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elf2dol.c
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elf2dol.c
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#include <stdlib.h>
#include <stdio.h>
#include <stdint.h>
#include <errno.h>
#include <string.h>
#include <sys/param.h>
#ifndef MAX
//! Get the maximum of two values
#define MAX(a, b) (((a) > (b)) ? (a) : (b))
#endif
#ifndef MIN
//! Get the minimum of two values
#define MIN(a, b) (((a) < (b)) ? (a) : (b))
#endif
#define EI_NIDENT 16
typedef struct {
unsigned char e_ident[EI_NIDENT];
uint16_t e_type;
uint16_t e_machine;
uint32_t e_version;
uint32_t e_entry;
uint32_t e_phoff;
uint32_t e_shoff;
uint32_t e_flags;
uint16_t e_ehsize;
uint16_t e_phentsize;
uint16_t e_phnum;
uint16_t e_shentsize;
uint16_t e_shnum;
uint16_t e_shstrndx;
} Elf32_Ehdr;
#define EI_CLASS 4
#define EI_DATA 5
#define EI_VERSION 6
#define EI_PAD 7
#define EI_NIDENT 16
#define ELFCLASS32 1
#define ELFDATA2MSB 2
#define EV_CURRENT 1
#define ET_EXEC 2
#define EM_PPC 20
typedef struct {
uint32_t p_type;
uint32_t p_offset;
uint32_t p_vaddr;
uint32_t p_paddr;
uint32_t p_filesz;
uint32_t p_memsz;
uint32_t p_flags;
uint32_t p_align;
} Elf32_Phdr;
#define PT_LOAD 1
#define PF_R 4
#define PF_W 2
#define PF_X 1
int verbosity = 0;
#if BYTE_ORDER == BIG_ENDIAN
#define swap32(x) (x)
#define swap16(x) (x)
#else
static inline uint32_t swap32(uint32_t v)
{
return (v >> 24) |
((v >> 8) & 0x0000FF00) |
((v << 8) & 0x00FF0000) |
(v << 24);
}
static inline uint16_t swap16(uint16_t v)
{
return (v >> 8) | (v << 8);
}
#endif /* BIG_ENDIAN */
typedef struct {
uint32_t text_off[7];
uint32_t data_off[11];
uint32_t text_addr[7];
uint32_t data_addr[11];
uint32_t text_size[7];
uint32_t data_size[11];
uint32_t bss_addr;
uint32_t bss_size;
uint32_t entry;
uint32_t pad[7];
} DOL_hdr;
#define HAVE_BSS 1
#define MAX_TEXT_SEGMENTS 7
#define MAX_DATA_SEGMENTS 11
#define DOL_ALIGNMENT 64
#define DOL_ALIGN(x) (((x) + DOL_ALIGNMENT - 1) & ~(DOL_ALIGNMENT - 1))
typedef struct {
DOL_hdr header;
int text_cnt;
int data_cnt;
uint32_t text_elf_off[7];
uint32_t data_elf_off[11];
uint32_t flags;
FILE *elf;
} DOL_map;
void usage(const char *name)
{
fprintf(stderr, "Usage: %s [-h] [-v] [--] elf-file dol-file\n", name);
fprintf(stderr, " Convert an ELF file to a DOL file (by segments)\n");
fprintf(stderr, " Options:\n");
fprintf(stderr, " -h Show this help\n");
fprintf(stderr, " -v Be more verbose (twice for even more)\n");
}
#define die(x) { fprintf(stderr, x "\n"); exit(1); }
#define perrordie(x) { perror(x); exit(1); }
void ferrordie(FILE *f, const char *str)
{
if(ferror(f)) {
fprintf(stderr, "Error while ");
perrordie(str);
} else if(feof(f)) {
fprintf(stderr, "EOF while %s\n", str);
exit(1);
} else {
fprintf(stderr, "Unknown error while %s\n", str);
exit(1);
}
}
void add_bss(DOL_map *map, uint32_t paddr, uint32_t memsz)
{
if(map->flags & HAVE_BSS) {
uint32_t start = swap32(map->header.bss_addr);
uint32_t size = swap32(map->header.bss_size);
if ( (start+size) == paddr) {
map->header.bss_size = swap32(size+memsz);
}
} else {
map->header.bss_addr = swap32(paddr);
map->header.bss_size = swap32(memsz);
map->flags |= HAVE_BSS;
}
}
void read_elf_segments(DOL_map *map, const char *elf)
{
int read, i;
Elf32_Ehdr ehdr;
if(verbosity >= 2)
fprintf(stderr, "Reading ELF file...\n");
map->elf = fopen(elf, "rb");
if(!map->elf)
perrordie("Could not open ELF file");
read = fread(&ehdr, sizeof(ehdr), 1, map->elf);
if(read != 1)
ferrordie(map->elf, "reading ELF header");
if(memcmp(&ehdr.e_ident[0], "\177ELF", 4))
die("Invalid ELF header");
if(ehdr.e_ident[EI_CLASS] != ELFCLASS32)
die("Invalid ELF class");
