static inline void
mips_init_global_got_iterator (struct mips_global_got_iterator *ggi, DSO *dso)
{
GElf_Word sym_size;
ggi->dso = dso;
ggi->entry_size = gelf_fsize (dso->elf, ELF_T_WORD, 1, EV_CURRENT);
ggi->got_addr = (dso->info[DT_PLTGOT]
+ (dso->info_DT_MIPS_LOCAL_GOTNO - 1) * ggi->entry_size);
ggi->sym_index = dso->info_DT_MIPS_GOTSYM - 1;
ggi->failed = 0;
sym_size = gelf_fsize (dso->elf, ELF_T_SYM, 1, EV_CURRENT);
init_data_iterator (&ggi->got_iterator, dso,
ggi->got_addr + ggi->entry_size);
init_data_iterator (&ggi->sym_iterator, dso,
dso->info[DT_SYMTAB] + (ggi->sym_index + 1) * sym_size);
}
static inline void
mips_init_local_got_iterator (struct mips_local_got_iterator *lgi, DSO *dso)
{
lgi->dso = dso;
lgi->entry_size = gelf_fsize (dso->elf, ELF_T_WORD, 1, EV_CURRENT);
lgi->got_index = RESERVED_GOTNO - 1;
lgi->failed = 0;
init_data_iterator (&lgi->got_iterator, dso,
dso->info[DT_PLTGOT]
+ (lgi->got_index + 1) * lgi->entry_size);
}
int
get_sym_from_iterator (struct data_iterator *it, GElf_Sym *sym)
{
GElf_Addr offset, size;
unsigned char *ptr;
size = gelf_fsize (it->dso->elf, ELF_T_SYM, 1, EV_CURRENT);
ptr = get_data_from_iterator (it, size);
if (ptr != NULL)
{
offset = ptr - (unsigned char *) it->data->d_buf;
if (offset % size == 0)
{
gelfx_getsym (it->dso->elf, it->data, offset / size, sym);
return 1;
}
}
return 0;
}
static int
has_dt_debug(Elf *elf, GElf_Ehdr *ehdr)
{
int i;
for (i = 0; i < ehdr->e_phnum; i++) {
GElf_Phdr phdr;
GElf_Shdr shdr;
Elf_Scn *scn;
Elf_Data *data;
unsigned int j;
if (gelf_getphdr(elf, i, &phdr) == NULL)
continue;
if (phdr.p_type != PT_DYNAMIC)
continue;
scn = gelf_offscn(elf, phdr.p_offset);
if (gelf_getshdr(scn, &shdr) == NULL)
continue;
if (shdr.sh_type != SHT_DYNAMIC)
continue;
if ((data = elf_getdata(scn, NULL)) == NULL)
continue;
for (j = 0;
j < shdr.sh_size / gelf_fsize(elf, ELF_T_DYN, 1, EV_CURRENT);
j++) {
GElf_Dyn dyn;
if (gelf_getdyn(data, j, &dyn)) {
if (dyn.d_tag == DT_DEBUG)
return 1;
}
}
}
return 0;
}
/* Try to find a dynamic symbol table via phdrs. */
static void
find_dynsym (Dwfl_Module *mod)
{
GElf_Ehdr ehdr_mem;
GElf_Ehdr *ehdr = gelf_getehdr (mod->main.elf, &ehdr_mem);
for (uint_fast16_t i = 0; i < ehdr->e_phnum; ++i)
{
GElf_Phdr phdr_mem;
GElf_Phdr *phdr = gelf_getphdr (mod->main.elf, i, &phdr_mem);
if (phdr == NULL)
break;
if (phdr->p_type == PT_DYNAMIC)
{
/* Examine the dynamic section for the pointers we need. */
Elf_Data *data = elf_getdata_rawchunk (mod->main.elf,
phdr->p_offset, phdr->p_filesz,
ELF_T_DYN);
if (data == NULL)
continue;
enum
{
i_symtab,
i_strtab,
i_hash,
i_gnu_hash,
i_max
};
GElf_Addr addrs[i_max] = { 0, };
GElf_Xword strsz = 0;
size_t n = data->d_size / gelf_fsize (mod->main.elf,
ELF_T_DYN, 1, EV_CURRENT);
for (size_t j = 0; j < n; ++j)
{
GElf_Dyn dyn_mem;
GElf_Dyn *dyn = gelf_getdyn (data, j, &dyn_mem);
if (dyn != NULL)
switch (dyn->d_tag)
{
case DT_SYMTAB:
addrs[i_symtab] = dyn->d_un.d_ptr;
continue;
case DT_HASH:
addrs[i_hash] = dyn->d_un.d_ptr;
continue;
case DT_GNU_HASH:
addrs[i_gnu_hash] = dyn->d_un.d_ptr;
continue;
case DT_STRTAB:
addrs[i_strtab] = dyn->d_un.d_ptr;
continue;
case DT_STRSZ:
strsz = dyn->d_un.d_val;
continue;
default:
continue;
case DT_NULL:
break;
}
break;
}
/* Translate pointers into file offsets. */
GElf_Off offs[i_max] = { 0, };
find_offsets (mod->main.elf, ehdr, i_max, addrs, offs);
/* Figure out the size of the symbol table. */
if (offs[i_hash] != 0)
{
/* In the original format, .hash says the size of .dynsym. */
size_t entsz = SH_ENTSIZE_HASH (ehdr);
data = elf_getdata_rawchunk (mod->main.elf,
offs[i_hash] + entsz, entsz,
entsz == 4 ? ELF_T_WORD
: ELF_T_XWORD);
if (data != NULL)
mod->syments = (entsz == 4
? *(const GElf_Word *) data->d_buf
: *(const GElf_Xword *) data->d_buf);
}
if (offs[i_gnu_hash] != 0 && mod->syments == 0)
{
/* In the new format, we can derive it with some work. */
const struct
{
Elf32_Word nbuckets;
Elf32_Word symndx;
Elf32_Word maskwords;
Elf32_Word shift2;
} *header;
data = elf_getdata_rawchunk (mod->main.elf, offs[i_gnu_hash],
sizeof *header, ELF_T_WORD);
if (data != NULL)
{
header = data->d_buf;
Elf32_Word nbuckets = header->nbuckets;
Elf32_Word symndx = header->symndx;
GElf_Off buckets_at = (offs[i_gnu_hash] + sizeof *header
+ (gelf_getclass (mod->main.elf)
* sizeof (Elf32_Word)
* header->maskwords));
data = elf_getdata_rawchunk (mod->main.elf, buckets_at,
nbuckets * sizeof (Elf32_Word),
ELF_T_WORD);
if (data != NULL && symndx < nbuckets)
{
const Elf32_Word *const buckets = data->d_buf;
Elf32_Word maxndx = symndx;
for (Elf32_Word bucket = 0; bucket < nbuckets; ++bucket)
if (buckets[bucket] > maxndx)
maxndx = buckets[bucket];
GElf_Off hasharr_at = (buckets_at
+ nbuckets * sizeof (Elf32_Word));
hasharr_at += (maxndx - symndx) * sizeof (Elf32_Word);
do
{
data = elf_getdata_rawchunk (mod->main.elf,
hasharr_at,
sizeof (Elf32_Word),
ELF_T_WORD);
if (data != NULL
&& (*(const Elf32_Word *) data->d_buf & 1u))
{
mod->syments = maxndx + 1;
break;
}
++maxndx;
hasharr_at += sizeof (Elf32_Word);
} while (data != NULL);
}
}
}
if (offs[i_strtab] > offs[i_symtab] && mod->syments == 0)
mod->syments = ((offs[i_strtab] - offs[i_symtab])
/ gelf_fsize (mod->main.elf,
ELF_T_SYM, 1, EV_CURRENT));
if (mod->syments > 0)
{
mod->symdata = elf_getdata_rawchunk (mod->main.elf,
offs[i_symtab],
gelf_fsize (mod->main.elf,
ELF_T_SYM,
mod->syments,
EV_CURRENT),
ELF_T_SYM);
if (mod->symdata != NULL)
{
mod->symstrdata = elf_getdata_rawchunk (mod->main.elf,
offs[i_strtab],
strsz,
ELF_T_BYTE);
if (mod->symstrdata == NULL)
mod->symdata = NULL;
}
if (mod->symdata == NULL)
mod->symerr = DWFL_E (LIBELF, elf_errno ());
else
{
mod->symfile = &mod->main;
mod->symerr = DWFL_E_NOERROR;
}
return;
}
}
}
}
int
main (void)
{
int result = 0;
size_t cnt;
AsmCtx_t *ctx;
Elf *elf;
int fd;
elf_version (EV_CURRENT);
Ebl *ebl = ebl_openbackend_machine (EM_386);
if (ebl == NULL)
{
puts ("cannot open backend library");
return 1;
}
ctx = asm_begin (fname, ebl, false);
if (ctx == NULL)
{
printf ("cannot create assembler context: %s\n", asm_errmsg (-1));
return 1;
}
if (asm_newcomsym (ctx, "commsym", 4, 16) == NULL)
{
printf ("cannot create common symbol: %s\n", asm_errmsg (-1));
asm_abort (ctx);
return 1;
}
/* Create the output file. */
if (asm_end (ctx) != 0)
{
printf ("cannot create output file: %s\n", asm_errmsg (-1));
asm_abort (ctx);
return 1;
}
/* Check the file. */
fd = open (fname, O_RDONLY);
if (fd == -1)
{
printf ("cannot open generated file: %m\n");
result = 1;
goto out;
}
elf = elf_begin (fd, ELF_C_READ, NULL);
if (elf == NULL)
{
printf ("cannot create ELF descriptor: %s\n", elf_errmsg (-1));
result = 1;
goto out_close;
}
if (elf_kind (elf) != ELF_K_ELF)
{
puts ("not a valid ELF file");
result = 1;
goto out_close2;
}
for (cnt = 1; 1; ++cnt)
{
Elf_Scn *scn;
GElf_Shdr shdr_mem;
GElf_Shdr *shdr;
scn = elf_getscn (elf, cnt);
if (scn == NULL)
{
printf ("cannot get section %Zd: %s\n", cnt, elf_errmsg (-1));
result = 1;
continue;
}
shdr = gelf_getshdr (scn, &shdr_mem);
if (shdr == NULL)
{
printf ("cannot get section header for section %Zd: %s\n",
cnt, elf_errmsg (-1));
result = 1;
continue;
}
/* We are looking for the symbol table. */
if (shdr->sh_type != SHT_SYMTAB)
continue;
for (cnt = 1; cnt< (shdr->sh_size
/ gelf_fsize (elf, ELF_T_SYM, 1, EV_CURRENT));
++cnt)
{
GElf_Sym sym_mem;
GElf_Sym *sym;
if (cnt > 1)
{
puts ("too many symbol");
result = 1;
break;
}
sym = gelf_getsym (elf_getdata (scn, NULL), cnt, &sym_mem);
if (sym == NULL)
{
printf ("cannot get symbol %zu: %s\n", cnt, elf_errmsg (-1));
result = 1;
}
else
{
if (sym->st_shndx != SHN_COMMON)
{
printf ("expected common symbol, got section %u\n",
(unsigned int) sym->st_shndx);
result = 1;
}
if (sym->st_value != 16)
{
printf ("requested alignment 16, is %" PRIuMAX "\n",
(uintmax_t) sym->st_value);
result = 1;
}
if (sym->st_size != 4)
{
printf ("requested size 4, is %" PRIuMAX "\n",
(uintmax_t) sym->st_value);
result = 1;
}
}
}
break;
}
out_close2:
elf_end (elf);
out_close:
close (fd);
out:
/* We don't need the file anymore. */
unlink (fname);
ebl_closebackend (ebl);
return result;
}
void *
_libelf_getphdr(Elf *e, int ec)
{
size_t phnum;
size_t fsz, msz;
uint64_t phoff;
Elf32_Ehdr *eh32;
Elf64_Ehdr *eh64;
void *ehdr, *phdr;
void (*xlator)(char *_d, char *_s, size_t _c, int _swap);
assert(ec == ELFCLASS32 || ec == ELFCLASS64);
if (e == NULL) {
LIBELF_SET_ERROR(ARGUMENT, 0);
return (NULL);
}
if ((phdr = (ec == ELFCLASS32 ?
