added some really ugly code to allow errors to propogate to

clients when writing to a rsync server

it works like this:

- we have an extra pipe from the receiver to the generator
- the server always runs with multiplexing on
- errors from the generator go down the multiplexed connection
- errors from the receiver go over the pipe, and from there to
  the multiplexed conn

it required some incredibly ugly code. damn.

clientserver.c

@@ -101,7 +101,7 @@ int start_socket_client(char *host, char *path, int argc, char *argv[])
 	}
 	io_printf(fd,"\n");
 
-	if (remote_version > 17 && !am_sender)
+	if (remote_version >= 22 || (remote_version > 17 && !am_sender))
 		io_start_multiplex_in(fd);
 
 	return client_run(fd, fd, -1, argc, argv);
@@ -316,9 +316,17 @@ static int rsync_module(int fd, int i)
 	argp = argv + optind;
 	optind = 0;
 
-	if (remote_version > 17 && am_sender)
+	if (remote_version >= 22 || (remote_version > 17 && am_sender))
 		io_start_multiplex_out(fd);
 
+	if (read_only) {
+		extern int am_sender;
+		if (!am_sender) {
+			rprintf(FERROR,"ERROR: module is read only\n");
+			return -1;
+		}
+	}
+
 	if (!ret) {
 		option_error();
 	}

io.c

@@ -38,6 +38,8 @@ extern int io_timeout;
 extern struct stats stats;
 
 static int buffer_f_in = -1;
+static int io_error_fd = -1;
+static int in_read_check;
 
 void setup_readbuffer(int f_in)
 {
@@ -64,6 +66,28 @@ static void check_timeout(void)
 	}
 }
 
+/* setup the fd used to propogate errors */
+void io_set_error_fd(int fd)
+{
+	io_error_fd = fd;
+}
+
+/* read some data from the error fd and write it to FERROR */
+static void read_error_fd(void)
+{
+	char buf[200];
+	int n;
+	int fd = io_error_fd;
+	io_error_fd = -1;
+
+	n = read(fd, buf, sizeof(buf)-1);
+	if (n > 0) {
+		rwrite(FERROR, buf, n);
+	}
+
+	io_error_fd = fd;
+}
+
 
 static char *read_buffer;
 static char *read_buffer_p;
@@ -86,17 +110,34 @@ static int read_timeout(int fd, char *buf, int len)
 	while (ret == 0) {
 		fd_set fds;
 		struct timeval tv;
+		int fd_count = fd+1;
 
 		FD_ZERO(&fds);
 		FD_SET(fd, &fds);
+		if (io_error_fd != -1) {
+			FD_SET(io_error_fd, &fds);
+			if (io_error_fd > fd) fd_count = io_error_fd+1;
+		}
+
 		tv.tv_sec = io_timeout?io_timeout:SELECT_TIMEOUT;
 		tv.tv_usec = 0;
 
-		if (select(fd+1, &fds, NULL, NULL, &tv) != 1) {
+		errno = 0;
+
+		if (select(fd_count, &fds, NULL, NULL, &tv) < 1) {
+			if (errno == EBADF) {
+				exit_cleanup(RERR_SOCKETIO);
+			}
 			check_timeout();
 			continue;
 		}
 
+		if (io_error_fd != -1 && FD_ISSET(io_error_fd, &fds)) {
+			read_error_fd();
+		}
+
+		if (!FD_ISSET(fd, &fds)) continue;
+
 		n = read(fd, buf, len);
 
 		if (n > 0) {
@@ -121,7 +162,7 @@ static int read_timeout(int fd, char *buf, int len)
 		}
 
 		/* this prevents us trying to write errors on a dead socket */
-		io_multiplexing_out = 0;
+		io_multiplexing_close();
 
 		rprintf(FERROR,"read error: %s\n", strerror(errno));
 		exit_cleanup(RERR_STREAMIO);
@@ -190,6 +231,8 @@ static int read_unbuffered(int fd, char *buf, int len)
 
 		rprintf(tag,"%s", line);
 		remaining = 0;
+
+		if (in_read_check) break;
 	}
 
 	return ret;
@@ -203,6 +246,8 @@ static int read_unbuffered(int fd, char *buf, int len)
 static void read_check(int f)
 {
 	int n = 8192;
+	
+	in_read_check = 1;
 
 	if (f == -1) return;
 