if(ehdr.e_ident[EI_DATA] != ELFDATA2MSB)
die("Invalid ELF byte order");
if(ehdr.e_ident[EI_VERSION] != EV_CURRENT)
die("Invalid ELF ident version");
if(swap32(ehdr.e_version) != EV_CURRENT)
die("Invalid ELF version");
if(swap16(ehdr.e_type) != ET_EXEC)
die("ELF is not an executable");
if(swap16(ehdr.e_machine) != EM_PPC)
die("Machine is not PowerPC");
if(!swap32(ehdr.e_entry))
die("ELF has no entrypoint");
map->header.entry = ehdr.e_entry;
if(verbosity >= 2)
fprintf(stderr, "Valid ELF header found\n");
uint16_t phnum = swap16(ehdr.e_phnum);
uint32_t phoff = swap32(ehdr.e_phoff);
Elf32_Phdr *phdrs;
if(!phnum || !phoff)
die("ELF has no program headers");
if(swap16(ehdr.e_phentsize) != sizeof(Elf32_Phdr))
die("Invalid program header entry size");
phdrs = malloc(phnum * sizeof(Elf32_Phdr));
if(fseek(map->elf, phoff, SEEK_SET) < 0)
ferrordie(map->elf, "reading ELF program headers");
read = fread(phdrs, sizeof(Elf32_Phdr), phnum, map->elf);
if(read != phnum)
ferrordie(map->elf, "reading ELF program headers");
for(i=0; i<phnum; i++) {
if(swap32(phdrs[i].p_type) == PT_LOAD) {
uint32_t offset = swap32(phdrs[i].p_offset);
uint32_t paddr = swap32(phdrs[i].p_paddr);
uint32_t filesz = swap32(phdrs[i].p_filesz);
uint32_t memsz = swap32(phdrs[i].p_memsz);
uint32_t flags = swap32(phdrs[i].p_flags);
if(memsz) {
if(verbosity >= 2)
fprintf(stderr, "PHDR %d: 0x%x [0x%x] -> 0x%08x [0x%x] flags 0x%x\n",
i, offset, filesz, paddr, memsz, flags);
if(flags & PF_X) {
// TEXT segment
if(!(flags & PF_R))
fprintf(stderr, "Warning: non-readable segment %d\n", i);
if(flags & PF_W)
fprintf(stderr, "Warning: writable and executable segment %d\n", i);
if(filesz > memsz) {
fprintf(stderr, "Error: TEXT segment %d memory size (0x%x) smaller than file size (0x%x)\n",
i, memsz, filesz);
exit(1);
} else if (memsz > filesz) {
add_bss(map, paddr + filesz, memsz - filesz);
}
if(map->text_cnt >= MAX_TEXT_SEGMENTS) {
die("Error: Too many TEXT segments");
}
map->header.text_addr[map->text_cnt] = swap32(paddr);
map->header.text_size[map->text_cnt] = swap32(filesz);
map->text_elf_off[map->text_cnt] = offset;
map->text_cnt++;
} else {
// DATA or BSS segment
if(!(flags & PF_R))
fprintf(stderr, "Warning: non-readable segment %d\n", i);
if(filesz == 0) {
// BSS segment
add_bss(map, paddr, memsz);
} else {
// DATA segment
if(filesz > memsz) {
fprintf(stderr, "Error: segment %d memory size (0x%x) is smaller than file size (0x%x)\n",
i, memsz, filesz);
exit(1);
}
if(map->data_cnt >= MAX_DATA_SEGMENTS) {
die("Error: Too many DATA segments");
}
map->header.data_addr[map->data_cnt] = swap32(paddr);
map->header.data_size[map->data_cnt] = swap32(filesz);
map->data_elf_off[map->data_cnt] = offset;
map->data_cnt++;
}
}
} else {
if(verbosity >= 1)
fprintf(stderr, "Skipping empty program header %d\n", i);
}
} else if(verbosity >= 1) {
fprintf(stderr, "Skipping program header %d of type %d\n", i, swap32(phdrs[i].p_type));
}
}
if(verbosity >= 2) {
fprintf(stderr, "Segments:\n");
for(i=0; i<map->text_cnt; i++) {
fprintf(stderr, " TEXT %d: 0x%08x [0x%x] from ELF offset 0x%x\n",
i, swap32(map->header.text_addr[i]), swap32(map->header.text_size[i]),
map->text_elf_off[i]);
}
for(i=0; i<map->data_cnt; i++) {
fprintf(stderr, " DATA %d: 0x%08x [0x%x] from ELF offset 0x%x\n",
i, swap32(map->header.data_addr[i]), swap32(map->header.data_size[i]),
map->data_elf_off[i]);
}
if(map->flags & HAVE_BSS)
fprintf(stderr, " BSS segment: 0x%08x [0x%x]\n", swap32(map->header.bss_addr),
swap32(map->header.bss_size));
}
}
void map_dol(DOL_map *map)
{
uint32_t fpos;
int i;
if(verbosity >= 2)
fprintf(stderr, "Laying out DOL file...\n");
fpos = DOL_ALIGN(sizeof(DOL_hdr));
for(i=0; i<map->text_cnt; i++) {
