consolidate all repos to one for archive
This commit is contained in:
23
semester_4/namenska_programska_oprema/Naloga_4/Makefile
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23
semester_4/namenska_programska_oprema/Naloga_4/Makefile
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@@ -0,0 +1,23 @@
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all: build run
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debug: buildd run clean
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zip:
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zip naloga.zip hello.c Makefile fun.c fun.h main.c
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build: build_hello build_elf_changer
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build_hello: hello.c
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gcc -m32 hello.c -o hello
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buildd: main.c fun.c
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gcc -g -m32 main.c fun.c -o elf_changer -fsanitize=address -fno-omit-frame-pointer -Wall -Wextra -Wpedantic -Werror
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build_elf_changer:
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gcc -m32 main.c fun.c -o elf_changer -Wall -Wextra -Wpedantic -Werror
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run:
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./elf_changer -h hello
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clean:
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rm -f hello elf_changer
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299
semester_4/namenska_programska_oprema/Naloga_4/fun.c
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299
semester_4/namenska_programska_oprema/Naloga_4/fun.c
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@@ -0,0 +1,299 @@
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#include "fun.h"
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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void printElf(const char *fileName)
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{
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FILE *fp = fopen(fileName, "rb");
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if (fp == NULL)
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{
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printf("Error: cannot open file\n");
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return;
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}
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Elf32_Ehdr ehdr;
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fread(&ehdr, sizeof(Elf32_Ehdr), 1, fp);
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fclose(fp);
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printf("ELF header:\n");
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printf(" Magic number:\t\t\t\t\t\t%02x %02x %02x %02x\n", ehdr.e_ident[0], ehdr.e_ident[1], ehdr.e_ident[2], ehdr.e_ident[3]);
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printf(" Class:\t\t\t\t\t\t");
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switch (ehdr.e_ident[EI_CLASS])
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{
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case ELFCLASSNONE:
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printf("Invalid class\n");
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break;
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case ELFCLASS32:
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printf("ELF32\n");
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break;
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case ELFCLASS64:
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printf("ELF64\n");
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break;
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default:
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printf("Unknown class (0x%x)\n", ehdr.e_ident[4]);
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break;
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}
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printf(" Data:\t\t\t\t\t\t\t");
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switch (ehdr.e_ident[EI_DATA])
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{
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case ELFDATANONE:
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printf("Invalid data encoding\n");
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break;
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case ELFDATA2LSB:
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printf("2's complement, little endian\n");
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break;
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case ELFDATA2MSB:
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printf("2's complement, big endian\n");
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break;
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default:
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printf("Unknown data encoding (0x%x)\n", ehdr.e_ident[5]);
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break;
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}
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printf(" Version:\t\t\t\t\t\t");
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switch (ehdr.e_ident[EI_VERSION])
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{
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case EV_NONE:
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printf("Invalid version\n");
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break;
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case EV_CURRENT:
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printf("Current version\n");
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break;
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default:
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printf("Unknown version (0x%x)\n", ehdr.e_ident[6]);
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break;
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}
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printf(" OS/ABI:\t\t\t\t\t\t");
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switch (ehdr.e_ident[EI_OSABI])
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{
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case ELFOSABI_NONE:
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printf("UNIX System V ABI\n");
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break;
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default:
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printf("Unknown OS/ABI (0x%x)\n", ehdr.e_ident[7]);
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break;
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}
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printf(" ABI Version:\t\t\t\t\t\t%d\n", ehdr.e_ident[EI_ABIVERSION]);
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printf(" Type:\t\t\t\t\t\t\t");
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switch (ehdr.e_type)
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{
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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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case ET_LOPROC:
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printf("Processor-specific\n");
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break;
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case ET_HIPROC:
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printf("Processor-specific\n");
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break;
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default:
