Summary:
This macro simplifies code which allows performing an operation on or
extracting information from a particular nsXPTType's native representation.
It is also used in part 2 to implement xpc::DestructValue.
Reviewers: mccr8!
Tags: #secure-revision
Bug #: 1480624
Differential Revision: https://phabricator.services.mozilla.com/D2689
Summary:
This patch ports xptcodegen.py over to the new perfecthash.py system, removing
some special-case code generators, and taking advantage of the easier-to-use
interface.
In addition, the code was changed to take advantage of the endianness
information from Part 2, allowing us to avoid having to perform endianness swaps
at runtime when hashing nsIDs.
Depends On D2616
Reviewers: froydnj!
Tags: #secure-revision
Bug #: 1479484
Differential Revision: https://phabricator.services.mozilla.com/D2618
Summary:
This more closely matches the C++ names, and reflects the fact that the
reflected type is not WebIDL's mozilla::dom::Sequence. The reasoning behind this
type difference is for ergonomics, due to xpidl only being exposed to internal
JS code.
Depends On D2335
Reviewers: mccr8!
Tags: #secure-revision
Bug #: 1474369
Differential Revision: https://phabricator.services.mozilla.com/D2337
Summary:
This is done so we can use Array as the name for the new nsTArray-based
type, rather than having to come up with a new name.
LegacyArray was chosen as the [array] attribute is now effectively deprecated,
and we'd like to remove it ASAP.
Depends On D2334
Reviewers: mccr8!
Tags: #secure-revision
Bug #: 1474369
Differential Revision: https://phabricator.services.mozilla.com/D2335
Summary:
This should make it more clear which types have which behaviours, and should
make it easier to add new types without forgetting to handle a special case
somewhere.
Depends On D2114
Reviewers: mccr8!
Tags: #secure-revision
Bug #: 1475409
Differential Revision: https://phabricator.services.mozilla.com/D2115
This will get us both more clarity as to what types are, but also will improve switch exhaustiveness checks.
Summary: Depends On D2113
Reviewers: mccr8!
Tags: #secure-revision
Bug #: 1475409
Differential Revision: https://phabricator.services.mozilla.com/D2114
Summary:
This patch adds support for the `Sequence<T>` type. This is largely a
straightforward type propagation patch, but there are a few notable things:
1. We allow `[iid_is(x)] Sequence<nsQIResult>`, so Sequence can be Dependent.
2. `Sequence<T>` is reflected into C++ as a `nsTArray<T>`, which is different
than WebIDL's `mozilla::dom::Sequence<T>` type. This decision was made for
general ergonomics reasons, as `nsTArray<T>` is more prevailent throughout
the codebase, and lengths in this case cannot be controlled by content, as
XPConnect is only exposed to Chrome JS.
3. Owned pointers in `Sequence<T>` are not reflected as their owned
counterparts. For example, `Sequence<nsISupports>` is reflected as
`nsTArray<nsISupports*>` rather than `nsTArray<RefPtr<nsISupports>>`. This
was done to avoid depending on `RefPtr<T>` and `T*` having the same
in-memory representation, however if that is considered an acceptable
dependency, it would be nice to support that.
4. We also don't reflect singly-owned pointers as their owned counterparts. For
example, `nsTArray<nsIIDPtr>` would be reflected as `nsTArray<nsIID*>`
rather than `nsTArray<mozilla::UniquePtr<nsIID>>`. If we are willing to
depend on `mozilla::UniquePtr<T>`'s in-memory representation, we could also
do this, however.
5. There are no restrictions on what types can appear inside of a `Sequence<T>`
or what can appear inside an `[array] T`. We may want to add restrictions
either at the xpidl level or in XPConnect.
Depends On D2109
Reviewers: mccr8!
Tags: #secure-revision
Bug #: 1474369
Differential Revision: https://phabricator.services.mozilla.com/D2110
Summary:
This more closely matches the C++ names, and reflects the fact that the
reflected type is not WebIDL's mozilla::dom::Sequence. The reasoning behind this
type difference is for ergonomics, due to xpidl only being exposed to internal
JS code.
Depends On D2335
Reviewers: mccr8!
Tags: #secure-revision
Bug #: 1474369
Differential Revision: https://phabricator.services.mozilla.com/D2337
Summary:
This is done so we can use Array as the name for the new nsTArray-based
type, rather than having to come up with a new name.
