1 files changed, 414 insertions, 352 deletions

diff --git a/src/server/utils.c b/src/server/utils.c
index 3fe1900..d6e7a61 100644
--- a/src/server/utils.c
+++ b/src/server/utils.c
@@ -31,6 +31,12 @@
 #include "utils.h"
 #include "memlog.h"
 
+static char parse_address(char *string, uint8_t *af, uint8_t *addr, uint16_t *port);
+static char is_valid_namespace(char *namespace);
+static char is_valid_imagename(char *namespace);
+static void strtolower(char *string);
+static dnbd3_image_t *prepare_image(char *image_name, int rid, char *image_file, char *cache_file, gchar **servers, gsize num_servers);
+
 /**
  * Parse IPv4 or IPv6 address in string representation to a suitable format usable by the BSD socket library
  * @string eg. "1.2.3.4" or "2a01::10:5", optially with port appended, eg "1.2.3.4:6666" or "2a01::10:5:6666"
@@ -65,19 +71,22 @@ static char parse_address(char *string, uint8_t *af, uint8_t *addr, uint16_t *po
 	char *portpos = NULL, *ptr = string;
 	while (*ptr)
 	{
-		if (*ptr == ':') portpos = ptr;
+		if (*ptr == ':')
+			portpos = ptr;
 		++ptr;
 	}
-	if (portpos == NULL) return 0; // No port in string
+	if (portpos == NULL)
+		return 0; // No port in string
 	// Consider IP being surrounded by [ ]
-	if (*string == '[' && *(portpos-1) == ']')
+	if (*string == '[' && *(portpos - 1) == ']')
 	{
 		++string;
-		*(portpos-1) = '\0';
+		*(portpos - 1) = '\0';
 	}
 	*portpos++ = '\0';
 	int p = atoi(portpos);
-	if (p < 1 || p > 65535) return 0; // Invalid port
+	if (p < 1 || p > 65535)
+		return 0; // Invalid port
 	*port = htons((uint16_t)p);
 
 	// Try IPv4 with port
@@ -101,30 +110,33 @@ static char parse_address(char *string, uint8_t *af, uint8_t *addr, uint16_t *po
 
 static char is_valid_namespace(char *namespace)
 {
-	if (*namespace == '\0' || *namespace == '/') return 0; // Invalid: Length = 0 or starting with a slash
+	if (*namespace == '\0' || *namespace == '/')
+		return 0; // Invalid: Length = 0 or starting with a slash
 	while (*namespace)
 	{
-		if (*namespace != '/' && *namespace != '-'
-				&& (*namespace < 'a' || *namespace > 'z')
-				&& (*namespace < 'A' || *namespace > 'Z')) return 0;
+		if (*namespace != '/' && *namespace != '-' && (*namespace < 'a' || *namespace > 'z')
+		   && (*namespace < 'A' || *namespace > 'Z'))
+			return 0;
 		++namespace;
 	}
-	if (*(namespace - 1) == '/') return 0; // Invalid: Ends in a slash
+	if (*(namespace - 1) == '/')
+		return 0; // Invalid: Ends in a slash
 	return 1;
 }
 
 static char is_valid_imagename(char *namespace)
 {
-	if (*namespace == '\0' || *namespace == ' ') return 0; // Invalid: Length = 0 or starting with a space
+	if (*namespace == '\0' || *namespace == ' ')
+		return 0; // Invalid: Length = 0 or starting with a space
 	while (*namespace)
 	{	// Check for invalid chars
-		if (*namespace != '.' && *namespace != '-' && *namespace != ' '
-				&& *namespace != '(' && *namespace != ')'
-				&& (*namespace < 'a' || *namespace > 'z')
-				&& (*namespace < 'A' || *namespace > 'Z')) return 0;
+		if (*namespace != '.' && *namespace != '-' && *namespace != ' ' && *namespace != '(' && *namespace != ')'
+		   && (*namespace < 'a' || *namespace > 'z') && (*namespace < 'A' || *namespace > 'Z'))
+			return 0;
 		++namespace;
 	}
-	if (*(namespace - 1) == ' ') return 0; // Invalid: Ends in a space
+	if (*(namespace - 1) == ' ')
+		return 0; // Invalid: Ends in a space
 	return 1;
 }
 
