This one sucks. I found out when running tests that we exploit some edge
case behaviour in our tests where passing an invalid value to an xpidl
array parameter will be passed as an empty array...
I figured that just respecting this behaviour for now is the easiest
approach, but we will probably want to fix it in the future.
Current XPIDL native arrays currently also require a custom entry point. With
the new arraylen parameter we can handle them in JSData2Native/NativeData2JS. As
these methods are more complex and don't share logic with an existing codepath,
I keep them in external helper methods.
XPIDL supports explicitly sized string types. These types currently have to be
handled by a separate entry point into XPCConvert, and don't share any logic
with the implicitly sized string types.
If we just add an array length parameter to the basic JSData2Native and
NativeData2JS methods we can handle them in the same place as every other type.
This also allows us to share a lot of code with non-sized string types, which is
nice :-).
Currently XPCVariant has some code for working with arrays of a series of basic
types. I want to unify and simplify code which works with nsXPTTypes to always
take the topmost level type (rather than passing in an array element type when
working with an array).
This is pretty easy for most of XPConnect, but XPCVariant occasionally needs to
perform calls on made-up array types, which isn't compatible with the current
implementation. Fortunately, it only needs a very small set of array types. This
patch adds a set of simple types (mostly the arithmetic types and
TD_INTERFACE_IS_TYPE for interfaces) to the extra types array unconditionally
with a known index, for XPCVariant.
An other option I was considering was to consider the value `0xff` in the data
byte on nsXPTType to be a flag which indicates that the array element type is
actually the type immediately following the current nsXPTType object in memory,
but that was incompatible with many of the existing nsXPTType consumers which
copy the nsXPTType objects around (e.g. onto the stack), rather than always
using them by reference, so I decided it was not a good approach to take.
When a jsval passed from JS code it needs to be stored in a nsXPTCVariant
object. This object is not rooted by default, as it is stored in some
C++-allocated memory. Currently, we root the values by adding a custom root
using the `js::AddRawValueRoot` API, which is deprecated, and only used by this
code and ErrorResult.
This also has the unfortunate effect that we cannot support XPCOM arrays of
jsvals, as we cannot root all of the values in the array using this API.
Fortunately, the JS engine has a better rooting API which we can use here
instead. I make the call context a custom rooter, like the SequenceRooter type
from WebIDL, and make sure to note every jsval when tracing, both in arrays and
as direct values.
This should allow us to avoid some hashtable operations with roots when
performing XPConnect calls, and remove a consumer of this gross legacy API.
In addition it allows us to support arrays. This will be even more useful in the
future when I add support for sequence<T> (which is a nsTArray<T>) to xpidl and
xpconnect.
In XPConnect, native values are passed around within nsXPTCMiniVariant objects.
an [nsXPTCMiniVariant] contains 64-bits of data in a union type.
nsXPTCMiniVariant values are created by the platform-specific glue code and
passed into XPConnect proper when calling from C++ into JS.
When calling from JS into C++, we instead create nsXPTCVariant objects and pass
them into the glue code. These objects have extra information in addition to the
nsXPTCMiniVariant: namely they also have a `type` field with the type stored in
the variant, space for flags, and a `ptr` field which is passed over IPC instead
of the inner nsXPTCMiniVariant when a flag (`PTR_IS_DATA`) is set.
The JSValue type in XPConnect is always passed as a pointer to a JSValue object,
both for in parameters and out parameters. This is handled by making the JSValue
type be unconditionally flagged as [`IsIndirect()`] This flag is also used for
all types of outparameters.
When the `IsIndirect()` flag is set, it means that the actual data is stored in
the nsXPTCVariant's val field, and it sets the flag to tell the glue code to
instead pass the `ptr` field (which is always pointing to the `val` field for
[legacy reasons]) into the C++ code.
In contrast "dipper" is a different and super weird flag. Currently only the
string class types (nsACString & nsAString) are marked as "dipper". A "dipper"
type is always passed as an "in" type (and thus always passed "directly"), even
when it's actually an out parameter.
XPConnect treats these types as though they are pointer types (nsAString*). This
means that there is no space in the nsXPTCVariant to store the actual nsAString
types when passing from JS into C++, so these values have to be allocated by a
different mechanism (in the current code, there is a size 2 buffer for each
string type in the context and once that buffer is exceeded, we heap allocate
the nsString values).
