Add write file descriptors to main select() call.

When running rsync on an existing directory structure, rsync may be too
busy to read everything that qarsh is writing to it from the remote
rsync daemon.  Create a buffer for each of stdin, stdout, and stderr
and keep it around until we are able to write it, holding off further
reads until it can be written.  We still don't handle partial writes.

1 files changed, 35 insertions, 21 deletions

diff --git a/qarsh.c b/qarsh.c
index 404a7fa..e1380c3 100644
--- a/qarsh.c
+++ b/qarsh.c
@@ -174,13 +174,13 @@ int
 run_remote_cmd(char *cmdline)
 {
 	struct qa_packet *qp;
-	char *buf;
-	int bufsize;
 	int rc;
 	int p_in, p_out, p_err;  /* Port numbers */
 	int l_in, l_out, l_err;  /* listening sockets */
 	int c_in, c_out, c_err;  /* client sockets */
-	fd_set readfds, testfds;
+	char *b_in, *b_out, *b_err; /* Buffers */
+	int z_in, z_out, z_err; /* size in buffer */
+	fd_set readfds, testfds, testwds;
 	int nset;
 	struct sockaddr_in caddr;
 	socklen_t clen;
@@ -265,8 +265,10 @@ run_remote_cmd(char *cmdline)
 			"fcntl stdin O_NONBLOCK failed, %d: %s\n", 
 			errno, strerror(errno));
 	}
-	buf = malloc(QARSH_BUFSIZE);
-	memset(buf, 0, QARSH_BUFSIZE);
+	/* allocate one buffer for each stream */
+	b_in = malloc(QARSH_BUFSIZE); memset(b_in, 0, QARSH_BUFSIZE); z_in = 0;
+	b_out = malloc(QARSH_BUFSIZE); memset(b_out, 0, QARSH_BUFSIZE); z_out = 0;
+	b_err = malloc(QARSH_BUFSIZE); memset(b_err, 0, QARSH_BUFSIZE); z_err = 0;
 
 	hbeat(qarsh_hb);
 	cmd_finished = 0;
@@ -279,9 +281,14 @@ run_remote_cmd(char *cmdline)
 			timeout.tv_nsec = 0;
 		}
 		testfds = readfds;
-		memset(buf, 0, QARSH_BUFSIZE);
-
-		nset = pselect(FD_SETSIZE, &testfds, NULL, NULL, &timeout, 
+		FD_ZERO(&testwds);
+		/* If there are things to write, set the write bit and clear the read */
+		/* We use one buffer per channel and we don't want to overwrite it */
+		if (z_in) { FD_CLR(fileno(stdin), &testfds); FD_SET(c_in, &testwds); }
+		if (z_out) { FD_CLR(c_out, &testfds); FD_SET(fileno(stdout), &testwds); }
+		if (z_err) { FD_CLR(c_err, &testfds); FD_SET(fileno(stderr), &testwds); }
+
+		nset = pselect(FD_SETSIZE, &testfds, &testwds, NULL, &timeout, 
 				&pselect_sigmask);
 
 		if (nset == 0) {
@@ -313,10 +320,8 @@ run_remote_cmd(char *cmdline)
 			hbeat_setstate(qarsh_hb, HOST_ALIVE);
 			
 			if (nset && FD_ISSET(fileno(stdin), &testfds)) {
-				bufsize = read(fileno(stdin), buf, QARSH_BUFSIZE);
-				if (bufsize > 0) {
-					write(c_in, buf, bufsize);
-				} else if (bufsize == 0) {
+				z_in = read(fileno(stdin), b_in, QARSH_BUFSIZE);
+				if (z_in == 0) {
 					FD_CLR(fileno(stdin), &readfds);
 					close(fileno(stdin));
 					close(c_in);
@@ -324,28 +329,37 @@ run_remote_cmd(char *cmdline)
 				}
 				nset--;
 			}
+			if (nset && c_in && FD_ISSET(c_in, &testwds)) {
+				write(c_in, b_in, z_in);
+				z_in = 0;
+				memset(b_in, 0, QARSH_BUFSIZE);
+			}
 			if (nset && c_out && FD_ISSET(c_out, &testfds)) {
-				bufsize = read(c_out, buf, QARSH_BUFSIZE);
-				if (bufsize > 0) {
-					write(fileno(stdout), buf, bufsize);
-				} else if (bufsize == 0) {
+				z_out = read(c_out, b_out, QARSH_BUFSIZE);
+				if (z_out == 0) {
 					FD_CLR(c_out, &readfds);
 					close(c_out);
 					c_out = 0;
 				}
 				nset--;
 			}
+			if (nset && FD_ISSET(fileno(stdout), &testwds)) {
+				write(fileno(stdout), b_out, z_out);
+				z_out = 0;
+			}
 			if (nset && c_err && FD_ISSET(c_err, &testfds)) {
-				bufsize = read(c_err, buf, QARSH_BUFSIZE);
-				if (bufsize > 0) {
-					write(fileno(stderr), buf, bufsize);
-				} else if (bufsize == 0) {
+				z_err = read(c_err, b_err, QARSH_BUFSIZE);
+				if (z_err == 0) {
 					FD_CLR(c_err, &readfds);
 					close(c_err);
 					c_err = 0;
 				}
 				nset--;
 			}
+			if (nset && FD_ISSET(fileno(stderr), &testwds)) {
+				write(fileno(stderr), b_err, z_err);
+				z_err = 0;
+			}
 			if (nset && FD_ISSET(qarsh_fd, &testfds)) {
 				qp = recv_packet(qarsh_fd);
 				if (qp == NULL) {
@@ -364,7 +378,7 @@ run_remote_cmd(char *cmdline)
 	}
 	if (c_out) close(c_out);
 	if (c_err) close(c_err);
-	free(buf);
+	free(b_in); free(b_out); free(b_err);
 	if (hbeat_getstate(qarsh_hb) == HOST_TIMEOUT) {
 		fprintf(stderr, "Didn't receive heartbeat for %d seconds\n", 
 				hbeat_getmaxtimeout(qarsh_hb));