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7fbd427f5e
Add the ability to get a C++ vtable ValueObject from another
ValueObject.
This patch adds the ability to ask a ValueObject for a ValueObject that
represents the virtual function table for a C++ class. If the
ValueObject is not a C++ class with a vtable, a valid ValueObject value
will be returned that contains an appropriate error. If it is successful
a valid ValueObject that represents vtable will be returned. The
ValueObject that is returned will have a name that matches the demangled
value for a C++ vtable mangled name like "vtable for <class-name>". It
will have N children, one for each virtual function pointer. Each
child's value is the function pointer itself, the summary is the
symbolication of this function pointer, and the type will be a valid
function pointer from the debug info if there is debug information
corresponding to the virtual function pointer.
The vtable SBValue will have the following:
- SBValue::GetName() returns "vtable for <class>"
- SBValue::GetValue() returns a string representation of the vtable
address
- SBValue::GetSummary() returns NULL
- SBValue::GetType() returns a type appropriate for a uintptr_t type for
the current process
- SBValue::GetLoadAddress() returns the address of the vtable adderess
- SBValue::GetValueAsUnsigned(...) returns the vtable address
- SBValue::GetNumChildren() returns the number of virtual function
pointers in the vtable
- SBValue::GetChildAtIndex(...) returns a SBValue that represents a
virtual function pointer
The child SBValue objects that represent a virtual function pointer has
the following values:
- SBValue::GetName() returns "[%u]" where %u is the vtable function
pointer index
- SBValue::GetValue() returns a string representation of the virtual
function pointer
- SBValue::GetSummary() returns a symbolicated respresentation of the
virtual function pointer
- SBValue::GetType() returns the function prototype type if there is
debug info, or a generic funtion prototype if there is no debug info
- SBValue::GetLoadAddress() returns the address of the virtual function
pointer
- SBValue::GetValueAsUnsigned(...) returns the virtual function pointer
- SBValue::GetNumChildren() returns 0
- SBValue::GetChildAtIndex(...) returns invalid SBValue for any index
Examples of using this API via python:
```
(lldb) script vtable = lldb.frame.FindVariable("shape_ptr").GetVTable()
(lldb) script vtable
vtable for Shape = 0x0000000100004088 {
[0] = 0x0000000100003d20 a.out`Shape::~Shape() at main.cpp:3
[1] = 0x0000000100003e4c a.out`Shape::~Shape() at main.cpp:3
[2] = 0x0000000100003e7c a.out`Shape::area() at main.cpp:4
[3] = 0x0000000100003e3c a.out`Shape::optional() at main.cpp:7
}
(lldb) script c = vtable.GetChildAtIndex(0)
(lldb) script c
(void ()) [0] = 0x0000000100003d20 a.out`Shape::~Shape() at main.cpp:3
```
88 lines
3.3 KiB
C++
88 lines
3.3 KiB
C++
//===-- CXXFunctionPointer.cpp---------------------------------------------===//
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//
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// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
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// See https://llvm.org/LICENSE.txt for license information.
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// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
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//
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//===----------------------------------------------------------------------===//
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#include "lldb/DataFormatters/CXXFunctionPointer.h"
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#include "lldb/Core/ValueObject.h"
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#include "lldb/Target/ABI.h"
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#include "lldb/Target/SectionLoadList.h"
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#include "lldb/Target/Target.h"
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#include "lldb/Utility/Stream.h"
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#include "lldb/lldb-enumerations.h"
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#include <string>
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using namespace lldb;
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using namespace lldb_private;
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using namespace lldb_private::formatters;
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bool lldb_private::formatters::CXXFunctionPointerSummaryProvider(
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ValueObject &valobj, Stream &stream, const TypeSummaryOptions &options) {
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std::string destination;
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StreamString sstr;
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AddressType func_ptr_address_type = eAddressTypeInvalid;
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addr_t func_ptr_address = valobj.GetPointerValue(&func_ptr_address_type);
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if (func_ptr_address != 0 && func_ptr_address != LLDB_INVALID_ADDRESS) {
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switch (func_ptr_address_type) {
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case eAddressTypeInvalid:
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case eAddressTypeFile:
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case eAddressTypeHost:
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break;
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case eAddressTypeLoad: {
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ExecutionContext exe_ctx(valobj.GetExecutionContextRef());
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Address so_addr;
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Target *target = exe_ctx.GetTargetPtr();
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if (target && !target->GetSectionLoadList().IsEmpty()) {
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target->GetSectionLoadList().ResolveLoadAddress(func_ptr_address,
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so_addr);
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if (so_addr.GetSection() == nullptr) {
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// If we have an address that doesn't correspond to any symbol,
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// it might have authentication bits. Strip them & see if it
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// now points to a symbol -- if so, do the SymbolContext lookup
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// based on the stripped address.
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// If we find a symbol with the ptrauth bits stripped, print the
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// raw value into the stream, and replace the Address with the
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// one that points to a symbol for a fuller description.
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if (Process *process = exe_ctx.GetProcessPtr()) {
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if (ABISP abi_sp = process->GetABI()) {
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addr_t fixed_addr = abi_sp->FixCodeAddress(func_ptr_address);
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if (fixed_addr != func_ptr_address) {
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Address test_address;
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test_address.SetLoadAddress(fixed_addr, target);
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if (test_address.GetSection() != nullptr) {
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int addrsize = target->GetArchitecture().GetAddressByteSize();
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sstr.Printf("actual=0x%*.*" PRIx64 " ", addrsize * 2,
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addrsize * 2, fixed_addr);
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so_addr = test_address;
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}
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}
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}
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}
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}
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if (so_addr.IsValid()) {
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so_addr.Dump(&sstr, exe_ctx.GetBestExecutionContextScope(),
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Address::DumpStyleResolvedDescription,
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Address::DumpStyleSectionNameOffset);
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}
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}
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} break;
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}
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}
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if (sstr.GetSize() > 0) {
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if (valobj.GetValueType() == lldb::eValueTypeVTableEntry)
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stream.PutCString(sstr.GetData());
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else
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stream.Printf("(%s)", sstr.GetData());
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return true;
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} else
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return false;
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}
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