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Bug 1475409 - Part 3: Make the different categories of types in xptinfo more explicit, r=mccr8 

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 commit is contained in:
Nika Layzell 2018-07-11 14:51:32 -04:00
Родитель b24e4f4b40
Коммит 4e4ab925ca
4 изменённых файлов: 81 добавлений и 81 удалений
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8
js/xpconnect/src/XPCConvert.cpp
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@ -1637,9 +1637,9 @@ xpc::InnerCleanupValue(const nsXPTType& aType, void* aValue, uint32_t aArrayLen)
MOZ_CRASH("Unknown Type!");
}
// Null out the pointer if we have it.
if (aType.HasPointerRepr()) {
*(void**)aValue = nullptr;
// Clear any non-complex values to the valid '0' state.
if (!aType.IsComplex()) {
aType.ZeroValue(aValue);
}
}
@ -1672,7 +1672,7 @@ xpc::InitializeValue(const nsXPTType& aType, void* aValue)
// The remaining types all have valid states where all bytes are '0'.
default:
memset(aValue, 0, aType.Stride());
aType.ZeroValue(aValue);
break;
}
}

5
js/xpconnect/src/XPCInlines.h
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@ -530,7 +530,10 @@ xpc::CleanupValue(const nsXPTType& aType,
// Check if we can do a cheap early return, and only perform the inner call
// if we can't. We never have to clean up null pointer types or arithmetic
// types.
if (aType.IsArithmetic() || (aType.HasPointerRepr() && !*(void**)aValue)) {
//
// NOTE: We can skip zeroing arithmetic types in CleanupValue, as they are
// already in a valid state.
if (aType.IsArithmetic() || (aType.IsPointer() && !*(void**)aValue)) {
return;
}
xpc::InnerCleanupValue(aType, aValue, aArrayLen);

30
js/xpconnect/src/XPCWrappedJSClass.cpp
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@ -745,25 +745,27 @@ nsXPCWrappedJSClass::CleanupOutparams(const nsXPTMethodInfo* info,
if (!param.IsOut())
continue;
// Extract the array length so we can use it in CleanupValue.
uint32_t arrayLen = 0;
if (!GetArraySizeFromParam(info, param.Type(), nativeParams, &arrayLen))
continue;
MOZ_ASSERT(param.IsIndirect(), "Outparams are always indirect");
// The inOutOnly flag is necessary because full outparams may contain
// uninitialized junk before the call is made, and we don't want to try
// to clean up uninitialized junk.
if (!inOutOnly || param.IsIn()) {
// Call 'CleanupValue' on parameters which we know to be initialized:
// 1. Complex parameters (initialized by caller)
// 2. 'inout' parameters (initialized by caller)
// 3. 'out' parameters when 'inOutOnly' is 'false' (initialized by us)
//
// We skip non-complex 'out' parameters before the call, as they may
// contain random junk.
if (param.Type().IsComplex() || param.IsIn() || !inOutOnly) {
uint32_t arrayLen = 0;
if (!GetArraySizeFromParam(info, param.Type(), nativeParams, &arrayLen))
continue;
xpc::CleanupValue(param.Type(), nativeParams[i].val.p, arrayLen);
}
// Even if we didn't call CleanupValue, null out any pointers. This is
// just to protect C++ callers which may read garbage if they forget to
// check the error value.
if (param.Type().HasPointerRepr()) {
*(void**)nativeParams[i].val.p = nullptr;
// Ensure our parameters are in a clean state. Complex values are always
// handled by CleanupValue, and others have a valid null representation.
if (!param.Type().IsComplex()) {
param.Type().ZeroValue(nativeParams[i].val.p);
}
}
}

119
xpcom/reflect/xptinfo/xptinfo.h
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@ -154,6 +154,13 @@ static_assert(sizeof(nsXPTInterfaceInfo) == 28, "wrong size?");
enum nsXPTTypeTag : uint8_t
{
// Arithmetic (POD) Types
// - Do not require cleanup,
// - All bit patterns are valid,
// - Outparams may be uninitialized by caller,
// - Directly supported in xptcall.
