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authorRich Felker <dalias@aerifal.cx>2012-08-25 17:13:28 -0400
committerRich Felker <dalias@aerifal.cx>2012-08-25 17:13:28 -0400
commit2bd05a4fc26c297754f7ee5745a1c3b072a44b7d (patch)
treecda641d312fcb25618727bbdd7dd59a493c72609 /src/ldso/dynlink.c
parent7dba0494e8153e4358b09cbf30ff07d5ba4dbf37 (diff)
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add gnu hash support in the dynamic linker
based on the patches contributed by boris brezillon.
Diffstat (limited to 'src/ldso/dynlink.c')
-rw-r--r--src/ldso/dynlink.c97
1 files changed, 85 insertions, 12 deletions
diff --git a/src/ldso/dynlink.c b/src/ldso/dynlink.c
index 9692c6b0..d7d68002 100644
--- a/src/ldso/dynlink.c
+++ b/src/ldso/dynlink.c
@@ -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;
}