Replace error prone signal() with sigaction()

Up to this date signal() was used which implementation could vary [1].
Sigaction() call is preferred. This commit introduces replacement
from signal() to sigaction() by the use of signal_s() wrapper.
Also remove redundant signal.h header includes.

[1] https://man7.org/linux/man-pages/man2/signal.2.html

Signed-off-by: Lukasz Florczak <lukasz.florczak@linux.intel.com>
Signed-off-by: Jes Sorensen <jsorensen@fb.com>

Grow.c

@@ -26,7 +26,6 @@
 #include	<sys/mman.h>
 #include	<stddef.h>
 #include	<stdint.h>
-#include	<signal.h>
 #include	<sys/wait.h>
 
 #if ! defined(__BIG_ENDIAN) && ! defined(__LITTLE_ENDIAN)
@@ -3566,7 +3565,8 @@ started:
 		fd = -1;
 	mlockall(MCL_FUTURE);
 
-	signal(SIGTERM, catch_term);
+	if (signal_s(SIGTERM, catch_term) == SIG_ERR)
+		goto release;
 
 	if (st->ss->external) {
 		/* metadata handler takes it from here */

Monitor.c

@@ -26,7 +26,6 @@
 #include	"md_p.h"
 #include	"md_u.h"
 #include	<sys/wait.h>
-#include	<signal.h>
 #include	<limits.h>
 #include	<syslog.h>
 #ifndef NO_LIBUDEV
@@ -435,8 +434,10 @@ static void alert(char *event, char *dev, char *disc, struct alert_info *info)
 		if (mp) {
 			FILE *mdstat;
 			char hname[256];
+
 			gethostname(hname, sizeof(hname));
-			signal(SIGPIPE, SIG_IGN);
+			signal_s(SIGPIPE, SIG_IGN);
+
 			if (info->mailfrom)
 				fprintf(mp, "From: %s\n", info->mailfrom);
 			else

managemon.c

@@ -106,7 +106,6 @@
 #include	"mdmon.h"
 #include	<sys/syscall.h>
 #include	<sys/socket.h>
-#include	<signal.h>
 
 static void close_aa(struct active_array *aa)
 {

mdadm.h

@@ -46,6 +46,7 @@ extern __off64_t lseek64 __P ((int __fd, __off64_t __offset, int __whence));
 #include	<string.h>
 #include	<syslog.h>
 #include	<stdbool.h>
+#include	<signal.h>
 /* Newer glibc requires sys/sysmacros.h directly for makedev() */
 #include	<sys/sysmacros.h>
 #ifdef __dietlibc__
@@ -1729,6 +1730,27 @@ static inline char *to_subarray(struct mdstat_ent *ent, char *container)
 	return &ent->metadata_version[10+strlen(container)+1];
 }
 
+/**
+ * signal_s() - Wrapper for sigaction() with signal()-like interface.
+ * @sig: The signal to set the signal handler to.
+ * @handler: The signal handler.
+ *
+ * Return: previous handler or SIG_ERR on failure.
+ */
+static inline sighandler_t signal_s(int sig, sighandler_t handler)
+{
+	struct sigaction new_act;
+	struct sigaction old_act;
+
+	new_act.sa_handler = handler;
+	new_act.sa_flags = 0;
+
+	if (sigaction(sig, &new_act, &old_act) == 0)
+		return old_act.sa_handler;
+
+	return SIG_ERR;
+}
+
 #ifdef DEBUG
 #define dprintf(fmt, arg...) \
 	fprintf(stderr, "%s: %s: "fmt, Name, __func__, ##arg)

mdmon.c

@@ -56,7 +56,6 @@
 #include	<errno.h>
 #include	<string.h>
 #include	<fcntl.h>
-#include	<signal.h>
 #include	<dirent.h>
 #ifdef USE_PTHREADS
 #include	<pthread.h>

