Switch the Linux minidump writer to use MDCVInfoELF for CV data.

src/common/linux/file_id.cc

 // Copyright (c) 2006, Google Inc.
 // All rights reserved.
 //
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 // notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
@@ skipping 30 matching lines @@
 #include <algorithm>
 
 #include "common/linux/elf_gnu_compat.h"
 #include "common/linux/elfutils.h"
 #include "common/linux/linux_libc_support.h"
 #include "common/linux/memory_mapped_file.h"
 #include "third_party/lss/linux_syscall_support.h"
 
 namespace google_breakpad {
 
+// Used in a few places for backwards-compatibility.
+const size_t kMDGUIDSize = sizeof(MDGUID);
+
 FileID::FileID(const char* path) : path_(path) {}
 
 // ELF note name and desc are 32-bits word padded.
 #define NOTE_PADDING(a) ((a + 3) & ~3)
 
 // These functions are also used inside the crashed process, so be safe
 // and use the syscall/libc wrappers instead of direct syscalls or libc.
 
 template<typename ElfClass>
 static bool ElfClassBuildIDNoteIdentifier(const void *section, size_t length,
-                                          uint8_t identifier[kMDGUIDSize]) {
+                                          uint8_t identifier[kMaxBuildID],
+                                          size_t* identifier_length) {
   typedef typename ElfClass::Nhdr Nhdr;
 
+  assert(identifier_length);
+
   const void* section_end = reinterpret_cast<const char*>(section) + length;
   const Nhdr* note_header = reinterpret_cast<const Nhdr*>(section);
   while (reinterpret_cast<const void *>(note_header) < section_end) {
     if (note_header->n_type == NT_GNU_BUILD_ID)
       break;
     note_header = reinterpret_cast<const Nhdr*>(
                   reinterpret_cast<const char*>(note_header) + sizeof(Nhdr) +
                   NOTE_PADDING(note_header->n_namesz) +
                   NOTE_PADDING(note_header->n_descsz));
   }
   if (reinterpret_cast<const void *>(note_header) >= section_end ||
       note_header->n_descsz == 0) {
     return false;
   }
 
-  const char* build_id = reinterpret_cast<const char*>(note_header) +
+  const uint8_t* build_id = reinterpret_cast<const uint8_t*>(note_header) +
     sizeof(Nhdr) + NOTE_PADDING(note_header->n_namesz);
   // Copy as many bits of the build ID as will fit
-  // into the GUID space.
-  my_memset(identifier, 0, kMDGUIDSize);
-  memcpy(identifier, build_id,
-         std::min(kMDGUIDSize, (size_t)note_header->n_descsz));
+  // into |identifier|. This should always fit unless someone has
+  // passed --build-id=0x... to the linker with a longer-than-standard
+  // hex string.
+  my_memset(identifier, 0, kMaxBuildID);
+  *identifier_length = std::min(kMaxBuildID, (size_t)note_header->n_descsz);
+  memcpy(identifier, build_id, *identifier_length);
 
   return true;
 }
 
 // Attempt to locate a .note.gnu.build-id section in an ELF binary
 // and copy as many bytes of it as will fit into |identifier|.
+// Set |*identifier_length| to the number of bytes copied.
 static bool FindElfBuildIDNote(const void *elf_mapped_base,
-                               uint8_t identifier[kMDGUIDSize]) {
+                               uint8_t identifier[kMaxBuildID],
+                               size_t* identifier_length) {
+  assert(identifier_length);
   void* note_section;
   size_t note_size;
   int elfclass;
   if ((!FindElfSegment(elf_mapped_base, PT_NOTE,
                        (const void**)&note_section, &note_size, &elfclass) ||
       note_size == 0)  &&
       (!FindElfSection(elf_mapped_base, ".note.gnu.build-id", SHT_NOTE,
                        (const void**)&note_section, &note_size, &elfclass) ||
       note_size == 0)) {
     return false;
   }
 
