linked list implementation

Makefile

@@ -1,19 +1,21 @@
 CC       = gcc
 CFLAGS   = -Wall -Wpedantic
 LD       = gcc
-LDFLAGS  =
+LDFLAGS  = -lpthread -lrt
 
 BIN_NAME = cfloor
 
 all: $(BIN_NAME)
 
-test: obj/test.o obj/networking.o
+test: obj/test.o obj/networking.o obj/linked.o
-	$(LD) -o $@ $^
+	$(LD) $(LDFLAGS) -o $@ $^
 
+obj/test.o: src/networking.h
 obj/networking.o: src/networking.h src/headers.h
+obj/linked.o: src/linked.h
 
 obj/%.o: src/%.c obj
-	$(CC) -c -o $@ $<
+	$(CC) $(CFLAGS) -c -o $@ $<
 
 obj:
 	@mkdir -p obj

src/linked.c

@@ -0,0 +1,205 @@
+#include <semaphore.h>
+#include <stdbool.h>
+#include <stdlib.h>
+
+#include "linked.h"
+
+linkedList_t linked_create() {
+	linkedList_t list = {
+		.first = NULL
+	};
+	sem_init(&(list.modify_sem), 0, 1);
+	return list;
+}
+
+size_t linked_push(linkedList_t* list, void* data) {
+	link_t* new = malloc(sizeof (link_t));
+	if (new == NULL)
+		return -1;
+
+	new->data = data;
+	sem_init(&(new->modify_sem), 0, 1);
+	new->inUse = 0;
+	new->list = list;
+	new->next = NULL;
+	new->unlinked = false;
+
+	size_t index = 0;
+
+	link_t* current = NULL;
+
+	sem_wait(&(list->modify_sem));
+	current = list->first;
+	if (current == NULL) {
+		new->prev = NULL;
+		list->first = new;
+		sem_post(&(list->modify_sem));
+		return index;
+	}
+	sem_post(&(list->modify_sem));
+
+	index++;
+	sem_wait(&(current->modify_sem));
+	while(current->next != NULL) {
+		sem_wait(&(current->next->modify_sem));
+		sem_post(&(current->modify_sem));
+		current = current->next;
+		index++;
+	}
+
+	new->prev = current;
+	current->next = new;
+	
+	sem_post(&(current->modify_sem));
+
+	return index;
+}
+
+link_t* linked_first(linkedList_t* list) {
+	if (list->first == NULL) {
+		return NULL;
+	}
+	link_t* link = list->first;
+
+	link->inUse++;
+
+	return link;
+}
+
+void linked_free(link_t* link) {
+	free(link);
+}
+
+void linked_unlock(link_t* link) {
+	link->inUse--;
+
+	if (link->unlinked && link->inUse == 0) {
+		linked_free(link);
+	}
+}
+
+link_t* linked_next(link_t* link) {
+	linked_unlock(link);
+
+	if (link->next == NULL) {
+		return NULL;
+	}
+	link = link->next;
+
+	link->inUse++;
+
+	return link;
+}
+
+link_t* linked_get(linkedList_t* list, size_t index) {
+	link_t* link = linked_first(list);
+
+	while(link != NULL) {		
+		if (index-- == 0) {
+			return link;
+		}
+	 
+		link = linked_next(link);
+	}
+
+	return NULL;
+}
+
+size_t linked_length(linkedList_t* list) {
+	link_t* link = linked_first(list);
+
+	size_t length = 0;
+
+	while(link != NULL) {
+		length++;
+		link = linked_next(link);
+	}
+
+	return length;
+}
+
+int linked_unlink(link_t* link) {
+	// need to get prev sem before link sem to avoid dead lock
+	sem_t* prevModify = NULL;
+	link_t** prevNext = NULL;
+
+	while(true) {
+		/*
+		 * Try to lock prev. If locked prev was modified try again.
+		 * Abort if link is unlinked.
+		 */
+
+		link_t* prev = link->prev;
+		if (prev == NULL) {
+			sem_wait(&(link->list->modify_sem));
+			if (link->list->first != link) {
+				sem_post(&(link->list->modify_sem));
+				if (link->unlinked) {
+					return -1;
+				}
+				continue;
+			}
+			prevModify = &(link->list->modify_sem);
+			prevNext = &(link->list->first);
+			break;
+		} else {
+			sem_wait(&(prev->modify_sem));
+			if (prev->next != link) {
+				sem_post(&(prev->modify_sem));
+				if (link->unlinked) {
+					return - 1;
+				}
+				continue;
+			}
+			prevModify = &(prev->modify_sem);
+			prevNext = &(prev->next);
+			break;
+		}
+	}
+
+	sem_wait(&(link->modify_sem));
+
+	if (link->unlinked) {
+		sem_post(&(link->modify_sem));
+		sem_post(prevModify);
+		return - 1;
+	}
+
+	if (link->next) {
+		sem_wait(&(link->next->modify_sem));
+		// we don't need to check for changes because link is already locked
+
+		// while we are here we can modify next
+		link->next->prev = link->prev;
+
+		// we don't need this one anymore
+		sem_post(&(link->next->modify_sem));
+	}
+
+	link->unlinked = true;
+
+	*prevNext = link->next;
+
+	// everything is done
+
+	sem_post(&(link->modify_sem));
+
+	sem_post(prevModify);
+
+	if (link->inUse == 0) {
+		linked_free(link);
+	}
+
+	return 0;
+}
+
+void linked_destroy(linkedList_t* list) {
+	link_t* link = linked_first(list);
+
+	while(link != NULL) {
+		link_t* next = link->next;
+		linked_unlink(link);
+		link = next;
+	}
+}
+

src/linked.h

@@ -0,0 +1,33 @@
+#ifndef LINKED_H
+#define LINKED_H
+
+#include <semaphore.h>
+#include <stdbool.h>
+#include <signal.h>
+
+typedef struct linkedList {
+	sem_t modify_sem;
+	struct link* first;
+} linkedList_t;
+
+typedef struct link {
+	void* data;
+	sem_t modify_sem;
+	volatile sig_atomic_t inUse;
+	bool unlinked;
+	struct link* next;
+	struct link* prev;
+	struct linkedList* list;	
+} link_t;
+
+linkedList_t linked_create();
+size_t linked_push(linkedList_t* list, void* data);
+link_t* linked_first(linkedList_t* list);
+link_t* linked_next(link_t* link);
+size_t linked_length(linkedList_t* list);
+void linked_unlock(link_t* link);
+link_t* linked_get(linkedList_t* list, size_t index);
+int linked_unlink(link_t* link);
+void linked_destroy(linkedList_t* list);
+
+#endif

src/main.c

@@ -1,7 +1,7 @@
 
 
 
-int main(int argc, char* argv) {
+int main(int argc, char** argv) {
 
 	
 }

src/test.c

@@ -6,7 +6,7 @@ handler_t handlerGetter(struct metaData metaData, const char* host) {
 	return NULL;
 }
 
-int main(int argc, char* argv) {
+int main(int argc, char** argv) {
 	initNetworking((struct networkingConfig) {
 		.connectionTimeout = 30000,
 		.defaultResponse = {