LegacyArray was chosen as the [array] attribute is now effectively deprecated,
and we'd like to remove it ASAP.
Depends On D2334
Reviewers: mccr8!
Tags: #secure-revision
Bug #: 1474369
Differential Revision: https://phabricator.services.mozilla.com/D2335
Summary:
This should make it more clear which types have which behaviours, and should
make it easier to add new types without forgetting to handle a special case
somewhere.
Depends On D2114
Reviewers: mccr8!
Tags: #secure-revision
Bug #: 1475409
Differential Revision: https://phabricator.services.mozilla.com/D2115
This will get us both more clarity as to what types are, but also will improve switch exhaustiveness checks.
Summary: Depends On D2113
Reviewers: mccr8!
Tags: #secure-revision
Bug #: 1475409
Differential Revision: https://phabricator.services.mozilla.com/D2114
Summary:
This patch adds support for the `Sequence<T>` type. This is largely a
straightforward type propagation patch, but there are a few notable things:
1. We allow `[iid_is(x)] Sequence<nsQIResult>`, so Sequence can be Dependent.
2. `Sequence<T>` is reflected into C++ as a `nsTArray<T>`, which is different
than WebIDL's `mozilla::dom::Sequence<T>` type. This decision was made for
general ergonomics reasons, as `nsTArray<T>` is more prevailent throughout
the codebase, and lengths in this case cannot be controlled by content, as
XPConnect is only exposed to Chrome JS.
3. Owned pointers in `Sequence<T>` are not reflected as their owned
counterparts. For example, `Sequence<nsISupports>` is reflected as
`nsTArray<nsISupports*>` rather than `nsTArray<RefPtr<nsISupports>>`. This
was done to avoid depending on `RefPtr<T>` and `T*` having the same
in-memory representation, however if that is considered an acceptable
dependency, it would be nice to support that.
4. We also don't reflect singly-owned pointers as their owned counterparts. For
example, `nsTArray<nsIIDPtr>` would be reflected as `nsTArray<nsIID*>`
rather than `nsTArray<mozilla::UniquePtr<nsIID>>`. If we are willing to
depend on `mozilla::UniquePtr<T>`'s in-memory representation, we could also
do this, however.
5. There are no restrictions on what types can appear inside of a `Sequence<T>`
or what can appear inside an `[array] T`. We may want to add restrictions
either at the xpidl level or in XPConnect.
Depends On D2109
Reviewers: mccr8!
Tags: #secure-revision
Bug #: 1474369
Differential Revision: https://phabricator.services.mozilla.com/D2110
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.
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
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.
Unlike the other lists in xptinfo, this list contains relocations. Each
DOMObject has 3 functions generated for it, `Wrap`, `Unwrap` and `Cleanup`,
which perform the necessary actions. These are stored as function pointers.
Wrap gets the DOMObject wrapper using the DOM binding code, Unwrap gets the
underlying C++ object, and addrefs it (as XPCOM methods return native types
via getter_AddRefs), and Cleanup releases a reference to the underlying
C++ object, for when the unwrapped object is used as a temporary during a call.
To generate the code, we need to have the declaration of the native C++ type
in scope, so we also emit #include-s for the headerFiles.
This patch contains the meat of the changes here. The following summarize the changes:
1. xptinfo.h is rewritten to expose the new interface for reading the XPT data,
The nsXPTInterfaceInfo object exposes methods with the same signatures as
the methods on nsIInterfaceInfo, to make converting code which used
nsIInterfaceInfo as easy as possible, even when those methods don't have
signatures which make a ton of sense anymore. There are also a few methods
which are unnecessary (they return `true` or similar), which should be
removed over time.
Members of the data structures are made private in order to prevent reading
them directly. Code should instead call the getter methods. This should make
it easier to change their memory representation in the future. Constructing
these structs is made possible by making the structs `friend class` with the
XPTConstruct class, which is implemented by the code generator, and is able
to access the private fields.
In addition, rather than using integers with flag constants, I opted for
using C++ bitfields to store individual flags, as I found it made it easier
to both write the code generator, and reason about the layouts of the types.
I was able to shave a byte off of each nsXPTParamInfo (4 bytes -> 3 bytes)
by shoving the flags into spare bits in the nsXPTType. Unfortunately there
was not enough room for the retval flag. Fortunately, we already depend in
our code on the retval parameter being the last parameter, so I worked
around this by removing the retval flag and instead having a `hasretval`
flag on the method itself.
