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add gnu hash support in the dynamic linker 

based on the patches contributed by boris brezillon.
This commit is contained in:
Rich Felker 2012-08-25 17:13:28 -04:00
parent 7dba0494e8
commit 2bd05a4fc2
2 changed files with 86 additions and 13 deletions
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2
configure vendored
View File

@ -268,7 +268,7 @@ fi
# Some patched GCC builds have these defaults messed up...
tryflag CFLAGS_AUTO -fno-stack-protector
tryldflag LDFLAGS_AUTO -Wl,--hash-style=sysv
tryldflag LDFLAGS_AUTO -Wl,--hash-style=both
# Disable dynamic linking if ld is broken and can't do -Bsymbolic-functions
LDFLAGS_DUMMY=

97
src/ldso/dynlink.c
View File

@ -53,6 +53,7 @@ struct dso {
int refcnt;
Sym *syms;
uint32_t *hashtab;
uint32_t *ghashtab;
char *strings;
unsigned char *map;
size_t map_len;
@ -95,7 +96,15 @@ static void decode_vec(size_t *v, size_t *a, size_t cnt)
}
}
static uint32_t hash(const char *s0)
static int search_vec(size_t *v, size_t *r, size_t key)
{
for (; v[0]!=key; v+=2)
if (!v[0]) return 0;
*r = v[1];
return 1;
}
static uint32_t sysv_hash(const char *s0)
{
const unsigned char *s = (void *)s0;
uint_fast32_t h = 0;
@ -106,7 +115,16 @@ static uint32_t hash(const char *s0)
return h & 0xfffffff;
}
static Sym *lookup(const char *s, uint32_t h, struct dso *dso)
static uint32_t gnu_hash(const char *s0)
{
const unsigned char *s = (void *)s0;
uint_fast32_t h = 5381;
for (; *s; s++)
h = h*33 + *s;
return h;
}
static Sym *sysv_lookup(const char *s, uint32_t h, struct dso *dso)
{
size_t i;
Sym *syms = dso->syms;
@ -119,20 +137,61 @@ static Sym *lookup(const char *s, uint32_t h, struct dso *dso)
return 0;
}
static Sym *gnu_lookup(const char *s, uint32_t h1, struct dso *dso)
{
Sym *sym;
char *strings;
uint32_t *hashtab = dso->ghashtab;
uint32_t nbuckets = hashtab[0];
uint32_t *buckets = hashtab + 4 + hashtab[2]*(sizeof(size_t)/4);
uint32_t h2;
uint32_t *hashval;
uint32_t n = buckets[h1 % nbuckets];
if (!n) return 0;
strings = dso->strings;
sym = dso->syms + n;
hashval = buckets + nbuckets + (n - hashtab[1]);
for (h1 |= 1; ; sym++) {
h2 = *hashval++;
if ((h1 == (h2|1)) && !strcmp(s, strings + sym->st_name))
return sym;
if (h2 & 1) break;
}
return 0;
}
#define OK_TYPES (1<<STT_NOTYPE | 1<<STT_OBJECT | 1<<STT_FUNC | 1<<STT_COMMON)
#define OK_BINDS (1<<STB_GLOBAL | 1<<STB_WEAK)
static void *find_sym(struct dso *dso, const char *s, int need_def)
{
uint32_t h = hash(s);
uint32_t h = 0, gh = 0;
void *def = 0;
if (h==0x6b366be && !strcmp(s, "dlopen")) rtld_used = 1;
if (h==0x6b3afd && !strcmp(s, "dlsym")) rtld_used = 1;
if (h==0x595a4cc && !strcmp(s, "__stack_chk_fail")) ssp_used = 1;
if (dso->ghashtab) {
gh = gnu_hash(s);
if (gh == 0xf9040207 && !strcmp(s, "dlopen")) rtld_used = 1;
if (gh == 0xf4dc4ae && !strcmp(s, "dlsym")) rtld_used = 1;
if (gh == 0x1f4039c9 && !strcmp(s, "__stack_chk_fail")) ssp_used = 1;
} else {
h = sysv_hash(s);
if (h == 0x6b366be && !strcmp(s, "dlopen")) rtld_used = 1;
if (h == 0x6b3afd && !strcmp(s, "dlsym")) rtld_used = 1;
if (h == 0x595a4cc && !strcmp(s, "__stack_chk_fail")) ssp_used = 1;
}
for (; dso; dso=dso->next) {
Sym *sym;
if (!dso->global) continue;
sym = lookup(s, h, dso);
if (dso->ghashtab) {
if (!gh) gh = gnu_hash(s);
sym = gnu_lookup(s, gh, dso);
} else {
if (!h) h = sysv_hash(s);
sym = sysv_lookup(s, h, dso);
}
if (sym && (!need_def || sym->st_shndx) && sym->st_value
&& (1<<(sym->st_info&0xf) & OK_TYPES)
&& (1<<(sym->st_info>>4) & OK_BINDS)) {
@ -325,8 +384,11 @@ static void decode_dyn(struct dso *p)
size_t dyn[DYN_CNT] = {0};
decode_vec(p->dynv, dyn, DYN_CNT);
p->syms = (void *)(p->base + dyn[DT_SYMTAB]);
p->hashtab = (void *)(p->base + dyn[DT_HASH]);
p->strings = (void *)(p->base + dyn[DT_STRTAB]);
if (dyn[0]&(1<<DT_HASH))
p->hashtab = (void *)(p->base + dyn[DT_HASH]);
if (search_vec(p->dynv, dyn, DT_GNU_HASH))
p->ghashtab = (void *)(p->base + *dyn);
}
static struct dso *load_library(const char *name)
@ -788,7 +850,7 @@ end:
static void *do_dlsym(struct dso *p, const char *s, void *ra)
{
size_t i;
uint32_t h;
uint32_t h = 0, gh = 0;
Sym *sym;
if (p == RTLD_NEXT) {
for (p=head; p && (unsigned char *)ra-p->map>p->map_len; p=p->next);
@ -802,12 +864,23 @@ static void *do_dlsym(struct dso *p, const char *s, void *ra)
if (!res) goto failed;
return res;
}
h = hash(s);
sym = lookup(s, h, p);
if (p->ghashtab) {
gh = gnu_hash(s);
sym = gnu_lookup(s, gh, p);
} else {
h = sysv_hash(s);
sym = sysv_lookup(s, h, p);
}
if (sym && sym->st_value && (1<<(sym->st_info&0xf) & OK_TYPES))
return p->base + sym->st_value;
if (p->deps) for (i=0; p->deps[i]; i++) {
sym = lookup(s, h, p->deps[i]);
if (p->deps[i]->ghashtab) {
if (!gh) gh = gnu_hash(s);
sym = gnu_lookup(s, h, p->deps[i]);
} else {
if (!h) h = sysv_hash(s);
sym = sysv_lookup(s, h, p->deps[i]);
}
if (sym && sym->st_value && (1<<(sym->st_info&0xf) & OK_TYPES))
return p->deps[i]->base + sym->st_value;
}