New siginfo member in uev_t for signal watchers

This patch adds support for exporting the signalfd_siginfo struct read
from the signal fd descriptor on signals.  This allows watcher callbacks
to, e.g., figure out who sent a signal.  See signalfd(2) for details on
struct signalfd_siginfo.

Signed-off-by: Joachim Wiberg <troglobit@gmail.com>

src/private.h

@@ -27,6 +27,7 @@
 
 #include <stdio.h>
 #include <sys/epoll.h>
+#include <sys/signalfd.h>
 
 /*
  * List functions.

src/uev.c

@@ -369,7 +369,9 @@ int uev_run(uev_ctx_t *ctx, int flags)
 						uev_signal_stop(w);
 						events = UEV_ERROR;
 					}
-				}
+					memset(&w->siginfo, 0, sizeof(w->siginfo));
+				} else
+					w->siginfo = fdsi;
 				break;
 
 			case UEV_TIMER_TYPE:

src/uev.h

@@ -61,6 +61,9 @@ typedef struct uev {
 	int             signo;
 	int             fd;
 	uev_ctx_t      *ctx;
+
+	/* Extra data for certain watcher types */
+	struct signalfd_siginfo siginfo;
 } uev_t;
 
 /*

tests/signal.c

@@ -67,14 +67,20 @@ static int callback(arg_t *arg, int event, void *foo)
 
 static void sigsegv_cb(uev_t *w, void *arg, int events)
 {
+	printf("Got SIGSEGV (%d) from PID %d\n", w->siginfo.ssi_signo,
+	       w->siginfo.ssi_pid);
 	warnx("PID %d caused segfault.", getpid());
 	exit(-1);
 }
 
 static void sigchld_cb(uev_t *w, void *arg, int events)
 {
-	pid_t pid = waitpid(-1, NULL, WNOHANG);
+	pid_t pid;
 
+	printf("Got SIGCHLD (%d) from PID %d\n",
+	       w->siginfo.ssi_signo, w->siginfo.ssi_pid);
+
+	pid = waitpid(-1, NULL, WNOHANG);
 	if (-1 != pid)
 		warnx("PID %d exited, bye.", pid);
 }