text: // Copyright (c) 2007, 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
  // copyright notice, this list of conditions and the following disclaimer
  // in the documentation and/or other materials provided with the
  // distribution.
  //     * Neither the name of Google Inc. nor the names of its
  // contributors may be used to endorse or promote products derived from
  // this software without specific prior written permission.
  //
  // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
  // "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
  // LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
  // A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
  // OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
  // SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
  // LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
  // DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
  // THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  // (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  // OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  
  // file_id.cc: Return a unique identifier for a file
  //
  // See file_id.h for documentation
  //
  // Author: Alfred Peng
  
  #include <elf.h>
  #include <fcntl.h>
  #include <gelf.h>
  #include <sys/mman.h>
  #include <sys/ksyms.h>
  #include <stdio.h>
  #include <string.h>
  #include <unistd.h>
  
  #include <cassert>
  #include <cstdio>
  
  #include "common/md5.h"
  #include "common/solaris/file_id.h"
  #include "common/solaris/message_output.h"
  #include "google_breakpad/common/minidump_format.h"
  
  namespace google_breakpad {
  
  class AutoElfEnder {
   public:
    AutoElfEnder(Elf *elf) : elf_(elf) {}
    ~AutoElfEnder() { if (elf_) elf_end(elf_); }
   private:
    Elf *elf_;
  };
  
  // Find the text section in elf object file.
  // Return the section start address and the size.
  static bool FindElfTextSection(int fd, const void *elf_base,
                                 const void **text_start,
                                 int *text_size) {
    assert(text_start);
    assert(text_size);
  
    *text_start = NULL;
    *text_size = 0;
  
    if (elf_version(EV_CURRENT) == EV_NONE) {
      print_message2(2, "elf_version() failed: %s\n", elf_errmsg(0));
      return false;
    }
  
    GElf_Ehdr elf_header;
    lseek(fd, 0L, 0);
    Elf *elf = elf_begin(fd, ELF_C_READ, NULL);
    AutoElfEnder elfEnder(elf);
  
    if (gelf_getehdr(elf, &elf_header) == (GElf_Ehdr *)NULL) {
      print_message2(2, "failed to read elf header: %s\n", elf_errmsg(-1));
      return false;
    }
  
    if (elf_header.e_ident[EI_MAG0] != ELFMAG0 ||
        elf_header.e_ident[EI_MAG1] != ELFMAG1 ||
        elf_header.e_ident[EI_MAG2] != ELFMAG2 ||
        elf_header.e_ident[EI_MAG3] != ELFMAG3) {
      print_message1(2, "header magic doesn't match\n");
      return false;
    }
  
    static const char kTextSectionName[] = ".text";
    const GElf_Shdr *text_section = NULL;
    Elf_Scn *scn = NULL;
    GElf_Shdr shdr;
  
    while ((scn = elf_nextscn(elf, scn)) != NULL) {
      if (gelf_getshdr(scn, &shdr) == (GElf_Shdr *)0) {
        print_message2(2, "failed to read section header: %s\n", elf_errmsg(0));
        return false;
      }
  
      if (shdr.sh_type == SHT_PROGBITS) {
        const char *section_name = elf_strptr(elf, elf_header.e_shstrndx,
                                              shdr.sh_name);
        if (!section_name) {
          print_message2(2, "Section name error: %s\n", elf_errmsg(-1));
          continue;
        }
  
        if (strcmp(section_name, kTextSectionName) == 0) {
          text_section = &shdr;
          break;
        }
      }
    }
    if (text_section != NULL && text_section->sh_size > 0) {
      *text_start = (char *)elf_base + text_section->sh_offset;
      *text_size = text_section->sh_size;
      return true;
    }
  
    return false;
  }
  
  FileID::FileID(const char *path) {
    strcpy(path_, path);
  }
  
  class AutoCloser {
   public:
    AutoCloser(int fd) : fd_(fd) {}
    ~AutoCloser() { if (fd_) close(fd_); }
   private:
    int fd_;
  };
  
  bool FileID::ElfFileIdentifier(unsigned char identifier[16]) {
    int fd = 0;
    if ((fd = open(path_, O_RDONLY)) < 0)
      return false;
  
    AutoCloser autocloser(fd);
    struct stat st;
    if (fstat(fd, &st) != 0 || st.st_size <= 0)
      return false;
  
    void *base = mmap(NULL, st.st_size, PROT_READ, MAP_PRIVATE, fd, 0);
    if (base == MAP_FAILED)
      return false;
  
    bool success = false;
    const void *text_section = NULL;
    int text_size = 0;
  
    if (FindElfTextSection(fd, base, &text_section, &text_size)) {
      MD5Context md5;
      MD5Init(&md5);
      MD5Update(&md5, (const unsigned char *)text_section, text_size);
      MD5Final(identifier, &md5);
      success = true;
    }
  
    munmap((char *)base, st.st_size);
    return success;
  }
  
  // static
  bool FileID::ConvertIdentifierToString(const unsigned char identifier[16],
                                         char *buffer, int buffer_length) {
    if (buffer_length < 34)
      return false;
  
    int buffer_idx = 0;
    for (int idx = 0; idx < 16; ++idx) {
      int hi = (identifier[idx] >> 4) & 0x0F;
      int lo = (identifier[idx]) & 0x0F;
  
      buffer[buffer_idx++] = (hi >= 10) ? 'A' + hi - 10 : '0' + hi;
      buffer[buffer_idx++] = (lo >= 10) ? 'A' + lo - 10 : '0' + lo;
    }
  
    // Add an extra "0" by the end.
    buffer[buffer_idx++] = '0';
  
    // NULL terminate
    buffer[buffer_idx] = 0;
  
    return true;
  }
  
  }  // namespace google_breakpad
  