src/java.base/unix/native/libjava/io_util_md.c

rev 16220 : 8168628: (fc) SIGBUS when extending file size to map it
Summary: Synchronize file extension and subsequent map0(); on Linux use fallocate64() instead of ftruncate64().
Reviewed-by: rehn, simonis, alanb

*** 1,7 ****
  /*
!  * Copyright (c) 2001, 2015, Oracle and/or its affiliates. All rights reserved.
   * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   *
   * This code is free software; you can redistribute it and/or modify it
   * under the terms of the GNU General Public License version 2 only, as
   * published by the Free Software Foundation.  Oracle designates this
--- 1,7 ----
  /*
!  * Copyright (c) 2001, 2016, Oracle and/or its affiliates. All rights reserved.
   * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   *
   * This code is free software; you can redistribute it and/or modify it
   * under the terms of the GNU General Public License version 2 only, as
   * published by the Free Software Foundation.  Oracle designates this
*** 213,222 ****
--- 213,236 ----
  
  jint
  handleSetLength(FD fd, jlong length)
  {
      int result;
+ #if defined(__linux__)
+     /*
+      * On Linux, if the file size is being increased, then ftruncate64()
+      * will modify the metadata value of the size without actually allocating
+      * any blocks which can cause a SIGBUS error if the file is subsequently
+      * memory-mapped.
+      */
+     struct stat64 sb;
+ 
+     if (fstat64(fd, &sb) == 0 && length > sb.st_blocks*512) {
+         RESTARTABLE(fallocate64(fd, 0, 0, length), result);
+         return result;
+     }
+ #endif
      RESTARTABLE(ftruncate64(fd, length), result);
      return result;
  }
  
  jlong