X-Git-Url: http://www.chiark.greenend.org.uk/ucgi/~ianmdlvl/git?a=blobdiff_plain;f=src%2Fshared%2Fhashmap.c;h=3762e3ab0deb045a98517b6d5fa7b48cb8d45e6e;hb=0371ca0dac1d70b2e5060a3c4e6fbbc2bdbd8671;hp=dcfbb67228e826b21260d4d995ca6ed3a5494bfb;hpb=a4bcff5ba36115495994e9f9ba66074471de76ab;p=elogind.git

diff --git a/src/shared/hashmap.c b/src/shared/hashmap.c
index dcfbb6722..3762e3ab0 100644
--- a/src/shared/hashmap.c
+++ b/src/shared/hashmap.c
@@ -24,11 +24,15 @@
 #include <string.h>
 #include <errno.h>
 
+#ifdef HAVE_SYS_AUXV_H
+#include <sys/auxv.h>
+#endif
+
 #include "util.h"
 #include "hashmap.h"
 #include "macro.h"
 
-#define NBUCKETS 127
+#define INITIAL_N_BUCKETS 31
 
 struct hashmap_entry {
         const void *key;
@@ -42,13 +46,14 @@ struct Hashmap {
         compare_func_t compare_func;
 
         struct hashmap_entry *iterate_list_head, *iterate_list_tail;
-        unsigned n_entries;
 
+        struct hashmap_entry ** buckets;
+        unsigned n_buckets, n_entries;
+
+        unsigned random_xor;
         bool from_pool;
 };
 
-#define BY_HASH(h) ((struct hashmap_entry**) ((uint8_t*) (h) + ALIGN(sizeof(Hashmap))))
-
 struct pool {
         struct pool *next;
         unsigned n_tiles;
@@ -61,9 +66,15 @@ static void *first_hashmap_tile = NULL;
 static struct pool *first_entry_pool = NULL;
 static void *first_entry_tile = NULL;
 
-static void* allocate_tile(struct pool **first_pool, void **first_tile, size_t tile_size) {
+static void* allocate_tile(struct pool **first_pool, void **first_tile, size_t tile_size, unsigned at_least) {
         unsigned i;
 
+        /* When a tile is released we add it to the list and simply
+         * place the next pointer at its offset 0. */
+
+        assert(tile_size >= sizeof(void*));
+        assert(at_least > 0);
+
         if (*first_tile) {
                 void *r;
 
@@ -78,7 +89,7 @@ static void* allocate_tile(struct pool **first_pool, void **first_tile, size_t t
                 struct pool *p;
 
                 n = *first_pool ? (*first_pool)->n_tiles : 0;
-                n = MAX(512U, n * 2);
+                n = MAX(at_least, n * 2);
                 size = PAGE_ALIGN(ALIGN(sizeof(struct pool)) + n*tile_size);
                 n = (size - ALIGN(sizeof(struct pool))) / tile_size;
 
@@ -103,7 +114,7 @@ static void deallocate_tile(void **first_tile, void *p) {
         *first_tile = p;
 }
 
-#ifndef __OPTIMIZE__
+#ifdef VALGRIND
 
 static void drop_pool(struct pool *p) {
         while (p) {
@@ -166,6 +177,10 @@ int uint64_compare_func(const void *_a, const void *_b) {
         return a < b ? -1 : (a > b ? 1 : 0);
 }
 
+static unsigned bucket_hash(Hashmap *h, const void *p) {
+        return (h->hash_func(p) ^ h->random_xor) % h->n_buckets;
+}
+
 Hashmap *hashmap_new(hash_func_t hash_func, compare_func_t compare_func) {
         bool b;
         Hashmap *h;
@@ -173,10 +188,10 @@ Hashmap *hashmap_new(hash_func_t hash_func, compare_func_t compare_func) {
 
         b = is_main_thread();
 