@@ -227,6 +272,8 @@ static void read_check(int f)
 
 	n = read_unbuffered(f,read_buffer+read_buffer_len,n);
 	read_buffer_len += n;
+
+	in_read_check = 0;
 }
 
 
@@ -335,7 +382,7 @@ static void writefd_unbuffered(int fd,char *buf,int len)
 		FD_ZERO(&w_fds);
 		FD_ZERO(&r_fds);
 		FD_SET(fd,&w_fds);
-		fd_count = fd+1;
+		fd_count = fd;
 
 		if (!no_flush_read) {
 			reading = (buffer_f_in != -1);
@@ -343,19 +390,30 @@ static void writefd_unbuffered(int fd,char *buf,int len)
 
 		if (reading) {
 			FD_SET(buffer_f_in,&r_fds);
-			if (buffer_f_in > fd) 
-				fd_count = buffer_f_in+1;
+			if (buffer_f_in > fd_count) 
+				fd_count = buffer_f_in;
+		}
+
+		if (io_error_fd != -1) {
+			FD_SET(io_error_fd,&r_fds);
+			if (io_error_fd > fd_count) 
+				fd_count = io_error_fd;
 		}
 
 		tv.tv_sec = io_timeout?io_timeout:SELECT_TIMEOUT;
 		tv.tv_usec = 0;
 
-		count = select(fd_count,
-			       reading?&r_fds:NULL,
+		errno = 0;
+
+		count = select(fd_count+1,
+			       (reading || io_error_fd != -1)?&r_fds:NULL,
 			       &w_fds,NULL,
 			       &tv);
 
 		if (count <= 0) {
+			if (errno == EBADF) {
+				exit_cleanup(RERR_SOCKETIO);
+			}
 			check_timeout();
 			continue;
 		}
@@ -364,6 +422,10 @@ static void writefd_unbuffered(int fd,char *buf,int len)
 			read_check(buffer_f_in);
 		}
 
+		if (io_error_fd != -1 && FD_ISSET(io_error_fd, &r_fds)) {
+			read_error_fd();
+		}
+
 		if (FD_ISSET(fd, &w_fds)) {
 			int ret, n = len-total;
 			
@@ -433,7 +495,7 @@ static void writefd(int fd,char *buf,int len)
 {
 	stats.total_written += len;
 
-	if (!io_buffer) {
+	if (!io_buffer || fd != multiplex_out_fd) {
 		writefd_unbuffered(fd, buf, len);
 		return;
 	}
@@ -559,7 +621,7 @@ void io_start_multiplex_in(int fd)
 	io_multiplexing_in = 1;
 }
 
-/* write an message to the error stream */
+/* write an message to the multiplexed error stream */
 int io_multiplex_write(int f, char *buf, int len)
 {
 	if (!io_multiplexing_out) return 0;
@@ -575,6 +637,20 @@ int io_multiplex_write(int f, char *buf, int len)
 	return 1;
 }
 
+/* write a message to the special error fd */
+int io_error_write(int f, char *buf, int len)
+{
+	if (f == -1) return 0;
+	writefd_unbuffered(f, buf, len);
+	return 1;
+}
+
+/* stop output multiplexing */
+void io_multiplexing_close(void)
+{
+	io_multiplexing_out = 0;
+}
+
 void io_close_input(int fd)
 {
 	buffer_f_in = -1;

log.c

@@ -24,7 +24,7 @@
 #include "rsync.h"
 
 static FILE *logfile;
-
+static int log_error_fd = -1;
 
 static void logit(int priority, char *buf)
 {
@@ -77,14 +77,18 @@ void log_open(void)
 	logit(LOG_INFO,"rsyncd started\n");
 #endif
 }
-		
 
-/* this is the rsync debugging function. Call it with FINFO, FERROR or FLOG */
- void rprintf(int fd, const char *format, ...)
+/* setup the error file descriptor - used when we are a server
+   that is receiving files */
+void set_error_fd(int fd)
+{
+	log_error_fd = fd;
+}
+
+/* this is the underlying (unformatted) rsync debugging function. Call
+   it with FINFO, FERROR or FLOG */
+void rwrite(int fd, char *buf, int len)
 {
-	va_list ap;  
-	char buf[1024];
-	int len;
 	FILE *f=NULL;
 	extern int am_daemon;
 	extern int quiet;
@@ -92,14 +96,8 @@ void log_open(void)
 
 	if (quiet != 0 && fd == FINFO) return;
 