(void *) e->e_u.e_elf.e_phdr.e_phdr32 :
(void *) e->e_u.e_elf.e_phdr.e_phdr64)) != NULL)
return (phdr);
/*
* Check the PHDR related fields in the EHDR for sanity.
*/
if ((ehdr = _libelf_ehdr(e, ec, 0)) == NULL)
return (NULL);
phnum = e->e_u.e_elf.e_nphdr;
if (ec == ELFCLASS32) {
eh32 = (Elf32_Ehdr *) ehdr;
phoff = (uint64_t) eh32->e_phoff;
} else {
eh64 = (Elf64_Ehdr *) ehdr;
phoff = (uint64_t) eh64->e_phoff;
}
fsz = gelf_fsize(e, ELF_T_PHDR, phnum, e->e_version);
assert(fsz > 0);
if ((uint64_t) e->e_rawsize < (phoff + fsz)) {
LIBELF_SET_ERROR(HEADER, 0);
return (NULL);
}
msz = _libelf_msize(ELF_T_PHDR, ec, EV_CURRENT);
assert(msz > 0);
if ((phdr = calloc(phnum, msz)) == NULL) {
LIBELF_SET_ERROR(RESOURCE, 0);
return (NULL);
}
if (ec == ELFCLASS32)
e->e_u.e_elf.e_phdr.e_phdr32 = phdr;
else
e->e_u.e_elf.e_phdr.e_phdr64 = phdr;
xlator = _libelf_get_translator(ELF_T_PHDR, ELF_TOMEMORY, ec);
(*xlator)(phdr, e->e_rawfile + phoff, phnum,
e->e_byteorder != _libelf_host_byteorder());
return (phdr);
}
static int
build_file(Elf *src_elf, GElf_Ehdr *src_ehdr, Cmd_Info *cmd_info)
{
Elf_Scn *src_scn;
Elf_Scn *dst_scn;
int new_sh_name = 0; /* to hold the offset for the new */
/* section's name */
Elf *dst_elf = 0;
Elf_Data *elf_data;
Elf_Data *data;
int64_t scn_no, x;
size_t no_of_symbols = 0;
section_info_table *info;
unsigned int c = 0;
int fdtmp;
GElf_Shdr src_shdr;
GElf_Shdr dst_shdr;
GElf_Ehdr dst_ehdr;
GElf_Off new_offset = 0, r;
size_t shnum, shstrndx;
if (elf_getshnum(src_elf, &shnum) == NULL) {
error_message(LIBELF_ERROR,
LIBelf_ERROR, elf_errmsg(-1), prog);
return (FAILURE);
}
if (elf_getshstrndx(src_elf, &shstrndx) == NULL) {
error_message(LIBELF_ERROR,
LIBelf_ERROR, elf_errmsg(-1), prog);
return (FAILURE);
}
if ((fdtmp = open(elftmpfile, O_RDWR |
O_TRUNC | O_CREAT, (mode_t)0666)) == -1) {
error_message(OPEN_TEMP_ERROR,
SYSTEM_ERROR, strerror(errno),
prog, elftmpfile);
return (FAILURE);
}
if ((dst_elf = elf_begin(fdtmp, ELF_C_WRITE, (Elf *) 0)) == NULL) {
error_message(READ_ERROR,
LIBelf_ERROR, elf_errmsg(-1),
prog, elftmpfile);
(void) close(fdtmp);
return (FAILURE);
}
if (gelf_newehdr(dst_elf, gelf_getclass(src_elf)) == NULL) {
error_message(LIBELF_ERROR,
LIBelf_ERROR, elf_errmsg(-1), prog);
return (FAILURE);
}
/* initialize dst_ehdr */
(void) gelf_getehdr(dst_elf, &dst_ehdr);
dst_ehdr = *src_ehdr;
/*
* flush the changes to the ehdr so the
* ident array is filled in.
*/
(void) gelf_update_ehdr(dst_elf, &dst_ehdr);
if (src_ehdr->e_phnum != 0) {
(void) elf_flagelf(dst_elf, ELF_C_SET, ELF_F_LAYOUT);
if (gelf_newphdr(dst_elf, src_ehdr->e_phnum) == NULL) {
error_message(LIBELF_ERROR,
LIBelf_ERROR, elf_errmsg(-1), prog);
return (FAILURE);
}
for (x = 0; x < src_ehdr->e_phnum; ++x) {
GElf_Phdr dst;
GElf_Phdr src;
/* LINTED */
(void) gelf_getphdr(src_elf, (int)x, &src);
/* LINTED */
(void) gelf_getphdr(dst_elf, (int)x, &dst);
(void) memcpy(&dst, &src, sizeof (GElf_Phdr));
/* LINTED */
(void) gelf_update_phdr(dst_elf, (int)x, &dst);
}
x = location(dst_ehdr.e_phoff, 0, src_elf);
if (x == AFTER)
new_offset = (GElf_Off)src_ehdr->e_ehsize;
}
scn_no = 1;
while ((src_scn = sec_table[scn_no].scn) != (Elf_Scn *) -1) {
info = &sec_table[scn_no];
/* If section should be copied to new file NOW */
if ((info->secno != (GElf_Word)DELETED) &&
info->secno <= scn_no) {
if ((dst_scn = elf_newscn(dst_elf)) == NULL) {
error_message(LIBELF_ERROR,
LIBelf_ERROR, elf_errmsg(-1), prog);
return (FAILURE);
}
(void) gelf_getshdr(dst_scn, &dst_shdr);
(void) gelf_getshdr(info->scn, &src_shdr);
(void) memcpy(&dst_shdr, &src_shdr, sizeof (GElf_Shdr));
/*
* Update link and info fields
* The sh_link field may have special values so
* check them first.
*/
if ((src_shdr.sh_link >= shnum) ||
(src_shdr.sh_link == 0))
dst_shdr.sh_link = src_shdr.sh_link;
else if ((int)sec_table[src_shdr.sh_link].secno < 0)
dst_shdr.sh_link = 0;
else
dst_shdr.sh_link =
sec_table[src_shdr.sh_link].secno;
if ((src_shdr.sh_type == SHT_REL) ||
(src_shdr.sh_type == SHT_RELA)) {
if ((src_shdr.sh_info >= shnum) ||
((int)sec_table[src_shdr.
sh_info].secno < 0))
dst_shdr.sh_info = 0;
else
dst_shdr.sh_info =
sec_table[src_shdr.sh_info].secno;
}
data = sec_table[scn_no].data;
if ((elf_data = elf_newdata(dst_scn)) == NULL) {
error_message(LIBELF_ERROR,
LIBelf_ERROR, elf_errmsg(-1), prog);
return (FAILURE);
}
*elf_data = *data;
/* SHT_{DYNSYM, SYMTAB} might need some change */
if (((src_shdr.sh_type == SHT_SYMTAB) ||
(src_shdr.sh_type == SHT_DYNSYM)) &&
src_shdr.sh_entsize != 0 &&
(cmd_info->no_of_delete != 0 ||
cmd_info->no_of_nulled != 0)) {
char *new_sym;
no_of_symbols = src_shdr.sh_size /
src_shdr.sh_entsize;
new_sym = malloc(no_of_symbols *
src_shdr.sh_entsize);
if (new_sym == NULL) {
error_message(MALLOC_ERROR,
PLAIN_ERROR, (char *)0, prog);
mcs_exit(FAILURE);
}
/* CSTYLED */
elf_data->d_buf = (void *) new_sym;
for (c = 0; c < no_of_symbols; c++) {
GElf_Sym csym;
(void) gelf_getsym(data, c, &csym);
if ((csym.st_shndx < SHN_LORESERVE) &&
(csym.st_shndx != SHN_UNDEF)) {
section_info_table *i;
i = &sec_table[csym.st_shndx];
if (((int)i->secno !=
DELETED) &&
((int)i->secno != NULLED))
csym.st_shndx =
i->secno;
else {
if (src_shdr.sh_type ==
SHT_SYMTAB)
/*
* The section which
* this * symbol relates
* to is removed.
* There is no way to
* specify this fact,
* just change the shndx
* to 1.
*/
csym.st_shndx = 1;
else {
/*
* If this is in a
* .dynsym, NULL it out.
*/
csym.st_shndx = 0;
csym.st_name = 0;
csym.st_value = 0;
csym.st_size = 0;
csym.st_info = 0;
csym.st_other = 0;
csym.st_shndx = 0;
}
}
}
(void) gelf_update_sym(elf_data, c,
&csym);
}
}
/* update SHT_SYMTAB_SHNDX */
if ((src_shdr.sh_type == SHT_SYMTAB_SHNDX) &&
(src_shdr.sh_entsize != 0) &&
((cmd_info->no_of_delete != 0) ||
(cmd_info->no_of_nulled != 0))) {
GElf_Word *oldshndx;
GElf_Word *newshndx;
uint_t entcnt;
entcnt = src_shdr.sh_size /
src_shdr.sh_entsize;
oldshndx = data->d_buf;
newshndx = malloc(entcnt *
src_shdr.sh_entsize);
if (newshndx == NULL) {
error_message(MALLOC_ERROR,
PLAIN_ERROR, (char *)0, prog);
mcs_exit(FAILURE);
}
elf_data->d_buf = (void *)newshndx;
for (c = 0; c < entcnt; c++) {
if (oldshndx[c] != SHN_UNDEF) {
section_info_table *i;
i = &sec_table[oldshndx[c]];
if (((int)i->secno !=
DELETED) &&
((int)i->secno != NULLED))
newshndx[c] = i->secno;
else
newshndx[c] =
oldshndx[c];
} else
newshndx[c] =
oldshndx[c];
}
}
/*
* If the section is to be updated,
* do so.
*/
if (ISCANDIDATE(info->flags)) {
if ((GET_LOC(info->flags) == PRIOR) &&
(((int)info->secno == NULLED) ||
((int)info->secno == EXPANDED) ||
((int)info->secno == SHRUNK))) {
/*
* The section is updated,
* but the position is not too
* good. Need to NULL this out.
*/
dst_shdr.sh_name = 0;
dst_shdr.sh_type = SHT_PROGBITS;
if ((int)info->secno != NULLED) {
(cmd_info->no_of_moved)++;
SET_MOVING(info->flags);
}
} else {
/*
* The section is positioned AFTER,
* or there are no segments.
* It is safe to update this section.
