Fix bug 1784

http://bugzilla.lyx.org/show_bug.cgi?id=1784


git-svn-id: svn://svn.lyx.org/lyx/lyx-devel/branches/BRANCH_1_5_X@26738 a592a061-630c-0410-9148-cb99ea01b6c8

src/Server.cpp

@@ -246,6 +246,12 @@ void LyXComm::read_ready()
 	int const charbuf_size = 100;
 	char charbuf[charbuf_size];
 
+	// As O_NONBLOCK is set, until no data is available for reading,
+	// read() doesn't block but returns -1 and set errno to EAGAIN.
+	// After a client that opened the pipe for writing, closes it
+	// (and no other client is using the pipe), read() would always
+	// return 0 and thus the connection has to be reset.
+
 	errno = 0;
 	int status;
 	// the single = is intended here.
@@ -268,12 +274,13 @@ void LyXComm::read_ready()
 					clientcb(client, cmd);
 					//\n or not \n?
 			}
-		}
-		if (errno == EAGAIN) {
-			errno = 0;
-			return;
-		}
-		if (errno != 0) {
+		} else {
+			if (errno == EAGAIN) {
+				// Nothing to read, continue
+				errno = 0;
+				return;
+			}
+			// An error occurred, better bailing out
 			lyxerr << "LyXComm: " << strerror(errno) << endl;
 			if (!read_buffer_.empty()) {
 				lyxerr << "LyXComm: truncated command: "
@@ -284,8 +291,9 @@ void LyXComm::read_ready()
 		}
 	}
 
-	// The connection gets reset in errno != EAGAIN
-	// Why does it need to be reset if errno == 0?
+	// The connection gets reset when read() returns 0 (meaning that the
+	// last client closed the pipe) or an error occurred, in which case
+	// read() returns -1 and errno != EAGAIN.
 	closeConnection();
 	openConnection();
 	errno = 0;

status.15x

@@ -135,6 +135,9 @@ What's new
 
 - Remove confusing warning about 'server socket' under MS Windows.
 
+- Fix problem that the lyxpipe was incorrectly reset after dispatching
+  certain functions (bug 1784).
+
 
 * DOCUMENTATION AND LOCALIZATION