text: // Copyright (c) 2010, 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
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  // 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.
  
  // linux_dumper.h: Define the google_breakpad::LinuxDumper class, which
  // is a base class for extracting information of a crashed process. It
  // was originally a complete implementation using the ptrace API, but
  // has been refactored to allow derived implementations supporting both
  // ptrace and core dump. A portion of the original implementation is now
  // in google_breakpad::LinuxPtraceDumper (see linux_ptrace_dumper.h for
  // details).
  
  #ifndef CLIENT_LINUX_MINIDUMP_WRITER_LINUX_DUMPER_H_
  #define CLIENT_LINUX_MINIDUMP_WRITER_LINUX_DUMPER_H_
  
  #include <assert.h>
  #include <elf.h>
  #if defined(__ANDROID__)
  #include <link.h>
  #endif
  #include <linux/limits.h>
  #include <stdint.h>
  #include <sys/types.h>
  #include <sys/user.h>
  
  #include <vector>
  
  #include "linux/dump_writer_common/mapping_info.h"
  #include "linux/dump_writer_common/thread_info.h"
  #include "common/linux/file_id.h"
  #include "common/memory_allocator.h"
  #include "google_breakpad/common/minidump_format.h"
  
  namespace google_breakpad {
  
  // Typedef for our parsing of the auxv variables in /proc/pid/auxv.
  #if defined(__i386) || defined(__ARM_EABI__) || \
   (defined(__mips__) && _MIPS_SIM == _ABIO32)
  typedef Elf32_auxv_t elf_aux_entry;
  #elif defined(__x86_64) || defined(__aarch64__) || \
       (defined(__mips__) && _MIPS_SIM != _ABIO32)
  typedef Elf64_auxv_t elf_aux_entry;
  #endif
  
  typedef __typeof__(((elf_aux_entry*) 0)->a_un.a_val) elf_aux_val_t;
  
  // When we find the VDSO mapping in the process's address space, this
  // is the name we use for it when writing it to the minidump.
  // This should always be less than NAME_MAX!
  const char kLinuxGateLibraryName[] = "linux-gate.so";
  
  class LinuxDumper {
   public:
    // The |root_prefix| is prepended to mapping paths before opening them, which
    // is useful if the crash originates from a chroot.
    explicit LinuxDumper(pid_t pid, const char* root_prefix = "");
  
    virtual ~LinuxDumper();
  
    // Parse the data for |threads| and |mappings|.
    virtual bool Init();
  
    // Take any actions that could not be taken in Init(). LateInit() is
    // called after all other caller's initialization is complete, and in
    // particular after it has called ThreadsSuspend(), so that ptrace is
    // available.
    virtual bool LateInit();
  
    // Return true if the dumper performs a post-mortem dump.
    virtual bool IsPostMortem() const = 0;
  
    // Suspend/resume all threads in the given process.
    virtual bool ThreadsSuspend() = 0;
    virtual bool ThreadsResume() = 0;
  
    // Read information about the |index|-th thread of |threads_|.
    // Returns true on success. One must have called |ThreadsSuspend| first.
    virtual bool GetThreadInfoByIndex(size_t index, ThreadInfo* info) = 0;
  
    size_t GetMainThreadIndex() const {
      for (size_t i = 0; i < threads_.size(); ++i) {
        if (threads_[i] == pid_) return i;
      }
      return -1u;
    }
  
    // These are only valid after a call to |Init|.
    const wasteful_vector<pid_t> &threads() { return threads_; }
    const wasteful_vector<MappingInfo*> &mappings() { return mappings_; }
    const MappingInfo* FindMapping(const void* address) const;
    // Find the mapping which the given memory address falls in. Unlike
    // FindMapping, this method uses the unadjusted mapping address
    // ranges from the kernel, rather than the ranges that have had the
    // load bias applied.
    const MappingInfo* FindMappingNoBias(uintptr_t address) const;
    const wasteful_vector<elf_aux_val_t>& auxv() { return auxv_; }
  
    // Find a block of memory to take as the stack given the top of stack pointer.
    //   stack: (output) the lowest address in the memory area
    //   stack_len: (output) the length of the memory area
    //   stack_top: the current top of the stack
    bool GetStackInfo(const void** stack, size_t* stack_len, uintptr_t stack_top);
  
