Fix two issues with apr_file_trunc() for buffered files:

 - The Win32 implementation incorrectly flushes the buffered writes _after_
   truncating a file.  Such files will have unexpected data written after
   the position at which they should've been truncated. PR 51017.
   (Under Unix, this issue has been fixed in r1044440)

 - Both Win32 and Unix implementations incorrectly keep the data read into
   a buffer after the file is truncated.  Thus, reading from a file after
   apr_file_trunc() can return invalid data from the previous file offset.

* file_io/win32/seek.c
  (apr_file_trunc): Flush the write buffer or discard the read buffer
   before truncating.  Propely update the internal file offset (filePtr)
   and the eof_hit marker.

* file_io/unix/seek.c
  (apr_file_trunc): Discard the read buffer before truncating.

* test/testfile.c
  (test_file_trunc): Extend the checks.  Factor out part of this test...
  (test_file_trunc_buffered_write): ...into this new test.
  (test_file_trunc_buffered_write2, test_file_trunc_buffered_read): New tests.
  (testfile): Run the new tests.

Patch by: Evgeny Kotkov <evgeny.kotkov {at} visualsvn.com>


git-svn-id: https://svn.apache.org/repos/asf/apr/apr/trunk@1788929 13f79535-47bb-0310-9956-ffa450edef68

1 files changed, 8 insertions, 0 deletions

diff --git a/CHANGES b/CHANGES
index 1c3dcad8e..c92afa72a 100644
--- a/CHANGES
+++ b/CHANGES
@@ -1,6 +1,14 @@
                                                      -*- coding: utf-8 -*-
 Changes for APR 2.0.0
 
+  *) apr_file_trunc: Truncating a buffered file could add unexpected
+     data after the truncate position. PR 51017.
+     [Evgeny Kotkov <evgeny.kotkov visualsvn.com>]
+
+  *) apr_file_trunc: Fix an issue where reading from a buffered file
+     after truncate could return stale data from the buffer.
+     [Evgeny Kotkov <evgeny.kotkov visualsvn.com>]
+
   *) apr_allocator, apr_pools: Add apr_allocator_page_size() and
      apr_allocator_min_order_set() to respectively get the (system's) page size
      in use and set the minimum allocation size for an allocator (expressed in