implement signal handling

Makefile

@@ -3,7 +3,7 @@
 # SPDX-License-Identifier: GPL-2.0-only
 
 CC ?= gcc
-CFLAGS ::= $(CFLAGS) -std=c99 -O2 -fstack-protector-strong -D_FORTIFY_SOURCE=2 -Wall -pedantic
+CFLAGS ::= $(CFLAGS) -std=c99 -O2 -fstack-protector-strong -D_FORTIFY_SOURCE=2 -D_POSIX_C_SOURCE=200809L -Wall -pedantic
 DEPS = src/wavfile.h src/tcpserver.h
 
 build/%.o: src/%.c $(DEPS)

src/main.c

@@ -4,6 +4,7 @@
  * SPDX-License-Identifier: GPL-2.0-only
  */
 
+#include <signal.h>
 #include <stdlib.h>
 #include <stdint.h>
 #include <unistd.h>
@@ -28,6 +29,30 @@ typedef struct {
 	sync_information sync;
 } sync_ack;
 
+/* global variables */
+char * filepath;
+uint8_t file_closed = -1;
+wavfile * file;
+int sock;
+
+/*
+ * Function: signal_handler
+ * ------------------------
+ *     handles TERM and INT to ensure an orderly shutdown
+ *
+ * signal: the number of the signal sent
+ */
+static void signal_handler(int signal) {
+	printf("signal %d received, shutting down\n", signal);
+	if (!file_closed) {
+		wavfile_close(file);
+	}
+	free(filepath);
+	shutdown(sock, SHUT_RDWR);
+	close(sock);
+	exit(EXIT_SUCCESS);
+}
+
 /*
  * Function: construct_file_path
  * ----------------------------------------
@@ -65,13 +90,11 @@ int main(int argc, char **argv) {
 	char * ip_address = NULL;
 	char * directory = NULL;
 	uint16_t port = 0;
-	int opt, sock, conn, bytes_received;
+	int opt, bytes_received, conn;
 	struct sockaddr_in client;
 	unsigned int namelen;
 	sync_information sync;
 	uint8_t buffer[BUF_SIZE];
-	wavfile * file;
-	char * file_path;
 	sync_ack ack_packet;
 	while ((opt = getopt(argc, argv, "i:p:d:")) != -1) {
 		switch(opt) {
@@ -90,12 +113,16 @@ int main(int argc, char **argv) {
 		printf("Usage: %s -i IPV4_ADDRESS -p PORT -d DIRECTORY\n", argv[0]);
 		return EXIT_SUCCESS;
 	}
+	struct sigaction action;
+	action.sa_handler = signal_handler;
+	sigaction(SIGTERM, &action,NULL);
+	sigaction(SIGINT, &action,NULL);
 	if ((sock = tcpserver_start(ip_address, port)) < 0 ) {
 		printf("Failed to start TCP server\n");
 		return EXIT_FAILURE;
 	}
-	file_path = malloc(strlen(directory) + 1 + 29);
-	if (file_path == NULL) {
+	filepath = malloc(strlen(directory) + 1 + 29);
+	if (filepath == NULL) {
 		printf("Error allocating memory for file path\n");
 		return EXIT_FAILURE;
 	}
@@ -110,9 +137,10 @@ int main(int argc, char **argv) {
 			printf("Invalid sample rate received\n");
 			continue;
 		}
-		construct_file_path(directory, file_path);
-		printf("Current file path: %s\n", file_path);
-		file = wavfile_create(file_path, 1, sync.sample_rate, sync.bits);
+		construct_file_path(directory, filepath);
+		printf("Current file path: %s\n", filepath);
+		file = wavfile_create(filepath, 1, sync.sample_rate, sync.bits);
+		file_closed = 0;
 		strncpy(ack_packet.ack,"ACK", 4);
 		ack_packet.sync = sync;
 		send(conn, &ack_packet, sizeof(ack_packet), 0);
@@ -125,6 +153,7 @@ int main(int argc, char **argv) {
 			wavfile_append_data(file, buffer, bytes_received);		
 		}
 		wavfile_close(file);
+		file_closed = 1;
 	}
 	return EXIT_SUCCESS;
 }