   if (elfclass == ELFCLASS32) {
     return ElfClassBuildIDNoteIdentifier<ElfClass32>(note_section, note_size,
-                                                     identifier);
+                                                     identifier,
+                                                     identifier_length);
   } else if (elfclass == ELFCLASS64) {
     return ElfClassBuildIDNoteIdentifier<ElfClass64>(note_section, note_size,
-                                                     identifier);
+                                                     identifier,
+                                                     identifier_length);
   }
 
   return false;
 }
 
 // Attempt to locate the .text section of an ELF binary and generate
 // a simple hash by XORing the first page worth of bytes into |identifier|.
 static bool HashElfTextSection(const void *elf_mapped_base,
-                               uint8_t identifier[kMDGUIDSize]) {
+                               uint8_t identifier[kMaxBuildID],
+                               size_t* identifier_length) {
+  assert(identifier_length);
   void* text_section;
   size_t text_size;
   if (!FindElfSection(elf_mapped_base, ".text", SHT_PROGBITS,
                       (const void**)&text_section, &text_size, NULL) ||
       text_size == 0) {
     return false;
   }
 
+  // Only provide |kMDGUIDSize| bytes to keep identifiers produced by this
+  // function backwards-compatible.
   my_memset(identifier, 0, kMDGUIDSize);
   const uint8_t* ptr = reinterpret_cast<const uint8_t*>(text_section);
   const uint8_t* ptr_end = ptr + std::min(text_size, static_cast<size_t>(4096));
   while (ptr < ptr_end) {
     for (unsigned i = 0; i < kMDGUIDSize; i++)
       identifier[i] ^= ptr[i];
     ptr += kMDGUIDSize;
   }
+  *identifier_length = kMDGUIDSize;
   return true;
 }
 
 // static
 bool FileID::ElfFileIdentifierFromMappedFile(const void* base,
-                                             uint8_t identifier[kMDGUIDSize]) {
+                                             uint8_t identifier[kMaxBuildID],
+                                             size_t* identifier_length) {
   // Look for a build id note first.
-  if (FindElfBuildIDNote(base, identifier))
+  if (FindElfBuildIDNote(base, identifier, identifier_length))
     return true;
 
   // Fall back on hashing the first page of the text section.
-  return HashElfTextSection(base, identifier);
+  return HashElfTextSection(base, identifier, identifier_length);
 }
 
-bool FileID::ElfFileIdentifier(uint8_t identifier[kMDGUIDSize]) {
+bool FileID::ElfFileIdentifier(uint8_t identifier[kMaxBuildID],
+                               size_t* identifier_length) {
   MemoryMappedFile mapped_file(path_.c_str(), 0);
   if (!mapped_file.data())  // Should probably check if size >= ElfW(Ehdr)?
     return false;
 
-  return ElfFileIdentifierFromMappedFile(mapped_file.data(), identifier);
+  return ElfFileIdentifierFromMappedFile(mapped_file.data(), identifier,
+                                         identifier_length);
 }
 
 // static
-void FileID::ConvertIdentifierToString(const uint8_t identifier[kMDGUIDSize],
+void FileID::ConvertIdentifierToString(const uint8_t identifier[kMaxBuildID],
                                        char* buffer, int buffer_length) {
   uint8_t identifier_swapped[kMDGUIDSize];
 
   // Endian-ness swap to match dump processor expectation.
   memcpy(identifier_swapped, identifier, kMDGUIDSize);
   uint32_t* data1 = reinterpret_cast<uint32_t*>(identifier_swapped);
   *data1 = htonl(*data1);
   uint16_t* data2 = reinterpret_cast<uint16_t*>(identifier_swapped + 4);
   *data2 = htons(*data2);
   uint16_t* data3 = reinterpret_cast<uint16_t*>(identifier_swapped + 6);
@@ skipping 11 matching lines @@
 
     buffer[buffer_idx++] = (hi >= 10) ? 'A' + hi - 10 : '0' + hi;
     buffer[buffer_idx++] = (lo >= 10) ? 'A' + lo - 10 : '0' + lo;
   }
 
   // NULL terminate
   buffer[(buffer_idx < buffer_length) ? buffer_idx : buffer_idx - 1] = 0;
 }
 
 }  // namespace google_breakpad