Implemented some more functions

src/backing.c

@@ -7,6 +7,8 @@
 #include <stdlib.h>
 #include <string.h>
 #include <unistd.h>
+#include <dirent.h>
+#include <errno.h>
 #include <sys/stat.h>
 
 char* get_backings_path(void) {
@@ -22,10 +24,16 @@ bool is_valid_backing_name(const char* name) {
 	if (length == 0)
 		return false;
 
-	// Check that the name is a number (the number is the timestamp of the backing disk creation)
+	// Check that the name starts with a number, corresponding to the timestamp of the backing disk creation
+	size_t timestamp_length = 0;
 	for (size_t i = 0; i < length; i++)
-		if (name[i] < '0' || name[i] > '9')
-			return false;
+		if (name[i] >= '0' && name[i] <= '9')
+			timestamp_length++;
+		else
+			break;
+
+	if (timestamp_length == 0)
+		return false;
 
 	return true;
 }
@@ -65,7 +73,112 @@ bool backing_exists(const char* backing) {
 	return true;
 }
 
-uint64_t get_backing_creation_time(const char* backing) {
-	// A valid backing name is a number, corresponding to the timestamp of the backing disk creation
-	return strtoull(backing, NULL, 10);
+char** list_backings(void) {
+	char* path = get_backings_path();
+	if (path == NULL)
+		return NULL;
+
+	// Open the directory
+	DIR* dir = opendir(path);
+	if (dir == NULL) {
+		log_msg(LOG_ERROR, "Failed to open directory '%s' (%s).", path, strerror(errno));
+		free(path);
+		return NULL;
+	}
+	free(path);
+
+	// Count the number of entries
+	size_t count = 0;
+	struct dirent* entry;
+	while ((entry = readdir(dir)) != NULL)
+		if (is_valid_backing_name(entry->d_name) && backing_exists(entry->d_name))
+			count++;
+
+	// Allocate the array of strings
+	char** backings = malloc((count + 1) * sizeof(char*));
+	if (backings == NULL) {
+		log_msg(LOG_ERROR, "Failed to allocate memory for the backings array.");
+		closedir(dir);
+		return NULL;
+	}
+
+	// Fill the array of strings
+	rewinddir(dir);
+	size_t index = 0;
+	while ((entry = readdir(dir)) != NULL) {
+		if (is_valid_backing_name(entry->d_name) && backing_exists(entry->d_name)) {
+			backings[index] = strdup(entry->d_name);
+			if (backings[index] == NULL) {
+				log_msg(LOG_ERROR, "Failed to allocate memory for the backing name.");
+				for (size_t i = 0; i < index; i++)
+					free(backings[i]);
+				free(backings);
+				closedir(dir);
+				return NULL;
+			}
+			index++;
+		}
+	}
+
+	// Terminate the array of strings
+	backings[count] = NULL;
+
+	// Close the directory
+	closedir(dir);
+
+	return backings;
+}
+
+uint64_t get_backing_creation_time(const char* backing) {
+	size_t length = strlen(backing);
+	size_t timestamp_length = 0;
+
+	// Find the length of the timestamp
+	for (size_t i = 0; i < length; i++)
+		if (backing[i] >= '0' && backing[i] <= '9')
+			timestamp_length++;
+		else
+			break;
+
+	// Extract the timestamp
+	char* timestamp = strndup(backing, timestamp_length);
+	if (timestamp == NULL)
+		return 0;
+
+	// Convert the timestamp to a number
+	uint64_t creation_time = strtoull(timestamp, NULL, 10);
+
+	// Free the timestamp
+	free(timestamp);
+
+	return creation_time;
+}
+
+char* find_latest_backing(void) {
+	char** backings = list_backings();
+	if (backings == NULL)
+		return NULL;
+
+	// Find the latest backing disk
+	char* latest_backing = NULL;
+	uint64_t latest_time = 0;
+
+	for (size_t i = 0; backings[i] != NULL; i++) {
+		uint64_t time = get_backing_creation_time(backings[i]);
+		if (time >= latest_time) {
+			latest_time = time;
+			latest_backing = backings[i];
+		}
+	}
+
+	// Duplicate the latest backing disk
+	if (latest_backing != NULL)
+		latest_backing = strdup(latest_backing);
+
+	// Free the backings
+	for (size_t i = 0; backings[i] != NULL; i++)
+		free(backings[i]);
+	free(backings);
+
+	return latest_backing;
 }