Cache memory regions in ProcessMinidump and use the linux maps as the source of the information if available

Breakpad creates minidump files that sometimes have:
- linux maps textual content
- no MemoryInfoList

Right now unless the file has a MemoryInfoList we get no region information.

This patch:

- reads and caches the memory region info one time and sorts it for easy subsequent access
- get the region info from the best source in this order:
  - linux maps info (if available)
  - MemoryInfoList (if available)
  - MemoryList or Memory64List
- returns memory region info for the gaps between regions (before the first and after the last)

Differential Revision: https://reviews.llvm.org/D55522

llvm-svn: 349182

3 files changed, 142 insertions, 0 deletions

diff --git a/lldb/source/Plugins/Process/Utility/CMakeLists.txt b/lldb/source/Plugins/Process/Utility/CMakeLists.txt
index b43756acea6..e36ce4dec98 100644
--- a/lldb/source/Plugins/Process/Utility/CMakeLists.txt
+++ b/lldb/source/Plugins/Process/Utility/CMakeLists.txt
@@ -5,6 +5,7 @@ add_lldb_library(lldbPluginProcessUtility PLUGIN
   HistoryThread.cpp
   HistoryUnwind.cpp
   InferiorCallPOSIX.cpp
+  LinuxProcMaps.cpp
   LinuxSignals.cpp
   MipsLinuxSignals.cpp
   NativeRegisterContextRegisterInfo.cpp
diff --git a/lldb/source/Plugins/Process/Utility/LinuxProcMaps.cpp b/lldb/source/Plugins/Process/Utility/LinuxProcMaps.cpp
new file mode 100644
index 00000000000..d45bf6dcd84
--- /dev/null
+++ b/lldb/source/Plugins/Process/Utility/LinuxProcMaps.cpp
@@ -0,0 +1,113 @@
+//===-- LinuxProcMaps.cpp ---------------------------------------*- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#include "LinuxProcMaps.h"
+#include "llvm/ADT/StringRef.h"
+#include "lldb/Target/MemoryRegionInfo.h"
+#include "lldb/Utility/Status.h"
+#include "lldb/Utility/StringExtractor.h"
+
+using namespace lldb_private;
+
+static Status
+ParseMemoryRegionInfoFromProcMapsLine(llvm::StringRef maps_line,
+                                      MemoryRegionInfo &memory_region_info) {
+  memory_region_info.Clear();
+  
+  StringExtractor line_extractor(maps_line);
+  
+  // Format: {address_start_hex}-{address_end_hex} perms offset  dev   inode
+  // pathname perms: rwxp   (letter is present if set, '-' if not, final
+  // character is p=private, s=shared).
+  
+  // Parse out the starting address
+  lldb::addr_t start_address = line_extractor.GetHexMaxU64(false, 0);
+  
+  // Parse out hyphen separating start and end address from range.
+  if (!line_extractor.GetBytesLeft() || (line_extractor.GetChar() != '-'))
+    return Status(
+        "malformed /proc/{pid}/maps entry, missing dash between address range");
+  
+  // Parse out the ending address
+  lldb::addr_t end_address = line_extractor.GetHexMaxU64(false, start_address);
+  
+  // Parse out the space after the address.
+  if (!line_extractor.GetBytesLeft() || (line_extractor.GetChar() != ' '))
+    return Status(
+        "malformed /proc/{pid}/maps entry, missing space after range");
+  
+  // Save the range.
+  memory_region_info.GetRange().SetRangeBase(start_address);
+  memory_region_info.GetRange().SetRangeEnd(end_address);
+  
+  // Any memory region in /proc/{pid}/maps is by definition mapped into the
+  // process.
+  memory_region_info.SetMapped(MemoryRegionInfo::OptionalBool::eYes);
+  
+  // Parse out each permission entry.
+  if (line_extractor.GetBytesLeft() < 4)
+    return Status("malformed /proc/{pid}/maps entry, missing some portion of "
+                  "permissions");
+  
+  // Handle read permission.
+  const char read_perm_char = line_extractor.GetChar();
+  if (read_perm_char == 'r')
+    memory_region_info.SetReadable(MemoryRegionInfo::OptionalBool::eYes);
+  else if (read_perm_char == '-')
+    memory_region_info.SetReadable(MemoryRegionInfo::OptionalBool::eNo);
+  else
+    return Status("unexpected /proc/{pid}/maps read permission char");
+  
+  // Handle write permission.
+  const char write_perm_char = line_extractor.GetChar();
+  if (write_perm_char == 'w')
+    memory_region_info.SetWritable(MemoryRegionInfo::OptionalBool::eYes);
+  else if (write_perm_char == '-')
+    memory_region_info.SetWritable(MemoryRegionInfo::OptionalBool::eNo);
+  else
+    return Status("unexpected /proc/{pid}/maps write permission char");
+  
+  // Handle execute permission.
+  const char exec_perm_char = line_extractor.GetChar();
+  if (exec_perm_char == 'x')
+    memory_region_info.SetExecutable(MemoryRegionInfo::OptionalBool::eYes);
+  else if (exec_perm_char == '-')
+    memory_region_info.SetExecutable(MemoryRegionInfo::OptionalBool::eNo);
+  else
+    return Status("unexpected /proc/{pid}/maps exec permission char");
+  
+  line_extractor.GetChar();              // Read the private bit
+  line_extractor.SkipSpaces();           // Skip the separator
+  line_extractor.GetHexMaxU64(false, 0); // Read the offset
+  line_extractor.GetHexMaxU64(false, 0); // Read the major device number
+  line_extractor.GetChar();              // Read the device id separator
+  line_extractor.GetHexMaxU64(false, 0); // Read the major device number
+  line_extractor.SkipSpaces();           // Skip the separator
+  line_extractor.GetU64(0, 10);          // Read the inode number
+  
+  line_extractor.SkipSpaces();
+  const char *name = line_extractor.Peek();
+  if (name)
+    memory_region_info.SetName(name);
+  
+  return Status();
+}
+
+void lldb_private::ParseLinuxMapRegions(llvm::StringRef linux_map,
+                                        LinuxMapCallback const &callback) {
+  llvm::StringRef lines(linux_map);
+  llvm::StringRef line;
+  while (!lines.empty()) {
+    std::tie(line, lines) = lines.split('\n');
+    MemoryRegionInfo region;
+    Status error = ParseMemoryRegionInfoFromProcMapsLine(line, region);
+    if (!callback(region, error))
+      break;
+  }
+}
diff --git a/lldb/source/Plugins/Process/Utility/LinuxProcMaps.h b/lldb/source/Plugins/Process/Utility/LinuxProcMaps.h
new file mode 100644
index 00000000000..e6eabb28fc8
--- /dev/null
+++ b/lldb/source/Plugins/Process/Utility/LinuxProcMaps.h
@@ -0,0 +1,28 @@
+//===-- LinuxProcMaps.h -----------------------------------------*- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef liblldb_LinuxProcMaps_H_
+#define liblldb_LinuxProcMaps_H_
+
+#include "lldb/lldb-forward.h"
+#include "llvm/ADT/StringRef.h"
+#include <functional>
+
+
+namespace lldb_private {
+
+typedef std::function<bool(const lldb_private::MemoryRegionInfo &,
+                           const lldb_private::Status &)> LinuxMapCallback;
+
+void ParseLinuxMapRegions(llvm::StringRef linux_map,
+                          LinuxMapCallback const &callback);
+
+} // namespace lldb_private
+
+#endif // liblldb_LinuxProcMaps_H_