134 lines
3.1 KiB
C
134 lines
3.1 KiB
C
#include <stdint.h>
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#include <stdbool.h>
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#include <stdio.h>
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#include <string.h>
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#include <stdbool.h>
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#include <assert.h>
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#define ET_NONE 0x00
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#define ET_REL 0x01
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#define ET_EXEC 0x02
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#define ET_DYN 0x03
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#define ET_CORE 0x04
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struct Elf32Header
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{
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uint8_t ident[16];
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uint16_t type;
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uint16_t machine;
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uint32_t version;
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uint32_t entry;
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uint32_t phoff;
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uint32_t shoff;
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uint32_t flags;
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uint16_t ehsize;
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uint16_t phentsize;
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uint16_t phnum;
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uint16_t shentsize;
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uint16_t shnum;
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uint16_t shstrndx;
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};
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#define PT_NULL 0x00000000
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#define PT_LOAD 0x00000001
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#define PT_DYNAMIC 0x00000002
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#define PT_INTERP 0x00000003
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#define PT_NOTE 0x00000004
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#define PT_SHLIB 0x00000005
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#define PT_PHDR 0x00000006
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#define PT_TLS 0x00000007
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#define PF_X 0x1
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#define PF_W 0x2
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#define PF_R 0x4
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struct Elf32ProgramHeader
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{
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uint32_t type;
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uint32_t offset;
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uint32_t vaddr;
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uint32_t paddr;
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uint32_t filesz;
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uint32_t memsz;
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uint32_t flags;
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uint32_t align;
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};
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bool load_elf(const char* file, char* mem, uint32_t mem_size, uint32_t* start_address)
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{
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FILE* fp = fopen(file, "rb");
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if (fp == NULL)
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{
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printf("Couldn't open input file\n");
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return false;
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}
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struct Elf32Header header;
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size_t read = fread(&header, sizeof(struct Elf32Header), 1, fp);
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if (read != 1)
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{
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printf("ELF header too small\n");
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return false;
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}
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static uint8_t kValidIdent[7] = {
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0x7f, 0x45, 0x4c, 0x46,
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1, 1, 1
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};
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if (memcmp(kValidIdent, header.ident, 7) != 0)
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{
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printf("Invalid ELF header\n");
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return false;
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}
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if (header.type != ET_EXEC)
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{
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printf("Can only link EXEC ELF files\n");
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return false;
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}
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memset(mem, 0, mem_size);
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assert(header.phnum == 0 || header.phentsize == sizeof(struct Elf32ProgramHeader));
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for (uint32_t i = 0; i < header.phnum; ++i)
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{
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struct Elf32ProgramHeader pheader;
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fseek(fp, header.phoff + i * header.phentsize, SEEK_SET);
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read = fread(&pheader, sizeof(struct Elf32ProgramHeader), 1, fp);
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if (read != 1)
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{
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printf("Error reading program header at index %u\n", i);
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return false;
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}
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if (pheader.type == PT_LOAD)
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{
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if (pheader.paddr + pheader.memsz > mem_size)
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{
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printf("Memory not large enough for ELF file\n");
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return false;
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}
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fseek(fp, pheader.offset, SEEK_SET);
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read = fread(mem + pheader.paddr, pheader.filesz, 1, fp);
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if (read != 1)
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{
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printf("Error when copying ELF segment\n");
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return false;
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}
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}
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}
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if (header.entry > mem_size)
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{
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printf("Entry address out of bounds\n");
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return false;
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}
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*start_address = header.entry;
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fclose(fp);
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return true;
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}
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