    // Sanitize a copy of the stack by overwriting words that are not
    // pointers with a sentinel (0x0defaced).
    //   stack_copy: a copy of the stack to sanitize. |stack_copy| might
    //               not be word aligned, but it represents word aligned
    //               data copied from another location.
    //   stack_len: the length of the allocation pointed to by |stack_copy|.
    //   stack_pointer: the address of the stack pointer (used to locate
    //                  the stack mapping, as an optimization).
    //   sp_offset: the offset relative to stack_copy that reflects the
    //              current value of the stack pointer.
    void SanitizeStackCopy(uint8_t* stack_copy, size_t stack_len,
                           uintptr_t stack_pointer, uintptr_t sp_offset);
  
    // Test whether |stack_copy| contains a pointer-aligned word that
    // could be an address within a given mapping.
    //   stack_copy: a copy of the stack to check. |stack_copy| might
    //               not be word aligned, but it represents word aligned
    //               data copied from another location.
    //   stack_len: the length of the allocation pointed to by |stack_copy|.
    //   sp_offset: the offset relative to stack_copy that reflects the
    //              current value of the stack pointer.
    //   mapping: the mapping against which to test stack words.
    bool StackHasPointerToMapping(const uint8_t* stack_copy, size_t stack_len,
                                  uintptr_t sp_offset,
                                  const MappingInfo& mapping);
  
    PageAllocator* allocator() { return &allocator_; }
  
    // Copy content of |length| bytes from a given process |child|,
    // starting from |src|, into |dest|. Returns true on success.
    virtual bool CopyFromProcess(void* dest, pid_t child, const void* src,
                                 size_t length) = 0;
  
    // Builds a proc path for a certain pid for a node (/proc/<pid>/<node>).
    // |path| is a character array of at least NAME_MAX bytes to return the
    // result.|node| is the final node without any slashes. Returns true on
    // success.
    virtual bool BuildProcPath(char* path, pid_t pid, const char* node) const = 0;
  
    // Generate a File ID from the .text section of a mapped entry.
    // If not a member, mapping_id is ignored. This method can also manipulate the
    // |mapping|.name to truncate "(deleted)" from the file name if necessary.
    bool ElfFileIdentifierForMapping(const MappingInfo& mapping,
                                     bool member,
                                     unsigned int mapping_id,
                                     wasteful_vector<uint8_t>& identifier);
  
    void SetCrashInfoFromSigInfo(const siginfo_t& siginfo);
  
    uintptr_t crash_address() const { return crash_address_; }
    void set_crash_address(uintptr_t crash_address) {
      crash_address_ = crash_address;
    }
  
    int crash_signal() const { return crash_signal_; }
    void set_crash_signal(int crash_signal) { crash_signal_ = crash_signal; }
    const char* GetCrashSignalString() const;
  
    void set_crash_signal_code(int code) { crash_signal_code_ = code; }
    int crash_signal_code() const { return crash_signal_code_; }
  
    void set_crash_exception_info(const std::vector<uint64_t>& exception_info) {
      assert(exception_info.size() <= MD_EXCEPTION_MAXIMUM_PARAMETERS);
      crash_exception_info_ = exception_info;
    }
    const std::vector<uint64_t>& crash_exception_info() const {
      return crash_exception_info_;
    }
  
    pid_t crash_thread() const { return crash_thread_; }
    void set_crash_thread(pid_t crash_thread) { crash_thread_ = crash_thread; }
  
    // Concatenates the |root_prefix_| and |mapping| path. Writes into |path| and
    // returns true unless the string is too long.
    bool GetMappingAbsolutePath(const MappingInfo& mapping,
                                char path[PATH_MAX]) const;
  
    // Extracts the effective path and file name of from |mapping|. In most cases
    // the effective name/path are just the mapping's path and basename. In some
    // other cases, however, a library can be mapped from an archive (e.g., when
    // loading .so libs from an apk on Android) and this method is able to
    // reconstruct the original file name.
    void GetMappingEffectiveNameAndPath(const MappingInfo& mapping,
                                        char* file_path,
                                        size_t file_path_size,
                                        char* file_name,
                                        size_t file_name_size);
  
   protected:
    bool ReadAuxv();
  
    virtual bool EnumerateMappings();
  
    virtual bool EnumerateThreads() = 0;
  
