1/*
2 * Copyright 2012, The Android Open Source Project
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 *     http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17#define CONCATENATE(arg1, arg2)   CONCATENATE1(arg1, arg2)
18#define CONCATENATE1(arg1, arg2)  CONCATENATE2(arg1, arg2)
19#define CONCATENATE2(arg1, arg2)  arg1##arg2
20
21#define INTERRUPTER(sym) \
22    if (real_##sym == NULL) \
23        __init_##sym(); \
24    if (maybe_interrupt()) { \
25        errno = EINTR; \
26        return -1; \
27    }
28
29#define CALL_FUNCTION_1(sym, ret, type1) \
30ret (*real_##sym)(type1) = NULL; \
31ret sym(type1 arg1) { \
32    INTERRUPTER(sym) \
33    return real_##sym(arg1); \
34}
35
36#define CALL_FUNCTION_2(sym, ret, type1, type2) \
37ret (*real_##sym)(type1, type2) = NULL; \
38ret sym(type1 arg1, type2 arg2) { \
39    INTERRUPTER(sym) \
40    return real_##sym(arg1, arg2); \
41}
42
43#define CALL_FUNCTION_3(sym, ret, type1, type2, type3) \
44ret (*real_##sym)(type1, type2, type3) = NULL; \
45ret sym(type1 arg1, type2 arg2, type3 arg3) { \
46    INTERRUPTER(sym) \
47    return real_##sym(arg1, arg2, arg3); \
48}
49
50#define CALL_FUNCTION_4(sym, ret, type1, type2, type3, type4) \
51ret (*real_##sym)(type1, type2, type3, type4) = NULL; \
52ret sym(type1 arg1, type2 arg2, type3 arg3, type4 arg4) { \
53    INTERRUPTER(sym) \
54    return real_##sym(arg1, arg2, arg3, arg4); \
55}
56
57#define CALL_FUNCTION_5(sym, ret, type1, type2, type3, type4, type5) \
58ret (*real_##sym)(type1, type2, type3, type4, type5) = NULL; \
59ret sym(type1 arg1, type2 arg2, type3 arg3, type4 arg4, type5 arg5) { \
60    INTERRUPTER(sym) \
61    return real_##sym(arg1, arg2, arg3, arg4, arg5); \
62}
63
64#define DEFINE_INTERCEPT_N(N, sym, ret, ...) \
65static void __init_##sym(void); \
66CONCATENATE(CALL_FUNCTION_, N)(sym, ret, __VA_ARGS__) \
67static void __init_##sym(void) { \
68    real_##sym = dlsym(RTLD_NEXT, #sym); \
69    if (real_##sym == NULL) { \
70        fprintf(stderr, "Error hooking " #sym ": %s\n", dlerror()); \
71    } \
72}
73
74#define INTERCEPT_NARG(...) INTERCEPT_NARG_N(__VA_ARGS__, INTERCEPT_RSEQ_N())
75#define INTERCEPT_NARG_N(...) INTERCEPT_ARG_N(__VA_ARGS__)
76#define INTERCEPT_ARG_N(_1, _2, _3, _4, _5, _6, _7, _8, N, ...) N
77#define INTERCEPT_RSEQ_N() 8, 7, 6, 5, 4, 3, 2, 1, 0
78
79#define DEFINE_INTERCEPT(sym, ret, ...) DEFINE_INTERCEPT_N(INTERCEPT_NARG(__VA_ARGS__), sym, ret, __VA_ARGS__)
80