console: add "write_logfile" to console_log struct

src/lxc/commands.c

@@ -994,6 +994,7 @@ int lxc_cmd_console_log(const char *name, const char *lxcpath,
 	data.clear = log->clear;
 	data.read = log->read;
 	data.read_max = *log->read_max;
+	data.write_logfile = log->write_logfile;
 
 	cmd.req.cmd = LXC_CMD_CONSOLE_LOG;
 	cmd.req.data = &data;
@@ -1006,7 +1007,7 @@ int lxc_cmd_console_log(const char *name, const char *lxcpath,
 	/* There is nothing to be read from the buffer. So clear any values we
 	 * where passed to clearly indicate to the user that nothing went wrong.
 	 */
-	if (cmd.rsp.ret == -ENODATA || cmd.rsp.ret == -EFAULT) {
+	if (cmd.rsp.ret == -ENODATA || cmd.rsp.ret == -EFAULT || cmd.rsp.ret == -ENOENT) {
 		*log->read_max = 0;
 		log->data = NULL;
 	}
@@ -1027,6 +1028,7 @@ static int lxc_cmd_console_log_callback(int fd, struct lxc_cmd_req *req,
 	struct lxc_cmd_rsp rsp;
 	uint64_t logsize = handler->conf->console.log_size;
 	const struct lxc_cmd_console_log *log = req->data;
+	struct lxc_console *console = &handler->conf->console;
 	struct lxc_ringbuf *buf = &handler->conf->console.ringbuf;
 
 	rsp.ret = -EFAULT;
@@ -1043,10 +1045,21 @@ static int lxc_cmd_console_log_callback(int fd, struct lxc_cmd_req *req,
 		rsp.datalen = log->read_max;
 
 	/* there's nothing to read */
+	rsp.ret = -ENODATA;
 	if (log->read && (buf->r_off == buf->w_off))
-		rsp.ret = -ENODATA;
-	else
-		rsp.ret = 0;
+		goto out;
+
+	if (log->write_logfile && rsp.datalen > 0) {
+		rsp.ret = -ENOENT;
+		if (!console->log_path)
+			goto out;
+
+		rsp.ret = lxc_console_write_ringbuffer(console);
+		if (rsp.ret < 0)
+			goto out;
+	}
+
+	rsp.ret = 0;
 
 	if (log->clear)
 		lxc_ringbuf_clear(buf);

src/lxc/commands.h

@@ -85,6 +85,7 @@ struct lxc_cmd_console_log {
 	bool clear;
 	bool read;
 	uint64_t read_max;
+	bool write_logfile;
 
 };
 

src/lxc/console.c

@@ -512,7 +512,7 @@ out:
 	return ret;
 }
 
-static int lxc_console_write_ringbuffer(struct lxc_console *console)
+int lxc_console_write_ringbuffer(struct lxc_console *console)
 {
 	int fd;
 	char *r_addr;
@@ -527,10 +527,10 @@ static int lxc_console_write_ringbuffer(struct lxc_console *console)
 	if (used == 0)
 		return 0;
 
-	fd = lxc_unpriv(open(console->log_path, O_CLOEXEC | O_RDWR | O_CREAT, 0600));
+	fd = lxc_unpriv(open(console->log_path, O_CLOEXEC | O_RDWR | O_CREAT | O_TRUNC, 0600));
 	if (fd < 0) {
 		SYSERROR("Failed to open console log file \"%s\"", console->log_path);
-		return -1;
+		return -EIO;
 	}
 	DEBUG("Using \"%s\" as console log file", console->log_path);
 
@@ -538,7 +538,7 @@ static int lxc_console_write_ringbuffer(struct lxc_console *console)
 	ret = lxc_write_nointr(fd, r_addr, used);
 	close(fd);
 	if (ret < 0)
-		return -1;
+		return -EIO;
 
 	return 0;
 }

src/lxc/console.h

@@ -215,4 +215,6 @@ extern int lxc_console_cb_sigwinch_fd(int fd, uint32_t events, void *cbdata,
  */
 extern void lxc_console_sigwinch_fini(struct lxc_tty_state *ts);
 
+extern int lxc_console_write_ringbuffer(struct lxc_console *console);
+
 #endif

src/lxc/lxccontainer.c

@@ -523,11 +523,15 @@ static int do_lxcapi_console_log(struct lxc_container *c, struct lxc_console_log
 	ret = lxc_cmd_console_log(c->name, do_lxcapi_get_config_path(c), log);
 	if (ret < 0) {
 		if (ret == -ENODATA)
-			NOTICE("%s - The console log is empty", strerror(-ret));
+			NOTICE("The console log is empty");
 		else if (ret == -EFAULT)
-			NOTICE("%s - The container does not have a console log configured", strerror(-ret));
+			NOTICE("The container does not keep a console log");
+		else if (ret == -ENOENT)
+			NOTICE("The container does not keep a console log file");
+		else if (ret == -EIO)
+			NOTICE("Failed to write console log to log file");
 		else
-			ERROR("%s - Failed to retrieve console log", strerror(-ret));
+			ERROR("Failed to retrieve console log");
 	}
 
 	return ret;

src/lxc/lxccontainer.h

@@ -953,6 +953,12 @@ struct lxc_console_log {
 	 * "data" is invalid.
 	 */
 	char *data;
+
+	/* If a console log file was specified this flag indicates whether the
+	 * contents of the ringbuffer should be written to the logfile when a
+	 * request is sent to the ringbuffer.
+	 */
+	bool write_logfile;
 };
 
 /*!