*/
data = sec_table[scn_no].mdata;
*elf_data = *data;
dst_shdr.sh_size = elf_data->d_size;
}
}
/* add new section name to shstrtab? */
else if (!Sect_exists &&
(new_sec_string != NULL) &&
(scn_no == shstrndx) &&
(dst_shdr.sh_type == SHT_STRTAB) &&
((src_ehdr->e_phnum == 0) ||
((x = scn_location(dst_scn, dst_elf)) != IN) ||
(x != PRIOR))) {
size_t sect_len;
sect_len = strlen(SECT_NAME);
if ((elf_data->d_buf =
malloc((dst_shdr.sh_size +
sect_len + 1))) == NULL) {
error_message(MALLOC_ERROR,
PLAIN_ERROR, (char *)0, prog);
mcs_exit(FAILURE);
}
/* put original data plus new data in section */
(void) memcpy(elf_data->d_buf,
data->d_buf, data->d_size);
(void) memcpy(&((char *)elf_data->d_buf)
[data->d_size],
SECT_NAME,
sect_len + 1);
/* LINTED */
new_sh_name = (int)dst_shdr.sh_size;
dst_shdr.sh_size += sect_len + 1;
elf_data->d_size += sect_len + 1;
}
/*
* Compute offsets.
*/
if (src_ehdr->e_phnum != 0) {
/*
* Compute section offset.
*/
if (off_table[scn_no] == 0) {
if (dst_shdr.sh_addralign != 0) {
r = new_offset %
dst_shdr.sh_addralign;
if (r)
new_offset +=
dst_shdr.sh_addralign - r;
}
dst_shdr.sh_offset = new_offset;
elf_data->d_off = 0;
} else {
if (nobits_table[scn_no] == 0)
new_offset = off_table[scn_no];
}
if (nobits_table[scn_no] == 0)
new_offset += dst_shdr.sh_size;
}
}
(void) gelf_update_shdr(dst_scn, &dst_shdr); /* flush changes */
scn_no++;
}
/*
* This is the real new section.
*/
if (!Sect_exists && new_sec_string != NULL) {
size_t string_size;
string_size = strlen(new_sec_string) + 1;
if ((dst_scn = elf_newscn(dst_elf)) == NULL) {
error_message(LIBELF_ERROR,
LIBelf_ERROR, elf_errmsg(-1), prog);
return (FAILURE);
}
(void) gelf_getshdr(dst_scn, &dst_shdr);
dst_shdr.sh_name = new_sh_name;
dst_shdr.sh_type = SHT_PROGBITS;
dst_shdr.sh_flags = 0;
dst_shdr.sh_addr = 0;
if (src_ehdr->e_phnum != NULL)
dst_shdr.sh_offset = new_offset;
else
dst_shdr.sh_offset = 0;
dst_shdr.sh_size = string_size + 1;
dst_shdr.sh_link = 0;
dst_shdr.sh_info = 0;
dst_shdr.sh_addralign = 1;
dst_shdr.sh_entsize = 0;
(void) gelf_update_shdr(dst_scn, &dst_shdr); /* flush changes */
if ((elf_data = elf_newdata(dst_scn)) == NULL) {
error_message(LIBELF_ERROR,
LIBelf_ERROR, elf_errmsg(-1), prog);
return (FAILURE);
}
elf_data->d_size = string_size + 1;
if ((elf_data->d_buf = (char *)
calloc(1, string_size + 1)) == NULL) {
error_message(MALLOC_ERROR,
PLAIN_ERROR, (char *)0,
prog);
mcs_exit(FAILURE);
}
(void) memcpy(&((char *)elf_data->d_buf)[1],
new_sec_string, string_size);
elf_data->d_align = 1;
new_offset += string_size + 1;
}
/*
* If there are sections which needed to be moved,
* then do it here.
*/
if (cmd_info->no_of_moved != 0) {
int cnt;
info = &sec_table[0];
for (cnt = 0; cnt < shnum; cnt++, info++) {
if ((GET_MOVING(info->flags)) == 0)
continue;
if ((src_scn = elf_getscn(src_elf, info->osecno)) ==
NULL) {
error_message(LIBELF_ERROR,
LIBelf_ERROR, elf_errmsg(-1), prog);
return (FAILURE);
}
if (gelf_getshdr(src_scn, &src_shdr) == NULL) {
error_message(LIBELF_ERROR,
LIBelf_ERROR, elf_errmsg(-1), prog);
return (FAILURE);
}
if ((dst_scn = elf_newscn(dst_elf)) == NULL) {
error_message(LIBELF_ERROR,
LIBelf_ERROR, elf_errmsg(-1), prog);
return (FAILURE);
}
if (gelf_getshdr(dst_scn, &dst_shdr) == NULL) {
error_message(LIBELF_ERROR,
LIBelf_ERROR, elf_errmsg(-1), prog);
return (FAILURE);
}
dst_shdr = src_shdr;
data = info->mdata;
dst_shdr.sh_offset = new_offset; /* UPDATE fields */
dst_shdr.sh_size = data->d_size;
if ((shnum >= src_shdr.sh_link) ||
(src_shdr.sh_link == 0))
dst_shdr.sh_link = src_shdr.sh_link;
else
dst_shdr.sh_link =
sec_table[src_shdr.sh_link].osecno;
if ((shnum >= src_shdr.sh_info) ||
(src_shdr.sh_info == 0))
dst_shdr.sh_info = src_shdr.sh_info;
else
dst_shdr.sh_info =
sec_table[src_shdr.sh_info].osecno;
(void) gelf_update_shdr(dst_scn, &dst_shdr);
if ((elf_data = elf_newdata(dst_scn)) == NULL) {
error_message(LIBELF_ERROR,
LIBelf_ERROR, elf_errmsg(-1), prog);
return (FAILURE);
}
(void) memcpy(elf_data, data, sizeof (Elf_Data));
new_offset += data->d_size;
}
}
/*
* In the event that the position of the sting table has changed,
* as a result of deleted sections, update the ehdr->e_shstrndx.
*/
if ((shstrndx > 0) && (shnum > 0) &&
(sec_table[shstrndx].secno < shnum)) {
if (sec_table[shstrndx].secno < SHN_LORESERVE) {
dst_ehdr.e_shstrndx =
sec_table[dst_ehdr.e_shstrndx].secno;
} else {
Elf_Scn *_scn;
GElf_Shdr shdr0;
/*
* If shstrndx requires 'Extended ELF Sections'
* then it is stored in shdr[0].sh_link
*/
dst_ehdr.e_shstrndx = SHN_XINDEX;
if ((_scn = elf_getscn(dst_elf, 0)) == NULL) {
error_message(LIBELF_ERROR,
LIBelf_ERROR, elf_errmsg(-1), prog);
return (FAILURE);
}
(void) gelf_getshdr(_scn, &shdr0);
shdr0.sh_link = sec_table[shstrndx].secno;
(void) gelf_update_shdr(_scn, &shdr0);
}
}
if (src_ehdr->e_phnum != 0) {
size_t align = gelf_fsize(dst_elf, ELF_T_ADDR, 1, EV_CURRENT);
/* UPDATE location of program header table */
if (location(dst_ehdr.e_phoff, 0, dst_elf) == AFTER) {
r = new_offset % align;
if (r)
new_offset += align - r;
dst_ehdr.e_phoff = new_offset;
new_offset += dst_ehdr.e_phnum
* dst_ehdr.e_phentsize;
}
/* UPDATE location of section header table */
if ((location(dst_ehdr.e_shoff, 0, src_elf) == AFTER) ||
((location(dst_ehdr.e_shoff, 0, src_elf) == PRIOR) &&
(!Sect_exists && new_sec_string != NULL))) {
r = new_offset % align;
if (r)
new_offset += align - r;
dst_ehdr.e_shoff = new_offset;
}
free(b_e_seg_table);
/*
* The NOTE segment is the one segment whos
* sections might get moved by mcs processing.
* Make sure that the NOTE segments offset points
* to the .note section.
*/
if ((notesegndx != -1) && (notesctndx != -1) &&
(sec_table[notesctndx].secno)) {
Elf_Scn * notescn;
GElf_Shdr nshdr;
notescn = elf_getscn(dst_elf,
sec_table[notesctndx].secno);
(void) gelf_getshdr(notescn, &nshdr);
if (gelf_getclass(dst_elf) == ELFCLASS32) {
Elf32_Phdr * ph = elf32_getphdr(dst_elf) +
notesegndx;
/* LINTED */
ph->p_offset = (Elf32_Off)nshdr.sh_offset;
} else {
Elf64_Phdr * ph = elf64_getphdr(dst_elf) +
notesegndx;
ph->p_offset = (Elf64_Off)nshdr.sh_offset;
}
}
}
/* copy ehdr changes back into real ehdr */
(void) gelf_update_ehdr(dst_elf, &dst_ehdr);
if (elf_update(dst_elf, ELF_C_WRITE) < 0) {
error_message(LIBELF_ERROR,
LIBelf_ERROR, elf_errmsg(-1), prog);
return (FAILURE);
}
(void) elf_end(dst_elf);
(void) close(fdtmp);
return (SUCCESS);
}
/* If the main file might have been prelinked, then we need to
discover the correct synchronization address between the main and
debug files. Because of prelink's section juggling, we cannot rely
on the address_sync computed from PT_LOAD segments (see open_elf).
We will attempt to discover a synchronization address based on the
section headers instead. But finding a section address that is
safe to use requires identifying which sections are SHT_PROGBITS.
We can do that in the main file, but in the debug file all the
allocated sections have been transformed into SHT_NOBITS so we have
lost the means to match them up correctly.
The only method left to us is to decode the .gnu.prelink_undo
section in the prelinked main file. This shows what the sections
looked like before prelink juggled them--when they still had a
direct correspondence to the debug file. */
static Dwfl_Error
find_prelink_address_sync (Dwfl_Module *mod, struct dwfl_file *file)
{
/* The magic section is only identified by name. */
size_t shstrndx;
if (elf_getshdrstrndx (mod->main.elf, &shstrndx) < 0)
return DWFL_E_LIBELF;
Elf_Scn *scn = NULL;
while ((scn = elf_nextscn (mod->main.elf, scn)) != NULL)
{
GElf_Shdr shdr_mem;
GElf_Shdr *shdr = gelf_getshdr (scn, &shdr_mem);
if (unlikely (shdr == NULL))
return DWFL_E_LIBELF;
if (shdr->sh_type == SHT_PROGBITS
&& !(shdr->sh_flags & SHF_ALLOC)
&& shdr->sh_name != 0)
{
const char *secname = elf_strptr (mod->main.elf, shstrndx,
shdr->sh_name);
if (unlikely (secname == NULL))
return DWFL_E_LIBELF;
if (!strcmp (secname, ".gnu.prelink_undo"))
break;
}
}
if (scn == NULL)
/* There was no .gnu.prelink_undo section. */
return DWFL_E_NOERROR;
Elf_Data *undodata = elf_rawdata (scn, NULL);
if (unlikely (undodata == NULL))
return DWFL_E_LIBELF;
/* Decode the section. It consists of the original ehdr, phdrs,
and shdrs (but omits section 0). */
union
{
Elf32_Ehdr e32;
Elf64_Ehdr e64;
} ehdr;
Elf_Data dst =
{
.d_buf = &ehdr,
.d_size = sizeof ehdr,
.d_type = ELF_T_EHDR,
.d_version = EV_CURRENT
};
Elf_Data src = *undodata;
src.d_size = gelf_fsize (mod->main.elf, ELF_T_EHDR, 1, EV_CURRENT);
src.d_type = ELF_T_EHDR;
if (unlikely (gelf_xlatetom (mod->main.elf, &dst, &src,
elf_getident (mod->main.elf, NULL)[EI_DATA])
== NULL))
return DWFL_E_LIBELF;
size_t shentsize = gelf_fsize (mod->main.elf, ELF_T_SHDR, 1, EV_CURRENT);
size_t phentsize = gelf_fsize (mod->main.elf, ELF_T_PHDR, 1, EV_CURRENT);
uint_fast16_t phnum;
uint_fast16_t shnum;
if (ehdr.e32.e_ident[EI_CLASS] == ELFCLASS32)
{
if (ehdr.e32.e_shentsize != shentsize
|| ehdr.e32.e_phentsize != phentsize)
return DWFL_E_BAD_PRELINK;
phnum = ehdr.e32.e_phnum;
shnum = ehdr.e32.e_shnum;
}
else
{
if (ehdr.e64.e_shentsize != shentsize
|| ehdr.e64.e_phentsize != phentsize)
return DWFL_E_BAD_PRELINK;
phnum = ehdr.e64.e_phnum;
shnum = ehdr.e64.e_shnum;
}
/* Since prelink does not store the zeroth section header in the undo
section, it cannot support SHN_XINDEX encoding. */
if (unlikely (shnum >= SHN_LORESERVE)
|| unlikely (undodata->d_size != (src.d_size
+ phnum * phentsize
+ (shnum - 1) * shentsize)))
return DWFL_E_BAD_PRELINK;
/* We look at the allocated SHT_PROGBITS (or SHT_NOBITS) sections. (Most
every file will have some SHT_PROGBITS sections, but it's possible to
have one with nothing but .bss, i.e. SHT_NOBITS.) The special sections
that can be moved around have different sh_type values--except for
.interp, the section that became the PT_INTERP segment. So we exclude
the SHT_PROGBITS section whose address matches the PT_INTERP p_vaddr.
