Implement xfer:libraries-svr4:read packet

Summary:
This is the fourth patch to improve module loading in a series that started here (where I explain the motivation and solution): D62499

Implement the `xfer:libraries-svr4` packet by adding a new function that generates the list and then in Handle_xfer I generate the XML for it. The XML is really simple so I'm just using string concatenation because I believe it's more readable than having to deal with a DOM api.

Reviewers: clayborg, xiaobai, labath

Reviewed By: labath

Subscribers: emaste, mgorny, srhines, krytarowski, lldb-commits

Tags: #lldb

Differential Revision: https://reviews.llvm.org/D62502

llvm-svn: 363707

lldb/include/lldb/Host/common/NativeProcessProtocol.h

@@ -32,6 +32,14 @@ namespace lldb_private {
 class MemoryRegionInfo;
 class ResumeActionList;
 
+struct SVR4LibraryInfo {
+  std::string name;
+  lldb::addr_t link_map;
+  lldb::addr_t base_addr;
+  lldb::addr_t ld_addr;
+  lldb::addr_t next;
+};
+
 // NativeProcessProtocol
 class NativeProcessProtocol {
 public:
@@ -86,6 +94,12 @@ public:
 
   virtual lldb::addr_t GetSharedLibraryInfoAddress() = 0;
 
+  virtual llvm::Expected<std::vector<SVR4LibraryInfo>>
+  GetLoadedSVR4Libraries() {
+    return llvm::createStringError(llvm::inconvertibleErrorCode(),
+                                   "Not implemented");
+  }
+
   virtual bool IsAlive() const;
 
   virtual size_t UpdateThreads() = 0;

lldb/packages/Python/lldbsuite/test/tools/lldb-server/gdbremote_testcase.py

@@ -513,7 +513,8 @@ class GdbRemoteTestCaseBase(TestBase):
             self,
             inferior_args=None,
             inferior_sleep_seconds=3,
-            inferior_exe_path=None):
+            inferior_exe_path=None,
+            inferior_env=None):
         """Prep the debug monitor, the inferior, and the expected packet stream.
 
         Handle the separate cases of using the debug monitor in attach-to-inferior mode
@@ -576,6 +577,9 @@ class GdbRemoteTestCaseBase(TestBase):
 
         # Build the expected protocol stream
         self.add_no_ack_remote_stream()
+        if inferior_env:
+            for name, value in inferior_env.items():
+                self.add_set_environment_packets(name, value)
         if self._inferior_startup == self._STARTUP_LAUNCH:
             self.add_verified_launch_packets(launch_args)
 
@@ -656,6 +660,12 @@ class GdbRemoteTestCaseBase(TestBase):
              {"direction": "send", "regex": r"^\$(.+)#[0-9a-fA-F]{2}$", "capture": {1: "process_info_raw"}}],
             True)
 
+    def add_set_environment_packets(self, name, value):
+        self.test_sequence.add_log_lines(
+            ["read packet: $QEnvironment:" + name + "=" + value + "#00",
+             "send packet: $OK#00",
+             ], True)
+
     _KNOWN_PROCESS_INFO_KEYS = [
         "pid",
         "parent-pid",
@@ -816,6 +826,7 @@ class GdbRemoteTestCaseBase(TestBase):
                     "error"])
             self.assertIsNotNone(val)
 
+        mem_region_dict["name"] = seven.unhexlify(mem_region_dict.get("name", ""))
         # Return the dictionary of key-value pairs for the memory region.
         return mem_region_dict
 
