michael@0: // Copyright (c) 2012, Google Inc.
michael@0: // All rights reserved.
michael@0: //
michael@0: // Redistribution and use in source and binary forms, with or without
michael@0: // modification, are permitted provided that the following conditions are
michael@0: // met:
michael@0: //
michael@0: //     * Redistributions of source code must retain the above copyright
michael@0: // notice, this list of conditions and the following disclaimer.
michael@0: //     * Redistributions in binary form must reproduce the above
michael@0: // copyright notice, this list of conditions and the following disclaimer
michael@0: // in the documentation and/or other materials provided with the
michael@0: // distribution.
michael@0: //     * Neither the name of Google Inc. nor the names of its
michael@0: // contributors may be used to endorse or promote products derived from
michael@0: // this software without specific prior written permission.
michael@0: //
michael@0: // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
michael@0: // "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
michael@0: // LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
michael@0: // A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
michael@0: // OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
michael@0: // SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
michael@0: // LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
michael@0: // DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
michael@0: // THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
michael@0: // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
michael@0: // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
michael@0: 
michael@0: #include "common/linux/elfutils.h"
michael@0: 
michael@0: #include <assert.h>
michael@0: #include <string.h>
michael@0: 
michael@0: #include "common/linux/linux_libc_support.h"
michael@0: #include "common/linux/elfutils-inl.h"
michael@0: 
michael@0: namespace google_breakpad {
michael@0: 
michael@0: namespace {
michael@0: 
michael@0: template<typename ElfClass>
michael@0: void FindElfClassSection(const char *elf_base,
michael@0:                          const char *section_name,
michael@0:                          typename ElfClass::Word section_type,
michael@0:                          const void **section_start,
michael@0:                          int *section_size) {
michael@0:   typedef typename ElfClass::Ehdr Ehdr;
michael@0:   typedef typename ElfClass::Shdr Shdr;
michael@0: 
michael@0:   assert(elf_base);
michael@0:   assert(section_start);
michael@0:   assert(section_size);
michael@0: 
michael@0:   assert(my_strncmp(elf_base, ELFMAG, SELFMAG) == 0);
michael@0: 
michael@0:   const Ehdr* elf_header = reinterpret_cast<const Ehdr*>(elf_base);
michael@0:   assert(elf_header->e_ident[EI_CLASS] == ElfClass::kClass);
michael@0: 
michael@0:   const Shdr* sections =
michael@0:     GetOffset<ElfClass,Shdr>(elf_header, elf_header->e_shoff);
michael@0:   const Shdr* section_names = sections + elf_header->e_shstrndx;
michael@0:   const char* names =
michael@0:     GetOffset<ElfClass,char>(elf_header, section_names->sh_offset);
michael@0:   const char *names_end = names + section_names->sh_size;
michael@0: 
michael@0:   const Shdr* section =
michael@0:     FindElfSectionByName<ElfClass>(section_name, section_type,
michael@0:                                    sections, names, names_end,
michael@0:                                    elf_header->e_shnum);
michael@0: 
michael@0:   if (section != NULL && section->sh_size > 0) {
michael@0:     *section_start = elf_base + section->sh_offset;
michael@0:     *section_size = section->sh_size;
michael@0:   }
michael@0: }
michael@0: 
michael@0: template<typename ElfClass>
michael@0: void FindElfClassSegment(const char *elf_base,
michael@0:                          typename ElfClass::Word segment_type,
michael@0:                          const void **segment_start,
michael@0:                          int *segment_size) {
michael@0:   typedef typename ElfClass::Ehdr Ehdr;
michael@0:   typedef typename ElfClass::Phdr Phdr;
