1 /*****************************************************************************
2 * override.c: overriden function calls for VLC media player
3 *****************************************************************************
4 * Copyright (C) 2010 RĂ©mi Denis-Courmont
6 * This program is free software; you can redistribute it and/or modify
7 * it under the terms of the GNU Lesser General Public License as published by
8 * the Free Software Foundation; either version 2.1 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 Lesser General Public License for more details.
16 * You should have received a copy of the GNU Lesser General Public License
17 * along with this program; if not, write to the Free Software
18 * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston MA 02110-1301, USA.
19 *****************************************************************************/
27 void vlc_enable_override (void);
29 #if defined (__GNUC__) /* typeof and statement-expression */ \
30 && (defined (__ELF__) && !defined (__sun__))
31 /* Solaris crashes on printf("%s", NULL); which is legal, but annoying. */
38 #ifdef HAVE_EXECINFO_H
39 # include <execinfo.h>
42 # undef HAVE_BACKTRACE
45 static bool override = false;
47 static void vlc_reset_override (void)
52 void vlc_enable_override (void)
55 pthread_atfork (NULL, NULL, vlc_reset_override);
58 static void vlogbug (const char *level, const char *func, const char *fmt,
62 const size_t framec = 4;
65 backtrace (framev, framec);
68 fprintf (stderr, "%s: call to %s(", level, func);
69 vfprintf (stderr, fmt, ap);
70 fputs (")\n", stderr);
73 backtrace_symbols_fd (framev + 2, framec - 2, fileno (stderr));
78 static void logbug (const char *level, const char *func, const char *fmt, ...)
83 vlogbug (level, func, fmt, ap);
87 static void *getsym (const char *name)
89 void *sym = dlsym (RTLD_NEXT, name);
92 fprintf (stderr, "Cannot resolve symbol %s: %s\n", name,
99 #define LOG(level, ...) logbug(level, __func__, __VA_ARGS__)
100 #define CALL(func, ...) \
101 ({ typeof (func) *sym = getsym ( # func); sym (__VA_ARGS__); })
106 * "Conforming multi-threaded applications shall not use the environ variable
107 * to access or modify any environment variable while any other thread is
108 * concurrently modifying any environment variable." -- POSIX.
110 * Some evil libraries modify the environment. We currently ignore the calls as
111 * they could crash the process. This may cause funny behaviour though. */
112 int putenv (char *str)
116 LOG("Blocked", "\"%s\"", str);
119 return CALL(putenv, str);
122 int setenv (const char *name, const char *value, int overwrite)
126 LOG("Blocked", "\"%s\", \"%s\", %d", name, value, overwrite);
129 return CALL(setenv, name, value, overwrite);
132 int unsetenv (const char *name)
136 LOG("Blocked", "\"%s\"", name);
139 return CALL(unsetenv, name);
143 /*** Pseudo random numbers ***
145 * The C PRNG is not thread-safe (and generally sucks, the POSIX 48-bits PRNG
146 * is much better as a reproducible non-secure PRNG). To work around this, we
147 * force evil callers to serialize. This makes the call safe, but fails to
148 * preserve reproducibility of the number sequence (which usually does not
151 static pthread_mutex_t prng_lock = PTHREAD_MUTEX_INITIALIZER;
153 void srand (unsigned int seed)
155 pthread_mutex_lock (&prng_lock);
156 LOG("Warning", "%d", seed);
158 pthread_mutex_unlock (&prng_lock);
165 pthread_mutex_lock (&prng_lock);
168 pthread_mutex_unlock (&prng_lock);
176 void (*signal (int signum, void (*handler) (int))) (int)
180 const char *msg = "Error";
182 if ((signum == SIGPIPE && handler == SIG_IGN)
183 || (signum != SIGPIPE && handler == SIG_DFL))
184 /* Same settings we already use */
186 LOG(msg, "%d, %p", signum, handler);
188 return CALL(signal, signum, handler);
191 int sigaction (int signum, const struct sigaction *act, struct sigaction *old)
194 LOG("Error", "%d, %p, %p", signum, act, old);
195 return CALL(sigaction, signum, act, old);
200 * setlocale() is not thread-safe and has a tendency to crash other threads as
201 * quite many libc and libintl calls depend on the locale.
202 * Use uselocale() instead for thread-safety.
206 char *setlocale (int cat, const char *locale)
208 if (override && locale != NULL)
210 LOG("Blocked", "%d, \"%s\"", cat, locale);
213 return CALL(setlocale, cat, locale);
218 #ifdef HAVE_X11_XLIB_H
219 # include <X11/Xlib.h>
221 static pthread_mutex_t xlib_lock = PTHREAD_MUTEX_INITIALIZER;
223 int (*XSetErrorHandler (int (*handler) (Display *, XErrorEvent *)))
224 (Display *, XErrorEvent *)
228 int (*ret) (Display *, XErrorEvent *);
230 pthread_mutex_lock (&xlib_lock);
231 LOG("Error", "%p", handler);
232 ret = CALL(XSetErrorHandler, handler);
233 pthread_mutex_unlock (&xlib_lock);
236 return CALL(XSetErrorHandler, handler);
239 int (*XSetIOErrorHandler (int (*handler) (Display *))) (Display *)
243 int (*ret) (Display *);
245 pthread_mutex_lock (&xlib_lock);
246 LOG("Error", "%p", handler);
247 ret = CALL(XSetIOErrorHandler, handler);
248 pthread_mutex_unlock (&xlib_lock);
251 return CALL(XSetIOErrorHandler, handler);
255 void vlc_enable_override (void)