Centralized list implementation.

adsbus/Makefile

@@ -6,7 +6,7 @@ LIBS ?= -ljansson -lprotobuf-c
 
 OBJ_NETWORK = incoming.o outgoing.o receive.o send.o
 OBJ_PROTOCOL = airspy_adsb.o beast.o json.o proto.o raw.o stats.o
-OBJ_UTIL = buf.o hex.o opts.o packet.o peer.o rand.o resolve.o server.o socket.o uuid.o wakeup.o
+OBJ_UTIL = buf.o hex.o list.o opts.o packet.o peer.o rand.o resolve.o server.o socket.o uuid.o wakeup.o
 OBJ_PROTO = adsb.pb-c.o
 
 all: adsbus

adsbus/incoming.c

@@ -8,6 +8,7 @@
 #include <errno.h>
 #include <unistd.h>
 
+#include "list.h"
 #include "peer.h"
 #include "resolve.h"
 #include "socket.h"
@@ -27,10 +28,10 @@ struct incoming {
 	incoming_connection_handler handler;
 	void *passthrough;
 	uint32_t *count;
-	struct incoming *next;
+	struct list_head incoming_list;
 };
 
-static struct incoming *incoming_head = NULL;
+static struct list_head incoming_head = LIST_HEAD_INIT(incoming_head);
 
 static void incoming_resolve_wrapper(struct peer *);
 
@@ -137,11 +138,9 @@ static void incoming_resolve_wrapper(struct peer *peer) {
 }
 
 void incoming_cleanup() {
-	struct incoming *iter = incoming_head;
-	while (iter) {
-		struct incoming *next = iter->next;
+	struct incoming *iter, *next;
+	list_for_each_entry_safe(iter, next, &incoming_head, incoming_list) {
 		incoming_del(iter);
-		iter = next;
 	}
 }
 
@@ -158,8 +157,7 @@ void incoming_new(char *node, char *service, incoming_connection_handler handler
 	incoming->passthrough = passthrough;
 	incoming->count = count;
 
-	incoming->next = incoming_head;
-	incoming_head = incoming;
+	list_add(&incoming->incoming_list, &incoming_head);
 
 	incoming_resolve(incoming);
 }

adsbus/list.c

@@ -0,0 +1,24 @@
+#include <stdlib.h>
+
+#include "list.h"
+
+void list_head_init(struct list_head *head) {
+	head->next = head->prev = head;
+}
+
+bool list_is_empty(const struct list_head *head) {
+	return head->next == head;
+}
+
+void list_add(struct list_head *new, struct list_head *head) {
+	new->next = head;
+	new->prev = head->prev;
+	new->prev->next = new;
+	head->prev = new;
+}
+
+void list_del(struct list_head *entry) {
+	entry->next->prev = entry->prev;
+	entry->prev->next = entry->next;
+	entry->prev = entry->next = NULL;
+}

adsbus/list.h

@@ -0,0 +1,39 @@
+#pragma once
+
+#include <stdbool.h>
+
+#pragma GCC diagnostic ignored "-Wcast-align"
+#pragma GCC diagnostic ignored "-Wgnu-statement-expression"
+#pragma GCC diagnostic ignored "-Wlanguage-extension-token"
+
+#define offset_of(type, member) ((size_t) &((type *) NULL)->member)
+
+#define container_of(ptr, type, member) ({ \
+		typeof( ((type *) NULL)->member ) *__mptr = (ptr); \
+		(type *)( (char *)__mptr - offset_of(type, member) );})
+
+struct list_head {
+	struct list_head *next;
+	struct list_head *prev;
+};
+
+#define LIST_HEAD_INIT(name) { &(name), &(name) }
+
+#define list_entry(ptr, type, member) \
+		container_of(ptr, type, member)
+
+#define list_for_each_entry(pos, head, member) \
+		for (pos = list_entry((head)->next, typeof(*pos), member); \
+				&pos->member != (head); \
+				pos = list_entry(pos->member.next, typeof(*pos), member))
+
+#define list_for_each_entry_safe(pos, n, head, member) \
+		for (pos = list_entry((head)->next, typeof(*pos), member), \
+					n = list_entry(pos->member.next, typeof(*pos), member); \
+				&pos->member != (head); \
+				pos = n, n = list_entry(n->member.next, typeof(*n), member))
+
+void list_head_init(struct list_head *);
+bool list_is_empty(const struct list_head *);
+void list_add(struct list_head *, struct list_head *);
+void list_del(struct list_head *);

adsbus/outgoing.c

@@ -8,6 +8,7 @@
 #include <string.h>
 #include <unistd.h>
 
+#include "list.h"
 #include "peer.h"
 #include "resolve.h"
 #include "socket.h"
@@ -28,10 +29,10 @@ struct outgoing {
 	outgoing_connection_handler handler;
 	void *passthrough;
 	uint32_t *count;
-	struct outgoing *next;
+	struct list_head outgoing_list;
 };
 
