src/client/linux/minidump_writer/linux_dumper.h

// Copyright (c) 2010, Google Inc.
// All rights reserved.
//
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// 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.
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// 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
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#ifndef CLIENT_LINUX_MINIDUMP_WRITER_LINUX_DUMPER_H_
#define CLIENT_LINUX_MINIDUMP_WRITER_LINUX_DUMPER_H_

#include <elf.h>
#include <linux/limits.h>
#include <stdint.h>
#include <sys/types.h>
#if !defined(__ANDROID__)
#include <sys/user.h>
#endif

#include "common/memory.h"
#include "google_breakpad/common/minidump_format.h"

namespace google_breakpad {

#if defined(__i386) || defined(__x86_64)
typedef typeof(((struct user*) 0)->u_debugreg[0]) debugreg_t;
#endif

// Typedef for our parsing of the auxv variables in /proc/pid/auxv.
#if defined(__i386) || defined(__ARM_EABI__)
#if !defined(__ANDROID__)
typedef Elf32_auxv_t elf_aux_entry;
#else
// Android is missing this structure definition
typedef struct
{
  uint32_t a_type;              /* Entry type */
  union
    {
      uint32_t a_val;           /* Integer value */
    } a_un;
} elf_aux_entry;

#if !defined(AT_SYSINFO_EHDR)
#define AT_SYSINFO_EHDR 33
#endif
#endif  // __ANDROID__
#elif defined(__x86_64__)
typedef Elf64_auxv_t elf_aux_entry;
#endif
// 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";

// We produce one of these structures for each thread in the crashed process.
struct ThreadInfo {
  pid_t tgid;   // thread group id
  pid_t ppid;   // parent process

  // Even on platforms where the stack grows down, the following will point to
  // the smallest address in the stack.
  const void* stack;  // pointer to the stack area
  size_t stack_len;  // length of the stack to copy


#if defined(__i386) || defined(__x86_64)
  user_regs_struct regs;
  user_fpregs_struct fpregs;
  static const unsigned kNumDebugRegisters = 8;
  debugreg_t dregs[8];
#if defined(__i386)
  user_fpxregs_struct fpxregs;
#endif  // defined(__i386)

#elif defined(__ARM_EABI__)
  // Mimicking how strace does this(see syscall.c, search for GETREGS)
#if defined(__ANDROID__)
  struct pt_regs regs;
#else
  struct user_regs regs;
  struct user_fpregs fpregs;
#endif  // __ANDROID__
#endif
};

// One of these is produced for each mapping in the process (i.e. line in
// /proc/$x/maps).
struct MappingInfo {
  uintptr_t start_addr;
  size_t size;
  size_t offset;  // offset into the backed file.
  char name[NAME_MAX];
};

class LinuxDumper {
 public:
  explicit LinuxDumper(pid_t pid);

  // Parse the data for |threads| and |mappings|.
  bool Init();

  // Suspend/resume all threads in the given process.
  bool ThreadsSuspend();
  bool ThreadsResume();

  // Read information about the given thread. Returns true on success. One must
  // have called |ThreadsSuspend| first.
  bool ThreadInfoGet(pid_t tid, ThreadInfo* info);

  // 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 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);

  PageAllocator* allocator() { return &allocator_; }

  // memcpy from a remote process.
  static void CopyFromProcess(void* dest, pid_t child, const void* src,
                              size_t length);

  // Builds a proc path for a certain pid for a node.  path is a
  // character array that is overwritten, and node is the final node
  // without any slashes.
  void BuildProcPath(char* path, pid_t pid, const char* node) const;

  // Generate a File ID from the .text section of a mapped entry.
  // If not a member, mapping_id is ignored.
  bool ElfFileIdentifierForMapping(const MappingInfo& mapping,
                                   bool member,
                                   unsigned int mapping_id,
                                   uint8_t identifier[sizeof(MDGUID)]);

  // Utility method to find the location of where the kernel has
  // mapped linux-gate.so in memory(shows up in /proc/pid/maps as
  // [vdso], but we can't guarantee that it's the only virtual dynamic
  // shared object.  Parsing the auxilary vector for AT_SYSINFO_EHDR
  // is the safest way to go.)
  void* FindBeginningOfLinuxGateSharedLibrary(const pid_t pid) const;
 private:
  bool EnumerateMappings(wasteful_vector<MappingInfo*>* result) const;
  bool EnumerateThreads(wasteful_vector<pid_t>* result) const;

  // 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;

  const pid_t pid_;

  mutable PageAllocator allocator_;

  bool threads_suspended_;
  wasteful_vector<pid_t> threads_;  // the ids of all the threads
  wasteful_vector<MappingInfo*> mappings_;  // info from /proc/<pid>/maps
};

}  // namespace google_breakpad

#endif  // CLIENT_LINUX_HANDLER_LINUX_DUMPER_H_