elf.cpp

Source Code of jlinkserver for Segger JLink

/** Read in an elf file
*/

#include "stdafx.h"

using namespace std;

ELF::ELF(const char* filename) {
	input = fopen(filename, "rb+");
	if (input == NULL) throw "Failed to open file";

	try {

		if (fread(&header, sizeof(header), 1, input) != 1) {
			throw "Failed to read header";
		}

		ReadSectionHeaders();
		ReadProgramHeaders();



	}
	catch (const char* ex) {
		fclose(input);
		throw ex;
	}

}

/** Read the section headers
*/
void ELF::ReadSectionHeaders() {
	sectionHeaders = new Elf32_Shdr[header.e_shnum];


	for (int i = 0; i < header.e_shnum; i++) {
		if (fseek(input, header.e_shoff + (i * header.e_shentsize), SEEK_SET)) {
			throw "Failed to seek to section headers";
		}

		if (fread(&sectionHeaders[i], sizeof(Elf32_Shdr), 1, input) != 1) {
			throw "Failed to read a section header";
		}
	}
}

/** Read the program headers
*/
void ELF::ReadProgramHeaders() {
	programHeaders = new Elf32_Phdr[header.e_phnum];

	for (int i = 0; i < header.e_phnum; i++) {
		if (fseek(input, header.e_phoff + (i * header.e_phentsize), SEEK_SET)) {
			throw "Failed to see to program headers";
		}

		if (fread(&programHeaders[i], sizeof(Elf32_Phdr), 1, input) != 1) {
			throw "Failed to read a program header";
		}
	}
}

/** Dump out the file
*/
void ELF::Dump() {
	cout << "ELF file" << endl;
	cout << "Number of sections: " << header.e_shnum << endl;
	for (int i = 0; i < header.e_shnum; i++) {
		cout << "Section[" << i << "] " << sectionHeaders[i].sh_name << endl;
	}

	cout << "Number of program segments: " << header.e_phnum << endl;
	for (int i = 0; i < header.e_phnum; i++) {
		cout << "Program[" << i << "]. Type " << programHeaders[i].p_type 
			<< " @ " << programHeaders[i].p_vaddr
			<< " : " << programHeaders[i].p_memsz
			<< endl;
	}
}

/** Retrieve the program segment
	@param index The index
	@param size The output size
	@return NULL or the heap allocated memory block
*/
void* ELF::ProgramSegment(int index) {
	if ((index < 0) || (index >= header.e_phnum)) {
		throw "Index out of range";
	}

	if (programHeaders[index].p_type != PT_LOAD) {
		return NULL;
	}

	if (programHeaders[index].p_memsz == 0) {
		return NULL;
	}


	void* buffer = new unsigned char[programHeaders[index].p_memsz];

	if (buffer) {
		if (fseek(input, programHeaders[index].p_offset, SEEK_SET)) {
			throw "Failed to seek to program segment";
		}

		if (fread(buffer, programHeaders[index].p_memsz, 1, input) != 1) {
			throw "Failed to read program segment";
		}
	}

	return buffer;
}