@@ -132,380 +144,430 @@ static void strtolower(char *string)
 {
 	while (*string)
 	{
-		if (*string >= 'A' && *string <= 'Z') *string += 32;
+		if (*string >= 'A' && *string <= 'Z')
+			*string += 32;
 		++string;
 	}
 }
 
-void dnbd3_load_config(char *file)
+void dnbd3_load_config()
 {
-    int fd;
-    gint i, j, k;
-    GKeyFile* gkf;
-
-    gkf = g_key_file_new();
-    if (!g_key_file_load_from_file(gkf, file, G_KEY_FILE_NONE, NULL))
-    {
-        printf("ERROR: Config file not found: %s\n", file);
-        exit(EXIT_FAILURE);
-    }
-
-    char *namespace = g_key_file_get_string(gkf, "settings", "default_namespace", NULL);
-    if (namespace && !is_valid_namespace(namespace))
-    {
-    	memlogf("[ERROR] Ignoring default namespace: '%s' is not a valid namespace", namespace);
-    	g_free(namespace);
-    	namespace = NULL;
-    }
-
-    gchar **groups = NULL;
-    gsize section_count;
-    groups = g_key_file_get_groups(gkf, &section_count);
-
-    for (i = 0; i < section_count; i++)
-    {
-    	// Special group
-    	if (strcmp(groups[i], "settings") == 0 || strcmp(groups[i], "trusted") == 0)
-    	{
-    		continue;
-    	}
-
-    	// An actual image definition
-
-    	if (!is_valid_imagename(groups[i]))
-    	{
-    		memlogf("[ERROR] Invalid image name: '%s'", groups[i]);
-    		continue;
-    	}
-
-    	int rid = g_key_file_get_integer(gkf, groups[i], "rid", NULL);
-    	if (rid <= 0)
-    	{
-    		memlogf("[ERROR] Invalid rid '%d' for image '%s'", rid, groups[i]);
-    		continue;
-    	}
-
-    	if (strchr(groups[i], '.') == NULL && namespace == NULL)
-    	{
-    		memlogf("[ERROR] Image '%s' has local name and no default namespace is defined; entry ignored.", groups[i]);
-    		continue;
-    	}
-
-    	dnbd3_image_t *image = g_new0(dnbd3_image_t, 1);
-    	if (image == NULL)
-    	{
-    		memlogf("[ERROR] Could not allocate dnbd3_image_t while reading config");
-    		continue;
-    	}
-
-        if (strchr(groups[i], '/') == NULL)
-        {	// Local image, build global name
-        	image->name = calloc(strlen(namespace) + strlen(groups[i]) + 2, sizeof(char));
-        	sprintf(image->name, "%s/%s", namespace, groups[i]);
-        }
-        else
-        {
-        	image->name = strdup(groups[i]);
-        }
-
-    	if (dnbd3_get_image(image->name, rid, 0))
-    	{
-    		memlogf("[ERROR] Duplicate image in config: '%s' rid:%d", image->name, rid);
-    		free(image->name);
-    		g_free(image);
-    		continue;
-    	}
-
-        image->low_name = strdup(image->name);
-        strtolower(image->low_name);
-
-    	image->rid = rid;
-    	image->file = g_key_file_get_string(gkf, groups[i], "file", NULL);
-    	char relayed = image->file == NULL || *image->file == '\0';
-    	if (relayed && image->file)
-    	{
-    		g_free(image->file);
-    		image->file = NULL;
-    	}
-
-    	if (relayed)	// Image is relayed (this server acts as proxy)
-    	{
-    		if (strchr(groups[i], '.') == NULL)
-    		{
-    			memlogf("[ERROR] Relayed image without global name in config: '%s'", groups[i]);
-    			g_free(image);
-    			continue;
-    		}
-    		image->cache_file = g_key_file_get_string(gkf, groups[i], "cache", NULL);
-    		if (image->cache_file && *image->cache_file == '\0') g_free(image->cache_file);
-    	}