-        size = ALIGN(sizeof(Hashmap)) + NBUCKETS * sizeof(struct hashmap_entry*);
+        size = ALIGN(sizeof(Hashmap)) + INITIAL_N_BUCKETS * sizeof(struct hashmap_entry*);
 
         if (b) {
-                h = allocate_tile(&first_hashmap_pool, &first_hashmap_tile, size);
+                h = allocate_tile(&first_hashmap_pool, &first_hashmap_tile, size, 8);
                 if (!h)
                         return NULL;
 
@@ -191,23 +206,46 @@ Hashmap *hashmap_new(hash_func_t hash_func, compare_func_t compare_func) {
         h->hash_func = hash_func ? hash_func : trivial_hash_func;
         h->compare_func = compare_func ? compare_func : trivial_compare_func;
 
+        h->n_buckets = INITIAL_N_BUCKETS;
         h->n_entries = 0;
         h->iterate_list_head = h->iterate_list_tail = NULL;
 
+        h->buckets = (struct hashmap_entry**) ((uint8_t*) h + ALIGN(sizeof(Hashmap)));
+
         h->from_pool = b;
 
+        /* Let's randomize our hash functions a bit so that they are
+         * harder to guess for clients. For this, start out by cheaply
+         * using some bits the kernel passed into the process using
+         * the auxiliary vector. If the hashmap grows later on we will
+         * rehash everything using a new random XOR mask from
+         * /dev/random. */
+#ifdef HAVE_SYS_AUXV_H
+        {
+                void *auxv;
+                auxv = (void*) getauxval(AT_RANDOM);
+                h->random_xor = auxv ? *(unsigned*) auxv : random_u();
+        }
+#else
+        h->random_xor = random_u();
+#endif
+
         return h;
 }
 
 int hashmap_ensure_allocated(Hashmap **h, hash_func_t hash_func, compare_func_t compare_func) {
+        Hashmap *q;
+
         assert(h);
 
         if (*h)
                 return 0;
 
-        if (!(*h = hashmap_new(hash_func, compare_func)))
+        q = hashmap_new(hash_func, compare_func);
+        if (!q)
                 return -ENOMEM;
 
+        *h = q;
         return 0;
 }
 
@@ -216,11 +254,11 @@ static void link_entry(Hashmap *h, struct hashmap_entry *e, unsigned hash) {
         assert(e);
 
         /* Insert into hash table */
-        e->bucket_next = BY_HASH(h)[hash];
+        e->bucket_next = h->buckets[hash];
         e->bucket_previous = NULL;
-        if (BY_HASH(h)[hash])
-                BY_HASH(h)[hash]->bucket_previous = e;
-        BY_HASH(h)[hash] = e;
+        if (h->buckets[hash])
+                h->buckets[hash]->bucket_previous = e;
+        h->buckets[hash] = e;
 
         /* Insert into iteration list */
         e->iterate_previous = h->iterate_list_tail;
@@ -260,7 +298,7 @@ static void unlink_entry(Hashmap *h, struct hashmap_entry *e, unsigned hash) {
         if (e->bucket_previous)
                 e->bucket_previous->bucket_next = e->bucket_next;
         else
-                BY_HASH(h)[hash] = e->bucket_next;
+                h->buckets[hash] = e->bucket_next;
 
         assert(h->n_entries >= 1);
         h->n_entries--;
@@ -272,8 +310,7 @@ static void remove_entry(Hashmap *h, struct hashmap_entry *e) {
         assert(h);
         assert(e);
 
-        hash = h->hash_func(e->key) % NBUCKETS;
-
+        hash = bucket_hash(h, e->key);
         unlink_entry(h, e, hash);
 
         if (h->from_pool)
@@ -291,6 +328,9 @@ void hashmap_free(Hashmap*h) {
 
         hashmap_clear(h);
 
