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tcc-stupidos/libtcc/tccelf.c

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/*
* ELF file handling for TCC
*
* Copyright (c) 2001-2004 Fabrice Bellard
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2 of the License, or (at your option) any later version.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*/
#ifdef HAVE_CONFIG_H
# include "config.h"
#endif /* HAVE_CONFIG_H */
#include <stdlib.h>
#include <tcc.h>
#include <tcc/path.h>
#include <tcc/memory.h>
#include "cc/cc.h"
#include "utils/string.h"
/* Define this to get some debug output during relocation processing. */
#undef DEBUG_RELOC
# define ELF_START_ADDR 0x08048000
# define ELF_PAGE_SIZE 0x1000
/********************************************************/
/* global variables */
/* special flag to indicate that the section should not be linked to the other ones */
#define SHF_PRIVATE 0x80000000
/* section is dynsymtab_section */
#define SHF_DYNSYM 0x40000000
#ifdef TCC_TARGET_PE
#define shf_RELRO SHF_ALLOC
static const char rdata[] = ".rdata";
#else
#define shf_RELRO SHF_ALLOC /* eventually made SHF_WRITE in sort_sections() */
static const char rdata[] = ".data.ro";
#endif
/* ------------------------------------------------------------------------- */
void tccelf_new(TCCState *s)
{
/* no section zero */
dynarray_add(&s->sections, &s->nb_sections, NULL);
/* create standard sections */
s->text_section = new_section(s, ".text", SHT_PROGBITS, SHF_ALLOC | SHF_EXECINSTR);
s->data_section = new_section(s, ".data", SHT_PROGBITS, SHF_ALLOC | SHF_WRITE);
/* create ro data section (make ro after relocation done with GNU_RELRO) */
s->rodata_section = new_section(s, rdata, SHT_PROGBITS, shf_RELRO);
s->bss_section = new_section(s, ".bss", SHT_NOBITS, SHF_ALLOC | SHF_WRITE);
/* symbols are always generated for linking stage */
s->symtab_section = new_symtab(s, ".symtab", SHT_SYMTAB, 0,
".strtab",
".hashtab", SHF_PRIVATE);
}
void free_section(Section *s)
{
if (!s)
return;
tcc_free(s->data);
s->data = NULL;
s->data_allocated = s->data_offset = 0;
}
void tccelf_delete(TCCState *s1)
{
int i;
/* free all sections */
for(i = 1; i < s1->nb_sections; i++)
free_section(s1->sections[i]);
dynarray_reset(&s1->sections, &s1->nb_sections);
for(i = 0; i < s1->nb_priv_sections; i++)
free_section(s1->priv_sections[i]);
dynarray_reset(&s1->priv_sections, &s1->nb_priv_sections);
s1->symtab_section = NULL; /* for tccrun.c:rt_printline() */
}
/* save section data state */
void tccelf_begin_file(TCCState *s1)
{
Section *s; int i;
for (i = 1; i < s1->nb_sections; i++) {
s = s1->sections[i];
s->sh_offset = s->data_offset;
}
/* disable symbol hashing during compilation */
s = s1->symtab_section, s->reloc = s->hash, s->hash = NULL;
}
static void update_relocs(TCCState *s1, Section *s, int *old_to_new_syms, int first_sym);
/* At the end of compilation, convert any UNDEF syms to global, and merge
with previously existing symbols */
void tccelf_end_file(TCCState *s1)
{
Section *s = s1->symtab_section;
int first_sym, nb_syms, *tr, i;
first_sym = s->sh_offset / sizeof (ElfSym);
nb_syms = s->data_offset / sizeof (ElfSym) - first_sym;
s->data_offset = s->sh_offset;
s->link->data_offset = s->link->sh_offset;
s->hash = s->reloc, s->reloc = NULL;
tr = tcc_mallocz(nb_syms * sizeof *tr);
for (i = 0; i < nb_syms; ++i) {
ElfSym *sym = (ElfSym*)s->data + first_sym + i;
if (sym->st_shndx == SHN_UNDEF) {
int sym_bind = ELFW(ST_BIND)(sym->st_info);
int sym_type = ELFW(ST_TYPE)(sym->st_info);
if (sym_bind == STB_LOCAL)
sym_bind = STB_GLOBAL;
#ifndef TCC_TARGET_PE
if (sym_bind == STB_GLOBAL && s1->output_type == TCC_OUTPUT_OBJ) {
/* undefined symbols with STT_FUNC are confusing gnu ld when
linking statically to STT_GNU_IFUNC */
sym_type = STT_NOTYPE;
}
#endif
sym->st_info = ELFW(ST_INFO)(sym_bind, sym_type);
}
tr[i] = set_elf_sym(s, sym->st_value, sym->st_size, sym->st_info,
sym->st_other, sym->st_shndx, (char*)s->link->data + sym->st_name);
}
/* now update relocations */
update_relocs(s1, s, tr, first_sym);
tcc_free(tr);
/* record text/data/bss output for -bench info */
for (i = 0; i < 4; ++i) {
s = s1->sections[i + 1];
s1->total_output[i] += s->data_offset - s->sh_offset;
}
}
Section *new_section(TCCState *s1, const char *name, int sh_type, int sh_flags)
{
Section *sec;
sec = tcc_mallocz(sizeof(Section) + strlen(name));
sec->s1 = s1;
strcpy(sec->old_name, name);
sec->sh_type = sh_type;
sec->sh_flags = sh_flags;
switch(sh_type) {
case SHT_GNU_versym:
sec->sh_addralign = 2;
break;
case SHT_HASH:
case SHT_GNU_HASH:
case SHT_REL:
case SHT_RELA:
case SHT_DYNSYM:
case SHT_SYMTAB:
case SHT_DYNAMIC:
case SHT_GNU_verneed:
case SHT_GNU_verdef:
sec->sh_addralign = PTR_SIZE;
break;
case SHT_STRTAB:
sec->sh_addralign = 1;
break;
default:
sec->sh_addralign = PTR_SIZE; /* gcc/pcc default alignment */
break;
}
if (sh_flags & SHF_PRIVATE) {
dynarray_add(&s1->priv_sections, &s1->nb_priv_sections, sec);
} else {
sec->sh_num = s1->nb_sections;
dynarray_add(&s1->sections, &s1->nb_sections, sec);
}
return sec;
}
void init_symtab(Section *s)
{
int *ptr, nb_buckets = 1;
put_elf_str(s->link, "");
section_ptr_add(s, sizeof (ElfW(Sym)));
ptr = section_ptr_add(s->hash, (2 + nb_buckets + 1) * sizeof(int));
ptr[0] = nb_buckets;
ptr[1] = 1;
memset(ptr + 2, 0, (nb_buckets + 1) * sizeof(int));
}
Section *new_symtab(TCCState *s1,
const char *symtab_name, int sh_type, int sh_flags,
const char *strtab_name,
const char *hash_name, int hash_sh_flags)
{
Section *symtab, *strtab, *hash;
symtab = new_section(s1, symtab_name, sh_type, sh_flags);
symtab->sh_entsize = sizeof(ElfW(Sym));
strtab = new_section(s1, strtab_name, SHT_STRTAB, sh_flags);
symtab->link = strtab;
hash = new_section(s1, hash_name, SHT_HASH, hash_sh_flags);
hash->sh_entsize = sizeof(int);
symtab->hash = hash;
hash->link = symtab;
init_symtab(symtab);
return symtab;
}
/* realloc section and set its content to zero */
void section_realloc(Section *sec, unsigned long new_size)
{