    // For the case where a running program has been deleted, it'll show up in
    // /proc/pid/maps as "/path/to/program (deleted)". If this is the case, then
    // see if '/path/to/program (deleted)' matches /proc/pid/exe and return
    // /proc/pid/exe in |path| so ELF identifier generation works correctly. This
    // also checks to see if '/path/to/program (deleted)' exists, so it does not
    // get fooled by a poorly named binary.
    // For programs that don't end with ' (deleted)', this is a no-op.
    // This assumes |path| is a buffer with length NAME_MAX.
    // Returns true if |path| is modified.
    bool HandleDeletedFileInMapping(char* path) const;
  
     // ID of the crashed process.
    const pid_t pid_;
  
    // Path of the root directory to which mapping paths are relative.
    const char* const root_prefix_;
  
    // Virtual address at which the process crashed.
    uintptr_t crash_address_;
  
    // Signal that terminated the crashed process.
    int crash_signal_;
  
    // The code associated with |crash_signal_|.
    int crash_signal_code_;
  
    // The additional fields associated with |crash_signal_|.
    std::vector<uint64_t> crash_exception_info_;
  
    // ID of the crashed thread.
    pid_t crash_thread_;
  
    mutable PageAllocator allocator_;
  
    // IDs of all the threads.
    wasteful_vector<pid_t> threads_;
  
    // Info from /proc/<pid>/maps.
    wasteful_vector<MappingInfo*> mappings_;
  
    // Info from /proc/<pid>/auxv
    wasteful_vector<elf_aux_val_t> auxv_;
  
  private:
    bool IsIPCSharedMemorySegment(const char* name);
  
  #if defined(__ANDROID__)
    // Android M and later support packed ELF relocations in shared libraries.
    // Packing relocations changes the vaddr of the LOAD segments, such that
    // the effective load bias is no longer the same as the start address of
    // the memory mapping containing the executable parts of the library. The
    // packing is applied to the stripped library run on the target, but not to
    // any other library, and in particular not to the library used to generate
    // breakpad symbols. As a result, we need to adjust the |start_addr| for
    // any mapping that results from a shared library that contains Android
    // packed relocations, so that it properly represents the effective library
    // load bias. The following functions support this adjustment.
  
    // Check that a given mapping at |start_addr| is for an ELF shared library.
    // If it is, place the ELF header in |ehdr| and return true.
    // The first LOAD segment in an ELF shared library has offset zero, so the
    // ELF file header is at the start of this map entry, and in already mapped
    // memory.
    bool GetLoadedElfHeader(uintptr_t start_addr, ElfW(Ehdr)* ehdr);
  
    // For the ELF file mapped at |start_addr|, iterate ELF program headers to
    // find the min vaddr of all program header LOAD segments, the vaddr for
    // the DYNAMIC segment, and a count of DYNAMIC entries. Return values in
    // |min_vaddr_ptr|, |dyn_vaddr_ptr|, and |dyn_count_ptr|.
    // The program header table is also in already mapped memory.
    void ParseLoadedElfProgramHeaders(ElfW(Ehdr)* ehdr,
                                      uintptr_t start_addr,
                                      uintptr_t* min_vaddr_ptr,
                                      uintptr_t* dyn_vaddr_ptr,
                                      size_t* dyn_count_ptr);
  
    // Search the DYNAMIC tags for the ELF file with the given |load_bias|, and
    // return true if the tags indicate that the file contains Android packed
    // relocations. Dynamic tags are found at |dyn_vaddr| past the |load_bias|.
    bool HasAndroidPackedRelocations(uintptr_t load_bias,
                                     uintptr_t dyn_vaddr,
                                     size_t dyn_count);
  
    // If the ELF file mapped at |start_addr| contained Android packed
    // relocations, return the load bias that the system linker (or Chromium
    // crazy linker) will have used. If the file did not contain Android
    // packed relocations, returns |start_addr|, indicating that no adjustment
    // is necessary.
    // The effective load bias is |start_addr| adjusted downwards by the
    // min vaddr in the library LOAD segments.
    uintptr_t GetEffectiveLoadBias(ElfW(Ehdr)* ehdr, uintptr_t start_addr);
  
    // Called from LateInit(). Iterates |mappings_| and rewrites the |start_addr|
    // field of any that represent ELF shared libraries with Android packed
    // relocations, so that |start_addr| is the load bias that the system linker
    // (or Chromium crazy linker) used. This value matches the addresses produced
    // when the non-relocation-packed library is used for breakpad symbol
    // generation.
    void LatePostprocessMappings();
  #endif  // __ANDROID__
  };
  
  }  // namespace google_breakpad
  
  #endif  // CLIENT_LINUX_HANDLER_LINUX_DUMPER_H_
  