+        if (h->buckets != (struct hashmap_entry**) ((uint8_t*) h + ALIGN(sizeof(Hashmap))))
+                free(h->buckets);
+
         if (h->from_pool)
                 deallocate_tile(&first_hashmap_tile, h);
         else
@@ -309,6 +349,17 @@ void hashmap_free_free(Hashmap *h) {
         hashmap_free(h);
 }
 
+void hashmap_free_free_free(Hashmap *h) {
+
+        /* Free the hashmap and all data and key objects in it */
+
+        if (!h)
+                return;
+
+        hashmap_clear_free_free(h);
+        hashmap_free(h);
+}
+
 void hashmap_clear(Hashmap *h) {
         if (!h)
                 return;
@@ -327,37 +378,108 @@ void hashmap_clear_free(Hashmap *h) {
                 free(p);
 }
 
+void hashmap_clear_free_free(Hashmap *h) {
+        if (!h)
+                return;
+
+        while (h->iterate_list_head) {
+                void *a, *b;
+
+                a = h->iterate_list_head->value;
+                b = (void*) h->iterate_list_head->key;
+                remove_entry(h, h->iterate_list_head);
+                free(a);
+                free(b);
+        }
+}
+
 static struct hashmap_entry *hash_scan(Hashmap *h, unsigned hash, const void *key) {
         struct hashmap_entry *e;
         assert(h);
-        assert(hash < NBUCKETS);
+        assert(hash < h->n_buckets);
 
-        for (e = BY_HASH(h)[hash]; e; e = e->bucket_next)
+        for (e = h->buckets[hash]; e; e = e->bucket_next)
                 if (h->compare_func(e->key, key) == 0)
                         return e;
 
         return NULL;
 }
 
+static bool resize_buckets(Hashmap *h) {
+        struct hashmap_entry **n, *i;
+        unsigned m, nxor;
+
+        assert(h);
+
+        if (_likely_(h->n_entries*4 < h->n_buckets*3))
+                return false;
+
+        /* Increase by four */
+        m = (h->n_entries+1)*4-1;
+
+        /* If we hit OOM we simply risk packed hashmaps... */
+        n = new0(struct hashmap_entry*, m);
+        if (!n)
+                return false;
+
+        /* Let's use a different randomized xor value for the
+         * extension, so that people cannot guess what we are using
+         * here forever */
+        nxor = random_u();
+
+        for (i = h->iterate_list_head; i; i = i->iterate_next) {
+                unsigned hash, x;
+
+                hash = h->hash_func(i->key);
+
+                /* First, drop from old bucket table */
+                if (i->bucket_next)
+                        i->bucket_next->bucket_previous = i->bucket_previous;
+
+                if (i->bucket_previous)
+                        i->bucket_previous->bucket_next = i->bucket_next;
+                else
+                        h->buckets[(hash ^ h->random_xor) % h->n_buckets] = i->bucket_next;
+
+                /* Then, add to new backet table */
+                x = (hash ^ nxor) % m;
+
+                i->bucket_next = n[x];
+                i->bucket_previous = NULL;
+                if (n[x])
+                        n[x]->bucket_previous = i;
+                n[x] = i;
+        }
+
+        if (h->buckets != (struct hashmap_entry**) ((uint8_t*) h + ALIGN(sizeof(Hashmap))))
+                free(h->buckets);
+
+        h->buckets = n;
+        h->n_buckets = m;
+        h->random_xor = nxor;
+
+        return true;
+}
+
 int hashmap_put(Hashmap *h, const void *key, void *value) {
         struct hashmap_entry *e;
         unsigned hash;
 
         assert(h);
 
-        hash = h->hash_func(key) % NBUCKETS;
-
+        hash = bucket_hash(h, key);
         e = hash_scan(h, hash, key);
         if (e) {
-
                 if (e->value == value)
                         return 0;
-
                 return -EEXIST;
         }
 