monitor.c

@@ -22,7 +22,6 @@
 #include "mdmon.h"
 #include <sys/syscall.h>
 #include <sys/select.h>
-#include <signal.h>
 
 static char *array_states[] = {
 	"clear", "inactive", "suspended", "readonly", "read-auto",

probe_roms.c

@@ -22,7 +22,6 @@
 #include "probe_roms.h"
 #include "mdadm.h"
 #include <unistd.h>
-#include <signal.h>
 #include <fcntl.h>
 #include <sys/mman.h>
 #include <sys/stat.h>
@@ -69,7 +68,8 @@ static int probe_address16(const __u16 *ptr, __u16 *val)
 
 void probe_roms_exit(void)
 {
-	signal(SIGBUS, SIG_DFL);
+	signal_s(SIGBUS, SIG_DFL);
+
 	if (rom_fd >= 0) {
 		close(rom_fd);
 		rom_fd = -1;
@@ -98,7 +98,7 @@ int probe_roms_init(unsigned long align)
 	if (roms_init())
 		return -1;
 
-	if (signal(SIGBUS, sigbus) == SIG_ERR)
+	if (signal_s(SIGBUS, sigbus) == SIG_ERR)
 		rc = -1;
 	if (rc == 0) {
 		fd = open("/dev/mem", O_RDONLY);

raid6check.c

@@ -24,7 +24,6 @@
 
 #include "mdadm.h"
 #include <stdint.h>
-#include <signal.h>
 #include <sys/mman.h>
 
 #define CHECK_PAGE_BITS (12)
@@ -130,30 +129,36 @@ void raid6_stats(int *disk, int *results, int raid_disks, int chunk_size)
 }
 
 int lock_stripe(struct mdinfo *info, unsigned long long start,
-		int chunk_size, int data_disks, sighandler_t *sig) {
+		int chunk_size, int data_disks, sighandler_t *sig)
+{
 	int rv;
+
+	sig[0] = signal_s(SIGTERM, SIG_IGN);
+	sig[1] = signal_s(SIGINT, SIG_IGN);
+	sig[2] = signal_s(SIGQUIT, SIG_IGN);
+
+	if (sig[0] == SIG_ERR || sig[1] == SIG_ERR || sig[2] == SIG_ERR)
+		return 1;
+
 	if(mlockall(MCL_CURRENT | MCL_FUTURE) != 0) {
 		return 2;
 	}
 
-	sig[0] = signal(SIGTERM, SIG_IGN);
-	sig[1] = signal(SIGINT, SIG_IGN);
-	sig[2] = signal(SIGQUIT, SIG_IGN);
-
 	rv = sysfs_set_num(info, NULL, "suspend_lo", start * chunk_size * data_disks);
 	rv |= sysfs_set_num(info, NULL, "suspend_hi", (start + 1) * chunk_size * data_disks);
 	return rv * 256;
 }
 
-int unlock_all_stripes(struct mdinfo *info, sighandler_t *sig) {
+int unlock_all_stripes(struct mdinfo *info, sighandler_t *sig)
+{
 	int rv;
 	rv = sysfs_set_num(info, NULL, "suspend_lo", 0x7FFFFFFFFFFFFFFFULL);
 	rv |= sysfs_set_num(info, NULL, "suspend_hi", 0);
 	rv |= sysfs_set_num(info, NULL, "suspend_lo", 0);
 
-	signal(SIGQUIT, sig[2]);
+	signal_s(SIGQUIT, sig[2]);
-	signal(SIGINT, sig[1]);
+	signal_s(SIGINT, sig[1]);
-	signal(SIGTERM, sig[0]);
+	signal_s(SIGTERM, sig[0]);
 
 	if(munlockall() != 0)
 		return 3;

util.c

@@ -35,7 +35,6 @@
 #include	<poll.h>
 #include	<ctype.h>
 #include	<dirent.h>
-#include	<signal.h>
 #include	<dlfcn.h>