lib/base/dll.c

   1 /***********************************************************************
   2  * Copyright (c) 2016 Kungliga Tekniska Högskolan
   3  * (Royal Institute of Technology, Stockholm, Sweden).
   4  * All rights reserved.
   5  *
   6  * Redistribution and use in source and binary forms, with or without
   7  * modification, are permitted provided that the following conditions
   8  * are met:
   9  *
  10  * 1. Redistributions of source code must retain the above copyright
  11  *    notice, this list of conditions and the following disclaimer.
  12  *
  13  * 2. Redistributions in binary form must reproduce the above copyright
  14  *    notice, this list of conditions and the following disclaimer in the
  15  *    documentation and/or other materials provided with the distribution.
  16  *
  17  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
  18  * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
  19  * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
  20  * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
  21  * COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT,
  22  * INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
  23  * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
  24  * SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  25  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
  26  * STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
  27  * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
  28  * OF THE POSSIBILITY OF SUCH DAMAGE.
  29  *
  30  **********************************************************************/
  31
  32 /*
  33  * This is an implementation of thread-specific storage with
  34  * destructors.  WIN32 doesn't quite have this.  Instead it has
  35  * DllMain(), an entry point in every DLL that gets called to notify the
  36  * DLL of thread/process "attach"/"detach" events.
  37  *
  38  * We use __thread (or __declspec(thread)) for the thread-local itself
  39  * and DllMain() DLL_THREAD_DETACH events to drive destruction of
  40  * thread-local values.
  41  *
  42  * When building in maintainer mode on non-Windows pthread systems this
  43  * uses a single pthread key instead to implement multiple keys.  This
  44  * keeps the code from rotting when modified by non-Windows developers.
  45  */
  46
  47 #include "baselocl.h"
  48
  49 #ifdef WIN32
  50 #include <windows.h>
  51 #endif
  52
  53 #ifdef HEIM_WIN32_TLS
  54 #include <assert.h>
  55 #include <err.h>
  56 #include <heim_threads.h>
  57
  58 #ifndef WIN32
  59 #include <pthread.h>
  60 #endif
  61
  62 /* Logical array of keys that grows lock-lessly */
  63 typedef struct tls_keys tls_keys;
  64 struct tls_keys {
  65     void (**keys_dtors)(void *);    /* array of destructors         */
  66     size_t keys_start_idx;          /* index of first destructor    */
  67     size_t keys_num;
  68     tls_keys *keys_next;
  69 };
  70
  71 /*
  72  * Well, not quite locklessly.  We need synchronization primitives to do
  73  * this locklessly.  An atomic CAS will do.
  74  */
  75 static HEIMDAL_MUTEX tls_key_defs_lock = HEIMDAL_MUTEX_INITIALIZER;
  76 static tls_keys *tls_key_defs;
  77
  78 /* Logical array of values (per-thread; no locking needed here) */
  79 struct tls_values {
  80     void **values; /* realloc()ed */
  81     size_t values_num;
  82 };
  83
  84 static HEIMDAL_THREAD_LOCAL struct tls_values values;
  85
  86 #define DEAD_KEY ((void *)8)
  87
  88 void
  89 heim_w32_service_thread_detach(void *unused)
  90 {
  91     tls_keys *key_defs;
  92     void (*dtor)(void*);
  93     size_t i;
  94
  95     HEIMDAL_MUTEX_lock(&tls_key_defs_lock);
  96     key_defs = tls_key_defs;
  97     HEIMDAL_MUTEX_unlock(&tls_key_defs_lock);