For this reason, we must examine the phdrs first to find PT_INTERP. */
GElf_Addr main_interp = 0;
{
size_t main_phnum;
if (unlikely (elf_getphdrnum (mod->main.elf, &main_phnum)))
return DWFL_E_LIBELF;
for (size_t i = 0; i < main_phnum; ++i)
{
GElf_Phdr phdr;
if (unlikely (gelf_getphdr (mod->main.elf, i, &phdr) == NULL))
return DWFL_E_LIBELF;
if (phdr.p_type == PT_INTERP)
{
main_interp = phdr.p_vaddr;
break;
}
}
}
src.d_buf += src.d_size;
src.d_type = ELF_T_PHDR;
src.d_size = phnum * phentsize;
GElf_Addr undo_interp = 0;
bool class32 = ehdr.e32.e_ident[EI_CLASS] == ELFCLASS32;
{
size_t phdr_size = class32 ? sizeof (Elf32_Phdr) : sizeof (Elf64_Phdr);
if (unlikely (phnum > SIZE_MAX / phdr_size))
return DWFL_E_NOMEM;
const size_t phdrs_bytes = phnum * phdr_size;
void *phdrs = malloc (phdrs_bytes);
if (unlikely (phdrs == NULL))
return DWFL_E_NOMEM;
dst.d_buf = phdrs;
dst.d_size = phdrs_bytes;
if (unlikely (gelf_xlatetom (mod->main.elf, &dst, &src,
ehdr.e32.e_ident[EI_DATA]) == NULL))
{
free (phdrs);
return DWFL_E_LIBELF;
}
if (class32)
{
Elf32_Phdr (*p32)[phnum] = phdrs;
for (uint_fast16_t i = 0; i < phnum; ++i)
if ((*p32)[i].p_type == PT_INTERP)
{
undo_interp = (*p32)[i].p_vaddr;
break;
}
}
else
{
Elf64_Phdr (*p64)[phnum] = phdrs;
for (uint_fast16_t i = 0; i < phnum; ++i)
if ((*p64)[i].p_type == PT_INTERP)
{
undo_interp = (*p64)[i].p_vaddr;
break;
}
}
free (phdrs);
}
if (unlikely ((main_interp == 0) != (undo_interp == 0)))
return DWFL_E_BAD_PRELINK;
src.d_buf += src.d_size;
src.d_type = ELF_T_SHDR;
src.d_size = gelf_fsize (mod->main.elf, ELF_T_SHDR, shnum - 1, EV_CURRENT);
size_t shdr_size = class32 ? sizeof (Elf32_Shdr) : sizeof (Elf64_Shdr);
if (unlikely (shnum - 1 > SIZE_MAX / shdr_size))
return DWFL_E_NOMEM;
const size_t shdrs_bytes = (shnum - 1) * shdr_size;
void *shdrs = malloc (shdrs_bytes);
if (unlikely (shdrs == NULL))
return DWFL_E_NOMEM;
dst.d_buf = shdrs;
dst.d_size = shdrs_bytes;
if (unlikely (gelf_xlatetom (mod->main.elf, &dst, &src,
ehdr.e32.e_ident[EI_DATA]) == NULL))
{
free (shdrs);
return DWFL_E_LIBELF;
}
/* Now we can look at the original section headers of the main file
before it was prelinked. First we'll apply our method to the main
file sections as they are after prelinking, to calculate the
synchronization address of the main file. Then we'll apply that
same method to the saved section headers, to calculate the matching
synchronization address of the debug file.
The method is to consider SHF_ALLOC sections that are either
SHT_PROGBITS or SHT_NOBITS, excluding the section whose sh_addr
matches the PT_INTERP p_vaddr. The special sections that can be
moved by prelink have other types, except for .interp (which
becomes PT_INTERP). The "real" sections cannot move as such, but
.bss can be split into .dynbss and .bss, with the total memory
image remaining the same but being spread across the two sections.
So we consider the highest section end, which still matches up. */
GElf_Addr highest;
inline void consider_shdr (GElf_Addr interp,
GElf_Word sh_type,
GElf_Xword sh_flags,
GElf_Addr sh_addr,
GElf_Xword sh_size)
{
if ((sh_flags & SHF_ALLOC)
&& ((sh_type == SHT_PROGBITS && sh_addr != interp)
|| sh_type == SHT_NOBITS))
{
const GElf_Addr sh_end = sh_addr + sh_size;
if (sh_end > highest)
highest = sh_end;
}
}
highest = 0;
scn = NULL;
while ((scn = elf_nextscn (mod->main.elf, scn)) != NULL)
{
GElf_Shdr sh_mem;
GElf_Shdr *sh = gelf_getshdr (scn, &sh_mem);
if (unlikely (sh == NULL))
{
free (shdrs);
return DWFL_E_LIBELF;
}
consider_shdr (main_interp, sh->sh_type, sh->sh_flags,
sh->sh_addr, sh->sh_size);
}
if (highest > mod->main.vaddr)
{
mod->main.address_sync = highest;
highest = 0;
if (class32)
{
Elf32_Shdr (*s32)[shnum - 1] = shdrs;
for (size_t i = 0; i < shnum - 1; ++i)
consider_shdr (undo_interp, (*s32)[i].sh_type,
(*s32)[i].sh_flags, (*s32)[i].sh_addr,
(*s32)[i].sh_size);
}
else
{
Elf64_Shdr (*s64)[shnum - 1] = shdrs;
for (size_t i = 0; i < shnum - 1; ++i)
consider_shdr (undo_interp, (*s64)[i].sh_type,
(*s64)[i].sh_flags, (*s64)[i].sh_addr,
(*s64)[i].sh_size);
}
if (highest > file->vaddr)
file->address_sync = highest;
else
{
free (shdrs);
return DWFL_E_BAD_PRELINK;
}
}
free (shdrs);
return DWFL_E_NOERROR;
}
/* Find the separate debuginfo file for this module and open libelf on it.
When we return success, MOD->debug is set up. */
static Dwfl_Error
find_debuginfo (Dwfl_Module *mod)
{
if (mod->debug.elf != NULL)
return DWFL_E_NOERROR;
GElf_Word debuglink_crc = 0;
const char *debuglink_file;
debuglink_file = INTUSE(dwelf_elf_gnu_debuglink) (mod->main.elf,
&debuglink_crc);
mod->debug.fd = (*mod->dwfl->callbacks->find_debuginfo) (MODCB_ARGS (mod),
mod->main.name,
debuglink_file,
debuglink_crc,
&mod->debug.name);
Dwfl_Error result = open_elf (mod, &mod->debug);
if (result == DWFL_E_NOERROR && mod->debug.address_sync != 0)
result = find_prelink_address_sync (mod, &mod->debug);
return result;
}
/* Try to find the alternative debug link for the given DWARF and set
it if found. Only called when mod->dw is already setup but still
might need an alternative (dwz multi) debug file. filename is either
the main or debug name from which the Dwarf was created. */
static void
find_debug_altlink (Dwfl_Module *mod, const char *filename)
{
assert (mod->dw != NULL);
const char *altname;
const void *build_id;
ssize_t build_id_len = INTUSE(dwelf_dwarf_gnu_debugaltlink) (mod->dw,
&altname,
&build_id);
if (build_id_len > 0)
{
/* We could store altfile in the module, but don't really need it. */
char *altfile = NULL;
mod->alt_fd = (*mod->dwfl->callbacks->find_debuginfo) (MODCB_ARGS (mod),
filename,
altname,
0,
&altfile);
/* The (internal) callbacks might just set mod->alt_elf directly
because they open the Elf anyway for sanity checking.
Otherwise open either the given file name or use the fd
returned. */
Dwfl_Error error = open_elf_file (&mod->alt_elf, &mod->alt_fd,
&altfile);
if (error == DWFL_E_NOERROR)
{
mod->alt = INTUSE(dwarf_begin_elf) (mod->alt_elf,
DWARF_C_READ, NULL);
if (mod->alt == NULL)
{
elf_end (mod->alt_elf);
mod->alt_elf = NULL;
close (mod->alt_fd);
mod->alt_fd = -1;
}
else
dwarf_setalt (mod->dw, mod->alt);
}
free (altfile); /* See above, we don't really need it. */
}
}
static int
ctf_write_elf(ctf_file_t *fp, Elf *src, Elf *dst, int flags)
{
GElf_Ehdr sehdr, dehdr;
Elf_Scn *sscn, *dscn;
Elf_Data *sdata, *ddata;
GElf_Shdr shdr;
int symtab_idx = -1;
off_t new_offset = 0;
off_t ctfnameoff = 0;
int compress = (flags & CTF_ELFWRITE_F_COMPRESS);
int *secxlate = NULL;
int srcidx, dstidx, pad, i;
int curnmoff = 0;
int changing = 0;
int ret;
size_t nshdr, nphdr, strndx;
void *strdatabuf = NULL, *symdatabuf = NULL;
size_t strdatasz = 0, symdatasz = 0;
void *cdata = NULL;
size_t elfsize, asize;
if ((flags & ~(CTF_ELFWRITE_F_COMPRESS)) != 0) {
ret = ctf_set_errno(fp, EINVAL);
goto out;
}
if (gelf_newehdr(dst, gelf_getclass(src)) == 0) {
ret = ctf_set_errno(fp, ECTF_ELF);
goto out;
}
if (gelf_getehdr(src, &sehdr) == NULL) {
ret = ctf_set_errno(fp, ECTF_ELF);
goto out;
}
(void) memcpy(&dehdr, &sehdr, sizeof (GElf_Ehdr));
if (gelf_update_ehdr(dst, &dehdr) == 0) {
ret = ctf_set_errno(fp, ECTF_ELF);
goto out;
}
/*
* Use libelf to get the number of sections and the string section to
* deal with ELF files that may have a large number of sections. We just
* always use this to make our live easier.