+        if (resize_buckets(h))
+                hash = bucket_hash(h, key);
+
         if (h->from_pool)
-                e = allocate_tile(&first_entry_pool, &first_entry_tile, sizeof(struct hashmap_entry));
+                e = allocate_tile(&first_entry_pool, &first_entry_tile, sizeof(struct hashmap_entry), 64U);
         else
                 e = new(struct hashmap_entry, 1);
 
@@ -378,7 +500,7 @@ int hashmap_replace(Hashmap *h, const void *key, void *value) {
 
         assert(h);
 
-        hash = h->hash_func(key) % NBUCKETS;
+        hash = bucket_hash(h, key);
         e = hash_scan(h, hash, key);
         if (e) {
                 e->key = key;
@@ -395,7 +517,7 @@ int hashmap_update(Hashmap *h, const void *key, void *value) {
 
         assert(h);
 
-        hash = h->hash_func(key) % NBUCKETS;
+        hash = bucket_hash(h, key);
         e = hash_scan(h, hash, key);
         if (!e)
                 return -ENOENT;
@@ -411,7 +533,7 @@ void* hashmap_get(Hashmap *h, const void *key) {
         if (!h)
                 return NULL;
 
-        hash = h->hash_func(key) % NBUCKETS;
+        hash = bucket_hash(h, key);
         e = hash_scan(h, hash, key);
         if (!e)
                 return NULL;
@@ -426,7 +548,7 @@ void* hashmap_get2(Hashmap *h, const void *key, void **key2) {
         if (!h)
                 return NULL;
 
-        hash = h->hash_func(key) % NBUCKETS;
+        hash = bucket_hash(h, key);
         e = hash_scan(h, hash, key);
         if (!e)
                 return NULL;
@@ -443,12 +565,8 @@ bool hashmap_contains(Hashmap *h, const void *key) {
         if (!h)
                 return false;
 
-        hash = h->hash_func(key) % NBUCKETS;
-
-        if (!hash_scan(h, hash, key))
-                return false;
-
-        return true;
+        hash = bucket_hash(h, key);
+        return !!hash_scan(h, hash, key);
 }
 
 void* hashmap_remove(Hashmap *h, const void *key) {
@@ -459,9 +577,9 @@ void* hashmap_remove(Hashmap *h, const void *key) {
         if (!h)
                 return NULL;
 
-        hash = h->hash_func(key) % NBUCKETS;
-
-        if (!(e = hash_scan(h, hash, key)))
+        hash = bucket_hash(h, key);
+        e = hash_scan(h, hash, key);
+        if (!e)
                 return NULL;
 
         data = e->value;
@@ -477,11 +595,12 @@ int hashmap_remove_and_put(Hashmap *h, const void *old_key, const void *new_key,
         if (!h)
                 return -ENOENT;
 
-        old_hash = h->hash_func(old_key) % NBUCKETS;
-        if (!(e = hash_scan(h, old_hash, old_key)))
+        old_hash = bucket_hash(h, old_key);
+        e = hash_scan(h, old_hash, old_key);
+        if (!e)
                 return -ENOENT;
 
-        new_hash = h->hash_func(new_key) % NBUCKETS;
+        new_hash = bucket_hash(h, new_key);
         if (hash_scan(h, new_hash, new_key))
                 return -EEXIST;
 
@@ -502,13 +621,14 @@ int hashmap_remove_and_replace(Hashmap *h, const void *old_key, const void *new_
         if (!h)
                 return -ENOENT;
 
-        old_hash = h->hash_func(old_key) % NBUCKETS;
-        if (!(e = hash_scan(h, old_hash, old_key)))
+        old_hash = bucket_hash(h, old_key);
+        e = hash_scan(h, old_hash, old_key);
+        if (!e)
                 return -ENOENT;
 