  98
  99     if (key_defs == NULL)
 100         return;
 101
 102     for (i = 0; i < values.values_num; i++) {
 103         assert(i >= key_defs->keys_start_idx);
 104         if (i >= key_defs->keys_start_idx + key_defs->keys_num) {
 105             HEIMDAL_MUTEX_lock(&tls_key_defs_lock);
 106             key_defs = key_defs->keys_next;
 107             HEIMDAL_MUTEX_unlock(&tls_key_defs_lock);
 108
 109             assert(key_defs != NULL);
 110             assert(i >= key_defs->keys_start_idx);
 111             assert(i < key_defs->keys_start_idx + key_defs->keys_num);
 112         }
 113         dtor = key_defs->keys_dtors[i - key_defs->keys_start_idx];
 114         if (values.values[i] != NULL && dtor != NULL && dtor != DEAD_KEY)
 115             dtor(values.values[i]);
 116         values.values[i] = NULL;
 117     }
 118 }
 119
 120 #if !defined(WIN32)
 121 static pthread_key_t pt_key;
 122 pthread_once_t pt_once = PTHREAD_ONCE_INIT;
 123
 124 static void
 125 atexit_del_tls_for_thread(void)
 126 {
 127     heim_w32_service_thread_detach(NULL);
 128 }
 129
 130 static void
 131 create_pt_key(void)
 132 {
 133     int ret;
 134
 135     /* The main thread may not execute TLS destructors */
 136     atexit(atexit_del_tls_for_thread);
 137     ret = pthread_key_create(&pt_key, heim_w32_service_thread_detach);
 138     if (ret != 0)
 139         err(1, "pthread_key_create() failed");
 140 }
 141
 142 #endif
 143
 144 int
 145 heim_w32_key_create(HEIM_PRIV_thread_key *key, void (*dtor)(void *))
 146 {
 147     tls_keys *key_defs, *new_key_defs;
 148     size_t i, k;
 149     int ret = ENOMEM;
 150
 151 #if !defined(WIN32)
 152     (void) pthread_once(&pt_once, create_pt_key);
 153     (void) pthread_setspecific(pt_key, DEAD_KEY);
 154 #endif
 155
 156     HEIMDAL_MUTEX_lock(&tls_key_defs_lock);
 157     if (tls_key_defs == NULL) {
 158         /* First key */
 159         new_key_defs = calloc(1, sizeof(*new_key_defs));
 160         if (new_key_defs == NULL) {
 161             HEIMDAL_MUTEX_unlock(&tls_key_defs_lock);
 162             return ENOMEM;
 163         }
 164         new_key_defs->keys_num = 8;
 165         new_key_defs->keys_dtors = calloc(new_key_defs->keys_num,
 166                                           sizeof(*new_key_defs->keys_dtors));
 167         if (new_key_defs->keys_dtors == NULL) {
 168             HEIMDAL_MUTEX_unlock(&tls_key_defs_lock);
 169             free(new_key_defs);
 170             return ENOMEM;
 171         }
 172         tls_key_defs = new_key_defs;
 173         new_key_defs->keys_dtors[0] = dtor;
 174         for (i = 1; i < new_key_defs->keys_num; i++)
 175             new_key_defs->keys_dtors[i] = NULL;
 176         HEIMDAL_MUTEX_unlock(&tls_key_defs_lock);
 177         return 0;
 178     }
 179
 180     for (key_defs = tls_key_defs;
 181          key_defs != NULL;
 182          key_defs = key_defs->keys_next) {
 183         k = key_defs->keys_start_idx;
 184         for (i = 0; i < key_defs->keys_num; i++, k++) {
 185             if (key_defs->keys_dtors[i] == NULL) {
 186                 /* Found free slot; use it */
 187                 key_defs->keys_dtors[i] = dtor;
 188                 *key = k;
 189                 HEIMDAL_MUTEX_unlock(&tls_key_defs_lock);
 190                 return 0;
 191             }
 192         }
 193         if (key_defs->keys_next != NULL)
 194             continue;
 195
 196         /* Grow the registration array */
 197         /* XXX DRY */
 198         new_key_defs = calloc(1, sizeof(*new_key_defs));
 199         if (new_key_defs == NULL)
 200             break;
 201
 202         new_key_defs->keys_dtors =
 203             calloc(key_defs->keys_num + key_defs->keys_num / 2,