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printf("Unknown type (0x%x)\n", ehdr.e_type);
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break;
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}
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printf(" Machine:\t\t\t\t\t\t");
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switch (ehdr.e_machine)
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{
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case EM_386:
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printf("Intel 80386\n");
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break;
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default:
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printf("Unknown type (0x%x)\n", ehdr.e_type);
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break;
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}
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printf(" Version:\t\t\t\t\t\t0x%x\n", ehdr.e_version);
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printf(" Entry point address:\t\t\t\t\t0x%x\n", ehdr.e_entry);
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printf(" Start of program headers:\t\t\t\t%d (bytes into file)\n", ehdr.e_phoff);
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printf(" Start of section headers:\t\t\t\t%d (bytes into file)\n", ehdr.e_shoff);
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printf(" Flags:\t\t\t\t\t\t0x%x\n", ehdr.e_flags);
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printf(" Size of this header:\t\t\t\t\t%d (bytes)\n", ehdr.e_ehsize);
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printf(" Size of program headers:\t\t\t\t%d (bytes)\n", ehdr.e_phentsize);
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printf(" Number of program headers:\t\t\t\t%d\n", ehdr.e_phnum);
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printf(" Size of section headers:\t\t\t\t%d (bytes)\n", ehdr.e_shentsize);
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printf(" Number of section headers:\t\t\t\t%d \n", ehdr.e_shnum);
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printf(" Section header string table index:\t\t\t%d \n", ehdr.e_shstrndx);
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}
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void printElfFunc(const char *fileName)
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{
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FILE *fd = fopen(fileName, "rb");
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if (!fd)
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{
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perror("Failed to open file");
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return;
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}
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Elf32_Ehdr ehdr;
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fread(&ehdr, sizeof(Elf32_Ehdr), 1, fd);
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fseek(fd, ehdr.e_shoff, SEEK_SET);
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Elf32_Shdr simbolHdr;
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Elf32_Shdr stringHdr;
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uint8_t strtab = 0;
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for (size_t i = 0; i < ehdr.e_shnum; i++)
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{
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Elf32_Shdr shdr;
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fread(&shdr, sizeof(Elf32_Shdr), 1, fd);
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if (shdr.sh_type == SHT_SYMTAB)
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{
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simbolHdr = shdr;
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}
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else if (shdr.sh_type == SHT_STRTAB)
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{
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strtab++;
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if (strtab == 2)
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{
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stringHdr = shdr;
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}
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}
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}
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size_t numOfSimbols = simbolHdr.sh_size / sizeof(Elf32_Sym);
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char name[20];
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memset(name, 0, sizeof(name));
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printf("%-10s%-10s %-10s%-20s\n", "NR", "Value", "Size", "Name");
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int pos = 0;
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for (size_t i = 0; i < numOfSimbols; i++)
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{
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fseek(fd, simbolHdr.sh_offset + i * sizeof(Elf32_Sym), SEEK_SET);
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Elf32_Sym sys;
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fread(&sys, sizeof(Elf32_Sym), 1, fd);
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if (sys.st_size > 50)
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{
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printf("%-10d", pos++);
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printf("0x%-8x ", sys.st_value);
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printf("%-10d", sys.st_size);
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fseek(fd, stringHdr.sh_offset + sys.st_name, SEEK_SET);
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fread(&name, sizeof(name), 1, fd);
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printf("%-20s\n", name);
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}
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}
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fclose(fd);
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return;
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}
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void changeElf(int argc, const char **argv)
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{
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FILE *fd = fopen(argv[2], "r+b");
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if (!fd)
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{
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perror("Failed to open file");
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return;
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}
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Elf32_Ehdr ehdr;
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fread(&ehdr, sizeof(Elf32_Ehdr), 1, fd);
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fseek(fd, ehdr.e_shoff, SEEK_SET);
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Elf32_Shdr simbolHdr;
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Elf32_Shdr stringHdr;
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uint8_t strtab = 0;
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for (size_t i = 0; i < ehdr.e_shnum; i++)
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{
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Elf32_Shdr shdr;
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fread(&shdr, sizeof(Elf32_Shdr), 1, fd);
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if (shdr.sh_type == SHT_SYMTAB)
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{
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simbolHdr = shdr;
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}
