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

2 files changed, 76 insertions, 0 deletions

diff --git a/lldb/source/Plugins/Process/POSIX/NativeProcessELF.cpp b/lldb/source/Plugins/Process/POSIX/NativeProcessELF.cpp
index 559b16c8fd6..3e08eccb9df 100644
--- a/lldb/source/Plugins/Process/POSIX/NativeProcessELF.cpp
+++ b/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
\ No newline at end of file
diff --git a/lldb/source/Plugins/Process/POSIX/NativeProcessELF.h b/lldb/source/Plugins/Process/POSIX/NativeProcessELF.h
index 84dc8d08a34..4fb513baebf 100644
--- a/lldb/source/Plugins/Process/POSIX/NativeProcessELF.h
+++ b/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;
 };