fuzz TEST add regression testing for previous issues found by fuzzing

add the inputs that caused the issues to tests/fuzz/corpus directories
for the corresponding fuzz target. This includes a fuzz_regression_test
binary which is used to set up a test for every fuzzing target, wrapping
the fuzz harness and reusing it as a part of the test. The appropriate
corpus is then sent into the fuzz harness to confirm that it doesn't
cause crashes or other similar issues anymore.
diff --git a/tests/fuzz/fuzz_regression_test.c b/tests/fuzz/fuzz_regression_test.c
new file mode 100644
index 0000000..53b2ec8
--- /dev/null
+++ b/tests/fuzz/fuzz_regression_test.c
@@ -0,0 +1,69 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <dirent.h>
+#include <unistd.h>
+#include <sys/types.h>
+#include <sys/wait.h>
+#include <sys/stat.h>
+#include<fcntl.h>
+
+int main(int argc, char **argv) 
+{
+	DIR *d;
+	struct dirent *dir;
+	pid_t p = 0;
+	int input_fd = 0;
+	int status = 0;
+	int rc = 0;
+	struct stat path_stat;
+	int i = 0;
+
+	if (argc != 3) {
+		fprintf(stderr, "invalid number of arguments. Call like this ./fuzz_regression_test fuzz_harness corpus_dir\n");
+		return EXIT_FAILURE;
+	}
+
+	d = opendir(argv[2]);
+	if (!d) {
+		fprintf(stderr, "error opening dir %s\n", argv[2]);
+		return EXIT_FAILURE;
+	}
+
+	while ((dir = readdir(d)) != NULL) {
+		stat(dir->d_name, &path_stat);
+		if (!S_ISREG(path_stat.st_mode)) {
+			continue;
+		}
+
+		p = fork();
+		if (p == -1) {
+			fprintf(stderr, "fork failed\n");
+			return EXIT_FAILURE;
+		} else if (p == 0) {
+			input_fd = open(dir->d_name, O_RDONLY);
+			if (input_fd == -1) {
+				fprintf(stderr, "error opening input file %s\n", dir->d_name);
+				return EXIT_FAILURE;
+			}
+			
+			dup2(input_fd, STDIN_FILENO);
+			execl(argv[1], argv[1], NULL);
+			return EXIT_SUCCESS;
+		}
+
+		rc = waitpid(p, &status, 0);
+		if (rc == -1) {
+			fprintf(stderr, "waitpid failed\n");
+			return EXIT_FAILURE;
+		}
+
+		if (!WIFEXITED(status)) {
+			fprintf(stderr, "test %s - %s failed\n", argv[1], argv[2]);
+			return EXIT_FAILURE;
+		}
+
+		printf("test %s - %s successful\n", argv[1], dir->d_name);
+	}
+
+	return EXIT_SUCCESS;
+}