-    	else	// Image is a local one, open file to get size
-        {
-			fd = open(image->file, O_RDONLY);
-			if (fd > 0) {
-				image->filesize = lseek(fd, 0, SEEK_END);
-				if (image->filesize & 4095) {
-					memlogf("[WARNING] Size of image '%s' is not a multiple of 4096. Last incomplete block will be ignored!", image->file);
-					image->filesize &= ~(uint64_t)4095;
-				}
-				close(fd);
-				image->working = 1;
-			} else {
-				memlogf("[ERROR] Image file not found: '%s'", image->file);
-			}
-        }
-
-    	// A list of servers that are known to also host or relay this image
-    	gsize num_servers;
-        gchar **servers = g_key_file_get_string_list(gkf, groups[i], "servers", &num_servers, NULL);
-        if (servers) for (k = 0, j = 0; j < MIN(num_servers, NUMBER_SERVERS); ++j)
-        {
-        	if (parse_address(servers[j], &(image->servers[k].hostaddrtype), image->servers[k].hostaddr, &(image->servers[k].port)))
-        	{
-        		++k; continue;
-        	}
-        	image->servers[k].hostaddrtype = 0;
-        }
-        g_strfreev(servers);
-
-        if (image->cache_file)
-        {
-        	// Determine size of cached image
-        	fd = open(image->cache_file, O_RDONLY);
-        	if (fd > 0)
-        	{
-        		image->filesize = lseek(fd, 0, SEEK_END);
-        		close(fd);
-        	}
-			if (image->filesize & 4095)
-			{	// Cache files should always be trincated to 4kib boundaries already
-				memlogf("[WARNING] Size of cache file '%s' is not a multiple of 4096. Something's fishy!", image->cache_file);
-				image->filesize = 0;
-			}
-			else if (image->filesize > 0)
-        	{
-				const size_t map_len_bytes = (image->filesize + (1 << 15) - 1) >> 15;
-				image->cache_map  = calloc(map_len_bytes, sizeof(uint8_t));
-				// read cache map from file
-				// one byte in the map covers 8 4kib blocks, so 32kib per byte
-				// "+ (1 << 15) - 1" is required to account for the last bit of
-				// the image that is smaller than 32kib
-				// this would be the case whenever the image file size is not a
-				// multiple of 32kib (= the number of blocks is not dividable by 8)
-				// ie: if the image is 49152 bytes and you do 49152 >> 15 you get 1,
-				// but you actually need 2 bytes to have a complete cache map
-				char tmp[strlen(image->cache_file)+4];
-				strcpy(tmp, image->cache_file);
-				strcat(tmp, ".map");
-				fd = open(tmp, O_RDONLY);
-				if (fd > 0)
-				{
-					read(fd, image->cache_map, map_len_bytes * sizeof(uint8_t));
-					close(fd);
-					// If the whole image is cached, mark it as working right away without waiting for an upstream server
-					image->working = 1;
-					for (j = 0; j < map_len_bytes - 1; ++j)
-					{
-						if (image->cache_map[j] != 0xFF)
-						{
-							image->working = 0;
-							break;
-						}
-					}
-					const int blocks_in_last_byte = (image->filesize >> 12) & 7;
-					uint8_t last_byte = 0;
-					if (blocks_in_last_byte == 0)
-						last_byte = 0xFF;
-					else
-						for (j = 0; j < k; ++j) last_byte = (last_byte << 1) | 1;
-					if ((image->cache_map[map_len_bytes-1] & last_byte) != last_byte)
-						image->working = 0;
-					else
-						memlogf("[INFO] Publishing relayed image '%s' because the local cache copy is complete", image->name);
-				}
+	gint i;
+	GKeyFile* gkf;
 
