Added disk trim function

src/disk.c

@@ -5,6 +5,7 @@
 #include <errno.h>
 #include <unistd.h>
 #include <sys/stat.h>
+#include <stdio.h>
 #include <json-c/json.h>
 
 Result create_root_disk(const char* path, uint64_t size, mode_t permissions) {
@@ -98,6 +99,82 @@ Result create_backed_disk(const char* path, const char* backing_disk, mode_t per
 	return SUCCESS;
 }
 
+Result trim_disk(const char* path) {
+	char* tmp_path;
+	Result result = format(&tmp_path, "%s.tmp", path);
+	if (result != SUCCESS)
+		return result;
+
+	DiskInfo info;
+	result = get_disk_info(path, &info);
+	if (result != SUCCESS) {
+		free(tmp_path);
+		return result;
+	}
+
+	// Create the trimmed disk
+	int exit_code;
+	char* stderr_buffer = NULL;
+
+	if (info.backing_file == NULL) {
+		// If the disk is not backed, we can simply convert it to a new disk
+		result = run_executable(&exit_code, NULL, &stderr_buffer, "qemu-img", "convert", "-f", "qcow2", "-O", "qcow2", path, tmp_path, NULL);
+	} else {
+		// If the disk is backed, we need to specify the backing file
+		char* backing_disk_arg;
+		result = format(&backing_disk_arg, "backing_file=%s", info.backing_file);
+		if (result != SUCCESS) {
+			free(tmp_path);
+			free_disk_info(&info);
+			return result;
+		}
+
+		result = run_executable(&exit_code, NULL, &stderr_buffer, "qemu-img", "convert", "-f", "qcow2", "-F", "qcow2", "-O", "qcow2", "-o", backing_disk_arg, path, tmp_path, NULL);
+
+		free(backing_disk_arg);
+	}
+
+	// Free the disk info as it is no longer needed
+	free_disk_info(&info);
+
+	if (result != SUCCESS) {
+		free(tmp_path);
+		free(stderr_buffer);
+		return result;
+	}
+
+	// Check the exit code
+	if (exit_code != EXIT_SUCCESS) {
+		if (stderr_buffer == NULL)
+			log_message(LOG_LEVEL_ERROR, "Failed to trim the disk '%s'.", path);
+		else {
+			// Remove newlines from the error message
+			for (size_t i = 0; i < strlen(stderr_buffer); i++)
+				if (stderr_buffer[i] == '\n')
+					stderr_buffer[i] = ' ';
+
+			log_message(LOG_LEVEL_ERROR, "Failed to trim the disk '%s' (%s).", path, stderr_buffer);
+			free(stderr_buffer);
+		}
+
+		free(tmp_path);
+		return FAILURE;
+	}
+
+	// Replace the original disk with the trimmed disk
+	if (rename(tmp_path, path) != 0) {
+		log_message(LOG_LEVEL_ERROR, "Failed to replace the disk '%s' with the trimmed disk '%s' (%s).", path, tmp_path, strerror(errno));
+
+		unlink(tmp_path);
+		free(tmp_path);
+		return FAILURE;
+	}
+
+	// Free the temporary path
+	free(tmp_path);
+	return SUCCESS;
+}
+
 Result rebase_disk(const char* path, const char* backing_disk) {
 	// Rebase the disk
 	int exit_code;

src/entry.h

@@ -56,3 +56,5 @@ Result clear_entries(void);
 /// @param out_path The pointer to the output path string. The caller is responsible for freeing the memory.
 /// @return The result of the operation.
 Result get_entry_disk_path(const char* entry_id, char** out_path);
+
+// TODO: Implement a function to reserve disk space to avoid running out of space while the sandbox is running.

src/sandbox.c

@@ -127,6 +127,7 @@ int command_add_backing(int argc, char* argv[]) {
 		return EXIT_FAILURE;
 	}
 
+	trim_disk("test2");
 	// TODO: Call add_backing
 
 	return EXIT_SUCCESS;