src/mapi/stub.c

/*
 * Mesa 3-D graphics library
 *
 * Copyright (C) 2010 LunarG Inc.
 *
 * Permission is hereby granted, free of charge, to any person obtaining a
 * copy of this software and associated documentation files (the "Software"),
 * to deal in the Software without restriction, including without limitation
 * the rights to use, copy, modify, merge, publish, distribute, sublicense,
 * and/or sell copies of the Software, and to permit persons to whom the
 * Software is furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included
 * in all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
 * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
 * DEALINGS IN THE SOFTWARE.
 *
 * Authors:
 *    Chia-I Wu <olv@lunarg.com>
 */

#include <stdlib.h>
#include <string.h>
#include <assert.h>
#include "c11/threads.h"

#include "util/macros.h"
#include "u_current.h"
#include "entry.h"
#include "stub.h"
#include "table.h"


struct mapi_stub {
   const void *name;
   int slot;
   mapi_func addr;
};

/* define public_string_pool and public_stubs */
#define MAPI_TMP_PUBLIC_STUBS
#include "mapi_tmp.h"

static struct mapi_stub dynamic_stubs[MAPI_TABLE_NUM_DYNAMIC];
static int num_dynamic_stubs;
static int next_dynamic_slot = MAPI_TABLE_NUM_STATIC;

void
stub_init_once(void)
{
   static once_flag flag = ONCE_FLAG_INIT;
   call_once(&flag, entry_patch_public);
}

static int
stub_compare(const void *key, const void *elem)
{
   const char *name = (const char *) key;
   const struct mapi_stub *stub = (const struct mapi_stub *) elem;
   const char *stub_name;

   stub_name = &public_string_pool[(size_t) stub->name];

   return strcmp(name, stub_name);
}

/**
 * Return the public stub with the given name.
 */
const struct mapi_stub *
stub_find_public(const char *name)
{
   return (const struct mapi_stub *) bsearch(name, public_stubs,
         ARRAY_SIZE(public_stubs), sizeof(public_stubs[0]), stub_compare);
}

/**
 * Add a dynamic stub.
 */
static struct mapi_stub *
stub_add_dynamic(const char *name)
{
   struct mapi_stub *stub;
   int idx;

   idx = num_dynamic_stubs;
   /* minus 1 to make sure we can never reach the last slot */
   if (idx >= MAPI_TABLE_NUM_DYNAMIC - 1)
      return NULL;

   stub = &dynamic_stubs[idx];

   /* dispatch to the last slot, which is reserved for no-op */
   stub->addr = entry_generate(
         MAPI_TABLE_NUM_STATIC + MAPI_TABLE_NUM_DYNAMIC - 1);
   if (!stub->addr)
      return NULL;

   stub->name = (const void *) strdup(name);
   /* to be fixed later */
   stub->slot = -1;

   num_dynamic_stubs = idx + 1;

   return stub;
}

/**
 * Return the dynamic stub with the given name.  If no such stub exists and
 * generate is true, a new stub is generated.
 */
struct mapi_stub *
stub_find_dynamic(const char *name, int generate)
{
   static mtx_t dynamic_mutex = _MTX_INITIALIZER_NP;
   struct mapi_stub *stub = NULL;
   int count, i;

   mtx_lock(&dynamic_mutex);

   if (generate)
      assert(!stub_find_public(name));

   count = num_dynamic_stubs;
   for (i = 0; i < count; i++) {
      if (strcmp(name, (const char *) dynamic_stubs[i].name) == 0) {
         stub = &dynamic_stubs[i];
         break;
      }
   }

   /* generate a dynamic stub */
   if (generate && !stub)
         stub = stub_add_dynamic(name);

   mtx_unlock(&dynamic_mutex);

   return stub;
}

static const struct mapi_stub *
search_table_by_slot(const struct mapi_stub *table, size_t num_entries,
                     int slot)
{
   size_t i;
   for (i = 0; i < num_entries; ++i) {
      if (table[i].slot == slot)
         return &table[i];
   }
   return NULL;
}

const struct mapi_stub *
stub_find_by_slot(int slot)
{
   const struct mapi_stub *stub =
      search_table_by_slot(public_stubs, ARRAY_SIZE(public_stubs), slot);
   if (stub)
      return stub;
   return search_table_by_slot(dynamic_stubs, num_dynamic_stubs, slot);
}

void
stub_fix_dynamic(struct mapi_stub *stub, const struct mapi_stub *alias)
{
   int slot;

   if (stub->slot >= 0)
      return;

   if (alias)
      slot = alias->slot;
   else
      slot = next_dynamic_slot++;

   entry_patch(stub->addr, slot);
   stub->slot = slot;
}

/**
 * Return the name of a stub.
 */
const char *
stub_get_name(const struct mapi_stub *stub)
{
   const char *name;

   if (stub >= public_stubs &&
       stub < public_stubs + ARRAY_SIZE(public_stubs))
      name = &public_string_pool[(size_t) stub->name];
   else
      name = (const char *) stub->name;

   return name;
}

/**
 * Return the slot of a stub.
 */
int
stub_get_slot(const struct mapi_stub *stub)
{
   return stub->slot;
}

/**
 * Return the address of a stub.
 */
mapi_func
stub_get_addr(const struct mapi_stub *stub)
{
   assert(stub->addr || (unsigned int) stub->slot < MAPI_TABLE_NUM_STATIC);
   return (stub->addr) ? stub->addr : entry_get_public(stub->slot);
}