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_VOID1(type, name, fd, type1, arg1) \
105 static type (*real_ ## name)(type1); \
106 type name(type1 arg1) { \
107 _HOOK_PRE_FD_(type, name, fd) \
108 real_ ## name(arg1); \
112 #define HOOK_FD2(type, name, fd, type1, arg1, type2, arg2) \
113 static type (*real_ ## name)(type1, type2); \
114 type name(type1 arg1, type2 arg2) { \
115 _HOOK_PRE_FD(type, name, fd) \
116 result = real_ ## name(arg1, arg2); \
119 #define HOOK_FD3(type, name, fd, type1, arg1, type2, arg2, type3, arg3) \
120 static type (*real_ ## name)(type1, type2, type3); \
121 type name(type1 arg1, type2 arg2, type3 arg3) { \
122 _HOOK_PRE_FD(type, name, fd) \
123 result = real_ ## name(arg1, arg2, arg3); \
127 #define HOOK_FILE1(type, name, file, type1, arg1) \
128 static type (*real_ ## name)(type1); \
129 type name(type1 arg1) { \
130 _HOOK_PRE_FILE(type, name, file) \
131 result = real_ ## name(arg1); \
132 _HOOK_POST_FILE(file) \
134 #define HOOK_FILE2(type, name, file, type1, arg1, type2, arg2) \
135 static type (*real_ ## name)(type1, type2); \
136 type name(type1 arg1, type2 arg2) { \
137 _HOOK_PRE_FILE(type, name, file) \
138 result = real_ ## name(arg1, arg2); \
139 _HOOK_POST_FILE(file) \
141 #define HOOK_FILE3(type, name, file, type1, arg1, type2, arg2, type3, arg3) \
142 static type (*real_ ## name)(type1, type2, type3); \
143 type name(type1 arg1, type2 arg2, type3 arg3) { \
144 _HOOK_PRE_FILE(type, name, file) \
145 result = real_ ## name(arg1, arg2, arg3); \
146 _HOOK_POST_FILE(file) \
148 #define HOOK_FILE4(type, name, file, type1, arg1, type2, arg2, type3, arg3, type4, arg4) \
149 static type (*real_ ## name)(type1, type2, type3, type4); \
150 type name(type1 arg1, type2 arg2, type3 arg3, type4 arg4) { \
151 _HOOK_PRE_FILE(type, name, file) \
152 result = real_ ## name(arg1, arg2, arg3, arg4); \
153 _HOOK_POST_FILE(file) \
156 #define HOOK_VAR_FILE1(type, name, file, func, type1, arg1) \
157 static type (*real_ ## func)(type1, va_list); \
158 type name(type1 arg1, ...) { \
160 _HOOK_PRE_FILE(type, func, file) \
161 va_start(ap, arg1); \
162 result = real_ ## func(arg1, ap); \
164 _HOOK_POST_FILE(file) \
166 #define HOOK_VAR_FILE2(type, name, file, func, type1, arg1, type2, arg2) \
167 static type (*real_ ## func)(type1, type2, va_list); \
168 type name(type1 arg1, type2 arg2, ...) { \
170 _HOOK_PRE_FILE(type, func, file) \
171 va_start(ap, arg2); \
172 result = real_ ## func(arg1, arg2, ap); \
174 _HOOK_POST_FILE(file) \
176 #define HOOK_VAR_FILE3(type, name, file, func, type1, arg1, type2, arg2, type3, arg3) \
177 static type (*real_ ## func)(type1, type2, type3, va_list); \
178 type name(type1 arg1, type2 arg2, type3 arg3, ...) { \
180 _HOOK_PRE_FILE(type, func, file) \
181 va_start(ap, arg3); \
182 result = real_ ## func(arg1, arg2, arg3, ap); \
184 _HOOK_POST_FILE(file) \