@@ -1000,6 +1011,22 @@ class GdbRemoteTestCaseBase(TestBase):
 
         return context
 
+    def continue_process_and_wait_for_stop(self):
+        self.test_sequence.add_log_lines(
+            [
+                "read packet: $vCont;c#a8",
+                {
+                    "direction": "send",
+                    "regex": r"^\$T([0-9a-fA-F]{2})(.*)#[0-9a-fA-F]{2}$",
+                    "capture": {1: "stop_signo", 2: "stop_key_val_text"},
+                },
+            ],
+            True,
+        )
+        context = self.expect_gdbremote_sequence()
+        self.assertIsNotNone(context)
+        return self.parse_interrupt_packets(context)
+
     def select_modifiable_register(self, reg_infos):
         """Find a register that can be read/written freely."""
         PREFERRED_REGISTER_NAMES = set(["rax", ])

lldb/packages/Python/lldbsuite/test/tools/lldb-server/libraries-svr4/Makefile

@@ -0,0 +1,17 @@
+LEVEL = ../../../make
+
+LIB_PREFIX := svr4lib
+LD_EXTRAS := -L. -l$(LIB_PREFIX)_a -l$(LIB_PREFIX)_b\"
+CXX_SOURCES := main.cpp
+USE_LIBDL := 1
+MAKE_DSYM := NO
+
+include $(LEVEL)/Makefile.rules
+
+a.out: $(LIB_PREFIX)_a $(LIB_PREFIX)_b_quote
+
+svr4lib_%:
+	$(MAKE) VPATH=$(SRCDIR) -I $(SRCDIR) -f "$(SRCDIR)/$(LIB_PREFIX)_$*.mk"
+
+clean::
+	$(MAKE) -f $(SRCDIR)/$(LIB_PREFIX)_a.mk clean

lldb/packages/Python/lldbsuite/test/tools/lldb-server/libraries-svr4/TestGdbRemoteLibrariesSvr4Support.py

@@ -0,0 +1,127 @@
+import xml.etree.ElementTree as ET
+
+import gdbremote_testcase
+from lldbsuite.test.decorators import *
+from lldbsuite.test.lldbtest import *
+
+
+class TestGdbRemoteLibrariesSvr4Support(gdbremote_testcase.GdbRemoteTestCaseBase):
+
+    mydir = TestBase.compute_mydir(__file__)
+
+    FEATURE_NAME = "qXfer:libraries-svr4:read"
+
+    def setup_test(self):
+        self.init_llgs_test()
+        self.build()
+        self.set_inferior_startup_launch()
+        env = {}
+        env[self.dylibPath] = self.getBuildDir()
+        self.prep_debug_monitor_and_inferior(inferior_env=env)
+        self.continue_process_and_wait_for_stop()
+
+    def has_libraries_svr4_support(self):
+        self.add_qSupported_packets()
+        context = self.expect_gdbremote_sequence()
+        self.assertIsNotNone(context)
+        features = self.parse_qSupported_response(context)
+        return self.FEATURE_NAME in features and features[self.FEATURE_NAME] == "+"
+
+    def get_libraries_svr4_data(self):
+        # Start up llgs and inferior, and check for libraries-svr4 support.
+        if not self.has_libraries_svr4_support():
+            self.skipTest("libraries-svr4 not supported")
+
+        # Grab the libraries-svr4 data.
+        self.reset_test_sequence()
+        self.test_sequence.add_log_lines(
+            [
+                "read packet: $qXfer:libraries-svr4:read::0,ffff:#00",
+                {
+                    "direction": "send",
+                    "regex": re.compile(
+                        r"^\$([^E])(.*)#[0-9a-fA-F]{2}$", re.MULTILINE | re.DOTALL
+                    ),
+                    "capture": {1: "response_type", 2: "content_raw"},
+                },
+            ],
+            True,
+        )
+
+        context = self.expect_gdbremote_sequence()
+        self.assertIsNotNone(context)
+
+        # Ensure we end up with all libraries-svr4 data in one packet.
+        self.assertEqual(context.get("response_type"), "l")
+
+        # Decode binary data.
+        content_raw = context.get("content_raw")
+        self.assertIsNotNone(content_raw)
+        return content_raw
+
+    def get_libraries_svr4_xml(self):
+        libraries_svr4 = self.get_libraries_svr4_data()
+        xml_root = None
+        try:
+            xml_root = ET.fromstring(libraries_svr4)
+        except xml.etree.ElementTree.ParseError:
+            pass
+        self.assertIsNotNone(xml_root, "Malformed libraries-svr4 XML")
+        return xml_root
+
+    def libraries_svr4_well_formed(self):
+        xml_root = self.get_libraries_svr4_xml()
+        self.assertEqual(xml_root.tag, "library-list-svr4")
+        for child in xml_root:
+            self.assertEqual(child.tag, "library")
+            self.assertItemsEqual(child.attrib.keys(), ["name", "lm", "l_addr", "l_ld"])
+
+    def libraries_svr4_has_correct_load_addr(self):
+        xml_root = self.get_libraries_svr4_xml()
+        for child in xml_root:
+            name = child.attrib.get("name")
+            if not name:
+                continue
+            load_addr = int(child.attrib.get("l_addr"), 16)
+            self.reset_test_sequence()
+            self.add_query_memory_region_packets(load_addr)
+            context = self.expect_gdbremote_sequence()
+            mem_region = self.parse_memory_region_packet(context)
+            self.assertEqual(load_addr, int(mem_region.get("start", 0), 16))
+            self.assertEqual(
+                os.path.realpath(name), os.path.realpath(mem_region.get("name", ""))
+            )
+
+    def libraries_svr4_libs_present(self):
+        xml_root = self.get_libraries_svr4_xml()
+        libraries_svr4_names = []
+        for child in xml_root:
+            name = child.attrib.get("name")
+            libraries_svr4_names.append(os.path.realpath(name))
+        expected_libs = ["libsvr4lib_a.so", 'libsvr4lib_b".so']
+        for lib in expected_libs:
+            self.assertIn(self.getBuildDir() + "/" + lib, libraries_svr4_names)
+
+    @llgs_test
+    @skipUnlessPlatform(["linux", "android", "netbsd"])
+    def test_supports_libraries_svr4(self):
+        self.setup_test()
+        self.assertTrue(self.has_libraries_svr4_support())
+
+    @llgs_test
+    @skipUnlessPlatform(["linux", "android", "netbsd"])
+    def test_libraries_svr4_well_formed(self):
+        self.setup_test()
+        self.libraries_svr4_well_formed()
+
+    @llgs_test
+    @skipUnlessPlatform(["linux", "android", "netbsd"])
+    def test_libraries_svr4_load_addr(self):
+        self.setup_test()
+        self.libraries_svr4_has_correct_load_addr()
+
+    @llgs_test
+    @skipUnlessPlatform(["linux", "android", "netbsd"])
+    def test_libraries_svr4_libs_present(self):
+        self.setup_test()
+        self.libraries_svr4_libs_present()