unsigned long size;
unsigned char *data;
size = sec->data_allocated;
if (size == 0)
size = 1;
while (size < new_size)
size = size * 2;
data = tcc_realloc(sec->data, size);
memset(data + sec->data_allocated, 0, size - sec->data_allocated);
sec->data = data;
sec->data_allocated = size;
}
/* reserve at least 'size' bytes aligned per 'align' in section
'sec' from current offset, and return the aligned offset */
size_t section_add(Section *sec, addr_t size, int align)
{
size_t offset, offset1;
offset = (sec->data_offset + align - 1) & -align;
offset1 = offset + size;
if (sec->sh_type != SHT_NOBITS && offset1 > sec->data_allocated)
section_realloc(sec, offset1);
sec->data_offset = offset1;
if (align > sec->sh_addralign)
sec->sh_addralign = align;
return offset;
}
/* reserve at least 'size' bytes in section 'sec' from
sec->data_offset. */
void *section_ptr_add(Section *sec, addr_t size)
{
size_t offset = section_add(sec, size, 1);
return sec->data + offset;
}
static Section *have_section(TCCState *s1, const char *name)
{
Section *sec;
int i;
for(i = 1; i < s1->nb_sections; i++) {
sec = s1->sections[i];
if (!strcmp(name, sec->old_name))
return sec;
}
return NULL;
}
/* return a reference to a section, and create it if it does not
exists */
Section *find_section(TCCState *s1, const char *name)
{
Section *sec = have_section(s1, name);
if (sec)
return sec;
/* sections are created as PROGBITS */
return new_section(s1, name, SHT_PROGBITS, SHF_ALLOC);
}
/* ------------------------------------------------------------------------- */
int put_elf_str(Section *s, const char *sym)
{
int offset, len;
char *ptr;
len = strlen(sym) + 1;
offset = s->data_offset;
ptr = section_ptr_add(s, len);
memmove(ptr, sym, len);
return offset;
}
/* elf symbol hashing function */
static ElfW(Word) elf_hash(const unsigned char *name)
{
ElfW(Word) h = 0, g;
while (*name) {
h = (h << 4) + *name++;
g = h & 0xf0000000;
if (g)
h ^= g >> 24;
h &= ~g;
}
return h;
}
/* rebuild hash table of section s */
/* NOTE: we do factorize the hash table code to go faster */
static void rebuild_hash(Section *s, unsigned int nb_buckets)
{
ElfW(Sym) *sym;
int *ptr, *hash, nb_syms, sym_index, h;
unsigned char *strtab;
strtab = s->link->data;
nb_syms = s->data_offset / sizeof(ElfW(Sym));
if (!nb_buckets)
nb_buckets = ((int*)s->hash->data)[0];
s->hash->data_offset = 0;
ptr = section_ptr_add(s->hash, (2 + nb_buckets + nb_syms) * sizeof(int));
ptr[0] = nb_buckets;
ptr[1] = nb_syms;
ptr += 2;
hash = ptr;
memset(hash, 0, (nb_buckets + 1) * sizeof(int));
ptr += nb_buckets + 1;
sym = (ElfW(Sym) *)s->data + 1;
for(sym_index = 1; sym_index < nb_syms; sym_index++) {
if (ELFW(ST_BIND)(sym->st_info) != STB_LOCAL) {
h = elf_hash(strtab + sym->st_name) % nb_buckets;
*ptr = hash[h];
hash[h] = sym_index;
} else {
*ptr = 0;
}
ptr++;
sym++;
}
}
/* return the symbol number */
int put_elf_sym(Section *s, addr_t value, unsigned long size,
int info, int other, int shndx, const char *name)
{
int name_offset, sym_index;
int nbuckets, h;
ElfW(Sym) *sym;
Section *hs;
sym = section_ptr_add(s, sizeof(ElfW(Sym)));
if (name && name[0])
name_offset = put_elf_str(s->link, name);
else
name_offset = 0;
/* XXX: endianness */
sym->st_name = name_offset;
sym->st_value = value;
sym->st_size = size;
sym->st_info = info;
sym->st_other = other;
sym->st_shndx = shndx;
sym_index = sym - (ElfW(Sym) *)s->data;
hs = s->hash;
if (hs) {
int *ptr, *base;
ptr = section_ptr_add(hs, sizeof(int));
base = (int *)hs->data;
/* only add global or weak symbols. */
if (ELFW(ST_BIND)(info) != STB_LOCAL) {
/* add another hashing entry */
nbuckets = base[0];
h = elf_hash((unsigned char *)s->link->data + name_offset) % nbuckets;
*ptr = base[2 + h];
base[2 + h] = sym_index;
base[1]++;
/* we resize the hash table */
hs->nb_hashed_syms++;
if (hs->nb_hashed_syms > 2 * nbuckets) {
rebuild_hash(s, 2 * nbuckets);
}
} else {
*ptr = 0;
base[1]++;
}
}
return sym_index;
}
int find_elf_sym(Section *s, const char *name)
{
ElfW(Sym) *sym;
Section *hs;
int nbuckets, sym_index, h;
const char *name1;
hs = s->hash;
if (!hs)
return 0;
nbuckets = ((int *)hs->data)[0];
h = elf_hash((unsigned char *) name) % nbuckets;
sym_index = ((int *)hs->data)[2 + h];
while (sym_index != 0) {
sym = &((ElfW(Sym) *)s->data)[sym_index];
name1 = (char *) s->link->data + sym->st_name;
if (!strcmp(name, name1))
return sym_index;
sym_index = ((int *)hs->data)[2 + nbuckets + sym_index];
}
return 0;
}
/* return elf symbol value, signal error if 'err' is nonzero, decorate
name if FORC */
addr_t get_sym_addr(TCCState *s1, const char *name, int err, int forc)
{
int sym_index;
ElfW(Sym) *sym;
char buf[256];
if (forc && s1->leading_underscore) {
buf[0] = '_';
pstrcpy(buf + 1, sizeof(buf) - 1, name);
name = buf;
}
sym_index = find_elf_sym(s1->symtab_section, name);
sym = &((ElfW(Sym) *)s1->symtab_section->data)[sym_index];
if (!sym_index || sym->st_shndx == SHN_UNDEF) {
if (err)
tcc_error_noabort("%s not defined", name);
return (addr_t)-1;
}
return sym->st_value;
}
/* add an elf symbol : check if it is already defined and patch
it. Return symbol index. NOTE that sh_num can be SHN_UNDEF. */
int set_elf_sym(Section *s, addr_t value, unsigned long size,
int info, int other, int shndx, const char *name)
{
TCCState *s1 = s->s1;
ElfW(Sym) *esym;
int sym_bind, sym_index, sym_type, esym_bind;
unsigned char sym_vis, esym_vis, new_vis;
sym_bind = ELFW(ST_BIND)(info);
sym_type = ELFW(ST_TYPE)(info);
sym_vis = ELFW(ST_VISIBILITY)(other);
if (sym_bind != STB_LOCAL) {
/* we search global or weak symbols */
sym_index = find_elf_sym(s, name);
if (!sym_index)
goto do_def;
esym = &((ElfW(Sym) *)s->data)[sym_index];
if (esym->st_value == value && esym->st_size == size && esym->st_info == info
&& esym->st_other == other && esym->st_shndx == shndx)
return sym_index;
if (esym->st_shndx != SHN_UNDEF) {
esym_bind = ELFW(ST_BIND)(esym->st_info);
/* propagate the most constraining visibility */
/* STV_DEFAULT(0)<STV_PROTECTED(3)<STV_HIDDEN(2)<STV_INTERNAL(1) */
