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[lldb] Add support to load object files from thin archives

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This fixes https://github.com/llvm/llvm-project/issues/50114 where lldb/mac
can't load object files from thin archives.  This patch allows lldb to identify
thin archives, and load object files contained in them.

Differential Revision: https://reviews.llvm.org/D126464
This commit is contained in:
Kaining Zhong 2022-07-05 10:50:37 +02:00 committed by Nico Weber
parent 00cb1c33ee
commit dc46ae6df5
7 changed files with 242 additions and 22 deletions
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208
lldb/source/Plugins/ObjectContainer/BSD-Archive/ObjectContainerBSDArchive.cpp
View File

@ -40,6 +40,8 @@ typedef struct ar_hdr {
using namespace lldb;
using namespace lldb_private;
using namespace llvm::object;
LLDB_PLUGIN_DEFINE(ObjectContainerBSDArchive)
ObjectContainerBSDArchive::Object::Object() : ar_name() {}
@ -55,6 +57,74 @@ void ObjectContainerBSDArchive::Object::Clear() {
file_size = 0;
}
lldb::offset_t ObjectContainerBSDArchive::Object::ExtractFromThin(
const DataExtractor &data, lldb::offset_t offset,
llvm::StringRef stringTable) {
size_t ar_name_len = 0;
std::string str;
char *err;
// File header
//
// The common format is as follows.
//
// Offset Length Name Format
// 0 16 File name ASCII right padded with spaces (no spaces
// allowed in file name)
// 16 12 File mod Decimal as cstring right padded with
// spaces
// 28 6 Owner ID Decimal as cstring right padded with
// spaces
// 34 6 Group ID Decimal as cstring right padded with
// spaces
// 40 8 File mode Octal as cstring right padded with
// spaces
// 48 10 File byte size Decimal as cstring right padded with
// spaces
// 58 2 File magic 0x60 0x0A
// Make sure there is enough data for the file header and bail if not
if (!data.ValidOffsetForDataOfSize(offset, 60))
return LLDB_INVALID_OFFSET;
str.assign((const char *)data.GetData(&offset, 16), 16);
if (!(llvm::StringRef(str).startswith("//") || stringTable.empty())) {
// Strip off any trailing spaces.
const size_t last_pos = str.find_last_not_of(' ');
if (last_pos != std::string::npos) {
if (last_pos + 1 < 16)
str.erase(last_pos + 1);
}
int start = strtoul(str.c_str() + 1, &err, 10);
int end = stringTable.find('\n', start);
str.assign(stringTable.data() + start, end - start - 1);
ar_name.SetCString(str.c_str());
}
str.assign((const char *)data.GetData(&offset, 12), 12);
modification_time = strtoul(str.c_str(), &err, 10);
str.assign((const char *)data.GetData(&offset, 6), 6);
uid = strtoul(str.c_str(), &err, 10);
str.assign((const char *)data.GetData(&offset, 6), 6);
gid = strtoul(str.c_str(), &err, 10);
str.assign((const char *)data.GetData(&offset, 8), 8);
mode = strtoul(str.c_str(), &err, 8);
str.assign((const char *)data.GetData(&offset, 10), 10);
size = strtoul(str.c_str(), &err, 10);
str.assign((const char *)data.GetData(&offset, 2), 2);
if (str == ARFMAG) {
file_offset = offset;
file_size = size - ar_name_len;
return offset;
}
return LLDB_INVALID_OFFSET;
}
lldb::offset_t
ObjectContainerBSDArchive::Object::Extract(const DataExtractor &data,
lldb::offset_t offset) {
@ -136,9 +206,10 @@ ObjectContainerBSDArchive::Object::Extract(const DataExtractor &data,
ObjectContainerBSDArchive::Archive::Archive(const lldb_private::ArchSpec &arch,
const llvm::sys::TimePoint<> &time,
lldb::offset_t file_offset,
lldb_private::DataExtractor &data)
lldb_private::DataExtractor &data,
ArchiveType archive_type)
: m_arch(arch), m_modification_time(time), m_file_offset(file_offset),
m_objects(), m_data(data) {}
m_objects(), m_data(data), m_archive_type(archive_type) {}
ObjectContainerBSDArchive::Archive::~Archive() = default;
@ -161,6 +232,48 @@ size_t ObjectContainerBSDArchive::Archive::ParseObjects() {
obj.Clear();
} while (data.ValidOffset(offset));
// Now sort all of the object name pointers
m_object_name_to_index_map.Sort();
} else if (str == ThinArchiveMagic) {
Object obj;
size_t obj_idx;
// Retrieve symbol table
