X-Git-Url: https://git.sesse.net/?a=blobdiff_plain;f=bin%2Foverride.c;h=b5de22d0f558b4c941937048c63ea11c75ffc0a9;hb=053f9d6ea00435633c3dcbf87041d868223c9ec7;hp=113a63844597d4f61151616d6e9ab350bdf9972d;hpb=209c152e39ae22bf3842ff81f5b829c099d3aae7;p=vlc

diff --git a/bin/override.c b/bin/override.c
index 113a638445..b5de22d0f5 100644
--- a/bin/override.c
+++ b/bin/override.c
@@ -26,18 +26,22 @@
 
 void vlc_enable_override (void);
 
-#if defined (__GNUC__) /* typeof and statement-expression */ \
+#if defined (__GNUC__) \
  && (defined (__ELF__) && !defined (__sun__))
 /* Solaris crashes on printf("%s", NULL); which is legal, but annoying. */
 
 #include <stdarg.h>
 #include <stdio.h>
 #include <stdlib.h>
+#include <string.h>
 #include <dlfcn.h>
 #include <pthread.h>
 #ifdef HAVE_EXECINFO_H
 # include <execinfo.h>
 #endif
+#ifdef NDEBUG
+# undef HAVE_BACKTRACE
+#endif
 
 static bool override = false;
 
@@ -56,7 +60,7 @@ static void vlogbug (const char *level, const char *func, const char *fmt,
                      va_list ap)
 {
 #ifdef HAVE_BACKTRACE
-    const size_t framec = 8;
+    const size_t framec = 4;
     void *framev[framec];
 
     backtrace (framev, framec);
@@ -86,15 +90,31 @@ static void *getsym (const char *name)
     void *sym = dlsym (RTLD_NEXT, name);
     if (sym == NULL)
     {
-        fprintf (stderr, "Cannot resolve symbol %s!\n", name);
+        fprintf (stderr, "Cannot resolve symbol %s: %s\n", name,
+                 dlerror ());
         abort ();
     }
     return sym;
 }
 
 #define LOG(level, ...) logbug(level, __func__, __VA_ARGS__)
+/* Evil non-standard GNU C macro ;)
+ *  typeof keyword,
+ *  statement-expression,
+ *  nested function...
+ */
 #define CALL(func, ...) \
-    ({ typeof (func) *sym = getsym ( # func); sym (__VA_ARGS__); })
+({ \
+    static typeof (func) *sym = NULL; \
+    static pthread_once_t once = PTHREAD_ONCE_INIT; \
+    auto void getsym_once (void); \
+    void getsym_once (void) \
+    { \
+        sym = getsym ( # func); \
+    } \
+    pthread_once (&once, getsym_once); \
+    sym (__VA_ARGS__); \
+})
 
 
 /*** Environment ***
@@ -144,24 +164,28 @@ int unsetenv (const char *name)
  * preserve reproducibility of the number sequence (which usually does not
  * matter).
  **/
-static pthread_mutex_t prng_lock = PTHREAD_MUTEX_INITIALIZER;
+static struct
+{
+    pthread_mutex_t lock;
+    unsigned int seed;
+} prng = { PTHREAD_MUTEX_INITIALIZER, 0, };
 
 void srand (unsigned int seed)
 {
-    pthread_mutex_lock (&prng_lock);
+    pthread_mutex_lock (&prng.lock);
     LOG("Warning", "%d", seed);
-    CALL(srand, seed);
-    pthread_mutex_unlock (&prng_lock);
+    prng.seed = seed;
+    pthread_mutex_unlock (&prng.lock);
 }
 
 int rand (void)
 {
     int ret;
 
-    pthread_mutex_lock (&prng_lock);
+    pthread_mutex_lock (&prng.lock);
     LOG("Warning", "");
-    ret = CALL(rand);
-    pthread_mutex_unlock (&prng_lock);
+    ret = rand_r (&prng.seed);
+    pthread_mutex_unlock (&prng.lock);
     return ret;
 }
 
@@ -169,29 +193,88 @@ int rand (void)
 /** Signals **/
 #include <signal.h>
 
+static bool blocked_signal (int num)
+{
+    switch (num)
+    {
+        case SIGINT:
+        case SIGHUP:
+        case SIGQUIT:
+        case SIGTERM:
+        case SIGPIPE:
+        case SIGCHLD:
+            return true;
+    }
+    return false;
+}
+
 void (*signal (int signum, void (*handler) (int))) (int)
 {
     if (override)
     {
-        const char *msg = "Error";
-
-        if ((signum == SIGPIPE && handler == SIG_IGN)
-         || (signum != SIGPIPE && handler == SIG_DFL))
-            /* Same settings we already use */
-            msg = "Warning";
-        LOG(msg, "%d, %p", signum, handler);
+        if (handler != SIG_IGN && handler != SIG_DFL)
+            goto error;
+        if (!blocked_signal (signum))
+            goto error;
+        /* For our blocked signals, the handler won't matter much... */
+        if (handler == SIG_DFL)
+            LOG("Warning", "%d, SIG_DFL", signum, handler);
     }
     return CALL(signal, signum, handler);
+error:
+    LOG("Blocked", "%d, %p", signum, handler);
+    return SIG_DFL;
 }
 
 int sigaction (int signum, const struct sigaction *act, struct sigaction *old)
 {
-    if (act != NULL)
-        LOG("Error", "%d, %p, %p", signum, act, old);
+    if (override && act != NULL)
+    {
+        if ((act->sa_flags & SA_SIGINFO)
+         || (act->sa_handler != SIG_IGN && act->sa_handler != SIG_DFL))
+            goto error;
+        if (act->sa_handler == SIG_DFL)
+            LOG("Warning", "%d, %p, SIG_DFL", signum, act);
+    }
     return CALL(sigaction, signum, act, old);
+error:
+    LOG("Blocked", "%d, %p, %p", signum, act, old);
+    return -1;
+}
+
+
+/*** Locales ***
+ * setlocale() is not thread-safe and has a tendency to crash other threads as
+ * quite many libc and libintl calls depend on the locale.
+ * Use uselocale() instead for thread-safety.
+ */
+#include <locale.h>
+
+char *setlocale (int cat, const char *locale)
+{
+    if (override && locale != NULL)
+    {
+        LOG("Blocked", "%d, \"%s\"", cat, locale);
+        return NULL;
+    }
+    return CALL(setlocale, cat, locale);
 }
 
 
+/* strerror() is not thread-safe in theory (POSIX), nor in practice (glibc).
+ * This caused quite nasty crashes in the history of VLC/Linux. */
+char *strerror (int val)
+{
+    if (override)
+    {
+        static const char msg[] =
+            "Error message unavailable (use strerror_r instead of strerror)!";
+        LOG("Blocked", "%d", val);
+        return (char *)msg;
+    }
+    return CALL(strerror, val);
+}
+
 /*** Xlib ****/
 #ifdef HAVE_X11_XLIB_H
 # include <X11/Xlib.h>
@@ -230,7 +313,7 @@ int (*XSetIOErrorHandler (int (*handler) (Display *))) (Display *)
 }
 #endif
 #else
-static void vlc_enable_override (void)
+void vlc_enable_override (void)
 {
 }
 #endif