-				/*
-				// TODO: Do this as soon as a connection to a upstream server is established
-				// open cache file
-				fd = open(_images[i].cache_file, O_WRONLY | O_CREAT, S_IRUSR | S_IWUSR);
-				if (fd < 1)
-					memlogf("ERROR: Could't create cache file '%s'", _images[i].cache_file);
+	if (_local_namespace != NULL || _dnbd3_images != NULL)
+	{
+		printf("dnbd3_load_config() called more than once\n\n");
+		exit(EXIT_FAILURE);
+	}
 
-				if (_images[i].filesize != lseek(fd, 0, SEEK_END))
-					fallocate(fd, 0, 0, _images[i].filesize);
+	gkf = g_key_file_new();
+	if (!g_key_file_load_from_file(gkf, _config_file_name, G_KEY_FILE_NONE, NULL))
+	{
+		printf("ERROR: Config file not found: %s\n", _config_file_name);
+		exit(EXIT_FAILURE);
+	}
 
-				close(fd);
-				*/
-        	}
-        } // end cache_file handling
-        pthread_spin_lock(&_spinlock);
-        _dnbd3_images = g_slist_append(_dnbd3_images, image);
-        pthread_spin_unlock(&_spinlock);
-        // DONE IMAGE
-    }
-
-    g_free(namespace);
-    g_strfreev(groups);
-    g_key_file_free(gkf);
-}
+	_local_namespace = g_key_file_get_string(gkf, "settings", "default_namespace", NULL);
+	if (_local_namespace && !is_valid_namespace(_local_namespace))
+	{
+		memlogf("[ERROR] Ignoring default namespace: '%s' is not a valid namespace", _local_namespace);
+		g_free(_local_namespace);
+		_local_namespace = NULL;
+	}
 
-int dnbd3_add_image(dnbd3_image_t *image, char *file)
-{
-	return ERROR_IMAGE_ALREADY_EXISTS; // TODO: Make it work with image names
-	/*
-	FILE* f = fopen(image->file,"r");
-	if (f == NULL)
+	gchar **groups = NULL;
+	gsize section_count;
+	groups = g_key_file_get_groups(gkf, &section_count);
+
+	for (i = 0; i < section_count; i++)
 	{
-		printf("ERROR: Image file not found: %s\n", image->file);
-		return ERROR_FILE_NOT_FOUND;
+		// Special group
+		if (strcmp(groups[i], "settings") == 0 || strcmp(groups[i], "trusted") == 0)
+		{
+			continue;
+		}
+
+		// An actual image definition
+
+		int rid = g_key_file_get_integer(gkf, groups[i], "rid", NULL);
+		if (rid <= 0)
+		{
+			memlogf("[ERROR] Invalid rid '%d' for image '%s'", rid, groups[i]);
+			continue;
+		}
+
+		char *image_file = g_key_file_get_string(gkf, groups[i], "file", NULL);
+		char *cache_file = g_key_file_get_string(gkf, groups[i], "cache", NULL);
+		gsize num_servers;
+		gchar **servers = g_key_file_get_string_list(gkf, groups[i], "servers", &num_servers, NULL);
+
+		pthread_spin_lock(&_spinlock);
+		dnbd3_image_t *image = prepare_image(groups[i], rid, image_file, cache_file, servers, num_servers);
+		if (image)
+		{
+			_dnbd3_images = g_slist_prepend(_dnbd3_images, image);
+		}
+		pthread_spin_unlock(&_spinlock);
+
+		g_free(image_file);
+		g_free(cache_file);
+		g_strfreev(servers);
 	}
-	fclose (f);
 
-	dnbd3_image_t* tmp = dnbd3_get_image(image->vid, image->rid);
+	g_strfreev(groups);
+	g_key_file_free(gkf);
+}
+
+int dnbd3_add_image(dnbd3_image_t *image)
+{
+	// Lock here to prevent concurrent add calls to mess rids up. Cannot happen currently
+	// as IPC clients are not threaded and they're the only place where this is called,
+	// but better be safe for the future...
+	pthread_spin_lock(&_spinlock);
 	if (image->rid == 0)
-	{
-		if(tmp)
-			image->rid = tmp->rid +1;
+	{	// TODO: globalize image->name somewhere for this call
+		const dnbd3_image_t *latest = dnbd3_get_image(image->name, image->rid, 0);
+		if (latest)
+			image->rid = latest->rid + 1;
 		else
 			image->rid = 1;
-	} else if (tmp)
+	}
+
+	dnbd3_image_t *newimage = prepare_image(image->name, image->rid, image->file, image->cache_file, NULL, 0);
+	if (newimage)
+	{
+		_dnbd3_images = g_slist_prepend(_dnbd3_images, image);
+	}
+	else
 	{
-		printf("ERROR: Image already exists (%d,%d)\n", image->vid, image->rid);
-		return ERROR_IMAGE_ALREADY_EXISTS;
+		pthread_spin_unlock(&_spinlock);
+		return ERROR_SEE_LOG;
 	}
 
