Add debug fission support.

src/common/dwarf/elf_reader.h

+// Copyright 2005 Google Inc. All Rights Reserved.

[ivanpe, 2016/04/27 01:11:45]

Where does this file come from?  Has it been reviewed before?

[yunlian, 2016/04/27 16:35:29]

It comes from internal google tree and it has been reviewed.

+// Author: chatham@google.com (Andrew Chatham)
+// Author: satorux@google.com (Satoru Takabayashi)
+//
+// ElfReader handles reading in ELF. It can extract symbols from the
+// current process, which may be used to symbolize stack traces
+// without having to make a potentially dangerous call to fork().
+//
+// ElfReader dynamically allocates memory, so it is not appropriate to
+// use once the address space might be corrupted, such as during
+// process death.
+//
+// ElfReader supports both 32-bit and 64-bit ELF binaries.
+
+#ifndef COMMON_DWARF_ELF_READER_H__
+#define COMMON_DWARF_ELF_READER_H__
+
+#include <string>
+#include <vector>
+
+#include "common/dwarf/types.h"
+
+using std::string;
+using std::vector;
+using std::pair;
+
+namespace dwarf2reader {
+
+class SymbolMap;
+class Elf32;
+class Elf64;
+template<typename ElfArch>
+class ElfReaderImpl;
+
+class ElfReader {
+ public:
+  explicit ElfReader(const string &path);
+  ~ElfReader();
+
+  // Parse the ELF prologue of this file and return whether it was
+  // successfully parsed and matches the word size and byte order of
+  // the current process.
+  bool IsNativeElfFile() const;
+
+  // Similar to IsNativeElfFile but checks if it's a 32-bit ELF file.
+  bool IsElf32File() const;
+
+  // Similar to IsNativeElfFile but checks if it's a 64-bit ELF file.
+  bool IsElf64File() const;
+
+  // Checks if it's an ELF file of type ET_DYN (shared object file).
+  bool IsDynamicSharedObject();
+
+  // Add symbols in the given ELF file into the provided SymbolMap,
+  // assuming that the file has been loaded into the specified
+  // offset.
+  //
+  // The remaining arguments are typically taken from a
+  // ProcMapsIterator (base/sysinfo.h) and describe which portions of
+  // the ELF file are mapped into which parts of memory:
+  //
+  // mem_offset - position at which the segment is mapped into memory
+  // file_offset - offset in the file where the mapping begins
+  // length - length of the mapped segment
+  void AddSymbols(SymbolMap *symbols,
+                  uint64 mem_offset, uint64 file_offset,
+                  uint64 length);
+
+  class SymbolSink {
+   public:
+    virtual ~SymbolSink() {}
+    virtual void AddSymbol(const char *name, uint64 address, uint64 size) = 0;
+  };
+
+  // Like AddSymbols above, but with no address correction.
+  // Processes any SHT_SYMTAB section, followed by any SHT_DYNSYM section.
+  void VisitSymbols(SymbolSink *sink);
+
+  // Like VisitSymbols above, but for a specific symbol binding/type.
+  // A negative value for the binding and type parameters means any
+  // binding or type.
+  void VisitSymbols(SymbolSink *sink, int symbol_binding, int symbol_type);
+
+  // Like VisitSymbols above but can optionally export raw symbol values instead
+  // of adjusted ones.
+  void VisitSymbols(SymbolSink *sink, int symbol_binding, int symbol_type,
+                    bool get_raw_symbol_values);
+
+  // p_vaddr of the first PT_LOAD segment (if any), or 0 if no PT_LOAD
+  // segments are present. This is the address an ELF image was linked
+  // (by static linker) to be loaded at. Usually (but not always) 0 for
+  // shared libraries and position-independent executables.
+  uint64 VaddrOfFirstLoadSegment();
+
+  // Return the name of section "shndx".  Returns NULL if the section
+  // is not found.
+  const char *GetSectionName(int shndx);
+
+  // Return the number of sections in the given ELF file.
+  uint64 GetNumSections();
+
+  // Get section "shndx" from the given ELF file.  On success, return
+  // the pointer to the section and store the size in "size".
+  // On error, return NULL.  The returned section data is only valid
+  // until the ElfReader gets destroyed.
+  const char *GetSectionByIndex(int shndx, size_t *size);
+
+  // Get section with "section_name" (ex. ".text", ".symtab") in the
+  // given ELF file.  On success, return the pointer to the section
+  // and store the size in "size".  On error, return NULL.  The
+  // returned section data is only valid until the ElfReader gets
+  // destroyed.
+  const char *GetSectionByName(const string &section_name, size_t *size);
+
+  // This is like GetSectionByName() but it returns a lot of extra information
+  // about the section. The SectionInfo structure is almost identical to
+  // the typedef struct Elf64_Shdr defined in <elf.h>, but is redefined
+  // here so that the many short macro names in <elf.h> don't have to be
+  // added to our already cluttered namespace.
+  struct SectionInfo {
+    uint32 type;                // Section type (SHT_xxx constant from elf.h).
+    uint64 flags;               // Section flags (SHF_xxx constants from elf.h).
+    uint64 addr;                // Section virtual address at execution.
+    uint64 offset;              // Section file offset.
+    uint64 size;                // Section size in bytes.
+    uint32 link;                // Link to another section.
+    uint32 info;                // Additional section information.
+    uint64 addralign;           // Section alignment.
+    uint64 entsize;             // Entry size if section holds a table.
+  };
+  const char *GetSectionInfoByName(const string &section_name,
+                                   SectionInfo *info);
+
+  // Check if "path" is an ELF binary that has not been stripped of symbol
+  // tables.  This function supports both 32-bit and 64-bit ELF binaries.
+  static bool IsNonStrippedELFBinary(const string &path);
+
+  // Check if "path" is an ELF binary that has not been stripped of debug
+  // info. Unlike IsNonStrippedELFBinary, this function will return
+  // false for binaries passed through "strip -S".
+  static bool IsNonDebugStrippedELFBinary(const string &path);
+
+  // Match a requested section name with the section name as it
+  // appears in the elf-file, adjusting for compressed debug section
+  // names.  For example, returns true if name == ".debug_abbrev" and
+  // sh_name == ".zdebug_abbrev"
+  static bool SectionNamesMatch(const string &name, const string &sh_name);
+
+ private:
+  // Lazily initialize impl32_ and return it.
+  ElfReaderImpl<Elf32> *GetImpl32();
+  // Ditto for impl64_.
+  ElfReaderImpl<Elf64> *GetImpl64();
+
+  // Path of the file we're reading.
+  const string path_;
+  // Read-only file descriptor for the file. May be -1 if there was an
+  // error during open.
+  int fd_;
+  ElfReaderImpl<Elf32> *impl32_;
+  ElfReaderImpl<Elf64> *impl64_;
+};
+
+}  // namespace dwarf2reader
+
+#endif  // COMMON_DWARF_ELF_READER_H__