Elf_Scn *
elf_newscn(Elf *e)
{
int ec;
void *ehdr;
Elf_Scn *scn;
if (e == NULL || e->e_kind != ELF_K_ELF) {
LIBELF_SET_ERROR(ARGUMENT, 0);
return (NULL);
}
if ((ec = e->e_class) != ELFCLASS32 && ec != ELFCLASS64) {
LIBELF_SET_ERROR(CLASS, 0);
return (NULL);
}
if ((ehdr = _libelf_ehdr(e, ec, 0)) == NULL)
return (NULL);
/*
* The application may be asking for a new section descriptor
* on an ELF object opened with ELF_C_RDWR or ELF_C_READ. We
* need to bring in the existing section information before
* appending a new one to the list.
*
* Per the ELF(3) API, an application is allowed to open a
* file using ELF_C_READ, mess with its internal structure and
* use elf_update(...,ELF_C_NULL) to compute its new layout.
*/
if (e->e_cmd != ELF_C_WRITE &&
(e->e_flags & LIBELF_F_SHDRS_LOADED) == 0 &&
_libelf_load_scn(e, ehdr) == 0)
return (NULL);
if (STAILQ_EMPTY(&e->e_u.e_elf.e_scn)) {
assert(e->e_u.e_elf.e_nscn == 0);
if ((scn = _libelf_allocate_scn(e, (size_t) SHN_UNDEF)) ==
NULL)
return (NULL);
e->e_u.e_elf.e_nscn++;
}
assert(e->e_u.e_elf.e_nscn > 0);
if ((scn = _libelf_allocate_scn(e, e->e_u.e_elf.e_nscn)) == NULL)
return (NULL);
e->e_u.e_elf.e_nscn++;
(void) elf_flagscn(scn, ELF_C_SET, ELF_F_DIRTY);
return (scn);
}
/*
* Retrieve section #0, allocating a new section if needed.
*/
static Elf_Scn *
_libelf_getscn0(Elf *e)
{
Elf_Scn *s;
if ((s = STAILQ_FIRST(&e->e_u.e_elf.e_scn)) != NULL)
return (s);
return (_libelf_allocate_scn(e, (size_t) SHN_UNDEF));
}
/*
* Retrieve counts for sections, phdrs and the section string table index
* from section header #0 of the ELF object.
*/
static int
_libelf_load_extended(Elf *e, int ec, uint64_t shoff, uint16_t phnum,
uint16_t strndx)
{
Elf_Scn *scn;
size_t fsz;
int (*xlator)(unsigned char *_d, size_t _dsz, unsigned char *_s,
size_t _c, int _swap);
uint32_t shtype;
assert(STAILQ_EMPTY(&e->e_u.e_elf.e_scn));
fsz = _libelf_fsize(ELF_T_SHDR, ec, e->e_version, 1);
assert(fsz > 0);
if (e->e_rawsize < shoff + fsz) { /* raw file too small */
LIBELF_SET_ERROR(HEADER, 0);
return (0);
}
if ((scn = _libelf_allocate_scn(e, (size_t) 0)) == NULL)
return (0);
xlator = _libelf_get_translator(ELF_T_SHDR, ELF_TOMEMORY, ec);
(*xlator)((unsigned char *) &scn->s_shdr, sizeof(scn->s_shdr),
(unsigned char *) e->e_rawfile + shoff, (size_t) 1,
e->e_byteorder != LIBELF_PRIVATE(byteorder));
#define GET_SHDR_MEMBER(M) ((ec == ELFCLASS32) ? scn->s_shdr.s_shdr32.M : \
scn->s_shdr.s_shdr64.M)
if ((shtype = GET_SHDR_MEMBER(sh_type)) != SHT_NULL) {
LIBELF_SET_ERROR(SECTION, 0);
return (0);
}
e->e_u.e_elf.e_nscn = (size_t) GET_SHDR_MEMBER(sh_size);
e->e_u.e_elf.e_nphdr = (phnum != PN_XNUM) ? phnum :
GET_SHDR_MEMBER(sh_info);
e->e_u.e_elf.e_strndx = (strndx != SHN_XINDEX) ? strndx :
GET_SHDR_MEMBER(sh_link);
#undef GET_SHDR_MEMBER
return (1);
}
/*
* Load an ELF section table and create a list of Elf_Scn structures.
*/
static int
_libelf_load_scn(Elf *e, void *ehdr)
{
int ec, swapbytes;
size_t fsz, i, shnum;
uint64_t shoff;
char *src;
Elf32_Ehdr *eh32;
Elf64_Ehdr *eh64;
Elf_Scn *scn;
void (*xlator)(char *_d, char *_s, size_t _c, int _swap);
assert(e != NULL);
assert(ehdr != NULL);
assert((e->e_flags & LIBELF_F_SHDRS_LOADED) == 0);
#define CHECK_EHDR(E,EH) do { \
if (fsz != (EH)->e_shentsize || \
shoff + fsz * shnum > e->e_rawsize) { \
LIBELF_SET_ERROR(HEADER, 0); \
return (0); \
} \
} while (0)
ec = e->e_class;
fsz = _libelf_fsize(ELF_T_SHDR, ec, e->e_version, (size_t) 1);
assert(fsz > 0);
shnum = e->e_u.e_elf.e_nscn;
if (ec == ELFCLASS32) {
eh32 = (Elf32_Ehdr *) ehdr;
shoff = (uint64_t) eh32->e_shoff;
CHECK_EHDR(e, eh32);
} else {
eh64 = (Elf64_Ehdr *) ehdr;
shoff = eh64->e_shoff;
CHECK_EHDR(e, eh64);
}
xlator = _libelf_get_translator(ELF_T_SHDR, ELF_TOMEMORY, ec);
swapbytes = e->e_byteorder != LIBELF_PRIVATE(byteorder);
src = e->e_rawfile + shoff;
/*
* If the file is using extended numbering then section #0
* would have already been read in.
*/
i = 0;
if (!STAILQ_EMPTY(&e->e_u.e_elf.e_scn)) {
assert(STAILQ_FIRST(&e->e_u.e_elf.e_scn) ==
STAILQ_LAST(&e->e_u.e_elf.e_scn, _Elf_Scn, s_next));
i = 1;
src += fsz;
}
for (; i < shnum; i++, src += fsz) {
if ((scn = _libelf_allocate_scn(e, i)) == NULL)
return (0);
(*xlator)((char *) &scn->s_shdr, src, (size_t) 1, swapbytes);
if (ec == ELFCLASS32) {
scn->s_offset = scn->s_rawoff =
scn->s_shdr.s_shdr32.sh_offset;
scn->s_size = scn->s_shdr.s_shdr32.sh_size;
} else {
scn->s_offset = scn->s_rawoff =
scn->s_shdr.s_shdr64.sh_offset;
scn->s_size = scn->s_shdr.s_shdr64.sh_size;
}
}
e->e_flags |= LIBELF_F_SHDRS_LOADED;
return (1);
}
