2 * Macros to hook functions.
4 * Copyright (C) 2013 Simon Ruderich
6 * This program is free software: you can redistribute it and/or modify
7 * it under the terms of the GNU General Public License as published by
8 * the Free Software Foundation, either version 3 of the License, or
9 * (at your option) any later version.
11 * This program is distributed in the hope that it will be useful,
12 * but WITHOUT ANY WARRANTY; without even the implied warranty of
13 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14 * GNU General Public License for more details.
16 * You should have received a copy of the GNU General Public License
17 * along with this program. If not, see <http://www.gnu.org/licenses/>.
23 /* Hook the function by creating a function with the same name. With
24 * LD_PRELOAD our function will be preferred. The original function is stored
25 * in a static variable (real_*). Any function called in these macros must
26 * make sure to restore the errno if it changes it.
28 * "Pseudo code" for the following macros. <name> is the name of the hooked
29 * function, <fd> is either a file descriptor or a FILE pointer.
32 * real_<name> = dlsym_function(<name>);
34 * init_from_environment();
37 * if (tracked_fds_find(<fd>)) {
38 * if (force_write_to_non_tty) {
41 * handle = isatty_noinline(<fd>);
48 * handle_<fd>_pre(<fd>);
50 * <type> result = real_<name>(<args>);
52 * handle_<fd>_post(<fd>);
57 #define _HOOK_PRE(type, name, fd) \
59 if (unlikely(!(real_ ## name ))) { \
60 *(void **) (&(real_ ## name)) = dlsym_function(#name); \
61 /* Initialize our data while we're at it. */ \
62 if (unlikely(!initialized)) { \
63 init_from_environment(); \
66 /* Check if this fd should be handled. */ \
67 if (unlikely(tracked_fds_find(fd))) { \
68 if (unlikely(force_write_to_non_tty)) { \
71 handle = isatty_noinline(fd); \
76 #define _HOOK_PRE_FD(type, name, fd) \
78 _HOOK_PRE_FD_(type, name, fd)
79 #define _HOOK_PRE_FD_(type, name, fd) \
80 _HOOK_PRE(type, name, fd) \
81 if (unlikely(handle)) { \
84 #define _HOOK_PRE_FILE(type, name, file) \
86 _HOOK_PRE(type, name, fileno(file)) \
87 if (unlikely(handle)) { \
88 handle_file_pre(file); \
90 #define _HOOK_POST_FD_(fd) \
91 if (unlikely(handle)) { \
94 #define _HOOK_POST_FD(fd) \
97 #define _HOOK_POST_FILE(file) \
98 if (unlikely(handle)) { \
99 handle_file_post(file); \
104 #define HOOK_FUNC_DEF1(type, name, type1, arg1) \
105 static type (*real_ ## name)(type1); \
106 type name(type1 arg1)
107 #define HOOK_FUNC_DEF2(type, name, type1, arg1, type2, arg2) \
108 static type (*real_ ## name)(type1, type2); \
109 type name(type1 arg1, type2 arg2)
110 #define HOOK_FUNC_DEF3(type, name, type1, arg1, type2, arg2, type3, arg3) \
111 static type (*real_ ## name)(type1, type2, type3); \
112 type name(type1 arg1, type2 arg2, type3 arg3)
114 #define HOOK_FUNC_VAR_DEF2(type, name, type1, arg1, type2, arg2) \
115 static type (*real_ ## name)(type1, type2, ...); \
116 type name(type1 arg1, type2 arg2, ...)
118 #define HOOK_VOID1(type, name, fd, type1, arg1) \
119 static type (*real_ ## name)(type1); \
120 type name(type1 arg1) { \
121 _HOOK_PRE_FD_(type, name, fd) \
122 real_ ## name(arg1); \
126 #define HOOK_FD2(type, name, fd, type1, arg1, type2, arg2) \
127 static type (*real_ ## name)(type1, type2); \
128 type name(type1 arg1, type2 arg2) { \
129 _HOOK_PRE_FD(type, name, fd) \
130 result = real_ ## name(arg1, arg2); \
133 #define HOOK_FD3(type, name, fd, type1, arg1, type2, arg2, type3, arg3) \
134 static type (*real_ ## name)(type1, type2, type3); \
135 type name(type1 arg1, type2 arg2, type3 arg3) { \
136 _HOOK_PRE_FD(type, name, fd) \
137 result = real_ ## name(arg1, arg2, arg3); \
141 #define HOOK_FILE1(type, name, file, type1, arg1) \
142 static type (*real_ ## name)(type1); \
143 type name(type1 arg1) { \
144 _HOOK_PRE_FILE(type, name, file) \
145 result = real_ ## name(arg1); \
146 _HOOK_POST_FILE(file) \
148 #define HOOK_FILE2(type, name, file, type1, arg1, type2, arg2) \
149 static type (*real_ ## name)(type1, type2); \
150 type name(type1 arg1, type2 arg2) { \
151 _HOOK_PRE_FILE(type, name, file) \
152 result = real_ ## name(arg1, arg2); \
153 _HOOK_POST_FILE(file) \
155 #define HOOK_FILE3(type, name, file, type1, arg1, type2, arg2, type3, arg3) \
156 static type (*real_ ## name)(type1, type2, type3); \
157 type name(type1 arg1, type2 arg2, type3 arg3) { \
158 _HOOK_PRE_FILE(type, name, file) \
159 result = real_ ## name(arg1, arg2, arg3); \
160 _HOOK_POST_FILE(file) \
162 #define HOOK_FILE4(type, name, file, type1, arg1, type2, arg2, type3, arg3, type4, arg4) \
163 static type (*real_ ## name)(type1, type2, type3, type4); \
164 type name(type1 arg1, type2 arg2, type3 arg3, type4 arg4) { \
165 _HOOK_PRE_FILE(type, name, file) \
166 result = real_ ## name(arg1, arg2, arg3, arg4); \
167 _HOOK_POST_FILE(file) \
170 #define HOOK_VAR_FILE1(type, name, file, func, type1, arg1) \
171 type name(type1 arg1, ...) { \
173 va_start(ap, arg1); \
174 type result = func(arg1, ap); \
178 #define HOOK_VAR_FILE2(type, name, file, func, type1, arg1, type2, arg2) \
179 type name(type1 arg1, type2 arg2, ...) { \
181 va_start(ap, arg2); \
182 type result = func(arg1, arg2, ap); \
186 #define HOOK_VAR_FILE3(type, name, file, func, type1, arg1, type2, arg2, type3, arg3) \
187 type name(type1 arg1, type2 arg2, type3 arg3, ...) { \
189 va_start(ap, arg3); \
190 type result = func(arg1, arg2, arg3, ap); \