Protecting LE agains error caused by SIGSTOP and SIGCONT

Author: amissael95

src/libltfs/ltfs.c

@@ -207,6 +207,18 @@ bool ltfs_is_interrupted(void)
 	return interrupted;
 }
 
+bool caught_sigcont = false;
+void _ltfs_sigcont(int signal)
+{
+	ltfsmsg(LTFS_DEBUG, 16503D, "_ltfs_sigcont", "");
+	caught_sigcont = true;
+}
+
+bool ltfs_caught_sigcont(void)
+{
+	return caught_sigcont;
+}
+
 /**
  * This function can be used to enable libltfs signal handler
  * to kill ltfs, mkltfs, ltfsck cleanly
@@ -251,6 +263,15 @@ int ltfs_set_signal_handlers(void)
 		return -LTFS_SIG_HANDLER_ERR;
 	}
 
+	ret = signal(SIGCONT, _ltfs_sigcont);
+	if (ret == SIG_ERR) {
+		signal(SIGINT, SIG_DFL);
+		signal(SIGHUP, SIG_DFL);
+		signal(SIGQUIT, SIG_DFL);
+		signal(SIGTERM, SIG_DFL);
+		return -LTFS_SIG_HANDLER_ERR;
+	}
+
 	return 0;
 }
 #endif
@@ -285,6 +306,10 @@ int ltfs_unset_signal_handlers(void)
 	if (rc == SIG_ERR)
 		ret = -LTFS_SIG_HANDLER_ERR;
 
+	rc = signal(SIGCONT, SIG_DFL);
+	if (rc == SIG_ERR)
+		ret = -LTFS_SIG_HANDLER_ERR;
+
 	return ret;
 }
 #endif

src/libltfs/ltfs.h

@@ -586,6 +586,7 @@ int ltfs_fs_init(void);
 void ltfs_set_log_level(int log_level);
 void ltfs_set_syslog_level(int syslog_level);
 bool ltfs_is_interrupted(void);
+bool ltfs_caught_sigcont(void);
 int ltfs_set_signal_handlers(void);
 int ltfs_unset_signal_handlers(void);
 int ltfs_finish();

src/libltfs/tape.c

@@ -1187,6 +1187,9 @@ int tape_spacefm(struct device_data *dev, int count)
 ssize_t tape_write(struct device_data *dev, const char *buf, size_t count, bool ignore_less, bool ignore_nospc)
 {
 	ssize_t ret;
+	struct tc_position current_position;
+	int ret_for_update_position = 0;
+	unsigned long long diff = 0;
 
 	CHECK_ARG_NULL(dev, -LTFS_NULL_ARG);
 	CHECK_ARG_NULL(buf, -LTFS_NULL_ARG);
@@ -1241,6 +1244,19 @@ ssize_t tape_write(struct device_data *dev, const char *buf, size_t count, bool
 			count = -LTFS_LESS_SPACE;
 	}
 
+	if (ltfs_caught_sigcont()) {
+		ltfsmsg(LTFS_DEBUG, 16503D, "ltfs_caught_sigcont", "tape_write");
+		ret_for_update_position = tape_update_position(dev, &current_position);
+		if (ret_for_update_position) {
+			// Implement the error handling
+		}
+		ltfsmsg(LTFS_INFO, 11334I, "compare offset in tape_write", (unsigned long long)dev->position.block, (unsigned long long)current_position.block);
+		diff = ((unsigned long long)dev->position.block - (unsigned long long)current_position.block);
+		if (diff) {
+			return -LTFS_WRITE_ERROR;
+		}
+	}
+
 	ltfs_mutex_lock(&dev->append_pos_mutex);
 	dev->append_pos[dev->position.partition] = dev->position.block;
 	ltfs_mutex_unlock(&dev->append_pos_mutex);