X-Git-Url: https://git.lyx.org/gitweb/?a=blobdiff_plain;f=src%2FServer.cpp;h=d7a2e2514c285a26a533bfa67b39ac6bf79c6b5e;hb=70a24259f8e3eb75677178ef5e28ecbb51c2935b;hp=286be5d4da9cea891424cd0257d0d686ccb9d71b;hpb=b89cc942eb458284f40f4d4e7db58890c3288979;p=lyx.git

diff --git a/src/Server.cpp b/src/Server.cpp
index 286be5d4da..d7a2e2514c 100644
--- a/src/Server.cpp
+++ b/src/Server.cpp
@@ -3,7 +3,7 @@
  * This file is part of LyX, the document processor.
  * Licence details can be found in the file COPYING.
  *
- * \author Lars Gullik Bjønnes
+ * \author Lars Gullik Bjønnes
  * \author Jean-Marc Lasgouttes
  * \author Angus Leeming
  * \author John Levon
@@ -40,15 +40,15 @@
 #include <config.h>
 
 #include "Server.h"
-#include "support/debug.h"
 #include "FuncRequest.h"
 #include "LyXAction.h"
 #include "LyXFunc.h"
+
 #include "frontends/Application.h"
 
+#include "support/debug.h"
 #include "support/FileName.h"
 #include "support/lstrings.h"
-#include "support/lyxlib.h"
 
 #include <boost/bind.hpp>
 
@@ -72,7 +72,7 @@ namespace lyx {
 #if !defined (HAVE_MKFIFO)
 // We provide a stub class that disables the lyxserver.
 
-LyXComm::LyXComm(std::string const &, Server *, ClientCallbackfct)
+LyXComm::LyXComm(string const &, Server *, ClientCallbackfct)
 {}
 
 void LyXComm::openConnection()
@@ -107,7 +107,7 @@ void LyXComm::send(string const & msg)
 #else // defined (HAVE_MKFIFO)
 
 
-LyXComm::LyXComm(std::string const & pip, Server * cli, ClientCallbackfct ccb)
+LyXComm::LyXComm(string const & pip, Server * cli, ClientCallbackfct ccb)
 	: pipename_(pip), client_(cli), clientcb_(ccb)
 {
 	ready_ = false;
@@ -178,13 +178,39 @@ void LyXComm::closeConnection()
 
 int LyXComm::startPipe(string const & file, bool write)
 {
+	static bool stalepipe = false;
 	FileName const filename(file);
-	if (::access(filename.toFilesystemEncoding().c_str(), F_OK) == 0) {
-		lyxerr << "LyXComm: Pipe " << filename << " already exists.\n"
-		       << "If no other LyX program is active, please delete"
-			" the pipe by hand and try again." << endl;
-		pipename_.erase();
-		return -1;
+	if (filename.exists()) {
+		if (!write) {
+			// Let's see whether we have a stale pipe.
+			int fd = ::open(filename.toFilesystemEncoding().c_str(),
+					O_WRONLY | O_NONBLOCK);
+			if (fd >= 0) {
+				// Another LyX instance is using it.
+				::close(fd);
+			} else if (errno == ENXIO) {
+				// No process is reading from the other end.
+				stalepipe = true;
+				LYXERR(Debug::LYXSERVER,
+					"LyXComm: trying to remove "
+					<< filename);
+				filename.removeFile();
+			}
+		} else if (stalepipe) {
+			LYXERR(Debug::LYXSERVER, "LyXComm: trying to remove "
+				<< filename);
+			filename.removeFile();
+			stalepipe = false;
+		}
+		if (filename.exists()) {
+			lyxerr << "LyXComm: Pipe " << filename
+			       << " already exists.\nIf no other LyX program"
+			          " is active, please delete the pipe by hand"
+				  " and try again."
+			       << endl;
+			pipename_.erase();
+			return -1;
+		}
 	}
 
 	if (::mkfifo(filename.toFilesystemEncoding().c_str(), 0600) < 0) {
@@ -252,6 +278,12 @@ 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.
@@ -273,12 +305,13 @@ 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
 			LYXERR0("LyXComm: " << strerror(errno));
 			if (!read_buffer_.empty()) {
 				LYXERR0("LyXComm: truncated command: " << read_buffer_);
@@ -288,8 +321,9 @@ 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;
@@ -344,7 +378,7 @@ void ServerCallback(Server * server, string const & msg)
 	server->callback(msg);
 }
 
-Server::Server(LyXFunc * f, std::string const & pipes)
+Server::Server(LyXFunc * f, string const & pipes)
 	: numclients_(0), func_(f), pipes_(pipes, this, &ServerCallback)
 {}
 
@@ -495,7 +529,7 @@ void Server::callback(string const & msg)
 }
 
 
-// Send a notify messge to a client, called by WorkAreaKeyPress
+// Send a notify message to a client, called by WorkAreaKeyPress
 void Server::notifyClient(string const & s)
 {
 	pipes_.send("NOTIFY:" + s + "\n");