Lua debugger: infinite loop detection.ldb

1 files changed, 35 insertions, 7 deletions

diff --git a/src/scripting.c b/src/scripting.c
index 63b78f4ca..060073e6c 100644
--- a/src/scripting.c
+++ b/src/scripting.c
@@ -1305,7 +1305,7 @@ void evalGenericCommand(client *c, int evalsha) {
         lua_sethook(lua,luaMaskCountHook,LUA_MASKCOUNT,100000);
         delhook = 1;
     } else if (ldb.active) {
-        lua_sethook(server.lua,luaLdbLineHook,LUA_MASKLINE,0);
+        lua_sethook(server.lua,luaLdbLineHook,LUA_MASKLINE|LUA_MASKCOUNT,100000);
         delhook = 1;
     }
 
@@ -2201,8 +2201,10 @@ void ldbMaxlen(sds *argv, int argc) {
     }
 }
 
-/* Read debugging commands from client. */
-void ldbRepl(lua_State *lua) {
+/* Read debugging commands from client.
+ * Return C_OK if the debugging session is continuing, otherwise
+ * C_ERR if the client closed the connection or is timing out. */
+int ldbRepl(lua_State *lua) {
     sds *argv;
     int argc;
 
@@ -2217,7 +2219,7 @@ void ldbRepl(lua_State *lua) {
                  * client is no longer connected. */
                 ldb.step = 0;
                 ldb.bpcount = 0;
-                return;
+                return C_ERR;
             }
             ldb.cbuf = sdscatlen(ldb.cbuf,buf,nread);
         }
@@ -2314,6 +2316,7 @@ ldbLog(sdsnew("                     in the next line of code."));
 
     /* Free the current command argv if we break inside the while loop. */
     sdsfreesplitres(argv,argc);
+    return C_OK;
 }
 
 /* This is the core of our Lua debugger, called each time Lua is about
@@ -2321,14 +2324,32 @@ ldbLog(sdsnew("                     in the next line of code."));
 void luaLdbLineHook(lua_State *lua, lua_Debug *ar) {
     lua_getstack(lua,0,ar);
     lua_getinfo(lua,"Sl",ar);
-    if(strstr(ar->short_src,"user_script") == NULL) return;
-
     ldb.currentline = ar->currentline;
+
     int bp = ldbIsBreakpoint(ldb.currentline) || ldb.luabp;
+    int timeout = 0;
+
+    /* Events outside our script are not interesting. */
+    if(strstr(ar->short_src,"user_script") == NULL) return;
+
+    /* Check if a timeout occurred. */
+    if (ar->event == LUA_HOOKCOUNT && ldb.step == 0 && bp == 0) {
+        mstime_t elapsed = mstime() - server.lua_time_start;
+        mstime_t timelimit = server.lua_time_limit ?
+                             server.lua_time_limit : 5000;
+        if (elapsed >= timelimit) {
+            timeout = 1;
+            ldb.step = 1;
+        } else {
+            return; /* No timeout, ignore the COUNT event. */
+        }
+    }
+
     if (ldb.step || bp) {
         char *reason = "step over";
         if (bp) reason = ldb.luabp ? "redis.breakpoint() called" :
                                      "break point";
+        else if (timeout) reason = "timeout reached, infinite loop?";
         ldb.step = 0;
         ldb.luabp = 0;
         ldbLog(sdscatprintf(sdsempty(),
@@ -2336,7 +2357,14 @@ void luaLdbLineHook(lua_State *lua, lua_Debug *ar) {
             ldb.currentline, reason));
         ldbLogSourceLine(ldb.currentline);
         ldbSendLogs();
-        ldbRepl(lua);
+        if (ldbRepl(lua) == C_ERR && timeout) {
+            /* If the client closed the connection and we have a timeout
+             * connection, let's kill the script otherwise the process
+             * will remain blocked indefinitely. */
+            lua_pushstring(lua, "timeout during Lua debugging with client closing connection");
+            lua_error(lua);
+        }
+        server.lua_time_start = mstime();
     }
 }