Make accesslists thread safe. Signal handler is working in its own thread now, waiting for a signal. All other threads ignore signals.

opentracker.c

@@ -65,6 +65,32 @@ static void signal_handler( int s ) {
   }
 }
 
+static void defaul_signal_handlers( void ) {
+  sigset_t signal_mask;
+  sigemptyset(&signal_mask);
+  sigaddset (&signal_mask, SIGPIPE);
+  sigaddset (&signal_mask, SIGHUP);
+  sigaddset (&signal_mask, SIGINT);
+  sigaddset (&signal_mask, SIGALRM);
+  pthread_sigmask (SIG_BLOCK, &signal_mask, NULL);  
+}
+
+static void install_signal_handlers( void ) {
+  struct   sigaction sa;
+  sigset_t signal_mask;
+  sigemptyset(&signal_mask);
+
+  sa.sa_handler = signal_handler;
+  sigemptyset(&sa.sa_mask);
+  sa.sa_flags = SA_RESTART;
+  if ((sigaction(SIGINT, &sa, NULL) == -1) || (sigaction(SIGALRM, &sa, NULL) == -1) )
+    panic( "install_signal_handlers" );
+
+  sigaddset (&signal_mask, SIGINT);
+  sigaddset (&signal_mask, SIGALRM);
+  pthread_sigmask (SIG_UNBLOCK, &signal_mask, NULL);  
+}
+
 static void usage( char *name ) {
   fprintf( stderr, "Usage: %s [-i ip] [-p port] [-P port] [-r redirect] [-d dir] [-A ip] [-f config] [-s livesyncport]"
 #ifdef WANT_ACCESSLIST_BLACK
@@ -254,12 +280,14 @@ static int64_t ot_try_bind( ot_ip6 ip, uint16_t port, PROTO_FLAG proto ) {
 #endif
 
 #ifdef _DEBUG
+  {
   char *protos[] = {"TCP","UDP","UDP mcast"};
   char _debug[512];
   int off = snprintf( _debug, sizeof(_debug), "Binding socket type %s to address [", protos[proto] );
   off += fmt_ip6c( _debug+off, ip);
   snprintf( _debug + off, sizeof(_debug)-off, "]:%d...", port);
   fputs( _debug, stderr );
+  }
 #endif
 
   if( socket_bind6_reuse( sock, ip, port, 0 ) == -1 )
@@ -540,10 +568,6 @@ while( scanon ) {
   if( drop_privileges( g_serverdir ? g_serverdir : "." ) == -1 )
     panic( "drop_privileges failed, exiting. Last error");
 
-  signal( SIGPIPE, SIG_IGN );
-  signal( SIGINT,  signal_handler );
-  signal( SIGALRM, signal_handler );
-
   g_now_seconds = time( NULL );
 
   /* Create our self pipe which allows us to interrupt mainloops
@@ -555,8 +579,10 @@ while( scanon ) {
   io_setcookie( g_self_pipe[0], (void*)FLAG_SELFPIPE );
   io_wantread( g_self_pipe[0] );
 
+  defaul_signal_handlers( );
   /* Init all sub systems. This call may fail with an exit() */
   trackerlogic_init( );
+  install_signal_handlers( );
 
   /* Kick off our initial clock setting alarm */
   alarm(5);

ot_accesslist.c

@@ -4,6 +4,7 @@
    $id$ */
 
 /* System */
+#include <pthread.h>
 #include <stdlib.h>
 #include <string.h>
 #include <stdio.h>
@@ -26,25 +27,18 @@
        char    *g_accesslist_filename;
 static ot_hash *g_accesslist;
 static size_t   g_accesslist_size;
+static pthread_mutex_t g_accesslist_mutex;
 
 static int vector_compare_hash(const void *hash1, const void *hash2 ) {
   return memcmp( hash1, hash2, OT_HASH_COMPARE_SIZE );
 }
 
