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authorIan Lance Taylor <iant@google.com>2006-11-07 18:51:39 +0000
committerIan Lance Taylor <iant@google.com>2006-11-07 18:51:39 +0000
commit645f81233bd13bc6102580bac4b886c6056028e3 (patch)
treee104ddfc8f2a1f52326b8a2fa9c3b5c50ae43fa0 /elfcpp/elfcpp_file.h
parent9e59254c41b56b91b7640ed5b727430cc537daac (diff)
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Add Elf_file interface which can be used by both Sized_relobj and
Sized_dynobj.
Diffstat (limited to 'elfcpp/elfcpp_file.h')
-rw-r--r--elfcpp/elfcpp_file.h255
1 files changed, 255 insertions, 0 deletions
diff --git a/elfcpp/elfcpp_file.h b/elfcpp/elfcpp_file.h
new file mode 100644
index 0000000..043c269
--- /dev/null
+++ b/elfcpp/elfcpp_file.h
@@ -0,0 +1,255 @@
+// elfcpp_file.h -- file access for elfcpp -*- C++ -*-
+
+// This header file defines the class Elf_file which can be used to
+// read useful data from an ELF file. The functions here are all
+// templates which take a file interface object as a parameter. This
+// type must have a subtype View. This type must support two methods:
+// View view(off_t file_offset, off_t data_size)
+// returns a View for the specified part of the file.
+// void error(const char* printf_format, ...)
+// prints an error message and does not return. The subtype View must
+// support a method
+// const unsigned char* data()
+// which returns a pointer to a buffer containing the requested data.
+// This general interface is used to read data from the file. Objects
+// of type View will never survive longer than the elfcpp function.
+
+// Some of these functions must return a reference to part of the
+// file. To use these, the file interface must support a subtype
+// Location:
+// Location(off_t file_offset, off_t data_size)
+// To use this in conjunction with the accessors types Shdr, etc., the
+// file interface should support an overload of view:
+// View view(Location)
+// This permits writing
+// elfcpp::Shdr shdr(file, ef.section_header(n));
+
+#ifndef ELFPCP_FILE_H
+#define ELFCPP_FILE_H
+
+#include <string>
+#include <cstring>
+
+namespace elfcpp
+{
+
+// This object is used to read an ELF file.
+// SIZE: The size of file, 32 or 64.
+// BIG_ENDIAN: Whether the file is in big-endian format.
+// FILE: A file reading type as described above.
+
+template<int size, bool big_endian, typename File>
+class Elf_file
+{
+ private:
+ typedef Elf_file<size, big_endian, File> This;
+
+ public:
+ static const int ehdr_size = Elf_sizes<size>::ehdr_size;
+ static const int phdr_size = Elf_sizes<size>::phdr_size;
+ static const int shdr_size = Elf_sizes<size>::shdr_size;
+ static const int sym_size = Elf_sizes<size>::sym_size;
+ static const int rel_size = Elf_sizes<size>::rel_size;
+ static const int rela_size = Elf_sizes<size>::rela_size;
+
+ typedef Ehdr<size, big_endian> Ef_ehdr;
+ typedef Phdr<size, big_endian> Ef_phdr;
+ typedef Shdr<size, big_endian> Ef_shdr;
+ typedef Sym<size, big_endian> Ef_sym;
+
+ // Construct an Elf_file given an ELF file header.
+ Elf_file(File* file, const Ef_ehdr& ehdr)
+ { this->construct(file, ehdr); }
+
+ // Construct an ELF file.
+ inline
+ Elf_file(File* file);
+
+ // Return the file offset to the section headers.
+ off_t
+ shoff() const
+ { return this->shoff_; }
+
+ // Return the number of sections.
+ unsigned int
+ shnum()
+ {
+ this->initialize_shnum();
+ return this->shnum_;
+ }
+
+ // Return the section index of the section name string table.
+ unsigned int
+ shstrndx()
+ {
+ this->initialize_shnum();
+ return this->shstrndx_;
+ }
+
+ // Return the location of the header of section SHNDX.
+ typename File::Location
+ section_header(unsigned int shndx)
+ {
+ return typename File::Location(this->section_header_offset(shndx),
+ shdr_size);
+ }
+
+ // Return the name of section SHNDX.
+ std::string
+ section_name(unsigned int shndx);
+
+ // Return the location of the contents of section SHNDX.
+ typename File::Location
+ section_contents(unsigned int shndx);
+
+ private:
+ // Shared constructor code.
+ void
+ construct(File* file, const Ef_ehdr& ehdr);
+
+ // Initialize shnum_ and shstrndx_.
+ void
+ initialize_shnum();
+
+ // Return the file offset of the header of section SHNDX.
+ off_t
+ section_header_offset(unsigned int shndx);
+
+ // The file we are reading.
+ File* file_;
+ // The file offset to the section headers.