lldb/packages/Python/lldbsuite/test/tools/lldb-server/libraries-svr4/main.cpp

@@ -0,0 +1,15 @@
+//===-- main.cpp ------------------------------------------------*- C++ -*-===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+int main(int argc, char **argv) {
+  // Perform a null pointer access.
+  int *const null_int_ptr = nullptr;
+  *null_int_ptr = 0xDEAD;
+
+  return 0;
+}

lldb/packages/Python/lldbsuite/test/tools/lldb-server/libraries-svr4/svr4lib_a.cpp

@@ -0,0 +1,9 @@
+//===-- main.cpp ------------------------------------------------*- C++ -*-===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+int svr4lib_a() { return 42; }

lldb/packages/Python/lldbsuite/test/tools/lldb-server/libraries-svr4/svr4lib_a.mk

@@ -0,0 +1,9 @@
+LEVEL = ../../../make
+
+LIB_PREFIX := svr4lib
+
+DYLIB_NAME := $(LIB_PREFIX)_a
+DYLIB_CXX_SOURCES := $(LIB_PREFIX)_a.cpp
+DYLIB_ONLY := YES
+
+include $(LEVEL)/Makefile.rules

lldb/packages/Python/lldbsuite/test/tools/lldb-server/libraries-svr4/svr4lib_b_quote.cpp

@@ -0,0 +1,9 @@
+//===-- main.cpp ------------------------------------------------*- C++ -*-===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+int svr4lib_b_quote() { return 42; }

lldb/packages/Python/lldbsuite/test/tools/lldb-server/libraries-svr4/svr4lib_b_quote.mk