esym_vis = ELFW(ST_VISIBILITY)(esym->st_other);
if (esym_vis == STV_DEFAULT) {
new_vis = sym_vis;
} else if (sym_vis == STV_DEFAULT) {
new_vis = esym_vis;
} else {
new_vis = (esym_vis < sym_vis) ? esym_vis : sym_vis;
}
esym->st_other = (esym->st_other & ~ELFW(ST_VISIBILITY)(-1))
| new_vis;
if (shndx == SHN_UNDEF) {
/* ignore adding of undefined symbol if the
corresponding symbol is already defined */
} else if (sym_bind == STB_GLOBAL && esym_bind == STB_WEAK) {
/* global overrides weak, so patch */
goto do_patch;
} else if (sym_bind == STB_WEAK && esym_bind == STB_GLOBAL) {
/* weak is ignored if already global */
} else if (sym_bind == STB_WEAK && esym_bind == STB_WEAK) {
/* keep first-found weak definition, ignore subsequents */
} else if (sym_vis == STV_HIDDEN || sym_vis == STV_INTERNAL) {
/* ignore hidden symbols after */
} else if (esym->st_shndx == s1->bss_section->sh_num
&& (shndx < SHN_LORESERVE
&& shndx != s1->bss_section->sh_num)) {
/* data symbol gets precedence over common/bss */
goto do_patch;
} else if (shndx == s1->bss_section->sh_num) {
/* data symbol keeps precedence over common/bss */
} else if (s->sh_flags & SHF_DYNSYM) {
/* we accept that two DLL define the same symbol */
} else if (esym->st_other & ST_ASM_SET) {
/* If the existing symbol came from an asm .set
we can override. */
goto do_patch;
} else {
tcc_error_noabort("'%s' defined twice", name);
}
} else {
esym->st_other = other;
do_patch:
esym->st_info = ELFW(ST_INFO)(sym_bind, sym_type);
esym->st_shndx = shndx;
s1->new_undef_sym = 1;
esym->st_value = value;
esym->st_size = size;
}
} else {
do_def:
sym_index = put_elf_sym(s, value, size,
ELFW(ST_INFO)(sym_bind, sym_type), other,
shndx, name);
}
return sym_index;
}
/* put relocation */
void put_elf_reloca(Section *symtab, Section *s, unsigned long offset,
int type, int symbol, addr_t addend)
{
TCCState *s1 = s->s1;
char buf[256];
Section *sr;
ElfW_Rel *rel;
sr = s->reloc;
if (!sr) {
/* if no relocation section, create it */
snprintf(buf, sizeof(buf), REL_SECTION_FMT, s->old_name);
/* if the symtab is allocated, then we consider the relocation
are also */
sr = new_section(s->s1, buf, SHT_RELX, symtab->sh_flags);
sr->sh_entsize = sizeof(ElfW_Rel);
sr->link = symtab;
sr->sh_info = s->sh_num;
s->reloc = sr;
}
rel = section_ptr_add(sr, sizeof(ElfW_Rel));
rel->r_offset = offset;
rel->r_info = ELFW(R_INFO)(symbol, type);
#if SHT_RELX == SHT_RELA
rel->r_addend = addend;
#endif
if (SHT_RELX != SHT_RELA && addend)
tcc_error_noabort("non-zero addend on REL architecture");
}
void put_elf_reloc(Section *symtab, Section *s, unsigned long offset,
int type, int symbol)
{
put_elf_reloca(symtab, s, offset, type, symbol, 0);
}
static void update_relocs(TCCState *s1, Section *s, int *old_to_new_syms, int first_sym)
{
int i, type, sym_index;
Section *sr;
ElfW_Rel *rel;
for(i = 1; i < s1->nb_sections; i++) {
sr = s1->sections[i];
if (sr->sh_type == SHT_RELX && sr->link == s) {
for_each_elem(sr, 0, rel, ElfW_Rel) {
sym_index = ELFW(R_SYM)(rel->r_info);
type = ELFW(R_TYPE)(rel->r_info);
if ((sym_index -= first_sym) < 0)
continue; /* zero sym_index in reloc (can happen with asm) */
sym_index = old_to_new_syms[sym_index];
rel->r_info = ELFW(R_INFO)(sym_index, type);
}
}
}
}
/* relocate symbol table, resolve undefined symbols if do_resolve is
true and output error if undefined symbol. */
void relocate_syms(TCCState *s1, Section *symtab, int do_resolve)
{
ElfW(Sym) *sym;
int sym_bind, sh_num;
const char *name;
for_each_elem(symtab, 1, sym, ElfW(Sym)) {
sh_num = sym->st_shndx;
if (sh_num == SHN_UNDEF) {
if (do_resolve == 2) /* relocating dynsym */
continue;
name = (char *) s1->symtab_section->link->data + sym->st_name;
/* Use ld.so to resolve symbol for us (for tcc -run) */
if (do_resolve) {
/* if dynamic symbol exist, it will be used in relocate_section */
}
/* XXX: _fp_hw seems to be part of the ABI, so we ignore
it */
if (!strcmp(name, "_fp_hw"))
goto found;
/* only weak symbols are accepted to be undefined. Their
value is zero */
sym_bind = ELFW(ST_BIND)(sym->st_info);
if (sym_bind == STB_WEAK)
sym->st_value = 0;
else
tcc_error_noabort("undefined symbol '%s'", name);
} else if (sh_num < SHN_LORESERVE) {
/* add section base */
sym->st_value += s1->sections[sym->st_shndx]->sh_addr;
}
found: ;
}
}
/* relocate a given section (CPU dependent) by applying the relocations
in the associated relocation section */
static void relocate_section(TCCState *s1, Section *s, Section *sr)
{
ElfW_Rel *rel;
ElfW(Sym) *sym;
int type, sym_index;
unsigned char *ptr;
addr_t tgt, addr;
qrel = (ElfW_Rel *)sr->data;
for_each_elem(sr, 0, rel, ElfW_Rel) {
ptr = s->data + rel->r_offset;
sym_index = ELFW(R_SYM)(rel->r_info);
sym = &((ElfW(Sym) *)s1->symtab_section->data)[sym_index];
type = ELFW(R_TYPE)(rel->r_info);
tgt = sym->st_value;
#if SHT_RELX == SHT_RELA
tgt += rel->r_addend;
#endif
addr = s->sh_addr + rel->r_offset;
relocate(s1, rel, type, ptr, addr, tgt);
}
}
/* relocate all sections */
void relocate_sections(TCCState *s1)
{
int i;
Section *s, *sr;
for (i = 1; i < s1->nb_sections; ++i) {
sr = s1->sections[i];
if (sr->sh_type != SHT_RELX)
continue;
s = s1->sections[sr->sh_info];
relocate_section(s1, s, sr);
#ifndef ELF_OBJ_ONLY
if (sr->sh_flags & SHF_ALLOC) {
ElfW_Rel *rel;
/* relocate relocation table in 'sr' */
for_each_elem(sr, 0, rel, ElfW_Rel)
rel->r_offset += s->sh_addr;
}
#endif
}
}
int set_global_sym(TCCState *s1, const char *name, Section *sec, addr_t offs)
{
int shn = sec ? sec->sh_num : offs || !name ? SHN_ABS : SHN_UNDEF;
if (sec && offs == -1)
offs = sec->data_offset;
return set_elf_sym(s1->symtab_section, offs, 0,
ELFW(ST_INFO)(name ? STB_GLOBAL : STB_LOCAL, STT_NOTYPE), 0, shn, name);
}
static void add_init_array_defines(TCCState *s1, const char *section_name)
{
Section *s;
addr_t end_offset;
char buf[1024];
s = have_section(s1, section_name);
if (!s || !(s->sh_flags & SHF_ALLOC)) {
end_offset = 0;
s = s1->text_section;
} else {
end_offset = s->data_offset;
}
snprintf(buf, sizeof(buf), "__%s_start", section_name + 1);