In effect, the current state looks something like this:
+------------+---------------------+---------------------+
| type | out (xpt/native) | in (xpt/native) |
+------------+---------------------+---------------------+
| TD_INT32 | indirect (int32_t*) | direct (int32_t) |
+------------+---------------------+---------------------+
| TD_JSVAL | indirect (JSValue*) | indirect (JSValue*) |
+------------+---------------------+---------------------+
| TD_ASTRING | direct (nsAString*) | direct (nsAString*) |
+------------+---------------------+---------------------+
This patch ensures there is enough space in the nsXPTCVariant to fit the
nsString value, and switches string class types to being unconditionally
indirect instead of using the dipper system. This allows us to delete a ton of
dipper-specific code, and unify the indirect and string class codepaths.
This only affects the size of nsXPTCVariant objects, and does not affect
nsXPTCMiniVariant objects. nsXPTCVariant objects are never allocated by the
platform-specific binding code, rather, they are allocated in an AutoTArray on
the stack as part of the CallMethodHelper object.
The size increase is a total of 1 word, so 4 bytes in 32-bit builds, and 8 bytes
in 64-bit builds, which is ignorable for stack allocated objects.
[nsXPTCMiniVariant]: https://searchfox.org/mozilla-central/rev/eb6c5214a63e20a3fff455e92c876287a8d2e188/xpcom/reflect/xptcall/xptcall.h#20-47
[`IsIndirect()`]: https://searchfox.org/mozilla-central/rev/c0d81882c7941c4ff13a50603e37095cdab0d1ea/xpcom/reflect/xptinfo/xptinfo.h#371
[legacy reasons]: https://searchfox.org/mozilla-central/rev/eb6c5214a63e20a3fff455e92c876287a8d2e188/xpcom/reflect/xptcall/xptcall.h#66-79
We are going to want to include some "gecko internal" types in more places in
the codebase, and we have unused includes of some of these headers in non-libxul
files.
This patch just cleans up these unnecssary includes.
It used to be that in XPConnect there were many different pieces of code for
each place where we may need to clean up some untyped values based on their
nsXPTType information. This was a mess, and meant that every time you needed to
add a new data type you'd have to find every one of these places and add support
for your new type to them.
In fact, this was bad enough that it appears that I missed some places when
adding my webidl support! Which means that in some edge cases we may clean up
one of these values incorrectly D:!
This patch adds a new unified method which performs the cleanup by looking at a
nsXPTType object. The idea is that this function takes a void* which is actually
a T* where T is a value of the nsXPTType parmaeter. It clears the value behind
the pointer to a valid state such that free-ing the memory would not cause any
leaks. e.g. it free(...)s owned pointers and sets the pointer to `nullptr`, and
truncates nsA[C]String values such that they reference the static empty string.
I also modify every one of these custom cleanup codepaths to instead call into
this unified cleanup method.
This also involved some simplification of helper methods in order to make the
implementation cleaner.
This type is fairly simple on the idl parsing side of things. I handle it in the
same way that special types such as ns[C]String, nsid, and jsval are handled, by
using a special native type.
The logic for converting the value between C++ and JS follows the existing logic
from the nsISupports <=> JS Promise conversions.
We do the following:
CreateRootNode();
nsresult rv = BindToFrame(this);
NS_ENSURE_SUCCESS(rv, rv);
aElements.AppendElement(mRootNode);
That means that if BindToFrame fails, mRootNode will never be appended to
aElements, and thus will never get the native anonymous bits in [1].
BindToFrame should assert, but it indeed can fail due to it being bound to a
different frame in print preview, because nsCSSFrameConstructor's
ReplicateFixedFrames is a massive hack. :(
Just ensure the NAC bit is properly set for now...
[1]: https://searchfox.org/mozilla-central/rev/a85db9e29eb3f022dbaf8b9a6390ecbacf51e7dd/layout/base/nsCSSFrameConstructor.cpp#4193
MozReview-Commit-ID: 6sE8iUk4PCG
We rely on :hover and :active being hierarchical, and on the fact that there are
only elements and documents in the flattened tree ancestor chain if the element
is in the composed doc.
MozReview-Commit-ID: LMQkidMe9wp
Removed comparison to NS_STYLE_BORDER_STYLE_NONE and replaced with NS_STYLE_TEXT_DECORATION_STYLE_NONE
--HG--
extra : rebase_source : 559d47c0379229c169c5da75d38db6850ff3d60b
