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#include <sys/types.h>
#include <sys/mman.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <stdio.h>
#include <stdlib.h>
#include <stdbool.h>
#include <string.h>
#include <unistd.h>
#include <errno.h>
#include "elf-parse.h"
struct elf_funcs elf_parser;
/*
* Get the whole file as a programming convenience in order to avoid
* malloc+lseek+read+free of many pieces. If successful, then mmap
* avoids copying unused pieces; else just read the whole file.
* Open for both read and write.
*/
static void *map_file(char const *fname, size_t *size)
{
int fd;
struct stat sb;
void *addr = NULL;
fd = open(fname, O_RDWR);
if (fd < 0) {
perror(fname);
return NULL;
}
if (fstat(fd, &sb) < 0) {
perror(fname);
goto out;
}
if (!S_ISREG(sb.st_mode)) {
fprintf(stderr, "not a regular file: %s\n", fname);
goto out;
}
addr = mmap(0, sb.st_size, PROT_READ|PROT_WRITE, MAP_SHARED, fd, 0);
if (addr == MAP_FAILED) {
fprintf(stderr, "Could not mmap file: %s\n", fname);
goto out;
}
*size = sb.st_size;
out:
close(fd);
return addr;
}
static int elf_parse(const char *fname, void *addr, uint32_t types)
{
Elf_Ehdr *ehdr = addr;
uint16_t type;
switch (ehdr->e32.e_ident[EI_DATA]) {
case ELFDATA2LSB:
elf_parser.r = rle;
elf_parser.r2 = r2le;
elf_parser.r8 = r8le;
elf_parser.w = wle;
elf_parser.w8 = w8le;
break;
case ELFDATA2MSB:
elf_parser.r = rbe;
elf_parser.r2 = r2be;
elf_parser.r8 = r8be;
elf_parser.w = wbe;
elf_parser.w8 = w8be;
break;
default:
fprintf(stderr, "unrecognized ELF data encoding %d: %s\n",
ehdr->e32.e_ident[EI_DATA], fname);
return -1;
}
if (memcmp(ELFMAG, ehdr->e32.e_ident, SELFMAG) != 0 ||
ehdr->e32.e_ident[EI_VERSION] != EV_CURRENT) {
fprintf(stderr, "unrecognized ELF file %s\n", fname);
return -1;
}
type = elf_parser.r2(&ehdr->e32.e_type);
if (!((1 << type) & types)) {
fprintf(stderr, "Invalid ELF type file %s\n", fname);
return -1;
}
switch (ehdr->e32.e_ident[EI_CLASS]) {
case ELFCLASS32: {
elf_parser.ehdr_shoff = ehdr32_shoff;
elf_parser.ehdr_shentsize = ehdr32_shentsize;
elf_parser.ehdr_shstrndx = ehdr32_shstrndx;
elf_parser.ehdr_shnum = ehdr32_shnum;
elf_parser.shdr_addr = shdr32_addr;
elf_parser.shdr_offset = shdr32_offset;
elf_parser.shdr_link = shdr32_link;
elf_parser.shdr_size = shdr32_size;
elf_parser.shdr_name = shdr32_name;
elf_parser.shdr_type = shdr32_type;
elf_parser.shdr_entsize = shdr32_entsize;
elf_parser.sym_type = sym32_type;
elf_parser.sym_name = sym32_name;
elf_parser.sym_value = sym32_value;
elf_parser.sym_shndx = sym32_shndx;
elf_parser.rela_offset = rela32_offset;
elf_parser.rela_info = rela32_info;
elf_parser.rela_addend = rela32_addend;
elf_parser.rela_write_addend = rela32_write_addend;
if (elf_parser.r2(&ehdr->e32.e_ehsize) != sizeof(Elf32_Ehdr) ||
elf_parser.r2(&ehdr->e32.e_shentsize) != sizeof(Elf32_Shdr)) {
fprintf(stderr,
"unrecognized ET_EXEC/ET_DYN file: %s\n", fname);
return -1;
}
}
break;
case ELFCLASS64: {
elf_parser.ehdr_shoff = ehdr64_shoff;
elf_parser.ehdr_shentsize = ehdr64_shentsize;
elf_parser.ehdr_shstrndx = ehdr64_shstrndx;
elf_parser.ehdr_shnum = ehdr64_shnum;
elf_parser.shdr_addr = shdr64_addr;
elf_parser.shdr_offset = shdr64_offset;
elf_parser.shdr_link = shdr64_link;
elf_parser.shdr_size = shdr64_size;
elf_parser.shdr_name = shdr64_name;
elf_parser.shdr_type = shdr64_type;
elf_parser.shdr_entsize = shdr64_entsize;
elf_parser.sym_type = sym64_type;
elf_parser.sym_name = sym64_name;
elf_parser.sym_value = sym64_value;
elf_parser.sym_shndx = sym64_shndx;
elf_parser.rela_offset = rela64_offset;
elf_parser.rela_info = rela64_info;
elf_parser.rela_addend = rela64_addend;
elf_parser.rela_write_addend = rela64_write_addend;
if (elf_parser.r2(&ehdr->e64.e_ehsize) != sizeof(Elf64_Ehdr) ||
elf_parser.r2(&ehdr->e64.e_shentsize) != sizeof(Elf64_Shdr)) {
fprintf(stderr,
"unrecognized ET_EXEC/ET_DYN file: %s\n",
fname);
return -1;
}
}
break;
default:
fprintf(stderr, "unrecognized ELF class %d %s\n",
ehdr->e32.e_ident[EI_CLASS], fname);
return -1;
}
return 0;
}
int elf_map_machine(void *addr)
{
Elf_Ehdr *ehdr = addr;
return elf_parser.r2(&ehdr->e32.e_machine);
}
int elf_map_long_size(void *addr)
{
Elf_Ehdr *ehdr = addr;
return ehdr->e32.e_ident[EI_CLASS] == ELFCLASS32 ? 4 : 8;
}
void *elf_map(char const *fname, size_t *size, uint32_t types)
{
void *addr;
int ret;
addr = map_file(fname, size);
if (!addr)
return NULL;
ret = elf_parse(fname, addr, types);
if (ret < 0) {
elf_unmap(addr, *size);
return NULL;
}
return addr;
}
void elf_unmap(void *addr, size_t size)
{
munmap(addr, size);
}
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