+// A small wrapper around SHT_STRTAB data mapped to memory. It checks that the
+// index is not out of bounds and the string is NULL-terminated.
+
+class Elf_strtab
+{
+ public:
+ // Construct an Elf_strtab for a section with contents *P and size SIZE.
+ Elf_strtab(const unsigned char* p, size_t size);
+
+ // Return the file offset to the section headers.
+ bool
+ get_c_string(size_t offset, const char** cstring) const
+ {
+ if (offset >= this->usable_size_)
+ return false;
+ *cstring = this->base_ + offset;
+ return true;
+ }
+
+ private:
+ // Contents of the section mapped to memory.
+ const char* base_;
+ // One larger that the position of the last NULL character in the section.
+ // For valid SHT_STRTAB sections, this is the size of the section.
+ size_t usable_size_;
+};
+
+// Inline function definitions.
+
+// Check for presence of the ELF magic number.
+
+inline bool
+Elf_recognizer::is_elf_file(const unsigned char* ehdr_buf, int size)
+{
+ if (size < 4)
+ return false;
+
+ static unsigned char elfmagic[4] =
+ {
+ elfcpp::ELFMAG0, elfcpp::ELFMAG1,
+ elfcpp::ELFMAG2, elfcpp::ELFMAG3
+ };
+ return memcmp(ehdr_buf, elfmagic, 4) == 0;
+}
+
+namespace
+{
+
+// Print a number to a string.
+
+inline std::string
+internal_printf_int(const char* format, int arg)
+{
+ char buf[256];
+ snprintf(buf, sizeof(buf), format, arg);
+ return std::string(buf);
+}
+
+} // End anonymous namespace.
+
+// Check the validity of the ELF header.
+
+inline bool
+Elf_recognizer::is_valid_header(
+ const unsigned char* ehdr_buf,
+ off_t bufsize,
+ int* size,
+ bool* big_endian,
+ std::string* error)
+{
+ if (bufsize < elfcpp::EI_NIDENT)
+ {
+ *error = _("ELF file too short");
+ return false;
+ }
+
+ int v = ehdr_buf[elfcpp::EI_VERSION];
+ if (v != elfcpp::EV_CURRENT)
+ {
+ if (v == elfcpp::EV_NONE)
+ *error = _("invalid ELF version 0");
+ else
+ *error = internal_printf_int(_("unsupported ELF version %d"), v);
+ return false;
+ }
+
+ int c = ehdr_buf[elfcpp::EI_CLASS];
+ if (c == elfcpp::ELFCLASSNONE)
+ {
+ *error = _("invalid ELF class 0");
+ return false;
+ }
+ else if (c != elfcpp::ELFCLASS32
+ && c != elfcpp::ELFCLASS64)
+ {
+ *error = internal_printf_int(_("unsupported ELF class %d"), c);
+ return false;
+ }
+
+ int d = ehdr_buf[elfcpp::EI_DATA];
+ if (d == elfcpp::ELFDATANONE)
+ {
+ *error = _("invalid ELF data encoding");
+ return false;
+ }
+ else if (d != elfcpp::ELFDATA2LSB
+ && d != elfcpp::ELFDATA2MSB)
+ {
+ *error = internal_printf_int(_("unsupported ELF data encoding %d"), d);
+ return false;
+ }
+
+ *big_endian = (d == elfcpp::ELFDATA2MSB);
+
+ if (c == elfcpp::ELFCLASS32)
+ {
+ if (bufsize < elfcpp::Elf_sizes<32>::ehdr_size)
+ {
+ *error = _("ELF file too short");
+ return false;
+ }
+ *size = 32;
+ }
+ else
+ {
+ if (bufsize < elfcpp::Elf_sizes<64>::ehdr_size)
+ {
+ *error = _("ELF file too short");
+ return false;
+ }
+ *size = 64;
+ }
+
+ return true;
+}
+