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