Remove need for extra bytes for remote consoles

Remote consoles are not always attached to a `conmon` process.  Don't bother
adding the "pre-byte" for the pipe, just add a `write()` system call for that
byte.  We also remove the null termination since all the operations must be done
by count (null bytes can be read from the pipe).

Signed-off-by: Peter Portante <peter.portante@redhat.com>

Author: portante

src/conn_sock.c

@@ -355,17 +355,23 @@ void schedule_main_stdin_write()
 	schedule_local_sock_write(&local_mainfd_stdin);
 }
 
-void write_back_to_remote_consoles(char *buf, int len)
+void write_back_to_remote_consoles(stdpipe_t pipe, char *buf, int len)
 {
 	if (local_mainfd_stdin.readers == NULL)
 		return;
 
 	for (int i = local_mainfd_stdin.readers->len; i > 0; i--) {
 		struct remote_sock_s *remote_sock = g_ptr_array_index(local_mainfd_stdin.readers, i - 1);
 
-		if (remote_sock->writable && write_all(remote_sock->fd, buf, len) < 0) {
-			nwarn("Failed to write to remote console socket");
-			remote_sock_shutdown(remote_sock, SHUT_WR);
+		if (remote_sock->writable) {
+			if (write_all(remote_sock->fd, &pipe, 1) < 0) {
+				nwarn("Failed to write to remote console socket");
+				remote_sock_shutdown(remote_sock, SHUT_WR);
+			}
+			if (write_all(remote_sock->fd, buf, len) < 0) {
+				nwarn("Failed to write to remote console socket");
+				remote_sock_shutdown(remote_sock, SHUT_WR);
+			}
 		}
 	}
 }

src/conn_sock.h

@@ -3,6 +3,7 @@
 
 #include <glib.h>   /* gboolean */
 #include "config.h" /* CONN_SOCK_BUF_SIZE */
+#include "utils.h"  /* stdpipe_t */
 
 #define SOCK_TYPE_CONSOLE 1
 #define SOCK_TYPE_NOTIFY 2
@@ -52,7 +53,7 @@ char *setup_seccomp_socket(const char *socket);
 char *setup_attach_socket(void);
 void setup_notify_socket(char *);
 void schedule_main_stdin_write();
-void write_back_to_remote_consoles(char *buf, int len);
+void write_back_to_remote_consoles(stdpipe_t pipe, char *buf, int len);
 void close_all_readers();
 
 #endif // CONN_SOCK_H

src/ctr_stdio.c

@@ -112,12 +112,7 @@ static void drain_log_buffers(stdpipe_t pipe)
 
 static bool read_stdio(int fd, stdpipe_t pipe, gboolean *eof)
 {
-	/* We use two extra bytes. One at the start, which we don't read into, instead
-	   we use that for marking the pipe when we write to the attached socket.
-	   One at the end to guarantee a null-terminated buffer for journald logging*/
-
-	char real_buf[STDIO_BUF_SIZE + 2];
-	char *buf = real_buf + 1;
+	char buf[STDIO_BUF_SIZE];
 	ssize_t num_read = 0;
 
 	if (eof)
@@ -143,15 +138,11 @@ static bool read_stdio(int fd, stdpipe_t pipe, gboolean *eof)
 		nwarnf("stdio_input read failed: %m");
 		return false;
 	} else {
-		// Always null terminate the buffer, just in case.
-		buf[num_read] = '\0';
-
 		bool written = write_to_logs(pipe, buf, num_read);
 		if (!written)
 			return false;
 
-		real_buf[0] = pipe;
-		write_back_to_remote_consoles(real_buf, num_read + 1);
+		write_back_to_remote_consoles(pipe, buf, num_read);
 		return true;
 	}
 }