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else if (shdr.sh_type == SHT_STRTAB)
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{
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strtab++;
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if (strtab == 2)
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{
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stringHdr = shdr;
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}
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}
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}
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size_t numOfSimbols = simbolHdr.sh_size / sizeof(Elf32_Sym);
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char name[20];
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memset(name, 0, sizeof(name));
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printf("%-10s\t%s\t\t%s\t%s\t\n", "IME", "NASLOV", "VREDNOST", "NOVA_VREDNOST");
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for (unsigned int i = 0; i < numOfSimbols; ++i)
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{
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fseek(fd, simbolHdr.sh_offset + i * sizeof(Elf32_Sym), SEEK_SET);
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Elf32_Sym sys;
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fread(&sys, sizeof(Elf32_Sym), 1, fd);
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if (!(ELF32_ST_TYPE(sys.st_info) == STT_OBJECT && ELF32_ST_BIND(sys.st_info) == STB_GLOBAL))
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continue;
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fseek(fd, stringHdr.sh_offset + sys.st_name, SEEK_SET);
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fread(&name, sizeof(name), 1, fd);
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int con = 1;
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for (int j = 3; j < argc; j++)
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{
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if (strcmp(name, argv[j]) == 0)
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{
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con = 0;
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break;
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}
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}
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if (con)
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continue;
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printf("%-10s\t", name);
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printf("%x\t\t", sys.st_value);
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fseek(fd, ehdr.e_shoff + sys.st_shndx * sizeof(Elf32_Shdr), SEEK_SET);
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Elf32_Shdr hdr;
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fread(&hdr, sizeof(Elf32_Shdr), 1, fd);
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uint32_t realAddr = (sys.st_value - hdr.sh_addr) + hdr.sh_offset;
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fseek(fd, realAddr, SEEK_SET);
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uint32_t val;
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fread(&val, sizeof(uint32_t), 1, fd);
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printf("%x\t\t", val);
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val += 10;
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fseek(fd, realAddr, SEEK_SET);
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fwrite(&val, sizeof(val), 1, fd);
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printf("%x\n", val);
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}
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fclose(fd);
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return;
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}
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4
semester_4/namenska_programska_oprema/Naloga_4/fun.h
Normal file
4
semester_4/namenska_programska_oprema/Naloga_4/fun.h
Normal file
@@ -0,0 +1,4 @@
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#include <elf.h>
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void printElf(const char *fileName);
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void printElfFunc(const char *fileName);
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void changeElf(int argc, const char **argv);
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18
semester_4/namenska_programska_oprema/Naloga_4/hello.c
Normal file
18
semester_4/namenska_programska_oprema/Naloga_4/hello.c
Normal file
@@ -0,0 +1,18 @@
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#include <stdio.h>
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int funkcija(int a)
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{
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return a + 1;
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}
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int g1;
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int g2 = 10;
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int g3 = 14;
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int main()
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{
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printf("Vrednost g1: %d\n", g1);
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printf("Vrednost g2: %d\n", g2);
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printf("Vrednost g3: %d\n", g3);
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return 0;
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}
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32
semester_4/namenska_programska_oprema/Naloga_4/main.c
Normal file
32
semester_4/namenska_programska_oprema/Naloga_4/main.c
Normal file
@@ -0,0 +1,32 @@
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#include <stdio.h>
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#include <stdlib.h>
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#include "fun.h"
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int main(int argc, const char *argv[])
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{
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if (argc < 3)
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{
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printf("Usage: %s [-hcl] <elf_path> \n", argv[0]);
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exit(1);
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}
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char var = argv[1][1];
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if (var == 'h')
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{
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printElf(argv[2]);
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}
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else if (var == 'i')
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{
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printElfFunc(argv[2]);
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}
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else if (var == 'c')
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{
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changeElf(argc, argv);
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}
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else
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{
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printf("You entered something else\n");
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}
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return 0;
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}
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