@@ -0,0 +1,9 @@
+LEVEL = ../../../make
+
+LIB_PREFIX := svr4lib
+
+DYLIB_NAME := $(LIB_PREFIX)_b\"
+DYLIB_CXX_SOURCES := $(LIB_PREFIX)_b_quote.cpp
+DYLIB_ONLY := YES
+
+include $(LEVEL)/Makefile.rules

lldb/source/Plugins/Process/NetBSD/NativeProcessNetBSD.h

@@ -9,12 +9,12 @@
 #ifndef liblldb_NativeProcessNetBSD_H_
 #define liblldb_NativeProcessNetBSD_H_
 
+#include "Plugins/Process/POSIX/NativeProcessELF.h"
 #include "lldb/Target/MemoryRegionInfo.h"
 #include "lldb/Utility/ArchSpec.h"
 #include "lldb/Utility/FileSpec.h"
 
 #include "NativeThreadNetBSD.h"
-#include "lldb/Host/common/NativeProcessProtocol.h"
 
 namespace lldb_private {
 namespace process_netbsd {
@@ -25,7 +25,7 @@ namespace process_netbsd {
 /// for debugging.
 ///
 /// Changes in the inferior process state are broadcasted.
-class NativeProcessNetBSD : public NativeProcessProtocol {
+class NativeProcessNetBSD : public NativeProcessELF {
 public:
   class Factory : public NativeProcessProtocol::Factory {
   public:

lldb/source/Plugins/Process/POSIX/NativeProcessELF.cpp

@@ -107,4 +107,73 @@ lldb::addr_t NativeProcessELF::GetELFImageInfoAddress() {
   return LLDB_INVALID_ADDRESS;
 }
 
+template <typename T>
+llvm::Expected<SVR4LibraryInfo>
+NativeProcessELF::ReadSVR4LibraryInfo(lldb::addr_t link_map_addr) {
+  ELFLinkMap<T> link_map;
+  size_t bytes_read;
+  auto error =
+      ReadMemory(link_map_addr, &link_map, sizeof(link_map), bytes_read);
+  if (!error.Success())
+    return error.ToError();
+
+  char name_buffer[PATH_MAX];
+  error = ReadMemory(link_map.l_name, &name_buffer, sizeof(name_buffer),
+                     bytes_read);
+  if (!error.Success())
+    return error.ToError();
+  name_buffer[PATH_MAX - 1] = '\0';
+
+  SVR4LibraryInfo info;
+  info.name = std::string(name_buffer);
+  info.link_map = link_map_addr;
+  info.base_addr = link_map.l_addr;
+  info.ld_addr = link_map.l_ld;
+  info.next = link_map.l_next;
+
+  return info;
+}
+
+llvm::Expected<std::vector<SVR4LibraryInfo>>
+NativeProcessELF::GetLoadedSVR4Libraries() {
+  // Address of DT_DEBUG.d_ptr which points to r_debug
+  lldb::addr_t info_address = GetSharedLibraryInfoAddress();
+  if (info_address == LLDB_INVALID_ADDRESS)
+    return llvm::createStringError(llvm::inconvertibleErrorCode(),
+                                   "Invalid shared library info address");
+  // Address of r_debug
+  lldb::addr_t address = 0;
+  size_t bytes_read;
+  auto status =
+      ReadMemory(info_address, &address, GetAddressByteSize(), bytes_read);
+  if (!status.Success())
+    return status.ToError();
+  if (address == 0)
+    return llvm::createStringError(llvm::inconvertibleErrorCode(),
+                                   "Invalid r_debug address");
+  // Read r_debug.r_map
+  lldb::addr_t link_map = 0;
+  status = ReadMemory(address + GetAddressByteSize(), &link_map,
+                      GetAddressByteSize(), bytes_read);
+  if (!status.Success())
+    return status.ToError();
+  if (address == 0)
+    return llvm::createStringError(llvm::inconvertibleErrorCode(),
+                                   "Invalid link_map address");
+
+  std::vector<SVR4LibraryInfo> library_list;
+  while (link_map) {
+    llvm::Expected<SVR4LibraryInfo> info =
+        GetAddressByteSize() == 8 ? ReadSVR4LibraryInfo<uint64_t>(link_map)
+                                  : ReadSVR4LibraryInfo<uint32_t>(link_map);
+    if (!info)
+      return info.takeError();
+    if (!info->name.empty() && info->base_addr != 0)
+      library_list.push_back(*info);
+    link_map = info->next;
+  }
+
+  return library_list;
+}
+
 } // namespace lldb_private

lldb/source/Plugins/Process/POSIX/NativeProcessELF.h

@@ -37,6 +37,13 @@ protected:
   template <typename ELF_EHDR, typename ELF_PHDR, typename ELF_DYN>
   lldb::addr_t GetELFImageInfoAddress();
 