*/
if (elf_getphdrnum(src, &nphdr) != 0) {
ret = ctf_set_errno(fp, ECTF_ELF);
goto out;
}
if (elf_getshdrnum(src, &nshdr) != 0) {
ret = ctf_set_errno(fp, ECTF_ELF);
goto out;
}
if (elf_getshdrstrndx(src, &strndx) != 0) {
ret = ctf_set_errno(fp, ECTF_ELF);
goto out;
}
/*
* Neither the existing debug sections nor the SUNW_ctf sections (new or
* existing) are SHF_ALLOC'd, so they won't be in areas referenced by
* program headers. As such, we can just blindly copy the program
* headers from the existing file to the new file.
*/
if (nphdr != 0) {
(void) elf_flagelf(dst, ELF_C_SET, ELF_F_LAYOUT);
if (gelf_newphdr(dst, nphdr) == 0) {
ret = ctf_set_errno(fp, ECTF_ELF);
goto out;
}
for (i = 0; i < nphdr; i++) {
GElf_Phdr phdr;
if (gelf_getphdr(src, i, &phdr) == NULL) {
ret = ctf_set_errno(fp, ECTF_ELF);
goto out;
}
if (gelf_update_phdr(dst, i, &phdr) == 0) {
ret = ctf_set_errno(fp, ECTF_ELF);
goto out;
}
}
}
secxlate = ctf_alloc(sizeof (int) * nshdr);
for (srcidx = dstidx = 0; srcidx < nshdr; srcidx++) {
Elf_Scn *scn = elf_getscn(src, srcidx);
GElf_Shdr shdr;
char *sname;
if (gelf_getshdr(scn, &shdr) == NULL) {
ret = ctf_set_errno(fp, ECTF_ELF);
goto out;
}
sname = elf_strptr(src, strndx, shdr.sh_name);
if (sname == NULL) {
ret = ctf_set_errno(fp, ECTF_ELF);
goto out;
}
if (strcmp(sname, CTF_ELF_SCN_NAME) == 0) {
secxlate[srcidx] = -1;
} else {
secxlate[srcidx] = dstidx++;
curnmoff += strlen(sname) + 1;
}
new_offset = (off_t)dehdr.e_phoff;
}
for (srcidx = 1; srcidx < nshdr; srcidx++) {
char *sname;
sscn = elf_getscn(src, srcidx);
if (gelf_getshdr(sscn, &shdr) == NULL) {
ret = ctf_set_errno(fp, ECTF_ELF);
goto out;
}
if (secxlate[srcidx] == -1) {
changing = 1;
continue;
}
dscn = elf_newscn(dst);
if (dscn == NULL) {
ret = ctf_set_errno(fp, ECTF_ELF);
goto out;
}
/*
* If this file has program headers, we need to explicitly lay
* out sections. If none of the sections prior to this one have
* been removed, then we can just use the existing location. If
* one or more sections have been changed, then we need to
* adjust this one to avoid holes.
*/
if (changing && nphdr != 0) {
pad = new_offset % shdr.sh_addralign;
if (pad != 0)
new_offset += shdr.sh_addralign - pad;
shdr.sh_offset = new_offset;
}
shdr.sh_link = secxlate[shdr.sh_link];
if (shdr.sh_type == SHT_REL || shdr.sh_type == SHT_RELA)
shdr.sh_info = secxlate[shdr.sh_info];
sname = elf_strptr(src, strndx, shdr.sh_name);
if (sname == NULL) {
ret = ctf_set_errno(fp, ECTF_ELF);
goto out;
}
if ((sdata = elf_getdata(sscn, NULL)) == NULL) {
ret = ctf_set_errno(fp, ECTF_ELF);
goto out;
}
if ((ddata = elf_newdata(dscn)) == NULL) {
ret = ctf_set_errno(fp, ECTF_ELF);
goto out;
}
bcopy(sdata, ddata, sizeof (Elf_Data));
if (srcidx == strndx) {
char seclen = strlen(CTF_ELF_SCN_NAME);
strdatasz = ddata->d_size + shdr.sh_size +
seclen + 1;
ddata->d_buf = strdatabuf = ctf_alloc(strdatasz);
if (ddata->d_buf == NULL) {
ret = ctf_set_errno(fp, ECTF_ELF);
goto out;
}
bcopy(sdata->d_buf, ddata->d_buf, shdr.sh_size);
(void) strcpy((caddr_t)ddata->d_buf + shdr.sh_size,
CTF_ELF_SCN_NAME);
ctfnameoff = (off_t)shdr.sh_size;
shdr.sh_size += seclen + 1;
ddata->d_size += seclen + 1;
if (nphdr != 0)
changing = 1;
}
if (shdr.sh_type == SHT_SYMTAB && shdr.sh_entsize != 0) {
int nsym = shdr.sh_size / shdr.sh_entsize;
symtab_idx = secxlate[srcidx];
symdatasz = shdr.sh_size;
ddata->d_buf = symdatabuf = ctf_alloc(symdatasz);
if (ddata->d_buf == NULL) {
ret = ctf_set_errno(fp, ECTF_ELF);
goto out;
}
(void) bcopy(sdata->d_buf, ddata->d_buf, shdr.sh_size);
for (i = 0; i < nsym; i++) {
GElf_Sym sym;
short newscn;
(void) gelf_getsym(ddata, i, &sym);
if (sym.st_shndx >= SHN_LORESERVE)
continue;
if ((newscn = secxlate[sym.st_shndx]) !=
sym.st_shndx) {
sym.st_shndx =
(newscn == -1 ? 1 : newscn);
if (gelf_update_sym(ddata, i, &sym) ==
0) {
ret = ctf_set_errno(fp,
ECTF_ELF);
goto out;
}
}
}
}
if (gelf_update_shdr(dscn, &shdr) == 0) {
ret = ctf_set_errno(fp, ECTF_ELF);
goto out;
}
new_offset = (off_t)shdr.sh_offset;
if (shdr.sh_type != SHT_NOBITS)
new_offset += shdr.sh_size;
}
if (symtab_idx == -1) {
ret = ctf_set_errno(fp, ECTF_ELF);
goto out;
}
/* Add the ctf section */
if ((dscn = elf_newscn(dst)) == NULL) {
ret = ctf_set_errno(fp, ECTF_ELF);
goto out;
}
if (gelf_getshdr(dscn, &shdr) == NULL) {
ret = ctf_set_errno(fp, ECTF_ELF);
goto out;
}
shdr.sh_name = ctfnameoff;
shdr.sh_type = SHT_PROGBITS;
shdr.sh_size = fp->ctf_size;
shdr.sh_link = symtab_idx;
shdr.sh_addralign = 4;
if (changing && nphdr != 0) {
pad = new_offset % shdr.sh_addralign;
if (pad)
new_offset += shdr.sh_addralign - pad;
shdr.sh_offset = new_offset;
new_offset += shdr.sh_size;
}
if ((ddata = elf_newdata(dscn)) == NULL) {
ret = ctf_set_errno(fp, ECTF_ELF);
goto out;
}
if (compress != 0) {
int err;
if (ctf_zopen(&err) == NULL) {
ret = ctf_set_errno(fp, err);
goto out;
}
if ((err = ctf_compress(fp, &cdata, &asize, &elfsize)) != 0) {
ret = ctf_set_errno(fp, err);
goto out;
}
ddata->d_buf = cdata;
ddata->d_size = elfsize;
} else {
ddata->d_buf = (void *)fp->ctf_base;
ddata->d_size = fp->ctf_size;
}
ddata->d_align = shdr.sh_addralign;
if (gelf_update_shdr(dscn, &shdr) == 0) {
ret = ctf_set_errno(fp, ECTF_ELF);
goto out;
}
/* update the section header location */
if (nphdr != 0) {
size_t align = gelf_fsize(dst, ELF_T_ADDR, 1, EV_CURRENT);
size_t r = new_offset % align;
if (r)
new_offset += align - r;
dehdr.e_shoff = new_offset;
}
/* commit to disk */
if (sehdr.e_shstrndx == SHN_XINDEX)
dehdr.e_shstrndx = SHN_XINDEX;
else
dehdr.e_shstrndx = secxlate[sehdr.e_shstrndx];
if (gelf_update_ehdr(dst, &dehdr) == 0) {
ret = ctf_set_errno(fp, ECTF_ELF);
goto out;
}
if (elf_update(dst, ELF_C_WRITE) < 0) {
ret = ctf_set_errno(fp, ECTF_ELF);
goto out;
}
ret = 0;
out:
if (strdatabuf != NULL)
ctf_free(strdatabuf, strdatasz);
if (symdatabuf != NULL)
ctf_free(symdatabuf, symdatasz);
if (cdata != NULL)
ctf_data_free(cdata, fp->ctf_size);
if (secxlate != NULL)
ctf_free(secxlate, sizeof (int) * nshdr);
return (ret);
}
void clone_elf(Elf *elf, Elf *newelf,
const char *elf_name,
const char *newelf_name,
bool *sym_filter, int num_symbols,
int shady
#ifdef SUPPORT_ANDROID_PRELINK_TAGS
, int *prelinked,
int *elf_little,
long *prelink_addr
#endif
, bool rebuild_shstrtab,
bool strip_debug,
bool dry_run)
{
GElf_Ehdr ehdr_mem, *ehdr; /* store ELF header of original library */
size_t shstrndx; /* section-strings-section index */
size_t shnum; /* number of sections in the original file */
/* string table for section headers in new file */
struct Ebl_Strtab *shst = NULL;
int dynamic_idx = -1; /* index in shdr_info[] of .dynamic section */
int dynsym_idx = -1; /* index in shdr_info[] of dynamic symbol table
section */
unsigned int cnt; /* general-purpose counter */
/* This flag is true when at least one section is dropped or when the
relative order of sections has changed, so that section indices in
the resulting file will be different from those in the original. */
bool sections_dropped_or_rearranged;
Elf_Scn *scn; /* general-purpose section */
size_t idx; /* general-purporse section index */
shdr_info_t *shdr_info = NULL;
unsigned int shdr_info_len = 0;
GElf_Phdr *phdr_info = NULL;
/* Get the information from the old file. */
ehdr = gelf_getehdr (elf, &ehdr_mem);
FAILIF_LIBELF(NULL == ehdr, gelf_getehdr);
/* Create new program header for the elf file */
FAILIF(gelf_newehdr (newelf, gelf_getclass (elf)) == 0 ||
(ehdr->e_type != ET_REL && gelf_newphdr (newelf,
ehdr->e_phnum) == 0),
"Cannot create new file: %s", elf_errmsg (-1));
#ifdef SUPPORT_ANDROID_PRELINK_TAGS
ASSERT(prelinked);
ASSERT(prelink_addr);
ASSERT(elf_little);
*elf_little = (ehdr->e_ident[EI_DATA] == ELFDATA2LSB);
*prelinked = check_prelinked(elf_name, *elf_little, prelink_addr);
#endif
INFO("\n\nCALCULATING MODIFICATIONS\n\n");
/* Copy out the old program header: notice that if the ELF file does not
have a program header, this loop won't execute.
*/
INFO("Copying ELF program header...\n");
phdr_info = (GElf_Phdr *)CALLOC(ehdr->e_phnum, sizeof(GElf_Phdr));
for (cnt = 0; cnt < ehdr->e_phnum; ++cnt) {
INFO("\tRetrieving entry %d\n", cnt);
FAILIF_LIBELF(NULL == gelf_getphdr(elf, cnt, phdr_info + cnt),
gelf_getphdr);
/* -- we update the header at the end
FAILIF_LIBELF(gelf_update_phdr (newelf, cnt, phdr_info + cnt) == 0,
gelf_update_phdr);
*/
}
/* Get the section-header strings section. This section contains the
strings used to name the other sections. */
FAILIF_LIBELF(elf_getshstrndx(elf, &shstrndx) < 0, elf_getshstrndx);
/* Get the number of sections. */
FAILIF_LIBELF(elf_getshnum (elf, &shnum) < 0, elf_getshnum);
INFO("Original ELF file has %zd sections.\n", shnum);
/* Allocate the section-header-info buffer. We allocate one more entry
for the section-strings section because we regenerate that one and
place it at the very end of the file. Note that just because we create
an extra entry in the shdr_info array, it does not mean that we create
one more section the header. We just mark the old section for removal
and create one as the last section.