-	va_start(ap, format);
-	len = vslprintf(buf, sizeof(buf), format, ap);
-	va_end(ap);
-
 	if (len < 0) exit_cleanup(RERR_MESSAGEIO);
 
-	if (len > sizeof(buf)-1) exit_cleanup(RERR_MESSAGEIO);
-
 	buf[len] = 0;
 
 	if (fd == FLOG) {
@@ -117,7 +115,9 @@ void log_open(void)
 		depth++;
 
 		log_open();
-		if (!io_multiplex_write(fd, buf, strlen(buf))) {
+
+		if (!io_error_write(log_error_fd, buf, strlen(buf)) &&
+		    !io_multiplex_write(fd, buf, strlen(buf))) {
 			logit(priority, buf);
 		}
 
@@ -143,6 +143,23 @@ void log_open(void)
 
 	if (buf[len-1] == '\r' || buf[len-1] == '\n') fflush(f);
 }
+		
+
+/* this is the rsync debugging function. Call it with FINFO, FERROR or FLOG */
+ void rprintf(int fd, const char *format, ...)
+{
+	va_list ap;  
+	char buf[1024];
+	int len;
+
+	va_start(ap, format);
+	len = vslprintf(buf, sizeof(buf), format, ap);
+	va_end(ap);
+
+	if (len > sizeof(buf)-1) exit_cleanup(RERR_MESSAGEIO);
+
+	rwrite(fd, buf, len);
+}
 
 void rflush(int fd)
 {

main.c

@@ -278,6 +278,7 @@ static int do_recv(int f_in,int f_out,struct file_list *flist,char *local_name)
 	int pid;
 	int status=0;
 	int recv_pipe[2];
+	int error_pipe[2];
 	extern int preserve_hard_links;
 
 	if (preserve_hard_links)
@@ -287,13 +288,25 @@ static int do_recv(int f_in,int f_out,struct file_list *flist,char *local_name)
 		rprintf(FERROR,"pipe failed in do_recv\n");
 		exit_cleanup(RERR_SOCKETIO);
 	}
+
+	if (pipe(error_pipe) < 0) {
+		rprintf(FERROR,"error pipe failed in do_recv\n");
+		exit_cleanup(RERR_SOCKETIO);
+	}
   
 	io_flush();
 
 	if ((pid=do_fork()) == 0) {
 		close(recv_pipe[0]);
+		close(error_pipe[0]);
 		if (f_in != f_out) close(f_out);
 
+		/* we can't let two processes write to the socket at one time */
+		io_multiplexing_close();
+
+		/* set place to send errors */
+		set_error_fd(error_pipe[1]);
+
 		recv_files(f_in,flist,local_name,recv_pipe[1]);
 		report(f_in);
 
@@ -302,11 +315,14 @@ static int do_recv(int f_in,int f_out,struct file_list *flist,char *local_name)
 	}
 
 	close(recv_pipe[1]);
+	close(error_pipe[1]);
 	io_close_input(f_in);
 	if (f_in != f_out) close(f_in);
 
 	io_start_buffering(f_out);
 
+	io_set_error_fd(error_pipe[0]);
+
 	generate_files(f_out,flist,local_name,recv_pipe[0]);
 
 	io_flush();

receiver.c

@@ -468,7 +468,7 @@ int recv_files(int f_in,struct file_list *flist,char *local_name,int f_gen)
 		finish_transfer(fname, fnametmp, file);
 
 		cleanup_disable();
-				
+
 		if (!recv_ok) {
 			if (csum_length == SUM_LENGTH) {
 				rprintf(FERROR,"ERROR: file corruption in %s. File changed during transfer?\n",

rsync.h

@@ -47,7 +47,7 @@
 #define SAME_TIME (1<<7)
 
 /* update this if you make incompatible changes */
-#define PROTOCOL_VERSION 21
+#define PROTOCOL_VERSION 22
 #define MIN_PROTOCOL_VERSION 11
 #define MAX_PROTOCOL_VERSION 30