-    GKeyFile* gkf;
-    gkf = g_key_file_new();
-    if (!g_key_file_load_from_file(gkf, file, G_KEY_FILE_NONE, NULL))
-    {
-        printf("ERROR: Config file not found: %s\n", file);
-        exit(EXIT_FAILURE);
-    }
-
-    g_key_file_set_integer(gkf, image->group, "vid", image->vid);
-    g_key_file_set_integer(gkf, image->group, "rid", image->rid);
-    g_key_file_set_string(gkf, image->group, "file", image->file);
-    g_key_file_set_string(gkf, image->group, "servers", image->serverss);
-    g_key_file_set_string(gkf, image->group, "cache", image->cache_file);
-
-    gchar* data = g_key_file_to_data(gkf, NULL, NULL);
-
-    f = fopen(file,"w");
-    if (f)
-    {
-    	fputs((char*) data, f);
-    	fclose(f);
-        g_free(data);
-        g_key_file_free(gkf);
-        return 0;
-    }
-    else
-    {
-    	g_free(data);
-    	g_key_file_free(gkf);
-    	printf("ERROR: Config file is not writable: %s\n", file);
-    	return ERROR_CONFIG_FILE_PERMISSIONS;
-    }
-    */
+	// Adding image was successful, write config file
+	 GKeyFile* gkf;
+	 gkf = g_key_file_new();
+	 if (!g_key_file_load_from_file(gkf, _config_file_name, G_KEY_FILE_NONE, NULL))
+	 {
+	 printf("ERROR: Config file not found: %s\n", _config_file_name);
+	 exit(EXIT_FAILURE);
+	 }
+
+	 g_key_file_set_integer(gkf, image->name, "rid", image->rid);
+	 g_key_file_set_string(gkf, image->name, "file", image->file);
+	 //g_key_file_set_string(gkf, image->name, "servers", image->serverss); // TODO: Save servers as string
+	 g_key_file_set_string(gkf, image->name, "cache", image->cache_file);
+
+	 gchar* data = g_key_file_to_data(gkf, NULL, NULL);
+
+	 int f = fopen(_config_file_name, "w");
+	 if (f >= 0)
+	 {
+		 fputs((char*) data, f);
+		 fclose(f);
+		 pthread_spin_unlock(&_spinlock);
+		 g_free(data);
+		 g_key_file_free(gkf);
+		 memlogf("[INFO] Added new image '%s' (rid %d)", newimage->name, newimage->rid);
+		 return 0;
+	 }
+	 pthread_spin_unlock(&_spinlock);
+	 g_free(data);
+	 g_key_file_free(gkf);
+	 memlogf("[ERROR] Image added, but config file is not writable (%s)", _config_file_name);
+	 return ERROR_SEE_LOG;
 }
 