offset = obj.ExtractFromThin(data, offset, "");
if (offset == LLDB_INVALID_OFFSET)
return m_objects.size();
obj_idx = m_objects.size();
m_objects.push_back(obj);
// Insert all of the C strings out of order for now...
m_object_name_to_index_map.Append(obj.ar_name, obj_idx);
offset += obj.file_size;
obj.Clear();
// Retrieve string table
offset = obj.ExtractFromThin(data, offset, "");
if (offset == LLDB_INVALID_OFFSET)
return m_objects.size();
obj_idx = m_objects.size();
m_objects.push_back(obj);
// Insert all of the C strings out of order for now...
m_object_name_to_index_map.Append(obj.ar_name, obj_idx);
// Extract string table
llvm::StringRef strtab((const char *)data.GetData(&offset, obj.size),
obj.size);
obj.Clear();
// Retrieve object files
do {
offset = obj.ExtractFromThin(data, offset, strtab);
if (offset == LLDB_INVALID_OFFSET)
break;
obj_idx = m_objects.size();
m_objects.push_back(obj);
// Insert all of the C strings out of order for now...
m_object_name_to_index_map.Append(obj.ar_name, obj_idx);
obj.Clear();
} while (data.ValidOffset(offset));
// Now sort all of the object name pointers
m_object_name_to_index_map.Sort();
}
@ -237,8 +350,9 @@ ObjectContainerBSDArchive::Archive::shared_ptr
ObjectContainerBSDArchive::Archive::ParseAndCacheArchiveForFile(
const FileSpec &file, const ArchSpec &arch,
const llvm::sys::TimePoint<> &time, lldb::offset_t file_offset,
DataExtractor &data) {
shared_ptr archive_sp(new Archive(arch, time, file_offset, data));
DataExtractor &data, ArchiveType archive_type) {
shared_ptr archive_sp(
new Archive(arch, time, file_offset, data, archive_type));
if (archive_sp) {
const size_t num_objects = archive_sp->ParseObjects();
if (num_objects > 0) {
@ -288,7 +402,8 @@ ObjectContainer *ObjectContainerBSDArchive::CreateInstance(
// contents for the archive and cache it
DataExtractor data;
data.SetData(data_sp, data_offset, length);
if (file && data_sp && ObjectContainerBSDArchive::MagicBytesMatch(data)) {
ArchiveType archive_type = ObjectContainerBSDArchive::MagicBytesMatch(data);
if (file && data_sp && archive_type != ArchiveType::Invalid) {
LLDB_SCOPED_TIMERF(
"ObjectContainerBSDArchive::CreateInstance (module = %s, file = "
"%p, file_offset = 0x%8.8" PRIx64 ", file_size = 0x%8.8" PRIx64 ")",
@ -312,7 +427,7 @@ ObjectContainer *ObjectContainerBSDArchive::CreateInstance(
std::unique_ptr<ObjectContainerBSDArchive> container_up(
new ObjectContainerBSDArchive(module_sp, archive_data_sp,
archive_data_offset, file, file_offset,
length));
length, archive_type));
if (container_up) {
if (archive_sp) {
@ -331,7 +446,8 @@ ObjectContainer *ObjectContainerBSDArchive::CreateInstance(
if (archive_sp) {
std::unique_ptr<ObjectContainerBSDArchive> container_up(
new ObjectContainerBSDArchive(module_sp, data_sp, data_offset, file,
file_offset, length));
file_offset, length,
archive_sp->GetArchiveType()));
if (container_up) {
// We already have this archive in our cache, use it
@ -343,23 +459,35 @@ ObjectContainer *ObjectContainerBSDArchive::CreateInstance(
return nullptr;
}
bool ObjectContainerBSDArchive::MagicBytesMatch(const DataExtractor &data) {
ArchiveType
ObjectContainerBSDArchive::MagicBytesMatch(const DataExtractor &data) {
uint32_t offset = 0;
const char *armag = (const char *)data.PeekData(offset, sizeof(ar_hdr));
if (armag && ::strncmp(armag, ARMAG, SARMAG) == 0) {
if (armag == nullptr)
return ArchiveType::Invalid;
if (::strncmp(armag, ARMAG, SARMAG) == 0) {
armag += offsetof(struct ar_hdr, ar_fmag) + SARMAG;
if (strncmp(armag, ARFMAG, 2) == 0)
return true;
return ArchiveType::Archive;
} else if (::strncmp(armag, ThinArchiveMagic, strlen(ThinArchiveMagic)) ==
0) {
armag += offsetof(struct ar_hdr, ar_fmag) + strlen(ThinArchiveMagic);
if (strncmp(armag, ARFMAG, 2) == 0) {
return ArchiveType::ThinArchive;
}
}
return false;
return ArchiveType::Invalid;
}
ObjectContainerBSDArchive::ObjectContainerBSDArchive(
const lldb::ModuleSP &module_sp, DataBufferSP &data_sp,
lldb::offset_t data_offset, const lldb_private::FileSpec *file,
lldb::offset_t file_offset, lldb::offset_t size)
