proxy: Deal with close() failures (and EINTR errnos) comprehensively

src/proxy.c

@@ -90,8 +90,9 @@ int proxy_connect_to_upstream( struct proxier* proxy )
 	}
 
 	if( !socket_nbd_read_hello( fd, &size ) ) {
-		FATAL_IF_NEGATIVE(
+		WARN_IF_NEGATIVE(
-			close( fd ), SHOW_ERRNO( "FIXME: shouldn't be fatal" )
+			sock_try_close( fd ),
+			"Couldn't close() after failed read of NBD hello on fd %i", fd
 		);
 		return 0;
 	}
@@ -114,10 +115,10 @@ void proxy_disconnect_from_upstream( struct proxier* proxy )
 		debug(" Closing upstream connection" );
 
 		/* TODO: An NBD disconnect would be pleasant here */
-
+		WARN_IF_NEGATIVE(
-		FATAL_IF_NEGATIVE(
+			sock_try_close( proxy->upstream_fd ),
-			close( proxy->upstream_fd ),
+			"Failed to close() fd %i when disconnecting from upstream",
-			SHOW_ERRNO( "FIXME: shouldn't be fatal" )
+			proxy->upstream_fd
 		);
 		proxy->upstream_fd = -1;
 	}
@@ -442,10 +443,11 @@ int proxy_accept( struct proxier* params )
 		params->downstream_fd = client_fd;
 		proxy_session( params );
 
-		if ( close( params->downstream_fd ) == -1 )  {
+		WARN_IF_NEGATIVE(
-			warn( SHOW_ERRNO( "FIXME: close returned" ) );
+			sock_try_close( params->downstream_fd ),
-		}
+			"Couldn't close() downstram fd %i after proxy session",
-
+			params->downstream_fd
+		);
 		params->downstream_fd = -1;
 	}
 
@@ -467,7 +469,10 @@ void proxy_cleanup( struct proxier* params )
 	info( "cleaning up" );
 
 	if ( -1 != params->listen_fd ) {
-		close( params->listen_fd );
+		WARN_IF_NEGATIVE(
+			sock_try_close( params->listen_fd ),
+			"Failed to close() listen_fd %i", params->listen_fd
+		);
 	}
 
 	debug( "Cleanup done" );

src/sockutil.c

@@ -216,3 +216,24 @@ out:
 	return result;
 }
 
+int sock_try_close( int fd )
+{
+	int result;
+
+	do {
+		result = close( fd );
+
+		if ( result == -1 ) {
+			if ( EINTR == errno ) {
+				continue; /* retry EINTR */
+			} else {
+				warn( SHOW_ERRNO( "Failed to close() fd %i", fd ) );
+				break; /* Other errors get reported */
+			}
+		}
+
+	} while( 0 );
+
+	return result;
+}
+

src/sockutil.h

@@ -34,5 +34,8 @@ int sock_try_select(int nfds, fd_set *readfds, fd_set *writefds, fd_set *exceptf
 /* Try to call connect(), timing out after wait seconds */
 int sock_try_connect( int fd, struct sockaddr* to, socklen_t addrlen, int wait );
 
+/* Try to call close(), retrying EINTR */
+int sock_try_close( int fd );
+
 #endif
 

src/util.h

@@ -150,5 +150,7 @@ void mylog(int line_level, const char* format, ...);
 
 #define SHOW_ERRNO( msg, ... ) msg ": %s (%i)", ##__VA_ARGS__, ( errno == 0 ? "EOF" : strerror(errno) ), errno
 
+#define WARN_IF_NEGATIVE( value, msg, ... ) if ( value < 0 ) { warn( msg, ##__VA_ARGS__ ); }
+
 #endif