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contrib/elftoolchain/elfcopy/sections.c

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#include "elfcopy.h" #include "elfcopy.h"
ELFTC_VCSID("$Id: sections.c 3443 2016-04-15 18:57:54Z kaiwang27 $"); ELFTC_VCSID("$Id: sections.c 3443 2016-04-15 18:57:54Z kaiwang27 $");
static void add_gnu_debuglink(struct elfcopy *ecp); static void add_gnu_debuglink(struct elfcopy *ecp);
static uint32_t calc_crc32(const char *p, size_t len, uint32_t crc); static uint32_t calc_crc32(const char *p, size_t len, uint32_t crc);
static void check_section_rename(struct elfcopy *ecp, struct section *s); static void check_section_rename(struct elfcopy *ecp, struct section *s);
static void filter_reloc(struct elfcopy *ecp, struct section *s);
static int get_section_flags(struct elfcopy *ecp, const char *name); static int get_section_flags(struct elfcopy *ecp, const char *name);
static void insert_sections(struct elfcopy *ecp); static void insert_sections(struct elfcopy *ecp);
static void insert_to_strtab(struct section *t, const char *s); static void insert_to_strtab(struct section *t, const char *s);
static int is_append_section(struct elfcopy *ecp, const char *name); static int is_append_section(struct elfcopy *ecp, const char *name);
static int is_compress_section(struct elfcopy *ecp, const char *name); static int is_compress_section(struct elfcopy *ecp, const char *name);
static int is_debug_section(const char *name); static int is_debug_section(const char *name);
static int is_dwo_section(const char *name); static int is_dwo_section(const char *name);
static int is_modify_section(struct elfcopy *ecp, const char *name); static int is_modify_section(struct elfcopy *ecp, const char *name);
▲ Show 20 Lines • Show All 518 Lines • ▼ Show 20 Lines TAILQ_FOREACH(s, &ecp->v_sec, sec_list) {
/* Skip special sections. */ /* Skip special sections. */
if (strcmp(s->name, ".symtab") == 0 || if (strcmp(s->name, ".symtab") == 0 ||
strcmp(s->name, ".strtab") == 0 || strcmp(s->name, ".strtab") == 0 ||
strcmp(s->name, ".shstrtab") == 0) strcmp(s->name, ".shstrtab") == 0)
continue; continue;
/* /*
* If strip action is STRIP_ALL, relocation info need
* to be stripped. Skip filtering otherwisw.
*/
if (ecp->strip == STRIP_ALL &&
(s->type == SHT_REL || s->type == SHT_RELA))
filter_reloc(ecp, s);
/*
* The section indices in the SHT_GROUP section needs * The section indices in the SHT_GROUP section needs
* to be updated since we might have stripped some * to be updated since we might have stripped some
* sections and changed section numbering. * sections and changed section numbering.
*/ */
if (s->type == SHT_GROUP) if (s->type == SHT_GROUP)
update_section_group(ecp, s); update_section_group(ecp, s);
if (is_modify_section(ecp, s->name)) if (is_modify_section(ecp, s->name))
▲ Show 20 Lines • Show All 72 Lines • ▼ Show 20 Lines#endif
for(i = 1, j = 1; (uint64_t)i < n; i++) { for(i = 1, j = 1; (uint64_t)i < n; i++) {
if (ws[i] != SHN_UNDEF && ws[i] < ishnum && if (ws[i] != SHN_UNDEF && ws[i] < ishnum &&
ecp->secndx[ws[i]] != 0) ecp->secndx[ws[i]] != 0)
wd[j++] = ecp->secndx[ws[i]]; wd[j++] = ecp->secndx[ws[i]];
else else
s->sz -= 4; s->sz -= 4;
} }
s->nocopy = 1;
}
/*
* Filter relocation entries, only keep those entries whose
* symbol is in the keep list.
*/
static void
filter_reloc(struct elfcopy *ecp, struct section *s)
{
const char *name;
GElf_Shdr ish;
GElf_Rel rel;
GElf_Rela rela;
Elf32_Rel *rel32;
Elf64_Rel *rel64;
Elf32_Rela *rela32;
Elf64_Rela *rela64;
Elf_Data *id;
uint64_t cap, n, nrels, sym;
int elferr, i;
if (gelf_getshdr(s->is, &ish) == NULL)
errx(EXIT_FAILURE, "gelf_getehdr() failed: %s",
elf_errmsg(-1));
/* We don't want to touch relocation info for dynamic symbols. */
if ((ecp->flags & SYMTAB_EXIST) == 0) {
/*
* No symbol table in output. If sh_link points to a section
* that exists in the output object, this relocation section
* is for dynamic symbols. Don't touch it.