 int dnbd3_del_image(dnbd3_image_t *image, char *file)
 {
 	return ERROR_IMAGE_NOT_FOUND; // TODO: Make it work with image names
 	/*
-	if (image->rid == 0)
-	{
-        printf("ERROR: Delete with rid=0 is not allowed\n");
-        return ERROR_RID;
-	}
-
-	dnbd3_image_t* tmp = dnbd3_get_image(image->vid, image->rid);
-	if (!tmp)
-	{
-        printf("ERROR: Image not found: (%d,%d)\n", image->vid, image->rid);
-        return ERROR_IMAGE_NOT_FOUND;
-	}
-
-	GSList *iterator = NULL;
-    for (iterator = _dnbd3_clients; iterator; iterator = iterator->next)
-    {
-        dnbd3_client_t *client = iterator->data;
-        if (tmp == client->image)
-        {
-        	printf("ERROR: Delete is not allowed, image is in use (%d,%d)\n", tmp->vid, tmp->rid);
-        	return ERROR_IMAGE_IN_USE;
-        }
-    }
-
-    GKeyFile* gkf;
-    gkf = g_key_file_new();
-    if (!g_key_file_load_from_file(gkf, file, G_KEY_FILE_NONE, NULL))
-    {
-        printf("ERROR: Config file not found: %s\n", file);
-        exit(EXIT_FAILURE);
-    }
-
-    g_key_file_remove_group(gkf, tmp->group, NULL);
-    gchar* data = g_key_file_to_data(gkf, NULL, NULL);
-
-    FILE* f = fopen(file,"w");
-    if (f)
-    {
-    	fputs((char*) data, f);
-    	fclose(f);
-        g_free(data);
-        g_key_file_free(gkf);
-        // TODO: unlink image file
-        return 0;
-    }
-    else
-    {
-    	g_free(data);
-    	g_key_file_free(gkf);
-    	printf("ERROR: Config file is not writable: %s\n", file);
-    	return ERROR_CONFIG_FILE_PERMISSIONS;
-    }
-    */
+	 if (image->rid == 0)
+	 {
+	 printf("ERROR: Delete with rid=0 is not allowed\n");
+	 return ERROR_RID;
+	 }
+
+	 dnbd3_image_t* tmp = dnbd3_get_image(image->vid, image->rid);
+	 if (!tmp)
+	 {
+	 printf("ERROR: Image not found: (%d,%d)\n", image->vid, image->rid);
+	 return ERROR_IMAGE_NOT_FOUND;
+	 }
+
+	 GSList *iterator = NULL;
+	 for (iterator = _dnbd3_clients; iterator; iterator = iterator->next)
+	 {
+	 dnbd3_client_t *client = iterator->data;
+	 if (tmp == client->image)
+	 {
+	 printf("ERROR: Delete is not allowed, image is in use (%d,%d)\n", tmp->vid, tmp->rid);
+	 return ERROR_IMAGE_IN_USE;
+	 }
+	 }
+
+	 GKeyFile* gkf;
+	 gkf = g_key_file_new();
+	 if (!g_key_file_load_from_file(gkf, file, G_KEY_FILE_NONE, NULL))
+	 {
+	 printf("ERROR: Config file not found: %s\n", file);
+	 exit(EXIT_FAILURE);
+	 }
+
+	 g_key_file_remove_group(gkf, tmp->group, NULL);
+	 gchar* data = g_key_file_to_data(gkf, NULL, NULL);
+
+	 FILE* f = fopen(file,"w");
+	 if (f)
+	 {
+	 fputs((char*) data, f);
+	 fclose(f);
+	 g_free(data);
+	 g_key_file_free(gkf);
+	 // TODO: unlink image file
+	 return 0;
+	 }
+	 else
+	 {
+	 g_free(data);
+	 g_key_file_free(gkf);
+	 printf("ERROR: Config file is not writable: %s\n", file);
+	 return ERROR_CONFIG_FILE_PERMISSIONS;
+	 }
+	 */
 }
 
 dnbd3_image_t* dnbd3_get_image(char *name_orig, int rid, const char do_lock)
 {
-    dnbd3_image_t *result = NULL, *image;
+	dnbd3_image_t *result = NULL, *image;
 	GSList *iterator;
 	char name[strlen(name_orig) + 1];
 	strcpy(name, name_orig);
 	strtolower(name);
-    if (do_lock) pthread_spin_lock(&_spinlock);
-    for (iterator = _dnbd3_images; iterator; iterator = iterator->next)
-    {
-        image = iterator->data;
-        if (rid != 0) // rid was specified
-        {
-            if (image->rid == rid && strcmp(name, image->low_name) == 0)
-            {
-                result = image;
-                break;
-            }
-        }
-        else // search max. rid available
-        {
-            if (strcmp(name, image->low_name) == 0 && (result == NULL || result->rid < image->rid))
-            {
-                result = image;
-            }
-        }
-    }
-    if (do_lock) pthread_spin_unlock(&_spinlock);
-    return result;
+	if (do_lock)
+		pthread_spin_lock(&_spinlock);
+	for (iterator = _dnbd3_images; iterator; iterator = iterator->next)
+	{
+		image = iterator->data;
+		if (rid != 0) // rid was specified
+		{
+			if (image->rid == rid && strcmp(name, image->low_name) == 0)
+			{
+				result = image;
+				break;
+			}
+		}
+		else // search max. rid available
+		{
+			if (strcmp(name, image->low_name) == 0 && (result == NULL || result->rid < image->rid))
+			{
+				result = image;
+			}
+		}
+	}
+	if (do_lock)
+		pthread_spin_unlock(&_spinlock);
+	return result;
 }
 
