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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 #include "c11/threads.h"
32 
33 #include "util/macros.h"
34 #include "u_current.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
stub_init_once(void)55 stub_init_once(void)
56 {
57    static once_flag flag = ONCE_FLAG_INIT;
58    call_once(&flag, entry_patch_public);
59 }
60 
61 static int
stub_compare(const void * key,const void * elem)62 stub_compare(const void *key, const void *elem)
63 {
64    const char *name = (const char *) key;
65    const struct mapi_stub *stub = (const struct mapi_stub *) elem;
66    const char *stub_name;
67 
68    stub_name = &public_string_pool[(unsigned long) stub->name];
69 
70    return strcmp(name, stub_name);
71 }
72 
73 /**
74  * Return the public stub with the given name.
75  */
76 const struct mapi_stub *
stub_find_public(const char * name)77 stub_find_public(const char *name)
78 {
79    return (const struct mapi_stub *) bsearch(name, public_stubs,
80          ARRAY_SIZE(public_stubs), sizeof(public_stubs[0]), stub_compare);
81 }
82 
83 /**
84  * Add a dynamic stub.
85  */
86 static struct mapi_stub *
stub_add_dynamic(const char * name)87 stub_add_dynamic(const char *name)
88 {
89    struct mapi_stub *stub;
90    int idx;
91 
92    idx = num_dynamic_stubs;
93    /* minus 1 to make sure we can never reach the last slot */
94    if (idx >= MAPI_TABLE_NUM_DYNAMIC - 1)
95       return NULL;
96 
97    stub = &dynamic_stubs[idx];
98 
99    /* dispatch to the last slot, which is reserved for no-op */
100    stub->addr = entry_generate(
101          MAPI_TABLE_NUM_STATIC + MAPI_TABLE_NUM_DYNAMIC - 1);
102    if (!stub->addr)
103       return NULL;
104 
105    stub->name = (const void *) strdup(name);
106    /* to be fixed later */
107    stub->slot = -1;
108 
109    num_dynamic_stubs = idx + 1;
110 
111    return stub;
112 }
113 
114 /**
115  * Return the dynamic stub with the given name.  If no such stub exists and
116  * generate is true, a new stub is generated.
117  */
118 struct mapi_stub *
stub_find_dynamic(const char * name,int generate)119 stub_find_dynamic(const char *name, int generate)
120 {
121    static mtx_t dynamic_mutex = _MTX_INITIALIZER_NP;
122    struct mapi_stub *stub = NULL;
123    int count, i;
124 
125    mtx_lock(&dynamic_mutex);
126 
127    if (generate)
128       assert(!stub_find_public(name));
129 
130    count = num_dynamic_stubs;
131    for (i = 0; i < count; i++) {
132       if (strcmp(name, (const char *) dynamic_stubs[i].name) == 0) {
133          stub = &dynamic_stubs[i];
134          break;
135       }
136    }
137 
138    /* generate a dynamic stub */
139    if (generate && !stub)
140          stub = stub_add_dynamic(name);
141 
142    mtx_unlock(&dynamic_mutex);
143 
144    return stub;
145 }
146 
147 static const struct mapi_stub *
search_table_by_slot(const struct mapi_stub * table,size_t num_entries,int slot)148 search_table_by_slot(const struct mapi_stub *table, size_t num_entries,
149                      int slot)
150 {
151    size_t i;
152    for (i = 0; i < num_entries; ++i) {
153       if (table[i].slot == slot)
154          return &table[i];
155    }
156    return NULL;
157 }
158 
159 const struct mapi_stub *
stub_find_by_slot(int slot)160 stub_find_by_slot(int slot)
161 {
162    const struct mapi_stub *stub =
163       search_table_by_slot(public_stubs, ARRAY_SIZE(public_stubs), slot);
164    if (stub)
165       return stub;
166    return search_table_by_slot(dynamic_stubs, num_dynamic_stubs, slot);
167 }
168 
169 void
stub_fix_dynamic(struct mapi_stub * stub,const struct mapi_stub * alias)170 stub_fix_dynamic(struct mapi_stub *stub, const struct mapi_stub *alias)
171 {
172    int slot;
173 
174    if (stub->slot >= 0)
175       return;
176 
177    if (alias)
178       slot = alias->slot;
179    else
180       slot = next_dynamic_slot++;
181 
182    entry_patch(stub->addr, slot);
183    stub->slot = slot;
184 }
185 
186 /**
187  * Return the name of a stub.
188  */
189 const char *
stub_get_name(const struct mapi_stub * stub)190 stub_get_name(const struct mapi_stub *stub)
191 {
192    const char *name;
193 
194    if (stub >= public_stubs &&
195        stub < public_stubs + ARRAY_SIZE(public_stubs))
196       name = &public_string_pool[(unsigned long) stub->name];
197    else
198       name = (const char *) stub->name;
199 
200    return name;
201 }
202 
203 /**
204  * Return the slot of a stub.
205  */
206 int
stub_get_slot(const struct mapi_stub * stub)207 stub_get_slot(const struct mapi_stub *stub)
208 {
209    return stub->slot;
210 }
211 
212 /**
213  * Return the address of a stub.
214  */
215 mapi_func
stub_get_addr(const struct mapi_stub * stub)216 stub_get_addr(const struct mapi_stub *stub)
217 {
218    assert(stub->addr || (unsigned int) stub->slot < MAPI_TABLE_NUM_STATIC);
219    return (stub->addr) ? stub->addr : entry_get_public(stub->slot);
220 }
221