer
will always be at the beginning of the file.
These only exist to ferry data into a Process instance and end up going
out of scope quite early. Because of this, we can just make it a plain
struct for holding things and just std::move it into the relevant
function. There's no need to make this inherit from the kernel's Object
type.
Regular value initialization is adequate here for zeroing out data. It
also has the benefit of not invoking undefined behavior if a non-trivial
type is ever added to the struct for whatever reason.
Now that all external dependencies are hidden, we can remove
json-headers from the publically linked libraries, as the use of this
library is now completely hidden from external users of the web_service
library. We can also make the web_services library private as well,
considering it's not a requirement. If a library needs to link in
web_service, it should be done explicitly -- not via indirect linking.
This adds the missing address range checking that the service functions
do before attempting to map or unmap memory. Given that both service
functions perform the same set of checks in the same order, we can wrap
these into a function and just call it from both functions, which
deduplicates a little bit of code.
HandheldVariant is for specific games which expect handheld controllers to be at position 8(kirby), however this doesn't fix all games as some games require handhelds to be at position 0(snipperclips)
There's no real need to use a shared pointer in these cases, and only
makes object management more fragile in terms of how easy it would be to
introduce cycles. Instead, just do the simple thing of using a regular
pointer. Much of this is just a hold-over from citra anyways.
It also doesn't make sense from a behavioral point of view for a
process' thread to prolong the lifetime of the process itself (the
process is supposed to own the thread, not the other way around).
We don't need to potentially heap-allocate a std::string instance here,
given the data is known ahead of time. We can just place it within an
array and pass this to the mbedtls functions.
Neither of these functions require the use of shared ownership of the
returned pointer. This makes it more difficult to create reference
cycles with, and makes the interface more generic, as std::shared_ptr
instances can be created from a std::unique_ptr, but the vice-versa
isn't possible. This also alters relevant functions to take NCA
arguments by const reference rather than a const reference to a
std::shared_ptr. These functions don't alter the ownership of the memory
used by the NCA instance, so we can make the interface more generic by
not assuming anything about the type of smart pointer the NCA is
contained within and make it the caller's responsibility to ensure the
supplied NCA is valid.
We can just compare the existing std::vector instance with a constexpr
std::array containing the desired match. This is lighter resource-wise,
as we don't need to allocate on the heap.
Adds missing includes to prevent potential compilation issues in the
future. Also moves the definition of a struct into the cpp file, so that
some includes don't need to be introduced within the header.
When loading NROs, svcBreak is called to signal to the debugger that a new "module" is loaded. As no debugger is technically attached we shouldn't be killing the programs execution.
Hardware tests show that trying to unmap an unmapped buffer already should always succeed. Hardware test was tested up to 32 iterations of attempting to unmap
This was the result of a typo accidentally introduced in
e51d715700. This restores the previous
correct behavior.
The behavior with the reference was incorrect and would cause some games
to fail to boot.
Conceptually, it doesn't make sense for a thread to be able to persist
the lifetime of a scheduler. A scheduler should be taking care of the
threads; the threads should not be taking care of the scheduler.
If the threads outlive the scheduler (or we simply don't actually
terminate/shutdown the threads), then it should be considered a bug
that we need to fix.
Attributing this to balika011, as they opened #1317 to attempt to fix
this in a similar way, but my refactoring of the kernel code caused
quite a few conflicts.
Specifically bugs/crashes that arise when putting them in positions that are legal but not typical, such as midline, between patch data, or between patch records.
Many of the member variables of the thread class aren't even used
outside of the class itself, so there's no need to make those variables
public. This change follows in the steps of the previous changes that
made other kernel types' members private.
The main motivation behind this is that the Thread class will likely
change in the future as emulation becomes more accurate, and letting
random bits of the emulator access data members of the Thread class
directly makes it a pain to shuffle around and/or modify internals.
Having all data members public like this also makes it difficult to
reason about certain bits of behavior without first verifying what parts
of the core actually use them.
Everything being public also generally follows the tendency for changes
to be introduced in completely different translation units that would
otherwise be better introduced as an addition to the Thread class'
public interface.
GetName() returns a std::string by value, not by reference, so after the
std::string_view is constructed, it's not well defined to actually
execute any member functions of std::string_view that attempt to access
the data, as the std::string has already been destroyed. Instead, we can
just use a std::string and erase the last four characters.
When searching for a file extension, it's generally preferable to begin
the search at the end of the string rather than the beginning, as the
whole string isn't going to be walked just to check for something at the
end of it.
If an error occurs when constructing the PartitionFilesystem instance,
the constructor would be exited early, which wouldn't initialize the
extracted data member, making it possible for other code to perform an
uninitialized read by calling the public IsExtractedType() member
function. This prevents that.
Like the other two bits of factored out code, this can also be put
within its own function. We can also modify the code so that it accepts
a const reference to a std::vector of files, this way, we can
deduplicate the file retrieval.
Now the constructor for NSP isn't a combination of multiple behaviors in
one spot. It's nice and separate.
This too, is completely separate behavior from what is in the
constructor, so we can move this to its own isolated function to keep
everything self-contained.