lldb::offset_t file_offset, lldb::offset_t size, ArchiveType archive_type)
: ObjectContainer(module_sp, file, file_offset, size, data_sp, data_offset),
m_archive_sp() {}
m_archive_sp() {
m_archive_type = archive_type;
}
void ObjectContainerBSDArchive::SetArchive(Archive::shared_ptr &archive_sp) {
m_archive_sp = archive_sp;
}
@ -373,7 +501,7 @@ bool ObjectContainerBSDArchive::ParseHeader() {
if (module_sp) {
m_archive_sp = Archive::ParseAndCacheArchiveForFile(
m_file, module_sp->GetArchitecture(),
module_sp->GetModificationTime(), m_offset, m_data);
module_sp->GetModificationTime(), m_offset, m_data, m_archive_type);
}
// Clear the m_data that contains the entire archive data and let our
// m_archive_sp hold onto the data.
@ -407,6 +535,19 @@ void ObjectContainerBSDArchive::Dump(Stream *s) const {
s->EOL();
}
FileSpec GetChildFileSpecificationsFromThin(llvm::StringRef childPath,
const FileSpec &parentFileSpec) {
llvm::SmallString<128> FullPath;
if (llvm::sys::path::is_absolute(childPath)) {
FullPath = childPath;
} else {
FullPath = parentFileSpec.GetDirectory().GetStringRef();
llvm::sys::path::append(FullPath, childPath);
}
FileSpec child = FileSpec(FullPath.str(), llvm::sys::path::Style::posix);
return child;
}
ObjectFileSP ObjectContainerBSDArchive::GetObjectFile(const FileSpec *file) {
ModuleSP module_sp(GetModule());
if (module_sp) {
@ -414,6 +555,22 @@ ObjectFileSP ObjectContainerBSDArchive::GetObjectFile(const FileSpec *file) {
Object *object = m_archive_sp->FindObject(
module_sp->GetObjectName(), module_sp->GetObjectModificationTime());
if (object) {
if (m_archive_type == ArchiveType::ThinArchive) {
// Set file to child object file
FileSpec child = GetChildFileSpecificationsFromThin(
object->ar_name.GetStringRef(), m_file);
lldb::offset_t file_offset = 0;
lldb::offset_t file_size = object->size;
std::shared_ptr<DataBuffer> child_data_sp =
FileSystem::Instance().CreateDataBuffer(child, file_size,
file_offset);
if (child_data_sp->GetByteSize() != object->file_size)
return ObjectFileSP();
lldb::offset_t data_offset = 0;
return ObjectFile::FindPlugin(
module_sp, &child, m_offset + object->file_offset,
object->file_size, child_data_sp, data_offset);
}
lldb::offset_t data_offset = object->file_offset;
return ObjectFile::FindPlugin(
module_sp, file, m_offset + object->file_offset, object->file_size,
@ -434,7 +591,8 @@ size_t ObjectContainerBSDArchive::GetModuleSpecifications(
// contents for the archive and cache it
DataExtractor data;
data.SetData(data_sp, data_offset, data_sp->GetByteSize());
if (!file || !data_sp || !ObjectContainerBSDArchive::MagicBytesMatch(data))
ArchiveType archive_type = ObjectContainerBSDArchive::MagicBytesMatch(data);
if (!file || !data_sp || archive_type == ArchiveType::Invalid)
return 0;
const size_t initial_count = specs.GetSize();
@ -449,7 +607,7 @@ size_t ObjectContainerBSDArchive::GetModuleSpecifications(
if (data_sp) {
data.SetData(data_sp, 0, data_sp->GetByteSize());
archive_sp = Archive::ParseAndCacheArchiveForFile(
file, ArchSpec(), file_mod_time, file_offset, data);
file, ArchSpec(), file_mod_time, file_offset, data, archive_type);
}
}
@ -458,6 +616,24 @@ size_t ObjectContainerBSDArchive::GetModuleSpecifications(
for (size_t idx = 0; idx < num_objects; ++idx) {
const Object *object = archive_sp->GetObjectAtIndex(idx);
if (object) {
if (archive_sp->GetArchiveType() == ArchiveType::ThinArchive) {
if (object->ar_name.IsEmpty())
continue;
FileSpec child = GetChildFileSpecificationsFromThin(
object->ar_name.GetStringRef(), file);
if (ObjectFile::GetModuleSpecifications(child, 0, object->file_size,
specs)) {
ModuleSpec &spec =
specs.GetModuleSpecRefAtIndex(specs.GetSize() - 1);
llvm::sys::TimePoint<> object_mod_time(
std::chrono::seconds(object->modification_time));
spec.GetObjectName() = object->ar_name;
spec.SetObjectOffset(0);
spec.SetObjectSize(object->file_size);
spec.GetObjectModificationTime() = object_mod_time;
}
continue;
}
const lldb::offset_t object_file_offset =
file_offset + object->file_offset;
if (object->file_offset < file_size && file_size > object_file_offset) {

