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!\n", name);
98 #define LOG(level, ...) logbug(level, __func__, __VA_ARGS__)
99 #define CALL(func, ...) \
100 ({ typeof (func) *sym = getsym ( # func); sym (__VA_ARGS__); })
105 * "Conforming multi-threaded applications shall not use the environ variable
106 * to access or modify any environment variable while any other thread is
107 * concurrently modifying any environment variable." -- POSIX.
109 * Some evil libraries modify the environment. We currently ignore the calls as
110 * they could crash the process. This may cause funny behaviour though. */
111 int putenv (char *str)
115 LOG("Blocked", "\"%s\"", str);
118 return CALL(putenv, str);
121 int setenv (const char *name, const char *value, int overwrite)
125 LOG("Blocked", "\"%s\", \"%s\", %d", name, value, overwrite);
128 return CALL(setenv, name, value, overwrite);
131 int unsetenv (const char *name)
135 LOG("Blocked", "\"%s\"", name);
138 return CALL(unsetenv, name);
142 /*** Pseudo random numbers ***
144 * The C PRNG is not thread-safe (and generally sucks, the POSIX 48-bits PRNG
145 * is much better as a reproducible non-secure PRNG). To work around this, we
146 * force evil callers to serialize. This makes the call safe, but fails to
147 * preserve reproducibility of the number sequence (which usually does not
150 static pthread_mutex_t prng_lock = PTHREAD_MUTEX_INITIALIZER;
152 void srand (unsigned int seed)
154 pthread_mutex_lock (&prng_lock);
155 LOG("Warning", "%d", seed);
157 pthread_mutex_unlock (&prng_lock);
164 pthread_mutex_lock (&prng_lock);
167 pthread_mutex_unlock (&prng_lock);
175 void (*signal (int signum, void (*handler) (int))) (int)
179 const char *msg = "Error";
181 if ((signum == SIGPIPE && handler == SIG_IGN)
182 || (signum != SIGPIPE && handler == SIG_DFL))
183 /* Same settings we already use */
185 LOG(msg, "%d, %p", signum, handler);
187 return CALL(signal, signum, handler);
190 int sigaction (int signum, const struct sigaction *act, struct sigaction *old)
193 LOG("Error", "%d, %p, %p", signum, act, old);
194 return CALL(sigaction, signum, act, old);
199 #ifdef HAVE_X11_XLIB_H
200 # include <X11/Xlib.h>
202 static pthread_mutex_t xlib_lock = PTHREAD_MUTEX_INITIALIZER;
204 int (*XSetErrorHandler (int (*handler) (Display *, XErrorEvent *)))
205 (Display *, XErrorEvent *)
209 int (*ret) (Display *, XErrorEvent *);
211 pthread_mutex_lock (&xlib_lock);
212 LOG("Error", "%p", handler);
213 ret = CALL(XSetErrorHandler, handler);
214 pthread_mutex_unlock (&xlib_lock);
217 return CALL(XSetErrorHandler, handler);
220 int (*XSetIOErrorHandler (int (*handler) (Display *))) (Display *)
224 int (*ret) (Display *);
226 pthread_mutex_lock (&xlib_lock);
227 LOG("Error", "%p", handler);
228 ret = CALL(XSetIOErrorHandler, handler);
229 pthread_mutex_unlock (&xlib_lock);
232 return CALL(XSetIOErrorHandler, handler);
236 void vlc_enable_override (void)