set_global_sym(s1, buf, s, 0);
snprintf(buf, sizeof(buf), "__%s_end", section_name + 1);
set_global_sym(s1, buf, s, end_offset);
}
void add_array (TCCState *s1, const char *sec, int c)
{
Section *s;
s = find_section(s1, sec);
s->sh_flags = shf_RELRO;
s->sh_type = sec[1] == 'i' ? SHT_INIT_ARRAY : SHT_FINI_ARRAY;
put_elf_reloc (s1->symtab_section, s, s->data_offset, R_DATA_PTR, c);
section_ptr_add(s, PTR_SIZE);
}
#if !defined TCC_TARGET_PE
/* add libc crt1/crti objects */
void tccelf_add_crtbegin(TCCState *s1)
{
tcc_add_crt(s1, "crt1.o");
tcc_add_crt(s1, "crti.o");
}
void tccelf_add_crtend(TCCState *s1)
{
tcc_add_crt(s1, "crtn.o");
}
#endif /* !defined TCC_TARGET_PE */
#ifndef TCC_TARGET_PE
/* add tcc runtime libraries */
void tcc_add_runtime(TCCState *s1)
{
s1->filetype = 0;
tcc_add_pragma_libs(s1);
/* add libc */
if (!s1->nostdlib) {
int lpthread = s1->option_pthread;
if (lpthread)
tcc_add_library(s1, "pthread");
tcc_add_library(s1, "c");
if (TCC_LIBTCC1[0])
tcc_add_support(s1, TCC_LIBTCC1);
tccelf_add_crtend(s1);
}
}
#endif /* ndef TCC_TARGET_PE */
/* add various standard linker symbols (must be done after the
sections are filled (for example after allocating common
symbols)) */
static void tcc_add_linker_symbols(TCCState *s1)
{
char buf[1024];
int i;
Section *s;
set_global_sym(s1, "_etext", s1->text_section, -1);
set_global_sym(s1, "_edata", s1->data_section, -1);
set_global_sym(s1, "_end", s1->bss_section, -1);
/* horrible new standard ldscript defines */
add_init_array_defines(s1, ".preinit_array");
add_init_array_defines(s1, ".init_array");
add_init_array_defines(s1, ".fini_array");
/* add start and stop symbols for sections whose name can be
expressed in C */
for(i = 1; i < s1->nb_sections; i++) {
s = s1->sections[i];
if ((s->sh_flags & SHF_ALLOC)
&& (s->sh_type == SHT_PROGBITS || s->sh_type == SHT_NOBITS
|| s->sh_type == SHT_STRTAB)) {
/* check if section name can be expressed in C */
const char *p0, *p;
p0 = s->old_name;
if (*p0 == '.')
++p0;
p = p0;
for(;;) {
int c = *p;
if (!c)
break;
if (!isid(c) && !isnum(c))
goto next_sec;
p++;
}
snprintf(buf, sizeof(buf), "__start_%s", p0);
set_global_sym(s1, buf, s, 0);
snprintf(buf, sizeof(buf), "__stop_%s", p0);
set_global_sym(s1, buf, s, -1);
}
next_sec: ;
}
}
void resolve_common_syms(TCCState *s1)
{
ElfW(Sym) *sym;
/* Allocate common symbols in BSS. */
for_each_elem(s1->symtab_section, 1, sym, ElfW(Sym)) {
if (sym->st_shndx == SHN_COMMON) {
/* symbol alignment is in st_value for SHN_COMMONs */
sym->st_value = section_add(s1->bss_section, sym->st_size,
sym->st_value);
sym->st_shndx = s1->bss_section->sh_num;
}
}
/* Now assign linker provided symbols their value. */
tcc_add_linker_symbols(s1);
}
#ifndef ELF_OBJ_ONLY
/* decide if an unallocated section should be output. */
static int set_sec_sizes(TCCState *s1)
{
int i;
Section *s;
int textrel = 0;
/* Allocate strings for section names */
for(i = 1; i < s1->nb_sections; i++) {
s = s1->sections[i];
if (s->sh_type == SHT_RELX && !(s->sh_flags & SHF_ALLOC)) {
/* when generating a DLL, we include relocations but
we may patch them */
} else if ((s->sh_flags & SHF_ALLOC)) {
s->sh_size = s->data_offset;
}
}
return textrel;
}
/* various data used under elf_output_file() */
struct dyn_inf {
Section *dynamic;
Section *dynstr;
struct {
/* Info to be copied in dynamic section */
unsigned long data_offset;
addr_t rel_addr;
addr_t rel_size;
};
ElfW(Phdr) *phdr;
int phnum;
int shnum;
Section *interp;
Section *note;
Section *gnu_hash;
/* read only segment mapping for GNU_RELRO */
Section _roinf, *roinf;
};
/* Decide the layout of sections loaded in memory. This must be done before
program headers are filled since they contain info about the layout.
We do the following ordering: interp, symbol tables, relocations, progbits,
nobits */
static int sort_sections(TCCState *s1, int *sec_order, struct dyn_inf *d)
{
Section *s;
int i, j, k, f, f0, n;
int nb_sections = s1->nb_sections;
int *sec_cls = sec_order + nb_sections;
for (i = 1; i < nb_sections; i++) {
s = s1->sections[i];
if (0 == s->sh_name) {
j = 0x900; /* no sh_name: won't go to file */
} else if (s->sh_flags & SHF_ALLOC) {
j = 0x100;
if (s->sh_flags & SHF_WRITE)
j = 0x200;
if (s->sh_flags & SHF_TLS)
j += 0x200;
} else {
j = 0x700;
}
if (j >= 0x700 && s1->output_format != TCC_OUTPUT_FORMAT_ELF)
s->sh_size = 0, j = 0x900;
if (s->sh_type == SHT_SYMTAB || s->sh_type == SHT_DYNSYM) {
k = 0x10;
} else if (s->sh_type == SHT_STRTAB && strcmp(s->old_name, ".stabstr")) {
k = 0x11;
if (i == nb_sections - 1) /* ".shstrtab" assumed to stay last */
k = 0xff;
} else if (s->sh_type == SHT_HASH || s->sh_type == SHT_GNU_HASH) {
k = 0x12;
} else if (s->sh_type == SHT_GNU_verdef
|| s->sh_type == SHT_GNU_verneed
|| s->sh_type == SHT_GNU_versym) {
k = 0x13;
} else if (s->sh_type == SHT_RELX) {
k = 0x20;
} else if (s->sh_flags & SHF_EXECINSTR) {
k = 0x30;
/* RELRO sections --> */
} else if (s->sh_type == SHT_PREINIT_ARRAY) {
k = 0x41;
} else if (s->sh_type == SHT_INIT_ARRAY) {
k = 0x42;
} else if (s->sh_type == SHT_FINI_ARRAY) {
k = 0x43;
} else if (s->sh_type == SHT_DYNAMIC) {
k = 0x46;
} else if (s->reloc && (s->reloc->sh_flags & SHF_ALLOC) && j == 0x100) {
k = 0x44;
/* <-- */
} else if (s->sh_type == SHT_NOTE) {
k = 0x60;
} else if (s->sh_type == SHT_NOBITS) {
k = 0x70; /* bss */
} else if (s == d->interp) {
k = 0x00;
} else {
k = 0x50; /* data */
}
k += j;
if ((k & 0xfff0) == 0x140) {
/* make RELRO section writable */
k += 0x100, s->sh_flags |= SHF_WRITE;
}
for (n = i; n > 1 && k < (f = sec_cls[n - 1]); --n)
sec_cls[n] = f, sec_order[n] = sec_order[n - 1];
sec_cls[n] = k, sec_order[n] = i;
}
sec_order[0] = 0;
d->shnum = 1;
/* count PT_LOAD headers needed */
n = f0 = 0;
for (i = 1; i < nb_sections; i++) {
s = s1->sections[sec_order[i]];
k = sec_cls[i];
f = 0;
if (k < 0x900)
++d->shnum;
if (k < 0x700) {
f = s->sh_flags & (SHF_ALLOC|SHF_WRITE|SHF_EXECINSTR|SHF_TLS);
#if TARGETOS_NetBSD
/* NetBSD only supports 2 PT_LOAD sections.