if(verbosity >= 2)
fprintf(stderr, " TEXT segment %d at 0x%x\n", i, fpos);
map->header.text_off[i] = swap32(fpos);
fpos = DOL_ALIGN(fpos + swap32(map->header.text_size[i]));
}
for(i=0; i<map->data_cnt; i++) {
if(verbosity >= 2)
fprintf(stderr, " DATA segment %d at 0x%x\n", i, fpos);
map->header.data_off[i] = swap32(fpos);
fpos = DOL_ALIGN(fpos + swap32(map->header.data_size[i]));
}
if(map->text_cnt == 0) {
if(verbosity >= 1)
fprintf(stderr, "Note: adding dummy TEXT segment to work around IOS bug\n");
map->header.text_off[0] = swap32(DOL_ALIGN(sizeof(DOL_hdr)));
}
if(map->data_cnt == 0) {
if(verbosity >= 1)
fprintf(stderr, "Note: adding dummy DATA segment to work around IOS bug\n");
map->header.data_off[0] = swap32(DOL_ALIGN(sizeof(DOL_hdr)));
}
}
#define BLOCK (1024*1024)
void fcpy(FILE *dst, FILE *src, uint32_t dst_off, uint32_t src_off, uint32_t size)
{
int left = size;
int read;
int written;
int block;
void *blockbuf;
if(fseek(src, src_off, SEEK_SET) < 0)
ferrordie(src, "reading ELF segment data");
if(fseek(dst, dst_off, SEEK_SET) < 0)
ferrordie(dst, "writing DOL segment data");
blockbuf = malloc(MIN(BLOCK, left));
while(left) {
block = MIN(BLOCK, left);
read = fread(blockbuf, 1, block, src);
if(read != block) {
free(blockbuf);
ferrordie(src, "reading ELF segment data");
}
written = fwrite(blockbuf, 1, block, dst);
if(written != block) {
free(blockbuf);
ferrordie(dst, "writing DOL segment data");
}
left -= block;
}
free(blockbuf);
}
void write_dol(DOL_map *map, const char *dol)
{
FILE *dolf;
int written;
int i;
if(verbosity >= 2)
fprintf(stderr, "Writing DOL file...\n");
dolf = fopen(dol, "wb");
if(!dolf)
perrordie("Could not open DOL file");
if(verbosity >= 2) {
fprintf(stderr, "DOL header:\n");
for(i=0; i<MAX(1,map->text_cnt); i++)
fprintf(stderr, " TEXT %d @ 0x%08x [0x%x] off 0x%x\n", i,
swap32(map->header.text_addr[i]), swap32(map->header.text_size[i]),
swap32(map->header.text_off[i]));
for(i=0; i<MAX(1,map->data_cnt); i++)
fprintf(stderr, " DATA %d @ 0x%08x [0x%x] off 0x%x\n", i,
swap32(map->header.data_addr[i]), swap32(map->header.data_size[i]),
swap32(map->header.data_off[i]));
if(swap32(map->header.bss_addr) && swap32(map->header.bss_size))
fprintf(stderr, " BSS @ 0x%08x [0x%x]\n", swap32(map->header.bss_addr),
swap32(map->header.bss_size));
fprintf(stderr, " Entry: 0x%08x\n", swap32(map->header.entry));
fprintf(stderr, "Writing DOL header...\n");
}
written = fwrite(&map->header, sizeof(DOL_hdr), 1, dolf);
if(written != 1)
ferrordie(dolf, "writing DOL header");
for(i=0; i<map->text_cnt; i++) {
if(verbosity >= 2)
fprintf(stderr, "Writing TEXT segment %d...\n", i);
fcpy(dolf, map->elf, swap32(map->header.text_off[i]), map->text_elf_off[i],
swap32(map->header.text_size[i]));
}
for(i=0; i<map->data_cnt; i++) {
if(verbosity >= 2)
fprintf(stderr, "Writing DATA segment %d...\n", i);
fcpy(dolf, map->elf, swap32(map->header.data_off[i]), map->data_elf_off[i],
swap32(map->header.data_size[i]));
}
if(verbosity >= 2)
fprintf(stderr, "All done!\n");
fclose(map->elf);
fclose(dolf);
}
int main(int argc, char **argv)
{
char **arg;
if(argc < 2) {
usage(argv[0]);
return 1;
}
arg = &argv[1];
argc--;
while(argc && *arg[0] == '-') {
if(!strcmp(*arg, "-h")) {
usage(argv[0]);
return 1;
} else if(!strcmp(*arg, "-v")) {
verbosity++;
} else if(!strcmp(*arg, "--")) {
arg++;
argc--;
break;
} else {
fprintf(stderr, "Unrecognized option %s\n", *arg);
usage(argv[0]);
return 1;
}
arg++;
argc--;
}
if(argc < 2) {
usage(argv[0]);
exit(1);
}
const char *elf_file = arg[0];
const char *dol_file = arg[1];
DOL_map map;
memset(&map, 0, sizeof(map));
read_elf_segments(&map, elf_file);
map_dol(&map);
write_dol(&map, dol_file);
return 0;
}