//
// NOTE: The name 'Arithmetic' comes from Harbison/Steele. Despite being a tad
// unclear, it is used frequently in xptcall, so is unlikely to be changed.
TD_INT8 = 0,
TD_INT16 = 1,
TD_INT32 = 2,
@ -167,27 +174,42 @@ enum nsXPTTypeTag : uint8_t
TD_BOOL = 10,
TD_CHAR = 11,
TD_WCHAR = 12,
_TD_LAST_ARITHMETIC = TD_WCHAR,
// Non-Arithmetic Types
// Pointer Types
// - Require cleanup unless NULL,
// - All-zeros (NULL) bit pattern is valid,
// - Outparams may be uninitialized by caller,
// - Supported in xptcall as raw pointer.
TD_VOID = 13,
TD_PNSIID = 14,
TD_DOMSTRING = 15,
TD_PSTRING = 16,
TD_PWSTRING = 17,
TD_INTERFACE_TYPE = 18,
TD_INTERFACE_IS_TYPE = 19,
TD_ARRAY = 20,
TD_PSTRING_SIZE_IS = 21,
TD_PWSTRING_SIZE_IS = 22,
TD_UTF8STRING = 23,
TD_CSTRING = 24,
TD_ASTRING = 25,
TD_JSVAL = 26,
TD_DOMOBJECT = 27,
TD_PROMISE = 28,
TD_SEQUENCE = 29
TD_PSTRING = 15,
TD_PWSTRING = 16,
TD_INTERFACE_TYPE = 17,
TD_INTERFACE_IS_TYPE = 18,
TD_ARRAY = 19,
TD_PSTRING_SIZE_IS = 20,
TD_PWSTRING_SIZE_IS = 21,
TD_DOMOBJECT = 22,
TD_PROMISE = 23,
_TD_LAST_POINTER = TD_PROMISE,
// Complex Types
// - Require cleanup,
// - Always passed indirectly,
// - Outparams must be initialized by caller,
// - Supported in xptcall due to indirection.
TD_DOMSTRING = 24,
TD_UTF8STRING = 25,
TD_CSTRING = 26,
TD_ASTRING = 27,
TD_JSVAL = 28,
TD_SEQUENCE = 29,
_TD_LAST_COMPLEX = TD_SEQUENCE
};
static_assert(_TD_LAST_COMPLEX < 32, "nsXPTTypeTag must fit in 5 bits");
/*
* A nsXPTType is a union used to identify the type of a method argument or
@ -239,33 +261,22 @@ public:
return xpt::detail::GetDOMObjectInfo(Data16());
}
// 'Arithmetic' here roughly means that the value is self-contained and
// doesn't depend on anything else in memory (ie: not a pointer, not an
// XPCOM object, not a jsval, etc).
//
// Supposedly this terminology comes from Harbison/Steele, but it's still
// a rather crappy name. We'd change it if it wasn't used all over the
// place in xptcall. :-(
bool IsArithmetic() const { return Tag() <= TD_WCHAR; }
// See the comments in nsXPTTypeTag for an explanation as to what each of
// these categories mean.
bool IsArithmetic() const { return Tag() <= _TD_LAST_ARITHMETIC; }
bool IsPointer() const { return !IsArithmetic() && Tag() <= _TD_LAST_POINTER; }
bool IsComplex() const { return Tag() > _TD_LAST_POINTER; }
bool IsInterfacePointer() const {
return Tag() == TD_INTERFACE_TYPE || Tag() == TD_INTERFACE_IS_TYPE;
}
bool IsArray() const { return Tag() == TD_ARRAY; }
bool IsDependent() const {
return (Tag() == TD_SEQUENCE && InnermostType().IsDependent()) ||
Tag() == TD_INTERFACE_IS_TYPE || Tag() == TD_ARRAY ||
Tag() == TD_PSTRING_SIZE_IS || Tag() == TD_PWSTRING_SIZE_IS;
}
bool IsAlwaysIndirect() const {
return Tag() == TD_ASTRING || Tag() == TD_DOMSTRING ||
Tag() == TD_CSTRING || Tag() == TD_UTF8STRING ||
Tag() == TD_JSVAL || Tag() == TD_SEQUENCE;
}
// Unwrap a nested type to its innermost value (e.g. through arrays).