See: https://blog.netbsd.org/tnf/entry/the_first_report_on_lld */
if ((f & SHF_WRITE) == 0)
f |= SHF_EXECINSTR;
#else
if ((k & 0xfff0) == 0x240) /* RELRO sections */
f |= 1<<4;
#endif
/* start new header when flags changed or relro, but avoid zero memsz */
if (f != f0 && s->sh_size)
f0 = f, ++n, f |= 1<<8;
}
sec_cls[i] = f;
//printf("ph %d sec %02d : %3X %3X %8.2X %04X %s\n", (f>0) * n, i, f, k, s->sh_type, (int)s->sh_size, s->name);
}
return n;
}
static ElfW(Phdr) *fill_phdr(ElfW(Phdr) *ph, int type, Section *s)
{
if (s) {
ph->p_offset = s->sh_offset;
ph->p_vaddr = s->sh_addr;
ph->p_filesz = s->sh_size;
ph->p_align = s->sh_addralign;
}
ph->p_type = type;
ph->p_flags = PF_R;
ph->p_paddr = ph->p_vaddr;
ph->p_memsz = ph->p_filesz;
return ph;
}
/* Assign sections to segments and decide how are sections laid out when loaded
in memory. This function also fills corresponding program headers. */
static int layout_sections(TCCState *s1, int *sec_order, struct dyn_inf *d)
{
Section *s;
addr_t addr, tmp, align, s_align, base;
ElfW(Phdr) *ph = NULL;
int i, f, n, phnum, phfill;
int file_offset;
/* compute number of program headers */
phnum = sort_sections(s1, sec_order, d);
phfill = 0; /* set to 1 to have dll's with a PT_PHDR */
if (d->interp)
phfill = 2;
phnum += phfill;
if (d->note)
++phnum;
if (d->dynamic)
++phnum;
if (d->roinf)
++phnum;
d->phnum = phnum;
d->phdr = tcc_mallocz(phnum * sizeof(ElfW(Phdr)));
file_offset = 0;
if (s1->output_format == TCC_OUTPUT_FORMAT_ELF) {
file_offset = (sizeof(ElfW(Ehdr)) + phnum * sizeof(ElfW(Phdr)) + 3) & -4;
file_offset += d->shnum * sizeof (ElfW(Shdr));
}
s_align = ELF_PAGE_SIZE;
if (s1->section_align)
s_align = s1->section_align;
addr = ELF_START_ADDR;
if (s1->has_text_addr) {
addr = s1->text_addr;
if (0) {
int a_offset, p_offset;
/* we ensure that (addr % ELF_PAGE_SIZE) == file_offset %
ELF_PAGE_SIZE */
a_offset = (int) (addr & (s_align - 1));
p_offset = file_offset & (s_align - 1);
if (a_offset < p_offset)
a_offset += s_align;
file_offset += (a_offset - p_offset);
}
}
base = addr;
/* compute address after headers */
addr += file_offset;
n = 0;
for(i = 1; i < s1->nb_sections; i++) {
s = s1->sections[sec_order[i]];
f = sec_order[i + s1->nb_sections];
align = s->sh_addralign - 1;
if (f == 0) { /* no alloc */
file_offset = (file_offset + align) & ~align;
s->sh_offset = file_offset;
if (s->sh_type != SHT_NOBITS)
file_offset += s->sh_size;
continue;
}
if ((f & 1<<8) && n) {
/* different rwx section flags */
if (s1->output_format == TCC_OUTPUT_FORMAT_ELF) {
/* if in the middle of a page, w e duplicate the page in
memory so that one copy is RX and the other is RW */
if ((addr & (s_align - 1)) != 0)
addr += s_align;
} else {
align = s_align - 1;
}
}
tmp = addr;
addr = (addr + align) & ~align;
file_offset += (int)(addr - tmp);
s->sh_offset = file_offset;
s->sh_addr = addr;
if (f & 1<<8) {
/* set new program header */
ph = &d->phdr[phfill + n];
ph->p_type = PT_LOAD;
ph->p_align = s_align;
ph->p_flags = PF_R;
if (f & SHF_WRITE)
ph->p_flags |= PF_W;
if (f & SHF_EXECINSTR)
ph->p_flags |= PF_X;
if (f & SHF_TLS) {
ph->p_type = PT_TLS;
ph->p_align = align + 1;
}
ph->p_offset = file_offset;
ph->p_vaddr = addr;
if (n == 0) {
/* Make the first PT_LOAD segment include the program
headers itself (and the ELF header as well), it'll
come out with same memory use but will make various
tools like binutils strip work better. */
ph->p_offset = 0;
ph->p_vaddr = base;
}
ph->p_paddr = ph->p_vaddr;
++n;
}
if (f & 1<<4) {
Section *roinf = &d->_roinf;
if (roinf->sh_size == 0) {
roinf->sh_offset = s->sh_offset;
roinf->sh_addr = s->sh_addr;
roinf->sh_addralign = 1;
}
roinf->sh_size = (addr - roinf->sh_addr) + s->sh_size;
}
addr += s->sh_size;
if (s->sh_type != SHT_NOBITS)
file_offset += s->sh_size;
ph->p_filesz = file_offset - ph->p_offset;
ph->p_memsz = addr - ph->p_vaddr;
}
/* Fill other headers */
if (d->note)
fill_phdr(++ph, PT_NOTE, d->note);
if (d->dynamic)
fill_phdr(++ph, PT_DYNAMIC, d->dynamic)->p_flags |= PF_W;
if (d->roinf)
fill_phdr(++ph, PT_GNU_RELRO, d->roinf)->p_flags |= PF_W;
if (d->interp)
fill_phdr(&d->phdr[1], PT_INTERP, d->interp);
if (phfill) {
ph = &d->phdr[0];
ph->p_offset = sizeof(ElfW(Ehdr));
ph->p_vaddr = base + ph->p_offset;
ph->p_filesz = phnum * sizeof(ElfW(Phdr));
ph->p_align = 4;
fill_phdr(ph, PT_PHDR, NULL);
}
return 0;
}
/* Remove gaps between RELX sections.
These gaps are a result of final_sections_reloc. Here some relocs are removed.
The gaps are then filled with 0 in tcc_output_elf. The 0 is intepreted as
R_...NONE reloc. This does work on most targets but on OpenBSD/arm64 this
is illegal. OpenBSD/arm64 does not support R_...NONE reloc. */
static void update_reloc_sections(TCCState *s1, struct dyn_inf *dyninf)
{
int i;
unsigned long file_offset = 0;
Section *s;
/* dynamic relocation table information, for .dynamic section */
dyninf->rel_addr = dyninf->rel_size = 0;
for(i = 1; i < s1->nb_sections; i++) {
s = s1->sections[i];
if (s->sh_type == SHT_RELX) {
if (dyninf->rel_size == 0) {
dyninf->rel_addr = s->sh_addr;
file_offset = s->sh_offset;
}
else {
s->sh_addr = dyninf->rel_addr + dyninf->rel_size;
s->sh_offset = file_offset + dyninf->rel_size;
}
dyninf->rel_size += s->sh_size;
}
}
}
#endif /* ndef ELF_OBJ_ONLY */
/* Create an ELF file on disk.
