1 files changed, 265 insertions, 0 deletions
diff --git a/ldso/include/inline-hashtab.h b/ldso/include/inline-hashtab.h
new file mode 100644
index 000000000..4a4812027
--- /dev/null
+++ b/ldso/include/inline-hashtab.h
@@ -0,0 +1,265 @@
+/*
+ * The hashcode handling code below is heavily inspired in libiberty's
+ * hashtab code, but with most adaptation points and support for
+ * deleting elements removed.
+ *
+ * Copyright (C) 1999, 2000, 2001, 2002, 2003 Free Software Foundation, Inc.
+ * Contributed by Vladimir Makarov (vmakarov@cygnus.com).
+ */
+
+#ifndef INLINE_HASHTAB_H
+# define INLINE_HASHTAB_H 1
+
+static __always_inline unsigned long
+higher_prime_number(unsigned long n)
+{
+	/* These are primes that are near, but slightly smaller than, a power of two. */
+	static const unsigned long primes[] = {
+		7,
+		13,
+		31,
+		61,
+		127,
+		251,
+		509,
+		1021,
+		2039,
+		4093,
+		8191,
+		16381,
+		32749,
+		65521,
+		131071,
+		262139,
+		524287,
+		1048573,
+		2097143,
+		4194301,
+		8388593,
+		16777213,
+		33554393,
+		67108859,
+		134217689,
+		268435399,
+		536870909,
+		1073741789,
+		/* 4294967291 */
+		((unsigned long) 2147483647) + ((unsigned long) 2147483644),
+	};
+	const unsigned long *low = &primes[0];
+	const unsigned long *high = &primes[ARRAY_SIZE(primes)];
+
+	while (low != high) {
+		const unsigned long *mid = low + (high - low) / 2;
+		if (n > *mid)
+			low = mid + 1;
+		else
+			high = mid;
+	}
+
+#if 0
+	/* If we've run out of primes, abort.  */
+	if (n > *low) {
+		fprintf(stderr, "Cannot find prime bigger than %lu\n", n);
+		abort();
+	}
+#endif
+
+	return *low;
+}
+
+struct funcdesc_ht
+{
+	/* Table itself */
+	void **entries;
+
+	/* Current size (in entries) of the hash table */
+	size_t size;
+
+	/* Current number of elements */
+	size_t n_elements;
+};
+
+static __always_inline struct funcdesc_ht *
+htab_create(void)
+{
+	struct funcdesc_ht *ht = _dl_malloc(sizeof(*ht));
+	size_t ent_size;
+
+	if (!ht)
+		return NULL;
+	ht->size = 3;
+	ent_size = sizeof(void *) * ht->size;
+	ht->entries = _dl_malloc(ent_size);
+	if (!ht->entries)
+		return NULL;
+
+	ht->n_elements = 0;
+	_dl_memset(ht->entries, 0, ent_size);
+
+	return ht;
+}
+
+/*
+ * This is only called from _dl_loadaddr_unmap, so it's safe to call
+ * _dl_free().  See the discussion below.
+ */
+static __always_inline void
+htab_delete(struct funcdesc_ht *htab)
+{
+	size_t i;
+
+	for (i = htab->size - 1; i >= 0; i--)
+		if (htab->entries[i])
+			_dl_free(htab->entries[i]);
+
+	_dl_free(htab->entries);
+	_dl_free(htab);
+}
+
+/*
+ * Similar to htab_find_slot, but without several unwanted side effects:
+ *  - Does not call htab->eq_f when it finds an existing entry.
+ *  - Does not change the count of elements/searches/collisions in the
+ *    hash table.
+ * This function also assumes there are no deleted entries in the table.
+ * HASH is the hash value for the element to be inserted.