+ off_t shoff_;
+ // The number of sections.
+ unsigned int shnum_;
+ // The section index of the section name string table.
+ unsigned int shstrndx_;
+};
+
+// Template function definitions.
+
+// Construct an Elf_file given an ELF file header.
+
+template<int size, bool big_endian, typename File>
+void
+Elf_file<size, big_endian, File>::construct(File* file, const Ef_ehdr& ehdr)
+{
+ this->file_ = file;
+ this->shoff_ = ehdr.get_e_shoff();
+ this->shnum_ = ehdr.get_e_shnum();
+ this->shstrndx_ = ehdr.get_e_shstrndx();
+ if (ehdr.get_e_ehsize() != This::ehdr_size)
+ file->error(_("bad e_ehsize (%d != %d)"),
+ ehdr.get_e_ehsize(), This::ehdr_size);
+ if (ehdr.get_e_shentsize() != This::shdr_size)
+ file->error(_("bad e_shentsize (%d != %d)"),
+ ehdr.get_e_shentsize(), This::shdr_size);
+}
+
+// Construct an ELF file.
+
+template<int size, bool big_endian, typename File>
+inline
+Elf_file<size, big_endian, File>::Elf_file(File* file)
+{
+ typename File::View v(file->view(file_header_offset, This::ehdr_size));
+ this->construct(file, Ef_ehdr(v.data()));
+}
+
+// Initialize the shnum_ and shstrndx_ fields, handling overflow.
+
+template<int size, bool big_endian, typename File>
+void
+Elf_file<size, big_endian, File>::initialize_shnum()
+{
+ if ((this->shnum_ == 0 || this->shstrndx_ == SHN_XINDEX)
+ && this->shoff_ != 0)
+ {
+ typename File::View v(this->file_->view(this->shoff_, This::shdr_size));
+ Ef_shdr shdr(v.data());
+ if (this->shnum_ == 0)
+ this->shnum_ = shdr.get_sh_size();
+ if (this->shstrndx_ == SHN_XINDEX)
+ this->shstrndx_ = shdr.get_sh_link();
+ }
+}
+
+// Return the file offset of the section header of section SHNDX.
+
+template<int size, bool big_endian, typename File>
+off_t
+Elf_file<size, big_endian, File>::section_header_offset(unsigned int shndx)
+{
+ if (shndx >= this->shnum())
+ this->file_->error(_("section_header_offset: bad shndx %u >= %u"),
+ shndx, this->shnum());
+ return this->shoff_ + This::shdr_size * shndx;
+}
+
+// Return the name of section SHNDX.
+
+template<int size, bool big_endian, typename File>
+std::string
+Elf_file<size, big_endian, File>::section_name(unsigned int shndx)
+{
+ File* const file = this->file_;
+
+ // Get the section name offset.
+ unsigned int sh_name;
+ {
+ typename File::View v(file->view(this->section_header_offset(shndx),
+ This::shdr_size));
+ Ef_shdr shdr(v.data());
+ sh_name = shdr.get_sh_name();
+ }
+
+ // Get the file offset for the section name string table data.
+ off_t shstr_off;
+ off_t shstr_size;
+ {
+ const unsigned int shstrndx = this->shstrndx_;
+ typename File::View v(file->view(this->section_header_offset(shstrndx),
+ This::shdr_size));
+ Ef_shdr shstr_shdr(v.data());
+ shstr_off = shstr_shdr.get_sh_offset();
+ shstr_size = shstr_shdr.get_sh_size();
+ }
+
+ if (sh_name >= shstr_size)
+ file->error(_("bad section name offset for section %u: %u"),
+ shndx, sh_name);
+
+ typename File::View v(file->view(shstr_off, shstr_size));
+
+ const unsigned char* datau = v.data();
+ const char* data = reinterpret_cast<const char*>(datau);
+ const void* p = ::memchr(data + sh_name, '\0', shstr_size - sh_name);
+ if (p == NULL)
+ file->error(_("missing null terminator for name of section %u"),
+ shndx);
+
+ size_t len = static_cast<const char*>(p) - (data + sh_name);
+
+ return std::string(data + sh_name, len);
+}
+
+// Return the contents of section SHNDX.
+
+template<int size, bool big_endian, typename File>
+typename File::Location
+Elf_file<size, big_endian, File>::section_contents(unsigned int shndx)
+{
+ File* const file = this->file_;
+
+ if (shndx >= this->shnum())
+ file->error(_("section_contents: bad shndx %u >= %u"),
+ shndx, this->shnum());
+
+ typename File::View v(file->view(this->section_header_offset(shndx),
+ This::shdr_size));
+ Ef_shdr shdr(v.data());
+ return typename File::Location(shdr.get_sh_offset(), shdr.get_sh_size());
+}
+
+} // End namespace elfcpp.
+
+#endif // !defined(ELFCPP_FILE_H)