 void dnbd3_handle_sigpipe(int signum)
 {
-    memlogf("ERROR: SIGPIPE received!\n");
+	memlogf("ERROR: SIGPIPE received!\n");
 }
 
 void dnbd3_handle_sigterm(int signum)
 {
-    memlogf("INFO: SIGTERM or SIGINT received!\n");
-    dnbd3_cleanup();
+	memlogf("INFO: SIGTERM or SIGINT received!\n");
+	dnbd3_cleanup();
+}
+
+/**
+ * Prepare image to be added to image list. Returns a pointer to a newly allocated image struct
+ * on success, NULL otherwise.
+ * Note: This function calls dnbd3_get_image without locking, so make sure you lock
+ * before calling this function while the server is active.
+ */
+static dnbd3_image_t *prepare_image(char *image_name, int rid, char *image_file, char *cache_file, gchar **servers, gsize num_servers)
+{
+	int j, k;
+	if (image_name == NULL)
+	{
+		memlogf("[ERROR] Null Image-Name");
+		return NULL;
+	}
+	if (!is_valid_imagename(image_name))
+	{
+		memlogf("[ERROR] Invalid image name: '%s'", image_name);
+		return NULL;
+	}
+
+	if (strchr(image_name, '.') == NULL && _local_namespace == NULL)
+	{
+		memlogf("[ERROR] Image '%s' has local name and no default namespace is defined; entry ignored.", image_name);
+		return NULL;
+	}
+
+	// Allocate image struct and zero it out by using g_new0
+	dnbd3_image_t *image = g_new0(dnbd3_image_t, 1);
+	if (image == NULL)
+	{
+		memlogf("[ERROR] Could not allocate dnbd3_image_t while reading config");
+		return NULL;
+	}
+
+	if (strchr(image_name, '/') == NULL)
+	{	// Local image, build global name
+		image->name = calloc(strlen(_local_namespace) + strlen(image_name) + 2, sizeof(char));
+		sprintf(image->name, "%s/%s", _local_namespace, image_name);
+	}
+	else
+	{
+		image->name = strdup(image_name);
+	}
+
+	if (dnbd3_get_image(image->name, rid, 0))
+	{
+		memlogf("[ERROR] Duplicate image in config: '%s' rid:%d", image->name, rid);
+		goto error;
+	}
+
+	image->low_name = strdup(image->name);
+	strtolower(image->low_name);
+
+	image->rid = rid;
+	const char relayed = (image_file == NULL || image_file == '\0');
+
+	if (relayed)	// Image is relayed (this server acts as proxy)
+	{
+		if (strchr(image_name, '/') == NULL)
+		{
+			memlogf("[ERROR] Relayed image without global name in config: '%s'", image_name);
+			goto error;
+		}
+		if (cache_file && *cache_file)
+			image->cache_file = strdup(cache_file);
+	}
+	else	// Image is a local one, open file to get size
+	{
+		image->file = strdup(image_file);
+		int fd = open(image->file, O_RDONLY);
+		if (fd < 0)
+		{
+			memlogf("[ERROR] Image file not found: '%s'", image->file);
+			goto error;
+		}
+		const off_t size = lseek(fd, 0, SEEK_END);
+		if (size <= 0)
+		{
+			memlogf("[ERROR] File '%s' of image '%s' has size '%lld'. Image ignored.", image->file, image->name, (long long)size);
+			goto error;
+		}
+		image->filesize = (uint64_t)size;
+		if (image->filesize & 4095)
+		{
+			memlogf("[WARNING] Size of image '%s' is not a multiple of 4096. Last incomplete block will be ignored!",
+				image->file);
+			image->filesize &= ~(uint64_t)4095;
+		}
+		close(fd);
+		image->working = 1;
+	}
+
+	// A list of servers that are known to also host or relay this image
+	if (servers)
+		for (k = 0, j = 0; j < MIN(num_servers, NUMBER_SERVERS); ++j)