*/
if (ish.sh_link != 0 && ecp->secndx[ish.sh_link] != 0)
return;
} else {
/* Symbol table exist, check if index equals. */
if (ish.sh_link != elf_ndxscn(ecp->symtab->is))
return;
}
#define COPYREL(REL, SZ) do { \
if (nrels == 0) { \
if ((REL##SZ = malloc(cap * \
sizeof(*REL##SZ))) == NULL) \
err(EXIT_FAILURE, "malloc failed"); \
} \
if (nrels >= cap) { \
cap *= 2; \
if ((REL##SZ = realloc(REL##SZ, cap * \
sizeof(*REL##SZ))) == NULL) \
err(EXIT_FAILURE, "realloc failed"); \
} \
REL##SZ[nrels].r_offset = REL.r_offset; \
REL##SZ[nrels].r_info = REL.r_info; \
if (s->type == SHT_RELA) \
rela##SZ[nrels].r_addend = rela.r_addend; \
nrels++; \
} while (0)
nrels = 0;
cap = 4; /* keep list is usually small. */
rel32 = NULL;
rel64 = NULL;
rela32 = NULL;
rela64 = NULL;
if ((id = elf_getdata(s->is, NULL)) == NULL)
errx(EXIT_FAILURE, "elf_getdata() failed: %s",
elf_errmsg(-1));
n = ish.sh_size / ish.sh_entsize;
for(i = 0; (uint64_t)i < n; i++) {
if (s->type == SHT_REL) {
if (gelf_getrel(id, i, &rel) != &rel)
errx(EXIT_FAILURE, "gelf_getrel failed: %s",
elf_errmsg(-1));
sym = GELF_R_SYM(rel.r_info);
} else {
if (gelf_getrela(id, i, &rela) != &rela)
errx(EXIT_FAILURE, "gelf_getrel failed: %s",
elf_errmsg(-1));
sym = GELF_R_SYM(rela.r_info);
}
/*
* If a relocation references a symbol and we are omitting
* either that symbol or the entire symbol table we cannot
* produce valid output, and so just omit the relocation.
* Broken output like this is generally not useful, but some
* uses of elfcopy/strip rely on it - for example, GCC's build
* process uses it to check for build reproducibility by
* stripping objects and comparing them.
*
* Relocations that do not reference a symbol are retained.
*/
if (sym != 0) {
if (ish.sh_link == 0 || ecp->secndx[ish.sh_link] == 0)
continue;
name = elf_strptr(ecp->ein, elf_ndxscn(ecp->strtab->is),
sym);
if (name == NULL)
errx(EXIT_FAILURE, "elf_strptr failed: %s",
elf_errmsg(-1));
if (lookup_symop_list(ecp, name, SYMOP_KEEP) == NULL)
continue;
}
if (ecp->oec == ELFCLASS32) {
if (s->type == SHT_REL)
COPYREL(rel, 32);
else
COPYREL(rela, 32);
} else {
if (s->type == SHT_REL)
COPYREL(rel, 64);
else
COPYREL(rela, 64);
}
}
elferr = elf_errno();
if (elferr != 0)
errx(EXIT_FAILURE, "elf_getdata() failed: %s",
elf_errmsg(elferr));
if (ecp->oec == ELFCLASS32) {
if (s->type == SHT_REL)
s->buf = rel32;
else
s->buf = rela32;
} else {
if (s->type == SHT_REL)
s->buf = rel64;
else
s->buf = rela64;
}
s->sz = gelf_fsize(ecp->eout, (s->type == SHT_REL ? ELF_T_REL :
ELF_T_RELA), nrels, EV_CURRENT);
s->nocopy = 1; s->nocopy = 1;
} }
static void static void
update_reloc(struct elfcopy *ecp, struct section *s) update_reloc(struct elfcopy *ecp, struct section *s)
{ {
GElf_Shdr osh; GElf_Shdr osh;
GElf_Rel rel; GElf_Rel rel;
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