2. An xptinfo.cpp file is added for out-of-line definitions of more complex
methods, and the internal implementation details of the perfect hash.
Notable is the handling of xptshim interfaces. As the type is uniform, a
flag is checked when trying to read constant information, and a different
table with pointers into webidl data structures is checked when the type is
determined to be a shim.
Ideally we could remove this once we remove the remaining consumers of the
existing shim interfaces.
3. A python code generator which takes in the json XPT files generated in the
previous part, and emits a xptdata.cpp file with the data structures. I did
my best to heavily comment the code.
This code uses the friend class trick to construct the private fields of the
structs, and avoid a dependency on the ordering of fields in xptinfo.h.
The sInterfaces array's order is determined by a generated perfect hash
which is also written into the binary. This should allow for fast lookups by
IID or name of interfaces in memory. The hash function used for the perfect
hash is a simple FNV hash, as they're pretty fast.
For perfect hashing of names, another table is created which contains
indexes into the sInterfaces table. Lookup by name is less common, and this
form of lookup should still be very fast.
4. The necessary Makefiles are updated to use the new code generator, and
generate the file correctly.
Many of these fields have accessors, and can only be read indirectly
by going through the XPTHeader data structure anyways, so they should
be marked private. This makes the generated XPT data file noisier due
to the need for constexpr constructors.
I had to fix the ctors for the classes in xptinfo.h to be less weird
because there was a compiler error.
Members in two of the classes need to be marked protected because they
have subclasses in xptinfo.h. Ideally those classes would be merged
in.
MozReview-Commit-ID: 70IdFAhp5je
--HG--
extra : rebase_source : 48cb1ec84c872b8fd6bb8c07f8ad2b47d0173f28
Many of these fields have accessors, and can only be read indirectly
by going through the XPTHeader data structure anyways, so they should
be marked private. This makes the generated XPT data file noisier due
to the need for constexpr constructors.
I had to fix the ctors for the classes in xptinfo.h to be less weird
because there was a compiler error.
Members in two of the classes need to be marked protected because they
have subclasses in xptinfo.h. Ideally those classes would be merged
in.
MozReview-Commit-ID: 70IdFAhp5je
--HG--
extra : rebase_source : a2670a65ace291defc47845c4058477f0ae5360a
This lets us hide later changes to how these arrays are stored. There
should be no behavioral change. Some methods in xpt_struct.h are
declared inline at the end of the header due to the order that classes
are declared in the header.
MozReview-Commit-ID: KAxUKn3sDOD
--HG--
extra : rebase_source : 867ce100e5178c85485e6c3bac5d6bfca098f78b
This lets us hide later changes to how these arrays are stored. There
should be no behavioral change. Some methods in xpt_struct.h are
declared inline at the end of the header due to the order that classes
are declared in the header.
MozReview-Commit-ID: KAxUKn3sDOD
--HG--
extra : rebase_source : 782fddc7bbf29c8ec73a0c6dbcca0621739e6c6e
Also, get rid of a gratuitous use of a trinary operator in
nsXPCWrappedJSClass::CallMethod, clean up the style a little, and mark
an unimplemented ctor as deleted.
MozReview-Commit-ID: Kp64sMxyRWc
--HG--
extra : rebase_source : e6082003d3759234cd5f4630b5560b14930c0a88
Also, clean up the style a little and mark an unimplemented ctor as
deleted.
MozReview-Commit-ID: JqmveE6qWFa
--HG--
extra : rebase_source : 62c8249de1f52686b4dd5d2a043261d2618d7433
This sounds weird, but either:
1) A method is notxpcom, so it can't be called from script and the XPT
information is unused.
2) A method is not notxpcom, in which case the result type is nsresult.
MozReview-Commit-ID: a7SRJn8PlP
--HG--
extra : rebase_source : 457051a47dd3f1f2f49b5f11ef3e5138f9d814e1
Nika Layzell
Cosmin Sabou
Jan de Mooij
Jorg K
Andrew McCreight
Andreea Pavel
Dorel Luca
Nicholas Nethercote
Andrea Marchesini
Ehsan Akhgari
Bobby Holley
Birunthan Mohanathas