[util] Readelf utility, actually reading some elfs. Cool.
This commit is contained in:
Kevin Lange
parent
60016e6e2b
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d31d763058
@ -1,10 +1,11 @@
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/*
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/**
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* ELF Binary Executable headers
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*
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* vim:noexpandtab
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* vim:tabstop=4
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*/
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#ifndef _ELF_H
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#define _ELF_H
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/*
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* Different bits of our build environment
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* require different header files for definitions
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@ -19,4 +20,119 @@
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# endif
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#endif
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/*
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* Unless otherwise stated, the definitions herein
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* are sourced from the Portable Formats Specification,
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* version 1.1 - ELF: Executable and Linkable Format
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*/
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/*
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* ELF Magic Signature
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*/
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#define ELFMAG0 0x7f
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#define ELFMAG1 'E'
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#define ELFMAG2 'L'
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#define ELFMAG3 'F'
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#define EI_NIDENT 16
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/*
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* ELF Datatypes
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*/
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typedef uint32_t Elf32_Word;
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typedef uint32_t Elf32_Addr;
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typedef uint32_t Elf32_Off;
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typedef uint32_t Elf32_Sword;
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typedef uint16_t Elf32_Half;
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/*
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* ELF Header
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*/
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typedef struct {
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unsigned char e_ident[EI_NIDENT];
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Elf32_Half e_type;
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Elf32_Half e_machine;
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Elf32_Word e_version;
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Elf32_Addr e_entry;
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Elf32_Off e_phoff;
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Elf32_Off e_shoff;
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Elf32_Word e_flags;
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Elf32_Half e_ehsize;
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Elf32_Half e_phentsize;
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Elf32_Half e_phnum;
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Elf32_Half e_shentsize;
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Elf32_Half e_shnum;
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Elf32_Half e_shstrndx;
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} Elf32_Header;
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/*
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* e_type
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*/
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#define ET_NONE 0 /* No file type */
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#define ET_REL 1 /* Relocatable file */
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#define ET_EXEC 2 /* Executable file */
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#define ET_DYN 3 /* Shared object file */
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#define ET_CORE 4 /* Core file */
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#define ET_LOPROC 0xff0 /* [Processor Specific] */
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#define ET_HIPROC 0xfff /* [Processor Specific] */
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/*
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* Machine types
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*/
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#define EM_NONE 0
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#define EM_386 3
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#define EV_NONE 0
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#define EV_CURRENT 1
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/** Program Header */
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typedef struct {
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Elf32_Word p_type;
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Elf32_Off p_offset;
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Elf32_Addr p_vaddr;
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Elf32_Addr p_paddr;
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Elf32_Word p_filesz;
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Elf32_Word p_flags;
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Elf32_Word p_align;
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} Elf32_Phdr;
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/* p_type values */
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#define PT_NULL 0 /* Unused, skip me */
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#define PT_LOAD 1 /* Loadable segment */
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#define PT_DYNAMIC 2 /* Dynamic linking information */
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#define PT_INTERP 3 /* Interpreter (null-terminated string, pathname) */
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#define PT_NOTE 4 /* Auxillary information */
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#define PT_SHLIB 5 /* Reserved. */
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#define PT_PHDR 6 /* Oh, it's me. Hello! Back-reference to the header table itself */
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#define PT_LOPROC 0x70000000
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#define PT_HIPROC 0x7FFFFFFF
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/** Section Header */
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typedef struct {
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Elf32_Word sh_name;
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Elf32_Word sh_type;
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Elf32_Word sh_flags;
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Elf32_Addr sh_addr;
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Elf32_Off sh_offset;
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Elf32_Word sh_size;
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Elf32_Word sh_link;
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Elf32_Word sh_info;
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Elf32_Word sh_addralign;
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Elf32_Word sh_entsize;
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} Elf32_Shdr;
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/* sh_type values */
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#define SHT_NONE 0
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#define SHT_PROGBITS 1
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#define SHT_SYMTAB 2
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#define SHT_STRTAB 3
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#endif /* _ELF_H*/
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/*
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* vim:noexpandtab
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* vim:tabstop=4
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*/
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189
util/readelf.c
189
util/readelf.c
@ -1,13 +1,192 @@
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/*
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* ToAruOS Miniature ELF Reader
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*
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* vim:noexpandtab
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* vim:tabstop=4
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* (C) 2011 Kevin Lange
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*/
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#include <stdio.h>
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#include <stdlib.h>
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#include <stdint.h>
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/* The Master ELF Header */
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#include "../kernel/include/elf.h"
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int main(int argc, char ** argv) {
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return -1;
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/**
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* Show usage for the readelf application.
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* @param argc Argument count (unused)
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* @param argv Arguments to binary
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*/
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void usage(int argc, char ** argv) {
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/* Show usage */
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printf("%s [filename]\n", argv[0]);
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printf("\tDisplays information on ELF binaries such as section names,\n");
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printf("\tlocations, sizes, and loading positions in memory.\n");
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exit(1);
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}
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/**
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* Application entry point.
