ACE VERSION: 5.6.4

HOST MACHINE and OPERATING SYSTEM:
    PC, Windows XP Prof. SP 2, VC 8

TARGET MACHINE and OPERATING SYSTEM, if different from HOST:
COMPILER NAME AND VERSION (AND PATCHLEVEL): -

THE $ACE_ROOT/ace/config.h FILE [if you use a link to a platform-
specific file, simply state which one]:
    #define _USE_32BIT_TIME_T 1 
    #define ACE_USES_WCHAR
    #include "ace/config-win32.h"

THE $ACE_ROOT/include/makeinclude/platform_macros.GNU FILE [if you
use a link to a platform-specific file, simply state which one
(unless this isn't used in this case, e.g., with Microsoft Visual
C++)]: -

CONTENTS OF $ACE_ROOT/bin/MakeProjectCreator/config/default.features
(used by MPC when you generate your own makefiles): file not exists

AREA/CLASS/EXAMPLE AFFECTED:
    ACE, File IO

DOES THE PROBLEM AFFECT:
    COMPILATION? no
    LINKING? no
    EXECUTION? yes
    OTHER (please specify)? -

SYNOPSIS:
    Can't read files with 1 Bytes when ACE_USES_WCHAR is defined.

DESCRIPTION:
    - Prepare a file with one character (one byte, no BOM) - verify with 
      hex editor.
    - Open and read the byte of this file (see the following example).
    - The fread() function will return 0. 

    The reason for this problem is the fuction checkUnicodeFormat() of the 
    file %ACE_ROOT%/ace/OS_NS_stdio.cpp. Within the fopen() call it's used
    to ignore the BOM.

    The fread call tries to tread two bytes in our One-Byte-ASCII file.
    The call fails but the file pointer is not the same as before (I guess).
    Also if I execute the fseek(fp, 0, FILE_BEGIN); before my own read
    everything works fine.

    #if defined (ACE_USES_WCHAR)
    void ACE_OS::checkUnicodeFormat (FILE* fp)
    {
      if (fp != 0)
      {
        // Due to the ACE_TCHAR definition, all default input files, such as
        // svc.conf, have to be in Unicode format (small endian) on WinCE
        // because ACE has all 'char' converted into ACE_TCHAR.
        // However, for TAO, ASCII files, such as IOR file, can still be read
        // and be written without any error since given buffers are all in
'char'
        // type instead of ACE_TCHAR.  Therefore, it is user's reponsibility to
        // select correct buffer type.

        // At this point, check if the file is Unicode or not.
        ACE_UINT16 first_two_bytes;
        size_t numRead =
          ACE_OS::fread(&first_two_bytes, sizeof (first_two_bytes), 1, fp);

        if (numRead == 1)
        {
          if ((first_two_bytes != 0xFFFE) && // not a small endian Unicode file
              (first_two_bytes != 0xFEFF))   // not a big endian Unicode file
          {
            // set file pointer back to the beginning
    #if defined (ACE_WIN32)
            ACE_OS::fseek(fp, 0, FILE_BEGIN);
    #else
            ACE_OS::fseek(fp, 0, SEEK_SET);
    #endif /* ACE_WIN32 */
          }
        }
        // if it is a Unicode file, file pointer will be right next to the
first
        // two-bytes
      }
    }
    #endif  // ACE_USES_WCHAR  


REPEAT BY:
    #include "ace/OS.h"

    int main()
    {
        FILE* pFile = ACE_OS::fopen("OneByteFile", L"rb");

        char Buffer[1000];
        size_t BytesRead = ACE_OS::fread(&Buffer, 1, 1, pFile);
        if(BytesRead == 0)
        {
            // This is an error: One byte should be read
        }

        ACE_OS::fclose(pFile);
    }


SAMPLE FIX/WORKAROUND:
    I see two options:
    - Maybe the file size has to be checked before the read in the
      checkUnicodeFormat() function.
    - Or alwyas do the seek if the numRead is 0.

please add a one button test to ace_wrappers/tests as reproducer

Created an attachment (id=1040) [details]
Bug_3532_Regression_Test

Fri Jan 30 12:55:52 UTC 2009  Johnny Willemsen  <jwillemsen@remedy.nl>

        * tests/run_test.lst:
        * tests/tests.mpc:
        * tests/Bug_3532_Regression.cpp:
          Added a new test for bugzilla 3532. This bug is not fixed, just
          integrating the regression test. Thanks to Martin Gaus <Gaus@gmx.de>
          for creating this test

Tue Mar 24 11:38:22 UTC 2009  Johnny Willemsen  <jwillemsen@remedy.nl>

        * ace/OS_NS_stdio.cpp (checkUnicodeFormat):
          Fixed a bug that the file pointer wasn't set toe the start of the
          file when the file is just 1 byte large. This fixes bugzilla
          3532, thanks to Martin Gaus <gaus at gmx dot de> for reporting
          this.

added dep