This function handle ELF specific layout requirements */
static int tcc_output_elf(TCCState *s1, FILE *f, int phnum, ElfW(Phdr) *phdr)
{
int i, shnum, offset, size, file_type;
Section *s;
ElfW(Ehdr) ehdr;
ElfW(Shdr) shdr, *sh;
file_type = s1->output_type;
shnum = s1->nb_sections;
memset(&ehdr, 0, sizeof(ehdr));
if (phnum > 0) {
ehdr.e_phentsize = sizeof(ElfW(Phdr));
ehdr.e_phnum = phnum;
ehdr.e_phoff = sizeof(ElfW(Ehdr));
}
/* fill header */
ehdr.e_ident[0] = ELFMAG0;
ehdr.e_ident[1] = ELFMAG1;
ehdr.e_ident[2] = ELFMAG2;
ehdr.e_ident[3] = ELFMAG3;
ehdr.e_ident[4] = ELFCLASSW;
ehdr.e_ident[5] = ELFDATA2LSB;
ehdr.e_ident[6] = EV_CURRENT;
if (file_type == TCC_OUTPUT_OBJ) {
ehdr.e_type = ET_REL;
} else {
ehdr.e_type = ET_EXEC;
if (s1->entryname)
ehdr.e_entry = get_sym_addr(s1, s1->entryname, 1, 0);
else
ehdr.e_entry = get_sym_addr(s1, "_start", !!(file_type & TCC_OUTPUT_EXE), 0);
if (ehdr.e_entry == (addr_t)-1)
ehdr.e_entry = s1->text_section->sh_addr;
if (s1->nb_errors)
return -1;
}
ehdr.e_machine = EM_386;
ehdr.e_version = EV_CURRENT;
ehdr.e_shoff = (sizeof(ElfW(Ehdr)) + phnum * sizeof(ElfW(Phdr)) + 3) & -4;
ehdr.e_ehsize = sizeof(ElfW(Ehdr));
ehdr.e_shentsize = sizeof(ElfW(Shdr));
ehdr.e_shnum = shnum;
ehdr.e_shstrndx = shnum - 1;
offset = fwrite(&ehdr, 1, sizeof(ElfW(Ehdr)), f);
if (phdr)
offset += fwrite(phdr, 1, phnum * sizeof(ElfW(Phdr)), f);
/* output section headers */
while (offset < ehdr.e_shoff) {
fputc(0, f);
offset++;
}
for(i = 0; i < shnum; i++) {
sh = &shdr;
memset(sh, 0, sizeof(ElfW(Shdr)));
if (i) {
s = s1->sections[i];
sh->sh_name = s->sh_name;
sh->sh_type = s->sh_type;
sh->sh_flags = s->sh_flags;
sh->sh_entsize = s->sh_entsize;
sh->sh_info = s->sh_info;
if (s->link)
sh->sh_link = s->link->sh_num;
sh->sh_addralign = s->sh_addralign;
sh->sh_addr = s->sh_addr;
sh->sh_offset = s->sh_offset;
sh->sh_size = s->sh_size;
}
offset += fwrite(sh, 1, sizeof(ElfW(Shdr)), f);
}
/* output sections */
for(i = 1; i < s1->nb_sections; i++) {
s = s1->sections[i];
if (s->sh_type != SHT_NOBITS) {
while (offset < s->sh_offset) {
fputc(0, f);
offset++;
}
size = s->sh_size;
if (size)
offset += fwrite(s->data, 1, size, f);
}
}
return 0;
}
static int tcc_output_binary(TCCState *s1, FILE *f)
{
Section *s;
int i, offset, size;
offset = 0;
for(i=1;i<s1->nb_sections;i++) {
s = s1->sections[i];
if (s->sh_type != SHT_NOBITS &&
(s->sh_flags & SHF_ALLOC)) {
while (offset < s->sh_offset) {
fputc(0, f);
offset++;
}
size = s->sh_size;
fwrite(s->data, 1, size, f);
offset += size;
}
}
return 0;
}
/* Write an elf, coff or "binary" file */
static int tcc_write_elf_file(TCCState *s1, const char *filename, int phnum,
ElfW(Phdr) *phdr)
{
int fd, mode, file_type, ret;
FILE *f;
file_type = s1->output_type;
if (file_type == TCC_OUTPUT_OBJ)
mode = 0666;
else
mode = 0777;
unlink(filename);
fd = open(filename, O_WRONLY | O_CREAT | O_TRUNC | O_BINARY, mode);
if (fd < 0 || (f = fdopen(fd, "wb")) == NULL)
return tcc_error_noabort("could not write '%s: %s'", filename, strerror(errno));
if (s1->verbose)
printf("<- %s\n", filename);
#ifdef TCC_TARGET_COFF
if (s1->output_format == TCC_OUTPUT_FORMAT_COFF)
tcc_output_coff(s1, f);
else
#endif
if (s1->output_format == TCC_OUTPUT_FORMAT_ELF)
ret = tcc_output_elf(s1, f, phnum, phdr);
else
ret = tcc_output_binary(s1, f);
fclose(f);
return ret;
}
#ifndef ELF_OBJ_ONLY
/* order sections according to sec_order, remove sections
that we aren't going to output. */
static void reorder_sections(TCCState *s1, int *sec_order)
{
int i, nnew, k, *backmap;
Section **snew, *s;
ElfW(Sym) *sym;
backmap = tcc_malloc(s1->nb_sections * sizeof(backmap[0]));
for (i = 0, nnew = 0, snew = NULL; i < s1->nb_sections; i++) {
k = sec_order[i];
s = s1->sections[k];
if (!i || s->sh_name) {
backmap[k] = nnew;
dynarray_add(&snew, &nnew, s);
} else {
backmap[k] = 0;
/* just remember to free them later */
dynarray_add(&s1->priv_sections, &s1->nb_priv_sections, s);
}
}
for (i = 1; i < nnew; i++) {
s = snew[i];
s->sh_num = i;
if (s->sh_type == SHT_RELX)
s->sh_info = backmap[s->sh_info];
else if (s->sh_type == SHT_SYMTAB || s->sh_type == SHT_DYNSYM)
for_each_elem(s, 1, sym, ElfW(Sym))
if (sym->st_shndx < s1->nb_sections)
sym->st_shndx = backmap[sym->st_shndx];
}
tcc_free(s1->sections);
s1->sections = snew;
s1->nb_sections = nnew;
tcc_free(backmap);
}
static void alloc_sec_names(TCCState *s1, int is_obj);
/* Output an elf, coff or binary file */
/* XXX: suppress unneeded sections */
static int elf_output_file(TCCState *s1, const char *filename)
{
int i, ret, file_type, *sec_order;
struct dyn_inf dyninf = {0};
Section *interp, *dynstr, *dynamic;
int textrel, got_sym;
file_type = s1->output_type;
s1->nb_errors = 0;
ret = -1;
interp = dynstr = dynamic = NULL;
sec_order = NULL;
dyninf.roinf = &dyninf._roinf;
/* if linking, also link in runtime libraries (libc, libgcc, etc.) */
tcc_add_runtime(s1);
resolve_common_syms(s1);
textrel = set_sec_sizes(s1);
/* create and fill .shstrtab section */
alloc_sec_names(s1, 0);
/* this array is used to reorder sections in the output file */
sec_order = tcc_malloc(sizeof(int) * 2 * s1->nb_sections);
/* compute section to program header mapping */
layout_sections(s1, sec_order, &dyninf);
/* if building executable or DLL, then relocate each section
except the GOT which is already relocated */
relocate_syms(s1, s1->symtab_section, 0);
if (s1->nb_errors != 0)
goto the_end;
relocate_sections(s1);
reorder_sections(s1, sec_order);
/* Create the ELF file with name 'filename' */
ret = tcc_write_elf_file(s1, filename, dyninf.phnum, dyninf.phdr);
the_end:
tcc_free(sec_order);
tcc_free(dyninf.phdr);
return ret;
}
#endif /* ndef ELF_OBJ_ONLY */
/* Allocate strings for section names */
static void alloc_sec_names(TCCState *s1, int is_obj)
{
int i;
Section *s, *strsec;
strsec = new_section(s1, ".shstrtab", SHT_STRTAB, 0);
put_elf_str(strsec, "");
