commit 131e3fd814a6e818b412407a222186aab08f3525
author Roberto Ierusalimschy <roberto@inf.puc-rio.br> Tue Nov 24 14:41:50 2020 -0300
committer Roberto Ierusalimschy <roberto@inf.puc-rio.br> Tue Nov 24 14:41:50 2020 -0300
tree 88224c7adda723ae6a558bb4e3e391f50f8292cf
parent 9d067ab73b6befa0a5418f1df35c711f6c6918b3

Avoid using 'signal' when 'sigaction' is available

The semantics of 'signal' varies a lot among different implementations;
'sigaction' ensures a more consistent behavior.

lua.c

diff --git a/lua.c b/lua.c
index b5b884b..46b48db 100644
--- a/lua.c
+++ b/lua.c
@@ -37,6 +37,26 @@
 static const char *progname = LUA_PROGNAME;
 
 
+#if defined(LUA_USE_POSIX)   /* { */
+
+/*
+** Use 'sigaction' when available.
+*/
+static void setsignal (int sig, void (*handler)(int)) {
+  struct sigaction sa;
+  sa.sa_handler = handler;
+  sa.sa_flags = 0;
+  sigemptyset(&sa.sa_mask);  /* do not mask any signal */
+  sigaction(sig, &sa, NULL);
+}
+
+#else           /* }{ */
+
+#define setsignal            signal
+
+#endif                               /* } */
+
+
 /*
 ** Hook set by signal function to stop the interpreter.
 */
@@ -55,7 +75,7 @@
 */
 static void laction (int i) {
   int flag = LUA_MASKCALL | LUA_MASKRET | LUA_MASKLINE | LUA_MASKCOUNT;
-  signal(i, SIG_DFL); /* if another SIGINT happens, terminate process */
+  setsignal(i, SIG_DFL); /* if another SIGINT happens, terminate process */
   lua_sethook(globalL, lstop, flag, 1);
 }
 
@@ -135,9 +155,9 @@
   lua_pushcfunction(L, msghandler);  /* push message handler */
   lua_insert(L, base);  /* put it under function and args */
   globalL = L;  /* to be available to 'laction' */
-  signal(SIGINT, laction);  /* set C-signal handler */
+  setsignal(SIGINT, laction);  /* set C-signal handler */
   status = lua_pcall(L, narg, nres, base);
-  signal(SIGINT, SIG_DFL); /* reset C-signal handler */
+  setsignal(SIGINT, SIG_DFL); /* reset C-signal handler */
   lua_remove(L, base);  /* remove message handler from the stack */
   return status;
 }