*/
INFO("Allocating section-header info structure (%zd) bytes...\n",
shnum*sizeof (shdr_info_t));
shdr_info_len = rebuild_shstrtab ? shnum + 1 : shnum;
shdr_info = (shdr_info_t *)CALLOC(shdr_info_len, sizeof (shdr_info_t));
/* Iterate over all the sections and initialize the internal section-info
array...
*/
INFO("Initializing section-header info structure...\n");
/* Gather information about the sections in this file. */
scn = NULL;
cnt = 1;
while ((scn = elf_nextscn (elf, scn)) != NULL) {
ASSERT(elf_ndxscn(scn) == cnt);
shdr_info[cnt].scn = scn;
FAILIF_LIBELF(NULL == gelf_getshdr(scn, &shdr_info[cnt].shdr),
gelf_getshdr);
/* Get the name of the section. */
shdr_info[cnt].name = elf_strptr (elf, shstrndx,
shdr_info[cnt].shdr.sh_name);
INFO("\tname: %s\n", shdr_info[cnt].name);
FAILIF(shdr_info[cnt].name == NULL,
"Malformed file: section %d name is null\n",
cnt);
/* Mark them as present but not yet investigated. By "investigating"
sections, we mean that we check to see if by stripping other
sections, the sections under investigation will be compromised. For
example, if we are removing a section of code, then we want to make
sure that the symbol table does not contain symbols that refer to
this code, so we investigate the symbol table. If we do find such
symbols, we will not strip the code section.
*/
shdr_info[cnt].idx = 1;
/* Remember the shdr.sh_link value. We need to remember this value
for those sections that refer to other sections. For example,
we need to remember it for relocation-entry sections, because if
we modify the symbol table that a relocation-entry section is
relative to, then we need to patch the relocation section. By the
time we get to deciding whether we need to patch the relocation
section, we will have overwritten its header's sh_link field with
a new value.
*/
shdr_info[cnt].old_shdr = shdr_info[cnt].shdr;
INFO("\t\toriginal sh_link: %08d\n", shdr_info[cnt].old_shdr.sh_link);
INFO("\t\toriginal sh_addr: %lld\n", shdr_info[cnt].old_shdr.sh_addr);
INFO("\t\toriginal sh_offset: %lld\n",
shdr_info[cnt].old_shdr.sh_offset);
INFO("\t\toriginal sh_size: %lld\n", shdr_info[cnt].old_shdr.sh_size);
if (shdr_info[cnt].shdr.sh_type == SHT_DYNAMIC) {
INFO("\t\tthis is the SHT_DYNAMIC section [%s] at index %d\n",
shdr_info[cnt].name,
cnt);
dynamic_idx = cnt;
}
else if (shdr_info[cnt].shdr.sh_type == SHT_DYNSYM) {
INFO("\t\tthis is the SHT_DYNSYM section [%s] at index %d\n",
shdr_info[cnt].name,
cnt);
dynsym_idx = cnt;
}
FAILIF(shdr_info[cnt].shdr.sh_type == SHT_SYMTAB_SHNDX,
"Cannot handle sh_type SHT_SYMTAB_SHNDX!\n");
FAILIF(shdr_info[cnt].shdr.sh_type == SHT_GROUP,
"Cannot handle sh_type SHT_GROUP!\n");
FAILIF(shdr_info[cnt].shdr.sh_type == SHT_GNU_versym,
"Cannot handle sh_type SHT_GNU_versym!\n");
/* Increment the counter. */
++cnt;
} /* while */
/* Get the EBL handling. */
Ebl *ebl = ebl_openbackend (elf);
FAILIF_LIBELF(NULL == ebl, ebl_openbackend);
FAILIF_LIBELF(0 != arm_init(elf, ehdr->e_machine, ebl, sizeof(Ebl)),
arm_init);
if (strip_debug) {
/* This will actually strip more than just sections. It will strip
anything not essential to running the image.
*/
INFO("Finding debug sections to strip.\n");
/* Now determine which sections can go away. The general rule is that
all sections which are not used at runtime are stripped out. But
there are a few exceptions:
- special sections named ".comment" and ".note" are kept
- OS or architecture specific sections are kept since we might not
know how to handle them
- if a section is referred to from a section which is not removed
in the sh_link or sh_info element it cannot be removed either
*/
for (cnt = 1; cnt < shnum; ++cnt) {
/* Check whether the section can be removed. */
if (SECTION_STRIP_P (ebl, elf, ehdr, &shdr_info[cnt].shdr,
shdr_info[cnt].name,
1, /* remove .comment sections */
1 /* remove all debug sections */) ||
/* The macro above is broken--check for .comment explicitly */
!strcmp(".comment", shdr_info[cnt].name)
#ifdef ARM_SPECIFIC_HACKS
||
/* We ignore this section, that's why we can remove it. */
!strcmp(".stack", shdr_info[cnt].name)
#endif
)
{
/* For now assume this section will be removed. */
INFO("Section [%s] will be stripped from image.\n",
shdr_info[cnt].name);
shdr_info[cnt].idx = 0;
}
#ifdef STRIP_STATIC_SYMBOLS
else if (shdr_info[cnt].shdr.sh_type == SHT_SYMTAB) {
/* Mark the static symbol table for removal */
INFO("Section [%s] (static symbol table) will be stripped from image.\n",
shdr_info[cnt].name);
shdr_info[cnt].idx = 0;
if (shdr_info[shdr_info[cnt].shdr.sh_link].shdr.sh_type ==
SHT_STRTAB)
{
/* Mark the symbol table's string table for removal. */
INFO("Section [%s] (static symbol-string table) will be stripped from image.\n",
shdr_info[shdr_info[cnt].shdr.sh_link].name);
shdr_info[shdr_info[cnt].shdr.sh_link].idx = 0;
}
else {
ERROR("Expecting the sh_link field of a symbol table to point to"
" associated symbol-strings table! This is not mandated by"
" the standard, but is a common practice and the only way "
" to know for sure which strings table corresponds to which"
" symbol table!\n");
}
}
#endif
}
/* Mark the SHT_NULL section as handled. */
shdr_info[0].idx = 2;
/* Handle exceptions: section groups and cross-references. We might have
to repeat this a few times since the resetting of the flag might
propagate.
*/
int exceptions_pass = 0;
bool changes;
do {
changes = false;
INFO("\nHandling exceptions, pass %d\n\n", exceptions_pass++);
for (cnt = 1; cnt < shnum; ++cnt) {
if (shdr_info[cnt].idx == 0) {
/* If a relocation section is marked as being removed but the
section it is relocating is not, then do not remove the
relocation section.
*/
if ((shdr_info[cnt].shdr.sh_type == SHT_REL
|| shdr_info[cnt].shdr.sh_type == SHT_RELA)
&& shdr_info[shdr_info[cnt].shdr.sh_info].idx != 0) {
PRINT("\tSection [%s] will not be removed because the "
"section it is relocating (%s) stays.\n",
shdr_info[cnt].name,
shdr_info[shdr_info[cnt].shdr.sh_info].name);
}
}
if (shdr_info[cnt].idx == 1) {
INFO("Processing section [%s]...\n", shdr_info[cnt].name);
/* The content of symbol tables we don't remove must not
reference any section which we do remove. Otherwise
we cannot remove the referred section.
*/
if (shdr_info[cnt].shdr.sh_type == SHT_DYNSYM ||
shdr_info[cnt].shdr.sh_type == SHT_SYMTAB)
{
Elf_Data *symdata;
size_t elsize;
INFO("\tSection [%s] is a symbol table that's not being"
" removed.\n\tChecking to make sure that no symbols"
" refer to sections that are being removed.\n",
shdr_info[cnt].name);
/* Make sure the data is loaded. */
symdata = elf_getdata (shdr_info[cnt].scn, NULL);
FAILIF_LIBELF(NULL == symdata, elf_getdata);
/* Go through all symbols and make sure the section they
reference is not removed. */
elsize = gelf_fsize (elf, ELF_T_SYM, 1, ehdr->e_version);
/* Check the length of the dynamic-symbol filter. */
FAILIF(sym_filter != NULL &&
(size_t)num_symbols != symdata->d_size / elsize,
"Length of dynsym filter (%d) must equal the number"
" of dynamic symbols (%zd)!\n",
num_symbols,
symdata->d_size / elsize);
size_t inner;
for (inner = 0;
inner < symdata->d_size / elsize;
++inner)
{
GElf_Sym sym_mem;
GElf_Sym *sym;
size_t scnidx;
sym = gelf_getsymshndx (symdata, NULL,
inner, &sym_mem, NULL);
FAILIF_LIBELF(sym == NULL, gelf_getsymshndx);
scnidx = sym->st_shndx;
FAILIF(scnidx == SHN_XINDEX,
"Can't handle SHN_XINDEX!\n");
if (scnidx == SHN_UNDEF ||
scnidx >= shnum ||
(scnidx >= SHN_LORESERVE &&
scnidx <= SHN_HIRESERVE) ||
GELF_ST_TYPE (sym->st_info) == STT_SECTION)
{
continue;
}
/* If the symbol is going to be thrown and it is a
global or weak symbol that is defined (not imported),
then continue. Since the symbol is going away, we
do not care whether it refers to a section that is
also going away.
*/
if (sym_filter && !sym_filter[inner])
{
bool global_or_weak =
ELF32_ST_BIND(sym->st_info) == STB_GLOBAL ||
ELF32_ST_BIND(sym->st_info) == STB_WEAK;
if (!global_or_weak && sym->st_shndx != SHN_UNDEF)
continue;
}
/* -- far too much output
INFO("\t\t\tSymbol [%s] (%d)\n",
elf_strptr(elf,
shdr_info[cnt].shdr.sh_link,
sym->st_name),
shdr_info[cnt].shdr.sh_info);
*/
if (shdr_info[scnidx].idx == 0)
{
PRINT("\t\t\tSymbol [%s] refers to section [%s], "
"which is being removed. Will keep that "
"section.\n",
elf_strptr(elf,
shdr_info[cnt].shdr.sh_link,
sym->st_name),
shdr_info[scnidx].name);
/* Mark this section as used. */
shdr_info[scnidx].idx = 1;
changes |= scnidx < cnt;
}
} /* for each symbol */
} /* section type is SHT_DYNSYM or SHT_SYMTAB */
/* Cross referencing happens:
- for the cases the ELF specification says. That are
+ SHT_DYNAMIC in sh_link to string table
+ SHT_HASH in sh_link to symbol table
+ SHT_REL and SHT_RELA in sh_link to symbol table
+ SHT_SYMTAB and SHT_DYNSYM in sh_link to string table
+ SHT_GROUP in sh_link to symbol table
+ SHT_SYMTAB_SHNDX in sh_link to symbol table
Other (OS or architecture-specific) sections might as
well use this field so we process it unconditionally.