+ */
+static __always_inline void **
+find_empty_slot_for_expand(struct funcdesc_ht *htab, int hash)
+{
+	size_t size = htab->size;
+	unsigned int index = hash % size;
+	void **slot = htab->entries + index;
+	int hash2;
+
+	if (!*slot)
+		return slot;
+
+	hash2 = 1 + hash % (size - 2);
+	for (;;) {
+		index += hash2;
+		if (index >= size)
+			index -= size;
+
+		slot = htab->entries + index;
+		if (!*slot)
+			return slot;
+	}
+}
+
+/*
+ * The following function changes size of memory allocated for the
+ * entries and repeatedly inserts the table elements.  The occupancy
+ * of the table after the call will be about 50%.  Naturally the hash
+ * table must already exist.  Remember also that the place of the
+ * table entries is changed.  If memory allocation failures are allowed,
+ * this function will return zero, indicating that the table could not be
+ * expanded.  If all goes well, it will return a non-zero value.
+ */
+static __always_inline int
+htab_expand(struct funcdesc_ht *htab, int (*hash_fn) (void *))
+{
+	void **oentries;
+	void **olimit;
+	void **p;
+	void **nentries;
+	size_t nsize;
+
+	oentries = htab->entries;
+	olimit = oentries + htab->size;
+
+	/*
+	 * Resize only when table after removal of unused elements is either
+	 * too full or too empty.
+	 */
+	if (htab->n_elements * 2 > htab->size)
+		nsize = higher_prime_number(htab->n_elements * 2);
+	else
+		nsize = htab->size;
+
+	nentries = _dl_malloc(sizeof(*nentries) * nsize);
+	_dl_memset(nentries, 0, sizeof(*nentries) * nsize);
+	if (nentries == NULL)
+		return 0;
+	htab->entries = nentries;
+	htab->size = nsize;
+
+	p = oentries;
+	do {
+		if (*p)
+			*find_empty_slot_for_expand(htab, hash_fn(*p)) = *p;
+		p++;
+	} while (p < olimit);
+
+#if 0
+	/*
+	 * We can't tell whether this was allocated by the _dl_malloc()
+	 * built into ld.so or malloc() in the main executable or libc,
+	 * and calling free() for something that wasn't malloc()ed could
+	 * do Very Bad Things (TM).  Take the conservative approach
+	 * here, potentially wasting as much memory as actually used by
+	 * the hash table, even if multiple growths occur.  That's not
+	 * so bad as to require some overengineered solution that would
+	 * enable us to keep track of how it was allocated.
+	 */
+	_dl_free(oentries);
+#endif
+	return 1;
+}
+
+/*
+ * This function searches for a hash table slot containing an entry
+ * equal to the given element.  To delete an entry, call this with
+ * INSERT = 0, then call htab_clear_slot on the slot returned (possibly
+ * after doing some checks).  To insert an entry, call this with
+ * INSERT = 1, then write the value you want into the returned slot.
+ * When inserting an entry, NULL may be returned if memory allocation
+ * fails.
+ */
+static __always_inline void **
+htab_find_slot(struct funcdesc_ht *htab, void *ptr, int insert,
+	       int (*hash_fn)(void *), int (*eq_fn)(void *, void *))
+{
+	unsigned int index;
+	int hash, hash2;
+	size_t size;
+	void **entry;
+
+	if (htab->size * 3 <= htab->n_elements * 4 &&
+	    htab_expand(htab, hash_fn) == 0)
+		return NULL;
+
+	hash = hash_fn(ptr);
+
+	size = htab->size;
+	index = hash % size;
+
+	entry = &htab->entries[index];
+	if (!*entry)
+		goto empty_entry;
+	else if (eq_fn(*entry, ptr))
+		return entry;
+
+	hash2 = 1 + hash % (size - 2);
+	for (;;) {
+		index += hash2;
+		if (index >= size)
+			index -= size;
+
+		entry = &htab->entries[index];
+		if (!*entry)
+			goto empty_entry;
+		else if (eq_fn(*entry, ptr))
+			return entry;
+	}
+
+ empty_entry:
+	if (!insert)
+		return NULL;
+
+	htab->n_elements++;
+	return entry;
+}
+
+#endif