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* @returns 0 on sucess, 1 on failure
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*/
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int main(int argc, char ** argv) {
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/* Process arguments */
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if (argc < 2) usage(argc,argv);
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FILE * binary; /**< File pointer for requested executable */
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size_t binary_size; /**< Size of the file */
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char * binary_buf; /**< Buffer to store the binary in memory */
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Elf32_Header * header; /**< ELF header */
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char * string_table[5]; /**< Room for some string tables */
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/* Open the requested binary */
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binary = fopen(argv[1], "r");
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/* Jump to the end so we can get the size */
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fseek(binary, 0, SEEK_END);
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binary_size = ftell(binary);
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fseek(binary, 0, SEEK_SET);
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/* Some sanity checks */
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if (binary_size < 4 || binary_size > 0xFFFFFFF) {
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printf("Oh no! I don't quite like the size of this binary.\n");
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return 1;
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}
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/* Read the binary into a buffer */
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binary_buf = malloc(binary_size);
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fread((void *)binary_buf, binary_size, 1, binary);
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/* Let's start considering this guy an elf, 'eh? */
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header = (Elf32_Header *)binary_buf;
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/* Verify the magic */
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if ( header->e_ident[0] != ELFMAG0 ||
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header->e_ident[1] != ELFMAG1 ||
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header->e_ident[2] != ELFMAG2 ||
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header->e_ident[3] != ELFMAG3) {
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printf("Header magic is wrong!\n");
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}
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/* Let's print out some of the header information, shall we? */
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printf("\033[1mELF Header\033[0m\n");
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/* File type */
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printf("[Type %d] ", header->e_type);
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switch (header->e_type) {
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case ET_NONE:
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printf("No file type.\n");
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break;
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case ET_REL:
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printf("Relocatable file.\n");
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break;
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case ET_EXEC:
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printf("Executable file.\n");
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break;
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case ET_DYN:
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printf("Shared object file.\n");
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break;
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case ET_CORE:
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printf("Core file.\n");
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break;
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default:
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printf("(Unknown file type)\n");
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break;
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}
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/* Machine Type */
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switch (header->e_machine) {
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case EM_386:
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printf("Intel x86\n");
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break;
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default:
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printf("Unknown machine: %d\n", header->e_machine);
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break;
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}
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/* Version == EV_CURRENT? */
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if (header->e_version == EV_CURRENT) {
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printf("ELF version is 1, as it should be.\n");
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}
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/* Entry point in memory */
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printf("Binary entry point in virtual memory is at 0x%x\n", header->e_entry);
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/* Program header table offset */
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printf("Program header table is at +0x%x and one entry is 0x%x bytes.\n"
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"There are %d total program headers.\n",
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header->e_phoff, header->e_phentsize, header->e_phnum);
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/* Section header table offset */
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printf("Section header table is at +0x%x and one entry is 0x%x bytes.\n"
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"There are %d total section headers.\n",
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header->e_shoff, header->e_shentsize, header->e_shnum);
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/* Read the program headers */
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printf("\033[1mProgram Headers\033[0m\n");
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for (uint32_t x = 0; x < header->e_phentsize * header->e_phnum; x += header->e_phentsize) {
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if (header->e_phoff + x > binary_size) {
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printf("Tried to read beyond the end of the file.\n");
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return 1;
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}
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/* Grab the program header */
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Elf32_Phdr * phdr = (Elf32_Phdr *)((uintptr_t)binary_buf + (header->e_phoff + x));
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/* Print the header type */
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switch (phdr->p_type) {
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case PT_LOAD:
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printf("[Loadable Segment]\n");
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break;
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case PT_DYNAMIC:
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printf("[Dynamic Loading Information]\n");
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break;
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case PT_INTERP:
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printf("[Interpreter Path]\n");
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break;
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default:
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printf("[Unused Segement]\n");
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break;
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}
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}
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printf("\033[1mString Tables\033[0m\n");
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uint32_t i = 0;
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for (uint32_t x = 0; x < header->e_shentsize * header->e_shnum; x += header->e_shentsize) {
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if (header->e_shoff + x > binary_size) {
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printf("Tried to read beyond the end of the file.\n");
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return 1;
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}
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Elf32_Shdr * shdr = (Elf32_Shdr *)((uintptr_t)binary_buf + (header->e_shoff + x));
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if (shdr->sh_type != SHT_STRTAB) continue;
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string_table[i] = (char *)((uintptr_t)binary_buf + shdr->sh_offset);
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printf("Found a string table at 0x%x\n", shdr->sh_offset);
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++i;
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if (i == 5) break;
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}
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printf("\033[1mSection Headers\033[0m\n");
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for (uint32_t x = 0; x < header->e_shentsize * header->e_shnum; x += header->e_shentsize) {
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if (header->e_shoff + x > binary_size) {
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printf("Tried to read beyond the end of the file.\n");
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return 1;
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}
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Elf32_Shdr * shdr = (Elf32_Shdr *)((uintptr_t)binary_buf + (header->e_shoff + x));
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printf("[%d] %s\n", shdr->sh_type, (char *)((uintptr_t)string_table[0] + shdr->sh_name));
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printf("Section starts at 0x%x and is 0x%x bytes long.\n", shdr->sh_offset, shdr->sh_size);
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if (shdr->sh_addr) {
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printf("It should be loaded at 0x%x.\n", shdr->sh_addr);
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}
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}
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/* Read the section headers */
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return 0;
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}
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/*
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* vim:noexpandtab
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* vim:tabstop=4
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* vim:shiftwidth=4
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*/
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