- references inside section groups
- specially marked references in sh_info if the SHF_INFO_LINK
flag is set
*/
if (shdr_info[shdr_info[cnt].shdr.sh_link].idx == 0) {
shdr_info[shdr_info[cnt].shdr.sh_link].idx = 1;
changes |= shdr_info[cnt].shdr.sh_link < cnt;
}
/* Handle references through sh_info. */
if (SH_INFO_LINK_P (&shdr_info[cnt].shdr) &&
shdr_info[shdr_info[cnt].shdr.sh_info].idx == 0) {
PRINT("\tSection [%s] links to section [%s], which was "
"marked for removal--it will not be removed.\n",
shdr_info[cnt].name,
shdr_info[shdr_info[cnt].shdr.sh_info].name);
shdr_info[shdr_info[cnt].shdr.sh_info].idx = 1;
changes |= shdr_info[cnt].shdr.sh_info < cnt;
}
/* Mark the section as investigated. */
shdr_info[cnt].idx = 2;
} /* if (shdr_info[cnt].idx == 1) */
} /* for (cnt = 1; cnt < shnum; ++cnt) */
} while (changes);
}
else {
INFO("Not stripping sections.\n");
/* Mark the SHT_NULL section as handled. */
shdr_info[0].idx = 2;
}
/* Mark the section header string table as unused, we will create
a new one as the very last section in the new ELF file.
*/
shdr_info[shstrndx].idx = rebuild_shstrtab ? 0 : 2;
/* We need a string table for the section headers. */
FAILIF_LIBELF((shst = ebl_strtabinit (1 /* null-terminated */)) == NULL,
ebl_strtabinit);
/* Assign new section numbers. */
INFO("Creating new sections...\n");
//shdr_info[0].idx = 0;
for (cnt = idx = 1; cnt < shnum; ++cnt) {
if (shdr_info[cnt].idx > 0) {
shdr_info[cnt].idx = idx++;
/* Create a new section. */
FAILIF_LIBELF((shdr_info[cnt].newscn =
elf_newscn(newelf)) == NULL, elf_newscn);
ASSERT(elf_ndxscn (shdr_info[cnt].newscn) == shdr_info[cnt].idx);
/* Add this name to the section header string table. */
shdr_info[cnt].se = ebl_strtabadd (shst, shdr_info[cnt].name, 0);
INFO("\tsection [%s] (old offset %lld, old size %lld) will have index %d "
"(was %zd).\n",
shdr_info[cnt].name,
shdr_info[cnt].old_shdr.sh_offset,
shdr_info[cnt].old_shdr.sh_size,
shdr_info[cnt].idx,
elf_ndxscn(shdr_info[cnt].scn));
} else {
INFO("\tIgnoring section [%s] (offset %lld, size %lld, index %zd), "
"it will be discarded.\n",
shdr_info[cnt].name,
shdr_info[cnt].shdr.sh_offset,
shdr_info[cnt].shdr.sh_size,
elf_ndxscn(shdr_info[cnt].scn));
}
} /* for */
sections_dropped_or_rearranged = idx != cnt;
Elf_Data *shstrtab_data = NULL;
#if 0
/* Fail if sections are being dropped or rearranged (except for moving shstrtab) or the
symbol filter is not empty, AND the file is an executable.
*/
FAILIF(((idx != cnt && !(cnt - idx == 1 && rebuild_shstrtab)) || sym_filter != NULL) &&
ehdr->e_type != ET_DYN,
"You may not rearrange sections or strip symbols on an executable file!\n");
#endif
INFO("\n\nADJUSTING ELF FILE\n\n");
adjust_elf(elf, elf_name,
newelf, newelf_name,
ebl,
ehdr, /* store ELF header of original library */
sym_filter, num_symbols,
shdr_info, shdr_info_len,
phdr_info,
idx, /* highest_scn_num */
shnum,
shstrndx,
shst,
sections_dropped_or_rearranged,
dynamic_idx, /* index in shdr_info[] of .dynamic section */
dynsym_idx, /* index in shdr_info[] of dynamic symbol table */
shady,
&shstrtab_data,
ehdr->e_type == ET_DYN, /* adjust section ofsets only when the file is a shared library */
rebuild_shstrtab);
/* We have everything from the old file. */
FAILIF_LIBELF(elf_cntl(elf, ELF_C_FDDONE) != 0, elf_cntl);
/* The ELF library better follows our layout when this is not a
relocatable object file. */
elf_flagelf (newelf,
ELF_C_SET,
(ehdr->e_type != ET_REL ? ELF_F_LAYOUT : 0));
/* Finally write the file. */
FAILIF_LIBELF(!dry_run && elf_update(newelf, ELF_C_WRITE) == -1, elf_update);
if (shdr_info != NULL) {
/* For some sections we might have created an table to map symbol
table indices. */
for (cnt = 1; cnt < shdr_info_len; ++cnt) {
FREEIF(shdr_info[cnt].newsymidx);
FREEIF(shdr_info[cnt].symse);
if(shdr_info[cnt].dynsymst != NULL)
ebl_strtabfree (shdr_info[cnt].dynsymst);
}
/* Free the memory. */
FREE (shdr_info);
}
FREEIF(phdr_info);
ebl_closebackend(ebl);
/* Free other resources. */
if (shst != NULL) ebl_strtabfree (shst);
if (shstrtab_data != NULL)
FREEIF(shstrtab_data->d_buf);
}
int
main (void)
{
int result = 0;
size_t cnt;
AsmCtx_t *ctx;
Elf *elf;
int fd;
elf_version (EV_CURRENT);
ctx = asm_begin (fname, false, EM_386, ELFCLASS32, ELFDATA2LSB);
if (ctx == NULL)
{
printf ("cannot create assembler context: %s\n", asm_errmsg (-1));
return 1;
}
if (asm_newabssym (ctx, "tst8-out.s", 4, 0xfeedbeef, STT_FILE, STB_LOCAL)
== NULL)
{
printf ("cannot create absolute symbol: %s\n", asm_errmsg (-1));
asm_abort (ctx);
return 1;
}
/* Create the output file. */
if (asm_end (ctx) != 0)
{
printf ("cannot create output file: %s\n", asm_errmsg (-1));
asm_abort (ctx);
return 1;
}
/* Check the file. */
fd = open (fname, O_RDONLY);
if (fd == -1)
{
printf ("cannot open generated file: %m\n");
result = 1;
goto out;
}
elf = elf_begin (fd, ELF_C_READ, NULL);
if (elf == NULL)
{
printf ("cannot create ELF descriptor: %s\n", elf_errmsg (-1));
result = 1;
goto out_close;
}
if (elf_kind (elf) != ELF_K_ELF)
{
puts ("not a valid ELF file");
result = 1;
goto out_close2;
}
for (cnt = 1; 1; ++cnt)
{
Elf_Scn *scn;
GElf_Shdr shdr_mem;
GElf_Shdr *shdr;
scn = elf_getscn (elf, cnt);
if (scn == NULL)
{
printf ("cannot get section %Zd: %s\n", cnt, elf_errmsg (-1));
result = 1;
continue;
}
shdr = gelf_getshdr (scn, &shdr_mem);
if (shdr == NULL)
{
printf ("cannot get section header for section %Zd: %s\n",
cnt, elf_errmsg (-1));
result = 1;
continue;
}
/* We are looking for the symbol table. */
if (shdr->sh_type != SHT_SYMTAB)
continue;
for (cnt = 1; cnt< (shdr->sh_size
/ gelf_fsize (elf, ELF_T_SYM, 1, EV_CURRENT));
++cnt)
{
GElf_Sym sym_mem;
GElf_Sym *sym;
if (cnt > 1)
{
puts ("too many symbol");
result = 1;
break;
}
sym = gelf_getsym (elf_getdata (scn, NULL), cnt, &sym_mem);
if (sym == NULL)
{
printf ("cannot get symbol %zu: %s\n", cnt, elf_errmsg (-1));
result = 1;
}
else
{
if (sym->st_shndx != SHN_ABS)
{
printf ("expected common symbol, got section %u\n",
(unsigned int) sym->st_shndx);
result = 1;
}
if (sym->st_value != 0xfeedbeef)
{
printf ("requested value 0xfeedbeef, is %#" PRIxMAX "\n",
(uintmax_t) sym->st_value);
result = 1;
}
if (sym->st_size != 4)
{
printf ("requested size 4, is %" PRIuMAX "\n",
(uintmax_t) sym->st_value);
result = 1;
}
if (GELF_ST_TYPE (sym->st_info) != STT_FILE)
{
printf ("requested type FILE, is %u\n",
(unsigned int) GELF_ST_TYPE (sym->st_info));
result = 1;
}
}
}
break;
}
out_close2:
elf_end (elf);
out_close:
close (fd);
out:
/* We don't need the file anymore. */
unlink (fname);
return result;
}
/* Search an ELF file for a ".gnu_debuglink" section. */
static const char *
find_debuglink (Elf *elf, GElf_Word *crc)
{
size_t shstrndx;
if (elf_getshdrstrndx (elf, &shstrndx) < 0)
return NULL;
Elf_Scn *scn = NULL;
while ((scn = elf_nextscn (elf, scn)) != NULL)
{
GElf_Shdr shdr_mem;
GElf_Shdr *shdr = gelf_getshdr (scn, &shdr_mem);
if (shdr == NULL)
return NULL;
const char *name = elf_strptr (elf, shstrndx, shdr->sh_name);
if (name == NULL)
return NULL;
if (!strcmp (name, ".gnu_debuglink"))
break;
}
if (scn == NULL)
return NULL;
/* Found the .gnu_debuglink section. Extract its contents. */
Elf_Data *rawdata = elf_rawdata (scn, NULL);
if (rawdata == NULL)
return NULL;
Elf_Data crcdata =
{
.d_type = ELF_T_WORD,
.d_buf = crc,
.d_size = sizeof *crc,
.d_version = EV_CURRENT,
};
Elf_Data conv =
{
.d_type = ELF_T_WORD,
.d_buf = rawdata->d_buf + rawdata->d_size - sizeof *crc,
.d_size = sizeof *crc,
.d_version = EV_CURRENT,
};
GElf_Ehdr ehdr_mem;
GElf_Ehdr *ehdr = gelf_getehdr (elf, &ehdr_mem);
if (ehdr == NULL)
return NULL;
Elf_Data *d = gelf_xlatetom (elf, &crcdata, &conv, ehdr->e_ident[EI_DATA]);
if (d == NULL)
return NULL;
assert (d == &crcdata);
return rawdata->d_buf;
}
/* If the main file might have been prelinked, then we need to
discover the correct synchronization address between the main and
debug files. Because of prelink's section juggling, we cannot rely
on the address_sync computed from PT_LOAD segments (see open_elf).
We will attempt to discover a synchronization address based on the
section headers instead. But finding a section address that is
safe to use requires identifying which sections are SHT_PROGBITS.
We can do that in the main file, but in the debug file all the
allocated sections have been transformed into SHT_NOBITS so we have
lost the means to match them up correctly.