for(i = 1; i < s1->nb_sections; i++) {
s = s1->sections[i];
if (is_obj)
s->sh_size = s->data_offset;
if (s->sh_size || s == strsec || (s->sh_flags & SHF_ALLOC) || is_obj)
s->sh_name = put_elf_str(strsec, s->old_name);
}
strsec->sh_size = strsec->data_offset;
}
/* Output an elf .o file */
static int elf_output_obj(TCCState *s1, const char *filename)
{
Section *s;
int i, ret, file_offset;
s1->nb_errors = 0;
/* Allocate strings for section names */
alloc_sec_names(s1, 1);
file_offset = (sizeof (ElfW(Ehdr)) + 3) & -4;
file_offset += s1->nb_sections * sizeof(ElfW(Shdr));
for(i = 1; i < s1->nb_sections; i++) {
s = s1->sections[i];
file_offset = (file_offset + 15) & -16;
s->sh_offset = file_offset;
if (s->sh_type != SHT_NOBITS)
file_offset += s->sh_size;
}
/* Create the ELF file with name 'filename' */
ret = tcc_write_elf_file(s1, filename, 0, NULL);
return ret;
}
int tcc_output_file(TCCState *s, const char *filename)
{
if (s->output_type == TCC_OUTPUT_OBJ)
return elf_output_obj(s, filename);
return elf_output_file(s, filename);
}
ssize_t full_read(int fd, void *buf, size_t count) {
char *cbuf = buf;
size_t rnum = 0;
while (1) {
ssize_t num = read(fd, cbuf, count-rnum);
if (num < 0) return num;
if (num == 0) return rnum;
rnum += num;
cbuf += num;
}
}
void *load_data(int fd, unsigned long file_offset, unsigned long size)
{
void *data;
data = tcc_malloc(size);
lseek(fd, file_offset, SEEK_SET);
full_read(fd, data, size);
return data;
}
typedef struct SectionMergeInfo {
Section *s; /* corresponding existing section */
unsigned long offset; /* offset of the new section in the existing section */
uint8_t new_section; /* true if section 's' was added */
uint8_t link_once; /* true if link once section */
} SectionMergeInfo;
int tcc_object_type(int fd, ElfW(Ehdr) *h)
{
int size = full_read(fd, h, sizeof *h);
if (size == sizeof *h && 0 == memcmp(h, ELFMAG, 4)) {
if (h->e_type == ET_REL)
return AFF_BINTYPE_REL;
if (h->e_type == ET_DYN)
return AFF_BINTYPE_DYN;
} else if (size >= 8) {
if (0 == memcmp(h, ARMAG, 8))
return AFF_BINTYPE_AR;
/* else if (((FILHDR *)h)->f_magic == F_MACH_I386)
return (AFF_BINTYPE_COFF);*/
}
return 0;
}
/* load an object file and merge it with current files */
/* XXX: handle correctly stab (debug) info */
int tcc_load_object_file(TCCState *s1,
int fd, unsigned long file_offset)
{
ElfW(Ehdr) ehdr;
ElfW(Shdr) *shdr, *sh;
unsigned long size, offset, offseti;
int i, j, nb_syms, sym_index, ret, seencompressed;
char *strsec, *strtab;
int *old_to_new_syms;
char *sh_name, *name;
SectionMergeInfo *sm_table, *sm;
ElfW(Sym) *sym, *symtab;
ElfW_Rel *rel;
Section *s;
lseek(fd, file_offset, SEEK_SET);
if (tcc_object_type(fd, &ehdr) != AFF_BINTYPE_REL)
goto invalid;
/* test CPU specific stuff */
if (ehdr.e_ident[5] != ELFDATA2LSB ||
ehdr.e_machine != EM_386) {
invalid:
return tcc_error_noabort("invalid object file");
}
/* read sections */
shdr = load_data(fd, file_offset + ehdr.e_shoff,
sizeof(ElfW(Shdr)) * ehdr.e_shnum);
sm_table = tcc_mallocz(sizeof(SectionMergeInfo) * ehdr.e_shnum);
/* load section names */
sh = &shdr[ehdr.e_shstrndx];
strsec = load_data(fd, file_offset + sh->sh_offset, sh->sh_size);
/* load symtab and strtab */
old_to_new_syms = NULL;
symtab = NULL;
strtab = NULL;
nb_syms = 0;
seencompressed = 0;
ret = -1;
for(i = 1; i < ehdr.e_shnum; i++) {
sh = &shdr[i];
if (sh->sh_type == SHT_SYMTAB) {
if (symtab) {
tcc_error_noabort("object must contain only one symtab");
goto the_end;
}
nb_syms = sh->sh_size / sizeof(ElfW(Sym));
symtab = load_data(fd, file_offset + sh->sh_offset, sh->sh_size);
sm_table[i].s = s1->symtab_section;
/* now load strtab */
sh = &shdr[sh->sh_link];
strtab = load_data(fd, file_offset + sh->sh_offset, sh->sh_size);
}
if (sh->sh_flags & SHF_COMPRESSED)
seencompressed = 1;
}
/* now examine each section and try to merge its content with the
ones in memory */
for(i = 1; i < ehdr.e_shnum; i++) {
/* no need to examine section name strtab */
if (i == ehdr.e_shstrndx)
continue;
sh = &shdr[i];
if (sh->sh_type == SHT_RELX)
sh = &shdr[sh->sh_info];
/* ignore sections types we do not handle (plus relocs to those) */
sh_name = strsec + sh->sh_name;
if (0 == strncmp(sh_name, ".debug_", 7)
|| 0 == strncmp(sh_name, ".stab", 5)) {
if (seencompressed)
continue;
} else
if (sh->sh_type != SHT_PROGBITS &&
sh->sh_type != SHT_NOTE &&
sh->sh_type != SHT_NOBITS &&
sh->sh_type != SHT_PREINIT_ARRAY &&
sh->sh_type != SHT_INIT_ARRAY &&
sh->sh_type != SHT_FINI_ARRAY
)
continue;
sh = &shdr[i];
sh_name = strsec + sh->sh_name;
if (sh->sh_addralign < 1)
sh->sh_addralign = 1;
/* find corresponding section, if any */
for(j = 1; j < s1->nb_sections;j++) {
s = s1->sections[j];
if (strcmp(s->old_name, sh_name))
continue;
if (!strncmp(sh_name, ".gnu.linkonce", 13)) {
/* if a 'linkonce' section is already present, we
do not add it again. It is a little tricky as
symbols can still be defined in
it. */
sm_table[i].link_once = 1;
goto next;
}
goto found;
}
/* not found: create new section */
s = new_section(s1, sh_name, sh->sh_type, sh->sh_flags & ~SHF_GROUP);
/* take as much info as possible from the section. sh_link and
sh_info will be updated later */
s->sh_addralign = sh->sh_addralign;
s->sh_entsize = sh->sh_entsize;
sm_table[i].new_section = 1;
found:
/* align start of section */
s->data_offset += -s->data_offset & (sh->sh_addralign - 1);
if (sh->sh_addralign > s->sh_addralign)
s->sh_addralign = sh->sh_addralign;
sm_table[i].offset = s->data_offset;
sm_table[i].s = s;
/* concatenate sections */
size = sh->sh_size;
if (sh->sh_type != SHT_NOBITS) {
unsigned char *ptr;
lseek(fd, file_offset + sh->sh_offset, SEEK_SET);
ptr = section_ptr_add(s, size);
full_read(fd, ptr, size);
} else {
s->data_offset += size;
}
/* align end of section */
/* This is needed if we compile a c file after this */
if (s == s1->text_section || s == s1->data_section || s == s1->rodata_section ||