-void accesslist_deinit( void ) {
-  free( g_accesslist );
-  g_accesslist = 0;
-  g_accesslist_size = 0;
-}
-
 /* Read initial access list */
-static void accesslist_readfile( int sig ) {
-  ot_hash *info_hash, *accesslist_new = NULL, *accesslist_old;
+static void accesslist_readfile( void ) {
+  ot_hash *info_hash, *accesslist_new = NULL;
   char    *map, *map_end, *read_offs;
   size_t   maplen;
 
-  if( sig != SIGHUP ) return;
-
   if( ( map = mmap_read( g_accesslist_filename, &maplen ) ) == NULL ) {
     char *wd = getcwd( NULL, 0 );
     fprintf( stderr, "Warning: Can't open accesslist file: %s (but will try to create it later, if necessary and possible).\nPWD: %s\n", g_accesslist_filename, wd );
@@ -84,7 +78,7 @@ static void accesslist_readfile( int sig ) {
     while( read_offs < map_end && *(read_offs++) != '\n' );
   }
 #ifdef _DEBUG
-  fprintf( stderr, "Added %d info_hashes to accesslist\n", info_hash - accesslist_new );
+  fprintf( stderr, "Added %zd info_hashes to accesslist\n", (size_t)(info_hash - accesslist_new) );
 #endif
 
   mmap_unmap( map, maplen);
@@ -92,15 +86,20 @@ static void accesslist_readfile( int sig ) {
   qsort( accesslist_new, info_hash - accesslist_new, sizeof( *info_hash ), vector_compare_hash );
 
   /* Now exchange the accesslist vector in the least race condition prone way */
-  g_accesslist_size = 0;
-  accesslist_old    = g_accesslist;
+  pthread_mutex_lock(&g_accesslist_mutex);
+  free( g_accesslist );
   g_accesslist      = accesslist_new;
   g_accesslist_size = info_hash - accesslist_new;
-  free( accesslist_old );  
+  pthread_mutex_unlock(&g_accesslist_mutex);
 }
 
 int accesslist_hashisvalid( ot_hash hash ) {
-  void *exactmatch = bsearch( hash, g_accesslist, g_accesslist_size, OT_HASH_COMPARE_SIZE, vector_compare_hash );
+  void *exactmatch;
+
+  /* Lock should hardly ever be contended */
+  pthread_mutex_lock(&g_accesslist_mutex);
+  exactmatch = bsearch( hash, g_accesslist, g_accesslist_size, OT_HASH_COMPARE_SIZE, vector_compare_hash );
+  pthread_mutex_unlock(&g_accesslist_mutex);
 
 #ifdef WANT_ACCESSLIST_BLACK
   return exactmatch == NULL;
@@ -109,12 +108,38 @@ int accesslist_hashisvalid( ot_hash hash ) {
 #endif
 }
 
+static void * accesslist_worker( void * args ) {
+  int sig;
+  sigset_t   signal_mask;
+
+  sigemptyset(&signal_mask);
+  sigaddset(&signal_mask, SIGHUP);
+
+  (void)args;
+
+  while( 1 ) {
+    
+    /* Initial attempt to read accesslist */
+    accesslist_readfile( );
+
+    /* Wait for signals */
+    while( sigwait (&signal_mask, &sig) != 0 && sig != SIGHUP );
+  }
+  return NULL;
+}
+
+static pthread_t thread_id;
 void accesslist_init( ) {
-  /* Passing "0" since read_blacklist_file also is SIGHUP handler */
-  if( g_accesslist_filename ) {
-    accesslist_readfile( SIGHUP );
-    signal( SIGHUP, accesslist_readfile );
+  pthread_mutex_init(&g_accesslist_mutex, NULL);
+  pthread_create( &thread_id, NULL, accesslist_worker, NULL );
 }
+
+void accesslist_deinit( void ) {
+  pthread_cancel( thread_id );
+  pthread_mutex_destroy(&g_accesslist_mutex);
+  free( g_accesslist );
+  g_accesslist = 0;
+  g_accesslist_size = 0;
 }
 #endif