The only method left to us is to decode the .gnu.prelink_undo
section in the prelinked main file. This shows what the sections
looked like before prelink juggled them--when they still had a
direct correspondence to the debug file. */
static Dwfl_Error
find_prelink_address_sync (Dwfl_Module *mod, struct dwfl_file *file)
{
/* The magic section is only identified by name. */
size_t shstrndx;
if (elf_getshdrstrndx (mod->main.elf, &shstrndx) < 0)
return DWFL_E_LIBELF;
Elf_Scn *scn = NULL;
while ((scn = elf_nextscn (mod->main.elf, scn)) != NULL)
{
GElf_Shdr shdr_mem;
GElf_Shdr *shdr = gelf_getshdr (scn, &shdr_mem);
if (unlikely (shdr == NULL))
return DWFL_E_LIBELF;
if (shdr->sh_type == SHT_PROGBITS
&& !(shdr->sh_flags & SHF_ALLOC)
&& shdr->sh_name != 0)
{
const char *secname = elf_strptr (mod->main.elf, shstrndx,
shdr->sh_name);
if (unlikely (secname == NULL))
return DWFL_E_LIBELF;
if (!strcmp (secname, ".gnu.prelink_undo"))
break;
}
}
if (scn == NULL)
/* There was no .gnu.prelink_undo section. */
return DWFL_E_NOERROR;
Elf_Data *undodata = elf_rawdata (scn, NULL);
if (unlikely (undodata == NULL))
return DWFL_E_LIBELF;
/* Decode the section. It consists of the original ehdr, phdrs,
and shdrs (but omits section 0). */
union
{
Elf32_Ehdr e32;
Elf64_Ehdr e64;
} ehdr;
Elf_Data dst =
{
.d_buf = &ehdr,
.d_size = sizeof ehdr,
.d_type = ELF_T_EHDR,
.d_version = EV_CURRENT
};
Elf_Data src = *undodata;
src.d_size = gelf_fsize (mod->main.elf, ELF_T_EHDR, 1, EV_CURRENT);
src.d_type = ELF_T_EHDR;
if (unlikely (gelf_xlatetom (mod->main.elf, &dst, &src,
elf_getident (mod->main.elf, NULL)[EI_DATA])
== NULL))
return DWFL_E_LIBELF;
size_t shentsize = gelf_fsize (mod->main.elf, ELF_T_SHDR, 1, EV_CURRENT);
size_t phentsize = gelf_fsize (mod->main.elf, ELF_T_PHDR, 1, EV_CURRENT);
uint_fast16_t phnum;
uint_fast16_t shnum;
if (ehdr.e32.e_ident[EI_CLASS] == ELFCLASS32)
{
if (ehdr.e32.e_shentsize != shentsize
|| ehdr.e32.e_phentsize != phentsize)
return DWFL_E_BAD_PRELINK;
phnum = ehdr.e32.e_phnum;
shnum = ehdr.e32.e_shnum;
}
else
{
if (ehdr.e64.e_shentsize != shentsize
|| ehdr.e64.e_phentsize != phentsize)
return DWFL_E_BAD_PRELINK;
phnum = ehdr.e64.e_phnum;
shnum = ehdr.e64.e_shnum;
}
/* Since prelink does not store the zeroth section header in the undo
section, it cannot support SHN_XINDEX encoding. */
if (unlikely (shnum >= SHN_LORESERVE)
|| unlikely (undodata->d_size != (src.d_size
+ phnum * phentsize
+ (shnum - 1) * shentsize)))
return DWFL_E_BAD_PRELINK;
/* We look at the allocated SHT_PROGBITS (or SHT_NOBITS) sections. (Most
every file will have some SHT_PROGBITS sections, but it's possible to
have one with nothing but .bss, i.e. SHT_NOBITS.) The special sections
that can be moved around have different sh_type values--except for
.interp, the section that became the PT_INTERP segment. So we exclude
the SHT_PROGBITS section whose address matches the PT_INTERP p_vaddr.
For this reason, we must examine the phdrs first to find PT_INTERP. */
GElf_Addr main_interp = 0;
{
size_t main_phnum;
if (unlikely (elf_getphdrnum (mod->main.elf, &main_phnum)))
return DWFL_E_LIBELF;
for (size_t i = 0; i < main_phnum; ++i)
{
GElf_Phdr phdr;
if (unlikely (gelf_getphdr (mod->main.elf, i, &phdr) == NULL))
return DWFL_E_LIBELF;
if (phdr.p_type == PT_INTERP)
{
main_interp = phdr.p_vaddr;
break;
}
}
}
src.d_buf += src.d_size;
src.d_type = ELF_T_PHDR;
src.d_size = phnum * phentsize;
GElf_Addr undo_interp = 0;
{
union
{
Elf32_Phdr p32[phnum];
Elf64_Phdr p64[phnum];
} phdr;
dst.d_buf = &phdr;
dst.d_size = sizeof phdr;
if (unlikely (gelf_xlatetom (mod->main.elf, &dst, &src,
ehdr.e32.e_ident[EI_DATA]) == NULL))
return DWFL_E_LIBELF;
if (ehdr.e32.e_ident[EI_CLASS] == ELFCLASS32)
{
for (uint_fast16_t i = 0; i < phnum; ++i)
if (phdr.p32[i].p_type == PT_INTERP)
{
undo_interp = phdr.p32[i].p_vaddr;
break;
}
}
else
{
for (uint_fast16_t i = 0; i < phnum; ++i)
if (phdr.p64[i].p_type == PT_INTERP)
{
undo_interp = phdr.p64[i].p_vaddr;
break;
}
}
}
if (unlikely ((main_interp == 0) != (undo_interp == 0)))
return DWFL_E_BAD_PRELINK;
src.d_buf += src.d_size;
src.d_type = ELF_T_SHDR;
src.d_size = gelf_fsize (mod->main.elf, ELF_T_SHDR, shnum - 1, EV_CURRENT);
union
{
Elf32_Shdr s32[shnum - 1];
Elf64_Shdr s64[shnum - 1];
} shdr;
dst.d_buf = &shdr;
dst.d_size = sizeof shdr;
if (unlikely (gelf_xlatetom (mod->main.elf, &dst, &src,
ehdr.e32.e_ident[EI_DATA]) == NULL))
return DWFL_E_LIBELF;
/* Now we can look at the original section headers of the main file
before it was prelinked. First we'll apply our method to the main
file sections as they are after prelinking, to calculate the
synchronization address of the main file. Then we'll apply that
same method to the saved section headers, to calculate the matching
synchronization address of the debug file.
The method is to consider SHF_ALLOC sections that are either
SHT_PROGBITS or SHT_NOBITS, excluding the section whose sh_addr
matches the PT_INTERP p_vaddr. The special sections that can be
moved by prelink have other types, except for .interp (which
becomes PT_INTERP). The "real" sections cannot move as such, but
.bss can be split into .dynbss and .bss, with the total memory
image remaining the same but being spread across the two sections.
So we consider the highest section end, which still matches up. */
GElf_Addr highest;
inline void consider_shdr (GElf_Addr interp,
GElf_Word sh_type,
GElf_Xword sh_flags,
GElf_Addr sh_addr,
GElf_Xword sh_size)
{
if ((sh_flags & SHF_ALLOC)
&& ((sh_type == SHT_PROGBITS && sh_addr != interp)
|| sh_type == SHT_NOBITS))
{
const GElf_Addr sh_end = sh_addr + sh_size;
if (sh_end > highest)
highest = sh_end;
}
}
highest = 0;
scn = NULL;
while ((scn = elf_nextscn (mod->main.elf, scn)) != NULL)
{
GElf_Shdr sh_mem;
GElf_Shdr *sh = gelf_getshdr (scn, &sh_mem);
if (unlikely (sh == NULL))
return DWFL_E_LIBELF;
consider_shdr (main_interp, sh->sh_type, sh->sh_flags,
sh->sh_addr, sh->sh_size);
}
if (highest > mod->main.vaddr)
{
mod->main.address_sync = highest;
highest = 0;
if (ehdr.e32.e_ident[EI_CLASS] == ELFCLASS32)
for (size_t i = 0; i < shnum - 1; ++i)
consider_shdr (undo_interp, shdr.s32[i].sh_type, shdr.s32[i].sh_flags,
shdr.s32[i].sh_addr, shdr.s32[i].sh_size);
else
for (size_t i = 0; i < shnum - 1; ++i)
consider_shdr (undo_interp, shdr.s64[i].sh_type, shdr.s64[i].sh_flags,
shdr.s64[i].sh_addr, shdr.s64[i].sh_size);
if (highest > file->vaddr)
file->address_sync = highest;
else
return DWFL_E_BAD_PRELINK;
}
return DWFL_E_NOERROR;
}
/* Find the separate debuginfo file for this module and open libelf on it.
When we return success, MOD->debug is set up. */
static Dwfl_Error
find_debuginfo (Dwfl_Module *mod)
{
if (mod->debug.elf != NULL)
return DWFL_E_NOERROR;
GElf_Word debuglink_crc = 0;
const char *debuglink_file = find_debuglink (mod->main.elf, &debuglink_crc);
mod->debug.fd = (*mod->dwfl->callbacks->find_debuginfo) (MODCB_ARGS (mod),
mod->main.name,
debuglink_file,
debuglink_crc,
&mod->debug.name);
Dwfl_Error result = open_elf (mod, &mod->debug);
if (result == DWFL_E_NOERROR && mod->debug.address_sync != 0)
result = find_prelink_address_sync (mod, &mod->debug);
return result;
}
/* Try to find a symbol table in FILE.
Returns DWFL_E_NOERROR if a proper one is found.
Returns DWFL_E_NO_SYMTAB if not, but still sets results for SHT_DYNSYM. */
static Dwfl_Error
load_symtab (struct dwfl_file *file, struct dwfl_file **symfile,
Elf_Scn **symscn, Elf_Scn **xndxscn,
size_t *syments, int *first_global, GElf_Word *strshndx)
{
bool symtab = false;
Elf_Scn *scn = NULL;
while ((scn = elf_nextscn (file->elf, scn)) != NULL)
{
GElf_Shdr shdr_mem, *shdr = gelf_getshdr (scn, &shdr_mem);
if (shdr != NULL)
switch (shdr->sh_type)
{
case SHT_SYMTAB:
symtab = true;
*symscn = scn;
*symfile = file;
*strshndx = shdr->sh_link;
*syments = shdr->sh_size / shdr->sh_entsize;
*first_global = shdr->sh_info;
if (*xndxscn != NULL)
return DWFL_E_NOERROR;
break;
case SHT_DYNSYM:
if (symtab)
break;
/* Use this if need be, but keep looking for SHT_SYMTAB. */
*symscn = scn;
*symfile = file;
*strshndx = shdr->sh_link;
*syments = shdr->sh_size / shdr->sh_entsize;
*first_global = shdr->sh_info;
break;
case SHT_SYMTAB_SHNDX:
*xndxscn = scn;
if (symtab)
return DWFL_E_NOERROR;
break;
default:
break;
}
}
if (symtab)
/* We found one, though no SHT_SYMTAB_SHNDX to go with it. */
return DWFL_E_NOERROR;
/* We found no SHT_SYMTAB, so any SHT_SYMTAB_SHNDX was bogus.
We might have found an SHT_DYNSYM and set *SYMSCN et al though. */
*xndxscn = NULL;
return DWFL_E_NO_SYMTAB;
}
/* Translate addresses into file offsets.
OFFS[*] start out zero and remain zero if unresolved. */
static void
find_offsets (Elf *elf, size_t phnum, size_t n,
GElf_Addr addrs[n], GElf_Off offs[n])
{
size_t unsolved = n;
for (size_t i = 0; i < phnum; ++i)
{
GElf_Phdr phdr_mem;
GElf_Phdr *phdr = gelf_getphdr (elf, i, &phdr_mem);
if (phdr != NULL && phdr->p_type == PT_LOAD && phdr->p_memsz > 0)
for (size_t j = 0; j < n; ++j)
if (offs[j] == 0
&& addrs[j] >= phdr->p_vaddr
&& addrs[j] - phdr->p_vaddr < phdr->p_filesz)
{
offs[j] = addrs[j] - phdr->p_vaddr + phdr->p_offset;
if (--unsolved == 0)
break;
}
}
}