22
lldb/source/Plugins/ObjectContainer/BSD-Archive/ObjectContainerBSDArchive.h
View File

@ -15,19 +15,24 @@
#include "lldb/Utility/ConstString.h"
#include "lldb/Utility/FileSpec.h"
#include "llvm/Object/Archive.h"
#include "llvm/Support/Chrono.h"
#include "llvm/Support/Path.h"
#include <map>
#include <memory>
#include <mutex>
enum class ArchiveType { Invalid, Archive, ThinArchive };
class ObjectContainerBSDArchive : public lldb_private::ObjectContainer {
public:
ObjectContainerBSDArchive(const lldb::ModuleSP &module_sp,
lldb::DataBufferSP &data_sp,
lldb::offset_t data_offset,
const lldb_private::FileSpec *file,
lldb::offset_t offset, lldb::offset_t length);
lldb::offset_t offset, lldb::offset_t length,
ArchiveType archive_type);
~ObjectContainerBSDArchive() override;
@ -54,7 +59,7 @@ public:
lldb::offset_t length,
lldb_private::ModuleSpecList &specs);
static bool MagicBytesMatch(const lldb_private::DataExtractor &data);
static ArchiveType MagicBytesMatch(const lldb_private::DataExtractor &data);
// Member Functions
bool ParseHeader() override;
@ -78,6 +83,10 @@ protected:
void Clear();
lldb::offset_t ExtractFromThin(const lldb_private::DataExtractor &data,
lldb::offset_t offset,
llvm::StringRef stringTable);
lldb::offset_t Extract(const lldb_private::DataExtractor &data,
lldb::offset_t offset);
/// Object name in the archive.
@ -112,7 +121,7 @@ protected:
Archive(const lldb_private::ArchSpec &arch,
const llvm::sys::TimePoint<> &mod_time, lldb::offset_t file_offset,
lldb_private::DataExtractor &data);
lldb_private::DataExtractor &data, ArchiveType archive_type);
~Archive();
@ -127,7 +136,7 @@ protected:
static Archive::shared_ptr ParseAndCacheArchiveForFile(
const lldb_private::FileSpec &file, const lldb_private::ArchSpec &arch,
const llvm::sys::TimePoint<> &mod_time, lldb::offset_t file_offset,
lldb_private::DataExtractor &data);
lldb_private::DataExtractor &data, ArchiveType archive_type);
size_t GetNumObjects() const { return m_objects.size(); }
@ -156,6 +165,8 @@ protected:
lldb_private::DataExtractor &GetData() { return m_data; }
ArchiveType GetArchiveType() { return m_archive_type; }
protected:
typedef lldb_private::UniqueCStringMap<uint32_t> ObjectNameToIndexMap;
// Member Variables
@ -167,11 +178,14 @@ protected:
lldb_private::DataExtractor m_data; ///< The data for this object container
///so we don't lose data if the .a files
///gets modified
ArchiveType m_archive_type;
};
void SetArchive(Archive::shared_ptr &archive_sp);
Archive::shared_ptr m_archive_sp;
ArchiveType m_archive_type;
};
#endif // LLDB_SOURCE_PLUGINS_OBJECTCONTAINER_BSD_ARCHIVE_OBJECTCONTAINERBSDARCHIVE_H