-        new_hash = h->hash_func(new_key) % NBUCKETS;
-
-        if ((k = hash_scan(h, new_hash, new_key)))
+        new_hash = bucket_hash(h, new_key);
+        k = hash_scan(h, new_hash, new_key);
+        if (k)
                 if (e != k)
                         remove_entry(h, k);
 
@@ -529,9 +649,10 @@ void* hashmap_remove_value(Hashmap *h, const void *key, void *value) {
         if (!h)
                 return NULL;
 
-        hash = h->hash_func(key) % NBUCKETS;
+        hash = bucket_hash(h, key);
 
-        if (!(e = hash_scan(h, hash, key)))
+        e = hash_scan(h, hash, key);
+        if (!e)
                 return NULL;
 
         if (e->value != value)
@@ -619,9 +740,10 @@ void *hashmap_iterate_skip(Hashmap *h, const void *key, Iterator *i) {
         if (!h)
                 return NULL;
 
-        hash = h->hash_func(key) % NBUCKETS;
+        hash = bucket_hash(h, key);
 
-        if (!(e = hash_scan(h, hash, key)))
+        e = hash_scan(h, hash, key);
+        if (!e)
                 return NULL;
 
         *i = (Iterator) e;
@@ -700,6 +822,14 @@ unsigned hashmap_size(Hashmap *h) {
         return h->n_entries;
 }
 
+unsigned hashmap_buckets(Hashmap *h) {
+
+        if (!h)
+                return 0;
+
+        return h->n_buckets;
+}
+
 bool hashmap_isempty(Hashmap *h) {
 
         if (!h)
@@ -719,9 +849,9 @@ int hashmap_merge(Hashmap *h, Hashmap *other) {
         for (e = other->iterate_list_head; e; e = e->iterate_next) {
                 int r;
 
-                if ((r = hashmap_put(h, e->key, e->value)) < 0)
-                        if (r != -EEXIST)
-                                return r;
+                r = hashmap_put(h, e->key, e->value);
+                if (r < 0 && r != -EEXIST)
+                        return r;
         }
 
         return 0;
@@ -743,13 +873,11 @@ void hashmap_move(Hashmap *h, Hashmap *other) {
 
                 n = e->iterate_next;
 
-                h_hash = h->hash_func(e->key) % NBUCKETS;
-
+                h_hash = bucket_hash(h, e->key);
                 if (hash_scan(h, h_hash, e->key))
                         continue;
 
-                other_hash = other->hash_func(e->key) % NBUCKETS;
-
+                other_hash = bucket_hash(other, e->key);
                 unlink_entry(other, e, other_hash);
                 link_entry(h, e, h_hash);
         }
@@ -764,12 +892,13 @@ int hashmap_move_one(Hashmap *h, Hashmap *other, const void *key) {
 
         assert(h);
 
-        h_hash = h->hash_func(key) % NBUCKETS;
+        h_hash = bucket_hash(h, key);
         if (hash_scan(h, h_hash, key))
                 return -EEXIST;
 
-        other_hash = other->hash_func(key) % NBUCKETS;
-        if (!(e = hash_scan(other, other_hash, key)))
+        other_hash = bucket_hash(other, key);
+        e = hash_scan(other, other_hash, key);
+        if (!e)
                 return -ENOENT;
 
         unlink_entry(other, e, other_hash);
@@ -783,7 +912,8 @@ Hashmap *hashmap_copy(Hashmap *h) {
 
         assert(h);
 
-        if (!(copy = hashmap_new(h->hash_func, h->compare_func)))
+        copy = hashmap_new(h->hash_func, h->compare_func);
+        if (!copy)
                 return NULL;
 
         if (hashmap_merge(copy, h) < 0) {
@@ -822,7 +952,7 @@ void *hashmap_next(Hashmap *h, const void *key) {
         if (!h)
                 return NULL;
 
-        hash = h->hash_func(key) % NBUCKETS;
+        hash = bucket_hash(h, key);
         e = hash_scan(h, hash, key);
         if (!e)
                 return NULL;