From 104c47d1068bc96dd4dfac8301fd2c3328d52413 Mon Sep 17 00:00:00 2001
From: Andrea Mazzoleni <amadvance@gmail.com>
Date: Mon, 26 Oct 2015 19:32:41 +0100
Subject: [PATCH] Add a proper signal handling

The most common signals are now intercepted with SA_RESTART
to allow a clean interruption.
---
 TODO               |  2 --
 cmdline/snapraid.c | 55 +++++++++++++++++++++++++++++++++-------------
 configure.ac       |  2 +-
 3 files changed, 41 insertions(+), 18 deletions(-)

diff --git a/TODO b/TODO
index 570c690b..3d9ea59b 100644
--- a/TODO
+++ b/TODO
@@ -43,8 +43,6 @@ The same for directories, when recreating the directory tree.
 * If a directory exists with the same name of a parity/content file be more explicative
 on the error message. See: https://sourceforge.net/projects/snapraid/forums/forum/1677233/topic/4861034
 
-* Support interrupted operations with EINTR. For remote filesystems it could be relevant.
-
 * Allow to specify more than one disk directories to cover the case of multi partitions.
 Different partitions have duplicate inode. The only way to support this is to
 add also a kind of device_id, increasing the memory required.
diff --git a/cmdline/snapraid.c b/cmdline/snapraid.c
index 5f88ec4a..d1ac4d7b 100644
--- a/cmdline/snapraid.c
+++ b/cmdline/snapraid.c
@@ -370,14 +370,33 @@ volatile int global_interrupt = 0;
 /* LCOV_EXCL_START */
 void signal_handler(int signum)
 {
-	switch (signum) {
-	case SIGINT :
-		global_interrupt = 1;
-		break;
-	}
+	(void)signum;
+
+	/* report the request of interruption */
+	global_interrupt = 1;
 }
 /* LCOV_EXCL_STOP */
 
+void signal_init(void)
+{
+#if HAVE_SIGACTION
+	struct sigaction sa;
+
+	sa.sa_handler = signal_handler;
+	sigemptyset(&sa.sa_mask);
+
+	/* use the SA_RESTART to automatically restart interrupted system calls */
+	sa.sa_flags = SA_RESTART;
+
+	sigaction(SIGHUP, &sa, 0);
+	sigaction(SIGTERM, &sa, 0);
+	sigaction(SIGINT, &sa, 0);
+	sigaction(SIGQUIT, &sa, 0);
+#else
+	signal(SIGINT, signal_handler);
+#endif
+}
+
 #define OPERATION_DIFF 0
 #define OPERATION_SYNC 1
 #define OPERATION_CHECK 2
@@ -1062,8 +1081,8 @@ int main(int argc, char* argv[])
 
 		memory();
 
-		/* intercept Ctrl+C */
-		signal(SIGINT, &signal_handler);
+		/* intercept signals while operating */
+		signal_init();
 
 		/* save the new state before the sync */
 		/* this allow to recover the case of the changes in the array after an aborted sync. */
@@ -1124,15 +1143,15 @@ int main(int argc, char* argv[])
 
 		memory();
 
-		/* intercept Ctrl+C */
-		signal(SIGINT, &signal_handler);
+		/* intercept signals while operating */
+		signal_init();
 
 		state_dry(&state, blockstart, blockcount);
 	} else if (operation == OPERATION_REHASH) {
 		state_read(&state);
 
-		/* intercept Ctrl+C */
-		signal(SIGINT, &signal_handler);
+		/* intercept signals while operating */
+		signal_init();
 
 		state_rehash(&state);
 
@@ -1144,8 +1163,8 @@ int main(int argc, char* argv[])
 
 		memory();
 
-		/* intercept Ctrl+C */
-		signal(SIGINT, &signal_handler);
+		/* intercept signals while operating */
+		signal_init();
 
 		ret = state_scrub(&state, percentage, olderthan);
 
@@ -1162,6 +1181,9 @@ int main(int argc, char* argv[])
 	} else if (operation == OPERATION_REWRITE) {
 		state_read(&state);
 
+		/* intercept signals while operating */
+		signal_init();
+
 		state_write(&state);
 
 		memory();
@@ -1174,6 +1196,9 @@ int main(int argc, char* argv[])
 
 		state_nano(&state);
 
+		/* intercept signals while operating */
+		signal_init();
+
 		state_write(&state);
 
 		memory();
@@ -1225,8 +1250,8 @@ int main(int argc, char* argv[])
 
 		memory();
 
-		/* intercept Ctrl+C */
-		signal(SIGINT, &signal_handler);
+		/* intercept signals while operating */
+		signal_init();
 
 		if (operation == OPERATION_CHECK) {
 			ret = state_check(&state, 0, blockstart, blockcount);
diff --git a/configure.ac b/configure.ac
index f83bb9be..698244f0 100644
--- a/configure.ac
+++ b/configure.ac
@@ -72,7 +72,7 @@ AC_CHECK_MEMBERS([struct statfs.f_type], [], [], [[
 
 dnl Checks for library functions.
 AC_CHECK_FUNCS([memset strchr strerror strrchr mkdir gettimeofday strtoul])
-AC_CHECK_FUNCS([getopt getopt_long snprintf vsnprintf])
+AC_CHECK_FUNCS([getopt getopt_long snprintf vsnprintf sigaction])
 AC_CHECK_FUNCS([ftruncate fallocate fsync access posix_fallocate posix_fadvise])
 AC_CHECK_FUNCS([pread pwrite getc_unlocked ferror_unlocked fnmatch])
 AC_CHECK_FUNCS([futimes futimens futimesat localtime_r])