const nsXPTType& InnermostType() const {
if (Tag() == TD_ARRAY || Tag() == TD_SEQUENCE) {
@ -274,15 +285,20 @@ public:
return *this;
}
// Helper methods for working with the type's native representation.
// In-memory size of native type in bytes.
inline size_t Stride() const;
inline bool HasPointerRepr() const;
// Offset the given base pointer to reference the element at the given index.
void* ElementPtr(const void* aBase, uint32_t aIndex) const {
return (char*)aBase + (aIndex * Stride());
}
// Zero out a native value of the given type. The type must not be 'complex'.
void ZeroValue(void* aValue) const {
MOZ_RELEASE_ASSERT(!IsComplex(), "Cannot zero a complex value");
memset(aValue, 0, Stride());
}
// Indexes into the extra types array of a small set of known types.
enum class Idx : uint8_t
{
@ -394,10 +410,10 @@ struct nsXPTParamInfo
const nsXPTType& GetType() const { return Type(); } // XXX remove (backcompat)
// Whether this parameter is passed indirectly on the stack. All out/inout
// params are passed indirectly, although some types are passed indirectly
// unconditionally.
// params are passed indirectly, and complex types are always passed
// indirectly.
bool IsIndirect() const {
return IsOut() || Type().IsAlwaysIndirect();
return IsOut() || Type().IsComplex();
}
////////////////////////////////////////////////////////////////
@ -634,29 +650,6 @@ GetString(uint32_t aIndex)
} // namespace detail
} // namespace xpt
inline bool
nsXPTType::HasPointerRepr() const
{
// This method should return `true` if the given type would be represented as
// a pointer when not passed indirectly.
switch (Tag()) {
case TD_VOID:
case TD_PNSIID:
case TD_PSTRING:
case TD_PWSTRING:
case TD_INTERFACE_TYPE:
case TD_INTERFACE_IS_TYPE:
case TD_ARRAY:
case TD_PSTRING_SIZE_IS:
case TD_PWSTRING_SIZE_IS:
case TD_DOMOBJECT:
case TD_PROMISE:
return true;
default:
return false;
}
}
inline size_t
nsXPTType::Stride() const
{
@ -675,6 +668,7 @@ nsXPTType::Stride() const
case TD_BOOL: return sizeof(bool);
case TD_CHAR: return sizeof(char);
case TD_WCHAR: return sizeof(char16_t);
case TD_VOID: return sizeof(void*);
case TD_PNSIID: return sizeof(nsIID*);
case TD_DOMSTRING: return sizeof(nsString);
@ -685,12 +679,13 @@ nsXPTType::Stride() const
case TD_ARRAY: return sizeof(void*);
case TD_PSTRING_SIZE_IS: return sizeof(char*);
case TD_PWSTRING_SIZE_IS: return sizeof(char16_t*);
case TD_DOMOBJECT: return sizeof(void*);
case TD_PROMISE: return sizeof(void*);
case TD_UTF8STRING: return sizeof(nsCString);
case TD_CSTRING: return sizeof(nsCString);
case TD_ASTRING: return sizeof(nsString);
case TD_JSVAL: return sizeof(JS::Value);
case TD_DOMOBJECT: return sizeof(void*);
case TD_PROMISE: return sizeof(void*);
case TD_SEQUENCE: return sizeof(xpt::detail::UntypedSequence);
}