 204                    sizeof(*new_key_defs->keys_dtors));
 205         if (new_key_defs->keys_dtors == NULL) {
 206             free(new_key_defs);
 207             break;
 208         }
 209         new_key_defs->keys_start_idx = key_defs->keys_start_idx +
 210             key_defs->keys_num;
 211         new_key_defs->keys_num = key_defs->keys_num + key_defs->keys_num / 2;
 212         new_key_defs->keys_dtors[i] = dtor;
 213         for (i = 1; i < new_key_defs->keys_num; i++)
 214             new_key_defs->keys_dtors[i] = NULL;
 215         key_defs->keys_next = new_key_defs;
 216         ret = 0;
 217         break;
 218     }
 219     HEIMDAL_MUTEX_unlock(&tls_key_defs_lock);
 220     return ret;
 221 }
 222
 223 static void
 224 key_lookup(HEIM_PRIV_thread_key key, tls_keys **kd,
 225            size_t *dtor_idx, void (**dtor)(void *))
 226 {
 227     tls_keys *key_defs;
 228
 229     if (kd != NULL)
 230         *kd = NULL;
 231     if (dtor_idx != NULL)
 232         *dtor_idx = 0;
 233     if (dtor != NULL)
 234         *dtor = NULL;
 235
 236     HEIMDAL_MUTEX_lock(&tls_key_defs_lock);
 237     key_defs = tls_key_defs;
 238     HEIMDAL_MUTEX_unlock(&tls_key_defs_lock);
 239
 240     while (key_defs != NULL) {
 241         if (key >= key_defs->keys_start_idx &&
 242             key < key_defs->keys_start_idx + key_defs->keys_num) {
 243             if (kd != NULL)
 244                 *kd = key_defs;
 245             if (dtor_idx != NULL)
 246                 *dtor_idx = key - key_defs->keys_start_idx;
 247             if (dtor != NULL)
 248                 *dtor = key_defs->keys_dtors[key - key_defs->keys_start_idx];
 249             return;
 250         }
 251
 252         HEIMDAL_MUTEX_lock(&tls_key_defs_lock);
 253         key_defs = key_defs->keys_next;
 254         HEIMDAL_MUTEX_unlock(&tls_key_defs_lock);
 255         assert(key_defs != NULL);
 256         assert(key >= key_defs->keys_start_idx);
 257     }
 258 }
 259
 260 int
 261 heim_w32_delete_key(HEIM_PRIV_thread_key key)
 262 {
 263     tls_keys *key_defs;
 264     size_t dtor_idx;
 265
 266     key_lookup(key, &key_defs, &dtor_idx, NULL);
 267     if (key_defs == NULL)
 268         return EINVAL;
 269     key_defs->keys_dtors[dtor_idx] = DEAD_KEY;
 270     return 0;
 271 }
 272
 273 int
 274 heim_w32_setspecific(HEIM_PRIV_thread_key key, void *value)
 275 {
 276     void **new_values;
 277     size_t new_num;
 278     void (*dtor)(void *);
 279     size_t i;
 280
 281 #if !defined(WIN32)
 282     (void) pthread_setspecific(pt_key, DEAD_KEY);
 283 #endif
 284
 285     key_lookup(key, NULL, NULL, &dtor);
 286     if (dtor == NULL)
 287         return EINVAL;
 288
 289     if (key >= values.values_num) {
 290         if (values.values_num == 0) {
 291             values.values = NULL;
 292             new_num = 8;
 293         } else {
 294             new_num = (values.values_num + values.values_num / 2);
 295         }
 296         new_values = realloc(values.values, sizeof(void *) * new_num);
 297         if (new_values == NULL)
 298             return ENOMEM;
 299         for (i = values.values_num; i < new_num; i++)
 300             new_values[i] = NULL;
 301         values.values = new_values;
 302         values.values_num = new_num;
 303     }
 304
 305     assert(key < values.values_num);
 306
 307     if (values.values[key] != NULL && dtor != NULL && dtor != DEAD_KEY)
 308         dtor(values.values[key]);
 309
 310     values.values[key] = value;
 311     return 0;
 312 }
 313
 314 void *
 315 heim_w32_getspecific(HEIM_PRIV_thread_key key)
 316 {
 317     if (key >= values.values_num)
 318         return NULL;
 319     return values.values[key];
 320 }
 321
 322 #else
 323 static char dummy;
 324 #endif /* HEIM_WIN32_TLS */