+  llvm::Expected<std::vector<SVR4LibraryInfo>>
+  GetLoadedSVR4Libraries() override;
+
+  template <typename T>
+  llvm::Expected<SVR4LibraryInfo>
+  ReadSVR4LibraryInfo(lldb::addr_t link_map_addr);
+
   std::unique_ptr<AuxVector> m_aux_vector;
   llvm::Optional<lldb::addr_t> m_shared_library_info_addr;
 };

lldb/source/Plugins/Process/gdb-remote/GDBRemoteCommunicationServerCommon.cpp

@@ -825,6 +825,7 @@ GDBRemoteCommunicationServerCommon::Handle_qSupported(
 #if defined(__linux__) || defined(__NetBSD__)
   response.PutCString(";QPassSignals+");
   response.PutCString(";qXfer:auxv:read+");
+  response.PutCString(";qXfer:libraries-svr4:read+");
 #endif
 
   return SendPacketNoLock(response.GetString());

lldb/source/Plugins/Process/gdb-remote/GDBRemoteCommunicationServerLLGS.cpp

@@ -2765,6 +2765,24 @@ GDBRemoteCommunicationServerLLGS::ReadXferObject(llvm::StringRef object,
     return std::move(*buffer_or_error);
   }
 
+  if (object == "libraries-svr4") {
+    auto library_list = m_debugged_process_up->GetLoadedSVR4Libraries();
+    if (!library_list)
+      return library_list.takeError();
+
+    StreamString response;
+    response.Printf("<library-list-svr4 version=\"1.0\">");
+    for (auto const &library : *library_list) {
+      response.Printf("<library name=\"%s\" ",
+                      XMLEncodeAttributeValue(library.name.c_str()).c_str());
+      response.Printf("lm=\"0x%" PRIx64 "\" ", library.link_map);
+      response.Printf("l_addr=\"0x%" PRIx64 "\" ", library.base_addr);
+      response.Printf("l_ld=\"0x%" PRIx64 "\" />", library.ld_addr);
+    }
+    response.Printf("</library-list-svr4>");
+    return MemoryBuffer::getMemBufferCopy(response.GetString(), __FUNCTION__);
+  }
+
   return llvm::make_error<PacketUnimplementedError>(
       "Xfer object not supported");
 }
@@ -3283,3 +3301,28 @@ GDBRemoteCommunicationServerLLGS::FindModuleFile(const std::string &module_path,
 
   return GDBRemoteCommunicationServerCommon::FindModuleFile(module_path, arch);
 }
+
+std::string GDBRemoteCommunicationServerLLGS::XMLEncodeAttributeValue(
+    llvm::StringRef value) {
+  std::string result;
+  for (const char &c : value) {
+    switch (c) {
+    case '\'':
+      result += "&apos;";
+      break;
+    case '"':
+      result += "&quot;";
+      break;
+    case '<':
+      result += "&lt;";
+      break;
+    case '>':
+      result += "&gt;";
+      break;
+    default:
+      result += c;
+      break;
+    }
+  }
+  return result;
+}

lldb/source/Plugins/Process/gdb-remote/GDBRemoteCommunicationServerLLGS.h

@@ -196,6 +196,8 @@ protected:
   llvm::Expected<std::unique_ptr<llvm::MemoryBuffer>>
   ReadXferObject(llvm::StringRef object, llvm::StringRef annex);
 
+  static std::string XMLEncodeAttributeValue(llvm::StringRef value);
+
 private:
   void HandleInferiorState_Exited(NativeProcessProtocol *process);