s == s1->bss_section)
s->data_offset += -s->data_offset & (s->sh_addralign - 1);
next: ;
}
/* second short pass to update sh_link and sh_info fields of new
sections */
for(i = 1; i < ehdr.e_shnum; i++) {
s = sm_table[i].s;
if (!s || !sm_table[i].new_section)
continue;
sh = &shdr[i];
if (sh->sh_link > 0)
s->link = sm_table[sh->sh_link].s;
if (sh->sh_type == SHT_RELX) {
s->sh_info = sm_table[sh->sh_info].s->sh_num;
/* update backward link */
s1->sections[s->sh_info]->reloc = s;
}
}
/* resolve symbols */
old_to_new_syms = tcc_mallocz(nb_syms * sizeof(int));
sym = symtab + 1;
for(i = 1; i < nb_syms; i++, sym++) {
if (sym->st_shndx != SHN_UNDEF &&
sym->st_shndx < SHN_LORESERVE) {
sm = &sm_table[sym->st_shndx];
if (sm->link_once) {
/* if a symbol is in a link once section, we use the
already defined symbol. It is very important to get
correct relocations */
if (ELFW(ST_BIND)(sym->st_info) != STB_LOCAL) {
name = strtab + sym->st_name;
sym_index = find_elf_sym(s1->symtab_section, name);
if (sym_index)
old_to_new_syms[i] = sym_index;
}
continue;
}
/* if no corresponding section added, no need to add symbol */
if (!sm->s)
continue;
/* convert section number */
sym->st_shndx = sm->s->sh_num;
/* offset value */
sym->st_value += sm->offset;
}
/* add symbol */
name = strtab + sym->st_name;
sym_index = set_elf_sym(s1->symtab_section, sym->st_value, sym->st_size,
sym->st_info, sym->st_other,
sym->st_shndx, name);
old_to_new_syms[i] = sym_index;
}
/* third pass to patch relocation entries */
for(i = 1; i < ehdr.e_shnum; i++) {
s = sm_table[i].s;
if (!s)
continue;
sh = &shdr[i];
offset = sm_table[i].offset;
size = sh->sh_size;
switch(s->sh_type) {
case SHT_RELX:
/* take relocation offset information */
offseti = sm_table[sh->sh_info].offset;
for (rel = (ElfW_Rel *) s->data + (offset / sizeof(*rel));
rel < (ElfW_Rel *) s->data + ((offset + size) / sizeof(*rel));
rel++) {
int type;
unsigned sym_index;
/* convert symbol index */
type = ELFW(R_TYPE)(rel->r_info);
sym_index = ELFW(R_SYM)(rel->r_info);
/* NOTE: only one symtab assumed */
if (sym_index >= nb_syms)
goto invalid_reloc;
sym_index = old_to_new_syms[sym_index];
/* ignore link_once in rel section. */
if (!sym_index && !sm_table[sh->sh_info].link_once
) {
invalid_reloc:
tcc_error_noabort("Invalid relocation entry [%2d] '%s' @ %.8x",
i, strsec + sh->sh_name, (int)rel->r_offset);
goto the_end;
}
rel->r_info = ELFW(R_INFO)(sym_index, type);
/* offset the relocation offset */
rel->r_offset += offseti;
}
break;
default:
break;
}
}
ret = 0;
the_end:
tcc_free(symtab);
tcc_free(strtab);
tcc_free(old_to_new_syms);
tcc_free(sm_table);
tcc_free(strsec);
tcc_free(shdr);
return ret;
}
typedef struct ArchiveHeader {
char ar_name[16]; /* name of this member */
char ar_date[12]; /* file mtime */
char ar_uid[6]; /* owner uid; printed as decimal */
char ar_gid[6]; /* owner gid; printed as decimal */
char ar_mode[8]; /* file mode, printed as octal */
char ar_size[10]; /* file size, printed as decimal */
char ar_fmag[2]; /* should contain ARFMAG */
} ArchiveHeader;
#define ARFMAG "`\n"
static unsigned long long get_be(const uint8_t *b, int n)
{
unsigned long long ret = 0;
while (n)
ret = (ret << 8) | *b++, --n;
return ret;
}
static int read_ar_header(int fd, int offset, ArchiveHeader *hdr)
{
char *p, *e;
int len;
lseek(fd, offset, SEEK_SET);
len = full_read(fd, hdr, sizeof(ArchiveHeader));
if (len != sizeof(ArchiveHeader))
return len ? -1 : 0;
if (memcmp(hdr->ar_fmag, ARFMAG, sizeof hdr->ar_fmag))
return -1;
p = hdr->ar_name;
for (e = p + sizeof hdr->ar_name; e > p && e[-1] == ' ';)
--e;
*e = '\0';
hdr->ar_size[sizeof hdr->ar_size-1] = 0;
return len;
}
/* load only the objects which resolve undefined symbols */
static int tcc_load_alacarte(TCCState *s1, int fd, int size, int entrysize)
{
int i, bound, nsyms, sym_index, len, ret = -1;
unsigned long long off;
uint8_t *data;
const char *ar_names, *p;
const uint8_t *ar_index;
ElfW(Sym) *sym;
ArchiveHeader hdr;
data = tcc_malloc(size);
if (full_read(fd, data, size) != size)
goto invalid;
nsyms = get_be(data, entrysize);
ar_index = data + entrysize;
ar_names = (char *) ar_index + nsyms * entrysize;
do {
bound = 0;
for (p = ar_names, i = 0; i < nsyms; i++, p += strlen(p)+1) {
Section *s = s1->symtab_section;
sym_index = find_elf_sym(s, p);
if (!sym_index)
continue;
sym = &((ElfW(Sym) *)s->data)[sym_index];
if(sym->st_shndx != SHN_UNDEF)
continue;
off = get_be(ar_index + i * entrysize, entrysize);
len = read_ar_header(fd, off, &hdr);
if (len <= 0 || memcmp(hdr.ar_fmag, ARFMAG, 2)) {
invalid:
tcc_error_noabort("invalid archive");
goto the_end;
}
off += len;
if (s1->verbose == 2)
printf(" -> %s\n", hdr.ar_name);
if (tcc_load_object_file(s1, fd, off) < 0)
goto the_end;
++bound;
}
} while(bound);
ret = 0;
the_end:
tcc_free(data);
return ret;
}
/* load a '.a' file */
int tcc_load_archive(TCCState *s1, int fd, int alacarte)
{
ArchiveHeader hdr;
/* char magic[8]; */
int size, len;
unsigned long file_offset;
ElfW(Ehdr) ehdr;
/* skip magic which was already checked */
/* full_read(fd, magic, sizeof(magic)); */
file_offset = sizeof ARMAG - 1;
for(;;) {
len = read_ar_header(fd, file_offset, &hdr);
if (len == 0)
return 0;
if (len < 0)
return tcc_error_noabort("invalid archive");
file_offset += len;
size = strtol(hdr.ar_size, NULL, 0);
if (alacarte) {
/* coff symbol table : we handle it */
if (!strcmp(hdr.ar_name, "/"))
return tcc_load_alacarte(s1, fd, size, 4);
if (!strcmp(hdr.ar_name, "/SYM64/"))
return tcc_load_alacarte(s1, fd, size, 8);
} else if (tcc_object_type(fd, &ehdr) == AFF_BINTYPE_REL) {
if (s1->verbose == 2)
printf(" -> %s\n", hdr.ar_name);
if (tcc_load_object_file(s1, fd, file_offset) < 0)
return -1;
}
/* align to even */
file_offset = (file_offset + size + 1) & ~1;
}
}
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