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// Copyright (c) 2006, Google Inc.
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// All rights reserved.
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// Redistribution and use in source and binary forms, with or without
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// modification, are permitted provided that the following conditions are
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// * Redistributions of source code must retain the above copyright
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// notice, this list of conditions and the following disclaimer.
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// * Redistributions in binary form must reproduce the above
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// copyright notice, this list of conditions and the following disclaimer
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// in the documentation and/or other materials provided with the
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// * Neither the name of Google Inc. nor the names of its
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// contributors may be used to endorse or promote products derived from
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// this software without specific prior written permission.
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// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
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// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
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// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
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// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
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// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
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// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
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// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
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// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
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// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
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// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
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// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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// file_id.cc: Return a unique identifier for a file
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// See file_id.h for documentation
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#include "common/linux/file_id.h"
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#include <arpa/inet.h>
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#if defined(__ANDROID__)
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#include <linux/elf.h>
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#include "client/linux/android_link.h"
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#include "common/linux/linux_libc_support.h"
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#include "common/linux/memory_mapped_file.h"
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#include "third_party/lss/linux_syscall_support.h"
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namespace google_breakpad {
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#ifndef NT_GNU_BUILD_ID
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#define NT_GNU_BUILD_ID 3
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FileID::FileID(const char* path) {
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strncpy(path_, path, sizeof(path_));
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typedef Elf32_Ehdr Ehdr;
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typedef Elf32_Nhdr Nhdr;
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typedef Elf32_Shdr Shdr;
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static const int kClass = ELFCLASS32;
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typedef Elf64_Ehdr Ehdr;
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typedef Elf64_Nhdr Nhdr;
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typedef Elf64_Shdr Shdr;
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static const int kClass = ELFCLASS64;
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// These six functions are also used inside the crashed process, so be safe
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// and use the syscall/libc wrappers instead of direct syscalls or libc.
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template<typename ElfClass>
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static void FindElfClassSection(const char *elf_base,
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const char *section_name,
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uint32_t section_type,
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const void **section_start,
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typedef typename ElfClass::Ehdr Ehdr;
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typedef typename ElfClass::Shdr Shdr;
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assert(section_start);
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assert(my_strncmp(elf_base, ELFMAG, SELFMAG) == 0);
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int name_len = my_strlen(section_name);
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const Ehdr* elf_header = reinterpret_cast<const Ehdr*>(elf_base);
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assert(elf_header->e_ident[EI_CLASS] == ElfClass::kClass);
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const Shdr* sections =
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reinterpret_cast<const Shdr*>(elf_base + elf_header->e_shoff);
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const Shdr* string_section = sections + elf_header->e_shstrndx;
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const Shdr* section = NULL;
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for (int i = 0; i < elf_header->e_shnum; ++i) {
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if (sections[i].sh_type == section_type) {
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const char* current_section_name = (char*)(elf_base +
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string_section->sh_offset +
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sections[i].sh_name);
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if (!my_strncmp(current_section_name, section_name, name_len)) {
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section = §ions[i];
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if (section != NULL && section->sh_size > 0) {
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*section_start = elf_base + section->sh_offset;
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*section_size = section->sh_size;
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// Attempt to find a section named |section_name| of type |section_type|
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// in the ELF binary data at |elf_mapped_base|. On success, returns true
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// and sets |*section_start| to point to the start of the section data,
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// and |*section_size| to the size of the section's data. If |elfclass|
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// is not NULL, set |*elfclass| to the ELF file class.
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static bool FindElfSection(const void *elf_mapped_base,
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const char *section_name,
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uint32_t section_type,
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const void **section_start,
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assert(elf_mapped_base);
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assert(section_start);
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assert(section_size);
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*section_start = NULL;
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const char* elf_base =
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static_cast<const char*>(elf_mapped_base);
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const ElfW(Ehdr)* elf_header =
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reinterpret_cast<const ElfW(Ehdr)*>(elf_base);
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if (my_strncmp(elf_base, ELFMAG, SELFMAG) != 0)
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*elfclass = elf_header->e_ident[EI_CLASS];
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if (elf_header->e_ident[EI_CLASS] == ELFCLASS32) {
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FindElfClassSection<ElfClass32>(elf_base, section_name, section_type,
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section_start, section_size);
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return *section_start != NULL;
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} else if (elf_header->e_ident[EI_CLASS] == ELFCLASS64) {
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FindElfClassSection<ElfClass64>(elf_base, section_name, section_type,
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section_start, section_size);
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return *section_start != NULL;
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template<typename ElfClass>
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static bool ElfClassBuildIDNoteIdentifier(const void *section,
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uint8_t identifier[kMDGUIDSize]) {
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typedef typename ElfClass::Nhdr Nhdr;
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const Nhdr* note_header = reinterpret_cast<const Nhdr*>(section);
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if (note_header->n_type != NT_GNU_BUILD_ID ||
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note_header->n_descsz == 0) {
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const char* build_id = reinterpret_cast<const char*>(section) +
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sizeof(Nhdr) + note_header->n_namesz;
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// Copy as many bits of the build ID as will fit
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// into the GUID space.
