better error reports for Write()

UnixDgramSocket.cpp

@@ -19,6 +19,9 @@
 #include <stdio.h>
 #include <unistd.h>
 #include <string.h>
+#include <cstring>
+#include <thread>
+#include <chrono>
 #include <errno.h>
 #include <fcntl.h>
 #include <sys/socket.h>
@@ -93,22 +96,36 @@ ssize_t CUnixDgramWriter::Write(void *buf, size_t size)
 	// open the socket
 	int fd = socket(AF_UNIX, SOCK_DGRAM, 0);
 	if (fd < 0) {
-		fprintf(stderr, "Failed to open socket %s\n", addr.sun_path+1);
+		fprintf(stderr, "Failed to open socket %s : %s\n", addr.sun_path+1, strerror(errno));
 		return -1;
 	}
 	// connect to the receiver
 	int rval = connect(fd, (struct sockaddr *)&addr, sizeof(addr));
 	if (rval < 0) {
-		fprintf(stderr, "Failed to connect to socket %s\n", addr.sun_path+1);
+		fprintf(stderr, "Failed to connect to socket %s : %s\n", addr.sun_path+1, strerror(errno));
 		close(fd);
 		return -1;
 	}
 
-	ssize_t written = -1;
+	ssize_t written = 0;
-	while (written < 0) {
+	int count = 0;
+	while (written <= 0) {
 		written = write(fd, buf, size);
-		if (written != (ssize_t)size)
+		if (written == (ssize_t)size)
-			fprintf(stderr, "ERROR: only wrote %d bytes of %d to %s\n", (int)written, (int)size, addr.sun_path+1);
+			break;
+		else if (written < 0)
+			fprintf(stderr, "ERROR: faied to write to %s : %s\n", addr.sun_path+1, strerror(errno));
+		else if (written == 0)
+			fprintf(stderr, "Warning: zero bytes written to %s\n", addr.sun_path+1);
+		else if (written != (ssize_t)size) {
+			fprintf(stderr, "ERROR: only %d of %d bytes written to %s\n", (int)written, (int)size, addr.sun_path+1);
+			break;
+		}
+		if (++count >= 100) {
+			fprintf(stderr, "ERROR: Write failed after %d attempts\n", count-1);
+			break;
+		}
+		std::this_thread::sleep_for(std::chrono::microseconds(5));
 	}
 
 	close(fd);