-static struct outgoing *outgoing_head = NULL;
+static struct list_head outgoing_head = LIST_HEAD_INIT(outgoing_head);
 
 static void outgoing_connect_result(struct outgoing *, int);
 static void outgoing_resolve(struct outgoing *);
@@ -147,11 +148,9 @@ static void outgoing_del(struct outgoing *outgoing) {
 }
 
 void outgoing_cleanup() {
-	struct outgoing *iter = outgoing_head;
-	while (iter) {
-		struct outgoing *next = iter->next;
+	struct outgoing *iter, *next;
+	list_for_each_entry_safe(iter, next, &outgoing_head, outgoing_list) {
 		outgoing_del(iter);
-		iter = next;
 	}
 }
 
@@ -167,8 +166,7 @@ void outgoing_new(char *node, char *service, outgoing_connection_handler handler
 	outgoing->passthrough = passthrough;
 	outgoing->count = count;
 
-	outgoing->next = outgoing_head;
-	outgoing_head = outgoing;
+	list_add(&outgoing->outgoing_list, &outgoing_head);
 
 	outgoing_resolve(outgoing);
 }

adsbus/send.c

@@ -13,6 +13,7 @@
 #include "beast.h"
 #include "buf.h"
 #include "json.h"
+#include "list.h"
 #include "peer.h"
 #include "proto.h"
 #include "raw.h"
@@ -26,15 +27,14 @@ struct send {
 	struct peer *on_close;
 	uint8_t id[UUID_LEN];
 	struct serializer *serializer;
-	struct send *prev;
-	struct send *next;
+	struct list_head send_list;
 };
 
 typedef void (*serialize)(struct packet *, struct buf *);
 static struct serializer {
 	char *name;
 	serialize serialize;
-	struct send *send_head;
+	struct list_head send_head;
 } serializers[] = {
 	{
 		.name = "airspy_adsb",
@@ -68,14 +68,7 @@ static void send_del(struct send *send) {
 	peer_count_out--;
 	peer_epoll_del((struct peer *) send);
 	assert(!close(send->peer.fd));
-	if (send->prev) {
-		send->prev->next = send->next;
-	} else {
-		send->serializer->send_head = send->next;
-	}
-	if (send->next) {
-		send->next->prev = send->prev;
-	}
+	list_del(&send->send_list);
 	peer_call(send->on_close);
 	free(send);
 }
@@ -98,13 +91,17 @@ static bool send_hello(int fd, struct serializer *serializer) {
 
 void send_init() {
 	assert(signal(SIGPIPE, SIG_IGN) != SIG_ERR);
+	for (size_t i = 0; i < NUM_SERIALIZERS; i++) {
+		list_head_init(&serializers[i].send_head);
+	}
 }
 
 void send_cleanup() {
 	for (size_t i = 0; i < NUM_SERIALIZERS; i++) {
 		struct serializer *serializer = &serializers[i];
-		while (serializer->send_head) {
-			send_del(serializer->send_head);
+		struct send *iter, *next;
+		list_for_each_entry_safe(iter, next, &serializer->send_head, send_list) {
+			send_del(iter);
 		}
 	}
 }
@@ -132,12 +129,7 @@ void send_new(int fd, struct serializer *serializer, struct peer *on_close) {
 	send->on_close = on_close;
 	uuid_gen(send->id);
 	send->serializer = serializer;
-	send->prev = NULL;
-	send->next = serializer->send_head;
-	if (send->next) {
-		send->next->prev = send;
-	}
-	serializer->send_head = send;
+	list_add(&send->send_list, &serializer->send_head);
 
 	peer_epoll_add((struct peer *) send, 0);
 
@@ -157,7 +149,7 @@ void send_new_wrapper(int fd, void *passthrough, struct peer *on_close) {
 void send_write(struct packet *packet) {
 	for (size_t i = 0; i < NUM_SERIALIZERS; i++) {
 		struct serializer *serializer = &serializers[i];
-		if (serializer->send_head == NULL) {
+		if (list_is_empty(&serializer->send_head)) {
 			continue;
 		}
 		struct buf buf = BUF_INIT;
@@ -165,14 +157,13 @@ void send_write(struct packet *packet) {
 		if (buf.length == 0) {
 			continue;
 		}
-		struct send *send = serializer->send_head;
-		while (send) {
-			if (write(send->peer.fd, buf_at(&buf, 0), buf.length) != (ssize_t) buf.length) {
+		struct send *iter, *next;
+		list_for_each_entry_safe(iter, next, &serializer->send_head, send_list) {
+			if (write(iter->peer.fd, buf_at(&buf, 0), buf.length) != (ssize_t) buf.length) {
 				// peer_loop() will see this shutdown and call send_del
-				int res = shutdown(send->peer.fd, SHUT_WR);
+				int res = shutdown(iter->peer.fd, SHUT_WR);
 				assert(res == 0 || (res == -1 && errno == ENOTSOCK));
 			}
-			send = send->next;
 		}
 	}
 }