+		{
+			if (parse_address(servers[j], &(image->servers[k].hostaddrtype), image->servers[k].hostaddr,
+			   &(image->servers[k].port)))
+			{
+				++k;
+				continue;
+			}
+			image->servers[k].hostaddrtype = 0;
+		}
+
+	if (image->cache_file)
+	{
+		// Determine size of cached image
+		int fd = open(image->cache_file, O_RDONLY);
+		if (fd >= 0)
+		{
+			const off_t size = lseek(fd, 0, SEEK_END);
+			if (size > 0)
+				image->filesize = (uint64_t)size;
+			close(fd);
+		}
+		if (image->filesize & 4095)
+		{	// Cache files should always be truncated to 4kib boundaries already
+			memlogf("[WARNING] Size of cache file '%s' is not a multiple of 4096. Something's fishy!", image->cache_file);
+			image->filesize = 0;
+		}
+		else if (image->filesize > 0)
+		{
+			const size_t map_len_bytes = (image->filesize + (1 << 15) - 1) >> 15;
+			image->cache_map = calloc(map_len_bytes, sizeof(uint8_t));
+			// read cache map from file
+			// one byte in the map covers 8 4kib blocks, so 32kib per byte
+			// "+ (1 << 15) - 1" is required to account for the last bit of
+			// the image that is smaller than 32kib
+			// this would be the case whenever the image file size is not a
+			// multiple of 32kib (= the number of blocks is not dividable by 8)
+			// ie: if the image is 49152 bytes and you do 49152 >> 15 you get 1,
+			// but you actually need 2 bytes to have a complete cache map
+			char tmp[strlen(image->cache_file) + 5];
+			strcpy(tmp, image->cache_file);
+			strcat(tmp, ".map");
+			fd = open(tmp, O_RDONLY); // TODO: Check if map file has expected size
+			if (fd >= 0)
+			{
+				read(fd, image->cache_map, map_len_bytes * sizeof(uint8_t));
+				close(fd);
+				// If the whole image is cached, mark it as working right away without waiting for an upstream server
+				image->working = 1;
+				for (j = 0; j < map_len_bytes - 1; ++j)
+				{
+					if (image->cache_map[j] != 0xFF)
+					{
+						image->working = 0;
+						break;
+					}
+				}
+				const int blocks_in_last_byte = (image->filesize >> 12) & 7;
+				uint8_t last_byte = 0;
+				if (blocks_in_last_byte == 0)
+					last_byte = 0xFF;
+				else
+					for (j = 0; j < blocks_in_last_byte; ++j)
+						last_byte = (last_byte << 1) | 1;
+				if ((image->cache_map[map_len_bytes - 1] & last_byte) != last_byte)
+					image->working = 0;
+				else
+					memlogf("[INFO] Instantly publishing relayed image '%s' because the local cache copy is complete", image->name);
+			}
+
+			/*
+			 // TODO: Do this as soon as a connection to a upstream server is established
+			 // open cache file
+			 fd = open(_images[i].cache_file, O_WRONLY | O_CREAT, S_IRUSR | S_IWUSR);
+			 if (fd < 1)
+			 memlogf("ERROR: Could't create cache file '%s'", _images[i].cache_file);
+
+			 if (_images[i].filesize != lseek(fd, 0, SEEK_END))
+			 fallocate(fd, 0, 0, _images[i].filesize);
+
+			 close(fd);
+			 */
+		}
+	} // end cache_file handling
+	return image;
+error:
+	// Free stuff. Some pointers might be zero, but calling free() on those is safe.
+	free(image->cache_map);
+	free(image->name);
+	free(image->low_name);
+	free(image->file);
+	free(image->cache_file);
+	g_free(image);
+	return NULL;
 }