11
lldb/test/API/functionalities/archives/Makefile
View File

@ -1,8 +1,8 @@
C_SOURCES := main.c a.c b.c
C_SOURCES := main.c a.c b.c c.c
EXE := # Define a.out explicitly
MAKE_DSYM := NO
all: a.out
all: a.out libbar.a
a.out: main.o libfoo.a
$(LD) $(LDFLAGS) $^ -o $@
@ -11,4 +11,11 @@ libfoo.a: a.o b.o
$(AR) $(ARFLAGS) $@ $^
$(RM) $^
# This tests whether lldb can load a thin archive
libbar.a: c.o
$(eval LLVM_AR := $(LLVM_TOOLS_DIR)/llvm-ar)
$(eval LLVM_ARFLAGS := -rcsDT)
$(LLVM_AR) $(LLVM_ARFLAGS) $@ $^
# Note for thin archive case, we cannot remove c.o
include Makefile.rules

7
lldb/test/API/functionalities/archives/TestBSDArchives.py
View File

@ -58,3 +58,10 @@ class BSDArchivesTestCase(TestBase):
self.expect("frame variable", VARIABLES_DISPLAYED_CORRECTLY,
substrs=['(int) arg = 2'])
self.expect_var_path("__b_global", type="int", value="2")
# Test loading thin archives
archive_path = self.getBuildArtifact("libbar.a")
module_specs = lldb.SBModuleSpecList.GetModuleSpecifications(archive_path)
num_specs = module_specs.GetSize()
self.assertEqual(num_specs, 1)
self.assertEqual(module_specs.GetSpecAtIndex(0).GetObjectName(), "c.o")

11
lldb/test/API/functionalities/archives/c.c Normal file
View File

@ -0,0 +1,11 @@
static int __c_global = 3;
int c(int arg) {
int result = arg + __c_global;
return result;
}
int cc(int arg1) {
int result3 = arg1 - __c_global;
return result3;
}

4
lldb/test/API/lit.cfg.py
View File

@ -162,6 +162,10 @@ if is_configured('dotest_args_str'):
if is_configured('llvm_libs_dir'):
dotest_cmd += ['--env', 'LLVM_LIBS_DIR=' + config.llvm_libs_dir]
# This path may be needed to locate required llvm tools
if is_configured('llvm_tools_dir'):
dotest_cmd += ['--env', 'LLVM_TOOLS_DIR=' + config.llvm_tools_dir]
# Forward ASan-specific environment variables to tests, as a test may load an
# ASan-ified dylib.
for env_var in ('ASAN_OPTIONS', 'DYLD_INSERT_LIBRARIES'):

1
lldb/test/CMakeLists.txt
View File

@ -148,6 +148,7 @@ add_lldb_test_dependency(
llvm-objcopy
llvm-pdbutil
llvm-readobj
llvm-ar
)
if(TARGET lld)