src/mapi/stub.c

   1 /*
   2  * Mesa 3-D graphics library
   3  *
   4  * Copyright (C) 2010 LunarG Inc.
   5  *
   6  * Permission is hereby granted, free of charge, to any person obtaining a
   7  * copy of this software and associated documentation files (the "Software"),
   8  * to deal in the Software without restriction, including without limitation
   9  * the rights to use, copy, modify, merge, publish, distribute, sublicense,
  10  * and/or sell copies of the Software, and to permit persons to whom the
  11  * Software is furnished to do so, subject to the following conditions:
  12  *
  13  * The above copyright notice and this permission notice shall be included
  14  * in all copies or substantial portions of the Software.
  15  *
  16  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  17  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  18  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
  19  * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  20  * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
  21  * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
  22  * DEALINGS IN THE SOFTWARE.
  23  *
  24  * Authors:
  25  *    Chia-I Wu <olv@lunarg.com>
  26  */
  27
  28 #include <stdlib.h>
  29 #include <string.h>
  30 #include <assert.h>
  31
  32 #include "util/macros.h"
  33 #include "u_current.h"
  34 #include "u_thread.h"
  35 #include "entry.h"
  36 #include "stub.h"
  37 #include "table.h"
  38
  39
  40 struct mapi_stub {
  41    const void *name;
  42    int slot;
  43    mapi_func addr;
  44 };
  45
  46 /* define public_string_pool and public_stubs */
  47 #define MAPI_TMP_PUBLIC_STUBS
  48 #include "mapi_tmp.h"
  49
  50 static struct mapi_stub dynamic_stubs[MAPI_TABLE_NUM_DYNAMIC];
  51 static int num_dynamic_stubs;
  52 static int next_dynamic_slot = MAPI_TABLE_NUM_STATIC;
  53
  54 void
  55 stub_init_once(void)
  56 {
  57 #ifdef HAVE_PTHREAD
  58    static pthread_once_t once = PTHREAD_ONCE_INIT;
  59    pthread_once(&once, entry_patch_public);
  60 #else
  61    static int first = 1;
  62    if (first) {
  63       first = 0;
  64       entry_patch_public();
  65    }
  66 #endif
  67 }
  68
  69 static int
  70 stub_compare(const void *key, const void *elem)
  71 {
  72    const char *name = (const char *) key;
  73    const struct mapi_stub *stub = (const struct mapi_stub *) elem;
  74    const char *stub_name;
  75
  76    stub_name = &public_string_pool[(unsigned long) stub->name];
  77
  78    return strcmp(name, stub_name);
  79 }
  80
  81 /**
  82  * Return the public stub with the given name.
  83  */
  84 const struct mapi_stub *
  85 stub_find_public(const char *name)
  86 {
  87    return (const struct mapi_stub *) bsearch(name, public_stubs,
  88          ARRAY_SIZE(public_stubs), sizeof(public_stubs[0]), stub_compare);
  89 }
  90
  91 /**
  92  * Add a dynamic stub.
  93  */
  94 static struct mapi_stub *
  95 stub_add_dynamic(const char *name)
  96 {
  97    struct mapi_stub *stub;
  98    int idx;
  99
 100    idx = num_dynamic_stubs;
 101    /* minus 1 to make sure we can never reach the last slot */
 102    if (idx >= MAPI_TABLE_NUM_DYNAMIC - 1)
 103       return NULL;
 104
 105    stub = &dynamic_stubs[idx];
 106
 107    /* dispatch to the last slot, which is reserved for no-op */
 108    stub->addr = entry_generate(
 109          MAPI_TABLE_NUM_STATIC + MAPI_TABLE_NUM_DYNAMIC - 1);
 110    if (!stub->addr)
 111       return NULL;
 112
 113    stub->name = (const void *) name;
 114    /* to be fixed later */
 115    stub->slot = -1;
 116
 117    num_dynamic_stubs = idx + 1;
 118
 119    return stub;
 120 }
 121
 122 /**
 123  * Return the dynamic stub with the given name.  If no such stub exists and
 124  * generate is true, a new stub is generated.
 125  */
 126 struct mapi_stub *
 127 stub_find_dynamic(const char *name, int generate)
 128 {
 129    static mtx_t dynamic_mutex = _MTX_INITIALIZER_NP;
 130    struct mapi_stub *stub = NULL;
 131    int count, i;
 132
 133    mtx_lock(&dynamic_mutex);
 134
 135    if (generate)
 136       assert(!stub_find_public(name));
 137
 138    count = num_dynamic_stubs;
 139    for (i = 0; i < count; i++) {
 140       if (strcmp(name, (const char *) dynamic_stubs[i].name) == 0) {
 141          stub = &dynamic_stubs[i];
 142          break;
 143       }
 144    }
 145
 146    /* generate a dynamic stub */
 147    if (generate && !stub)
 148          stub = stub_add_dynamic(name);
 149
 150    mtx_unlock(&dynamic_mutex);
 151
 152    return stub;
 153 }
 154
 155 static const struct mapi_stub *
 156 search_table_by_slot(const struct mapi_stub *table, size_t num_entries,
 157                      int slot)
 158 {
 159    size_t i;
 160    for (i = 0; i < num_entries; ++i) {
 161       if (table[i].slot == slot)
 162          return &table[i];
 163    }
 164    return NULL;
 165 }
 166
 167 const struct mapi_stub *
 168 stub_find_by_slot(int slot)
 169 {
 170    const struct mapi_stub *stub =
 171       search_table_by_slot(public_stubs, ARRAY_SIZE(public_stubs), slot);
 172    if (stub)
 173       return stub;
 174    return search_table_by_slot(dynamic_stubs, num_dynamic_stubs, slot);
 175 }
 176
 177 void
 178 stub_fix_dynamic(struct mapi_stub *stub, const struct mapi_stub *alias)
 179 {
 180    int slot;
 181
 182    if (stub->slot >= 0)
 183       return;
 184
 185    if (alias)
 186       slot = alias->slot;
 187    else
 188       slot = next_dynamic_slot++;
 189
 190    entry_patch(stub->addr, slot);
 191    stub->slot = slot;
 192 }
 193
 194 /**
 195  * Return the name of a stub.
 196  */
 197 const char *
 198 stub_get_name(const struct mapi_stub *stub)
 199 {
 200    const char *name;
 201
 202    if (stub >= public_stubs &&
 203        stub < public_stubs + ARRAY_SIZE(public_stubs))
 204       name = &public_string_pool[(unsigned long) stub->name];
 205    else
 206       name = (const char *) stub->name;
 207
 208    return name;
 209 }
 210
 211 /**
 212  * Return the slot of a stub.
 213  */
 214 int
 215 stub_get_slot(const struct mapi_stub *stub)
 216 {
 217    return stub->slot;
 218 }
 219
 220 /**
 221  * Return the address of a stub.
 222  */
 223 mapi_func
 224 stub_get_addr(const struct mapi_stub *stub)
 225 {
 226    assert(stub->addr || (unsigned int) stub->slot < MAPI_TABLE_NUM_STATIC);
 227    return (stub->addr) ? stub->addr : entry_get_public(stub->slot);
 228 }