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my_memset(identifier, 0, kMDGUIDSize);
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memcpy(identifier, build_id,
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std::min(kMDGUIDSize, (size_t)note_header->n_descsz));
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// Attempt to locate a .note.gnu.build-id section in an ELF binary
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// and copy as many bytes of it as will fit into |identifier|.
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static bool FindElfBuildIDNote(const void *elf_mapped_base,
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uint8_t identifier[kMDGUIDSize]) {
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int note_size, elfclass;
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if (!FindElfSection(elf_mapped_base, ".note.gnu.build-id", SHT_NOTE,
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(const void**)¬e_section, ¬e_size, &elfclass) ||
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if (elfclass == ELFCLASS32) {
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return ElfClassBuildIDNoteIdentifier<ElfClass32>(note_section, identifier);
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} else if (elfclass == ELFCLASS64) {
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return ElfClassBuildIDNoteIdentifier<ElfClass64>(note_section, identifier);
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// Attempt to locate the .text section of an ELF binary and generate
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// a simple hash by XORing the first page worth of bytes into |identifier|.
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static bool HashElfTextSection(const void *elf_mapped_base,
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uint8_t identifier[kMDGUIDSize]) {
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if (!FindElfSection(elf_mapped_base, ".text", SHT_PROGBITS,
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(const void**)&text_section, &text_size, NULL) ||
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my_memset(identifier, 0, kMDGUIDSize);
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const uint8_t* ptr = reinterpret_cast<const uint8_t*>(text_section);
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const uint8_t* ptr_end = ptr + std::min(text_size, 4096);
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while (ptr < ptr_end) {
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for (unsigned i = 0; i < kMDGUIDSize; i++)
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identifier[i] ^= ptr[i];
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bool FileID::ElfFileIdentifierFromMappedFile(const void* base,
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uint8_t identifier[kMDGUIDSize]) {
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// Look for a build id note first.
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if (FindElfBuildIDNote(base, identifier))
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// Fall back on hashing the first page of the text section.
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return HashElfTextSection(base, identifier);
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bool FileID::ElfFileIdentifier(uint8_t identifier[kMDGUIDSize]) {
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MemoryMappedFile mapped_file(path_);
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if (!mapped_file.data()) // Should probably check if size >= ElfW(Ehdr)?
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return ElfFileIdentifierFromMappedFile(mapped_file.data(), identifier);
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void FileID::ConvertIdentifierToString(const uint8_t identifier[kMDGUIDSize],
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char* buffer, int buffer_length) {
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uint8_t identifier_swapped[kMDGUIDSize];
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// Endian-ness swap to match dump processor expectation.
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memcpy(identifier_swapped, identifier, kMDGUIDSize);
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uint32_t* data1 = reinterpret_cast<uint32_t*>(identifier_swapped);
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*data1 = htonl(*data1);
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uint16_t* data2 = reinterpret_cast<uint16_t*>(identifier_swapped + 4);
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*data2 = htons(*data2);
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uint16_t* data3 = reinterpret_cast<uint16_t*>(identifier_swapped + 6);
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*data3 = htons(*data3);
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for (unsigned int idx = 0;
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(buffer_idx < buffer_length) && (idx < kMDGUIDSize);
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int hi = (identifier_swapped[idx] >> 4) & 0x0F;
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int lo = (identifier_swapped[idx]) & 0x0F;
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if (idx == 4 || idx == 6 || idx == 8 || idx == 10)
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buffer[buffer_idx++] = '-';
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buffer[buffer_idx++] = (hi >= 10) ? 'A' + hi - 10 : '0' + hi;
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buffer[buffer_idx++] = (lo >= 10) ? 'A' + lo - 10 : '0' + lo;
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buffer[(buffer_idx < buffer_length) ? buffer_idx : buffer_idx - 1] = 0;
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} // namespace google_breakpad
added
removed
thirdparty/breakpad/common/linux/file_id.cc
