[LyX/master] In fileLock, take in account the case where the file cannot be opened

[Jean-Marc Lasgouttes]

commit 1e4adc512e1901e2c031bd375afe2825692620a5
Author: Jean-Marc Lasgouttes <lasgout...@lyx.org>
Date:   Sat Sep 12 23:49:32 2015 +0200

    In fileLock, take in account the case where the file cannot be opened
    
    overity issue 23352

diff --git a/src/support/filetools.cpp b/src/support/filetools.cpp
index bab9687..4c37fa1 100644
--- a/src/support/filetools.cpp
+++ b/src/support/filetools.cpp
@@ -1219,14 +1219,17 @@ int fileLock(const char * lock_file)
        int fd = -1;
 #if defined(HAVE_LOCKF)
        fd = open(lock_file, O_CREAT|O_APPEND|O_SYNC|O_RDWR, 0666);
+       if (fd == -1)
+               return -1;
        if (lockf(fd, F_LOCK, 0) != 0) {
                close(fd);
-               return(-1);
+               return -1;
        }
 #endif
-       return(fd);
+       return fd;
 }
 
+
 void fileUnlock(int fd, const char * /* lock_file*/)
 {
 #if defined(HAVE_LOCKF)