michael@0: 
michael@0:   assert(elf_base);
michael@0:   assert(segment_start);
michael@0:   assert(segment_size);
michael@0: 
michael@0:   assert(my_strncmp(elf_base, ELFMAG, SELFMAG) == 0);
michael@0: 
michael@0:   const Ehdr* elf_header = reinterpret_cast<const Ehdr*>(elf_base);
michael@0:   assert(elf_header->e_ident[EI_CLASS] == ElfClass::kClass);
michael@0: 
michael@0:   const Phdr* phdrs =
michael@0:     GetOffset<ElfClass,Phdr>(elf_header, elf_header->e_phoff);
michael@0: 
michael@0:   for (int i = 0; i < elf_header->e_phnum; ++i) {
michael@0:     if (phdrs[i].p_type == segment_type) {
michael@0:       *segment_start = elf_base + phdrs[i].p_offset;
michael@0:       *segment_size = phdrs[i].p_filesz;
michael@0:       return;
michael@0:     }
michael@0:   }
michael@0: }
michael@0: 
michael@0: }  // namespace
michael@0: 
michael@0: bool IsValidElf(const void* elf_base) {
michael@0:   return my_strncmp(reinterpret_cast<const char*>(elf_base),
michael@0:                     ELFMAG, SELFMAG) == 0;
michael@0: }
michael@0: 
michael@0: int ElfClass(const void* elf_base) {
michael@0:   const ElfW(Ehdr)* elf_header =
michael@0:     reinterpret_cast<const ElfW(Ehdr)*>(elf_base);
michael@0: 
michael@0:   return elf_header->e_ident[EI_CLASS];
michael@0: }
michael@0: 
michael@0: bool FindElfSection(const void *elf_mapped_base,
michael@0:                     const char *section_name,
michael@0:                     uint32_t section_type,
michael@0:                     const void **section_start,
michael@0:                     int *section_size,
michael@0:                     int *elfclass) {
michael@0:   assert(elf_mapped_base);
michael@0:   assert(section_start);
michael@0:   assert(section_size);
michael@0: 
michael@0:   *section_start = NULL;
michael@0:   *section_size = 0;
michael@0: 
michael@0:   if (!IsValidElf(elf_mapped_base))
michael@0:     return false;
michael@0: 
michael@0:   int cls = ElfClass(elf_mapped_base);
michael@0:   if (elfclass) {
michael@0:     *elfclass = cls;
michael@0:   }
michael@0: 
michael@0:   const char* elf_base =
michael@0:     static_cast<const char*>(elf_mapped_base);
michael@0: 
michael@0:   if (cls == ELFCLASS32) {
michael@0:     FindElfClassSection<ElfClass32>(elf_base, section_name, section_type,
michael@0:                                     section_start, section_size);
michael@0:     return *section_start != NULL;
michael@0:   } else if (cls == ELFCLASS64) {
michael@0:     FindElfClassSection<ElfClass64>(elf_base, section_name, section_type,
michael@0:                                     section_start, section_size);
michael@0:     return *section_start != NULL;
michael@0:   }
michael@0: 
michael@0:   return false;
michael@0: }
michael@0: 
michael@0: bool FindElfSegment(const void *elf_mapped_base,
michael@0:                     uint32_t segment_type,
michael@0:                     const void **segment_start,
michael@0:                     int *segment_size,
michael@0:                     int *elfclass) {
michael@0:   assert(elf_mapped_base);
michael@0:   assert(segment_start);
michael@0:   assert(segment_size);
michael@0: 
michael@0:   *segment_start = NULL;
michael@0:   *segment_size = 0;
michael@0: 
michael@0:   if (!IsValidElf(elf_mapped_base))
michael@0:     return false;
michael@0: 
michael@0:   int cls = ElfClass(elf_mapped_base);
michael@0:   if (elfclass) {
michael@0:     *elfclass = cls;
michael@0:   }
michael@0: 
michael@0:   const char* elf_base =
michael@0:     static_cast<const char*>(elf_mapped_base);
michael@0: 
michael@0:   if (cls == ELFCLASS32) {
michael@0:     FindElfClassSegment<ElfClass32>(elf_base, segment_type,
michael@0:                                     segment_start, segment_size);
michael@0:     return *segment_start != NULL;
michael@0:   } else if (cls == ELFCLASS64) {
michael@0:     FindElfClassSegment<ElfClass64>(elf_base, segment_type,
michael@0:                                     segment_start, segment_size);
michael@0:     return *segment_start != NULL;
michael@0:   }
michael@0: 
michael@0:   return false;
michael@0: }
michael@0: 
michael@0: }  // namespace google_breakpad