int xreloc_relocate( xreloc xr ) {
table *t = (table *) xr;
int loc;
int word;
int mask;
int err = 0;
symbol *sym;
symbol *rel = NULL;
reloc *r;
rel = findsym( t, REL_NAME );
rel->flags = FLAG_RELOCAT | FLAG_GLOBAL;
rel->loc = 0;
for( sym = t->syms; sym; sym = sym->next ) {
if( sym->flags & FLAG_GLOBAL ) { /* symbols to be written to symbol table */
continue;
} else if( sym->flags & FLAG_RELOCAT ) { /* symbols need to be relocated */
sym->flags |= FLAG_WRITTEN;
for( r = sym->relocs; r; r = r->next ) {
add_reloc( t, rel, r->loc, r->size, XRELOC_ABSOLUTE );
word = GETWORD( t->mem, r->loc );
mask = ( 1 << r->size ) - 1;
loc = ( word & mask ) + sym->loc;
if( loc & ~mask ) {
fprintf( t->err, "error: relocation out of range for symbol '%s'\n",
sym->name );
err = 1;
}
word = ( word & ~mask ) | ( loc & mask );
t->mem[r->loc] = word >> 8;
t->mem[r->loc + 1] = word;
}
} else if( sym->loc != INV_ADDR ) { /* symbol is defined */
int xreloc_reloc( xreloc xr, int loc, int size, char *name,
unsigned char flags ) {
table *t = (table *) xr;
symbol *sym;
assert( t );
assert( name );
if( loc == INV_ADDR ) {
fprintf( stderr, "error: invalid address '%x', object may be too big\n",
INV_ADDR );
return 0;
}
sym = findsym( t, name );
assert( sym );
add_reloc( t, sym, loc, size, flags );
return 1;
}
void write_elf(FILE *outfile, Elf *elf) {
add_symtab(elf);
add_reloc(elf);
add_shstrtab(elf);
// Section header
String *sh = make_string();
for (int i = 0; i < 64; i++)
o1(sh, 0); // NULL section header
// Body
String *content = make_string();
for (int i = 0; i < LIST_LEN(elf->sections); i++) {
write_section(sh, content, LIST_REF(elf->sections, i), 64);
}
align(content, 16);
// ELF header
String *eh = make_string();
int numsect = LIST_LEN(elf->sections) + 1;
out(eh, elf_ident, sizeof(elf_ident));
o2(eh, 1); // e_type = ET_REL
o2(eh, 62); // e_machine = EM_X86_64
o4(eh, 1); // e_version = EV_CURRENT
o8(eh, 0); // e_entry
o8(eh, 0); // e_phoff
o8(eh, STRING_LEN(content) + 64); // e_shoff;
o4(eh, 0); // e_flags
o2(eh, 64); // e_ehsize
o2(eh, 0); // e_phentsize
o2(eh, 0); // e_phnum
o2(eh, 64); // e_shentsize
o2(eh, numsect); // e_shnum
o2(eh, elf->shnum); // e_shstrndx
fwrite(STRING_BODY(eh), STRING_LEN(eh), 1, outfile);
fwrite(STRING_BODY(content), STRING_LEN(content), 1, outfile);
fwrite(STRING_BODY(sh), STRING_LEN(sh), 1, outfile);
fclose(outfile);
}
int xreloc_load_table( xreloc xr, int size, int base ) {
table *t = (table *) xr;
int i, ent, loc;
short chksum = 0;
int code_size = 0;
symbol *sym;
char buf[10];
assert( t );
assert( size >= 0 );
assert( base >= 0 );
assert( ( base + size ) <= XIS_MEM_SIZE );
if( size & 1 ) { /* Cannot have a valid table because size is odd */
return -1;
}
for( i = 0; i < size; i += 2 ) {
chksum += GETWORD( t->mem, i + base );
}
if( chksum ) { /* chksum failed, no table */
return -1;
}
i = GETWORD( t->mem, size + base - 4 );
if( i != XIS_VERSION ) {
fprintf( t->err, "error: unknown version %x\n", i );
return 0;
}
ent = GETWORD( t->mem, size + base - 6 ) + base + 1; /* 1 is the padding */
code_size = GETWORD( t->mem, size + base - 6 );
while( t->mem[ent] && ( ent < ( base + size ) ) ) {
if( !strcmp( REL_NAME, (char *)&t->mem[ent] ) ) {
sprintf( buf, "%s%x", REL_NAME, t->rel_cnt );
t->rel_cnt++;
sym = findsym( t, buf );
sym->flags = FLAG_RELOCAT;
} else {
sym = findsym( t, (char *) &t->mem[ent] );
}
ent += strlen( (char *) &t->mem[ent] ) + 1;
loc = GETWORD( t->mem, ent );
ent += 2;
if( loc != INV_ADDR ) {
if( sym->loc == INV_ADDR ) {
sym->loc = loc + base;
} else {
fprintf( t->err, "error: Multiple instances of symbol '%s'\n",
sym->name );
code_size = 0;
}
}
for( loc = GETWORD( t->mem, ent ); loc != INV_ADDR;
loc = GETWORD( t->mem, ent ) ) {
ent += 2;
i = t->mem[ent++] & 0xff;
add_reloc( t, sym, loc + base, i, t->mem[ent++] );
}
ent += 2;
}
return code_size;
}
