IV74072: BAD FILE DESCRIPTOR DUE TO OFSTREAM NOT RELEASING FILE AFTER ENOSPC

XL C/C++ for AIX Fix Pack 4 (July 2015 PTF) for 13.1
XL C/C++ Runtime for AIX Fix Pack 3 (July 2015 PTF) for 13.1
XL C/C++ for AIX Fix Pack 5 (November 2015 PTF) for 13.1
XL C/C++ Runtime for AIX Fix Pack 4 (November 2015 PTF) for 13.1
XL C/C++ for AIX Fix Pack 6 (February 2016 PTF) for 13.1
XL C/C++ Runtime for AIX Fix Pack 5 (February 2016 PTF) for 13.1
XL C/C++ for AIX Fix Pack 7 (May 2016 PTF) for 13.1
XL C/C++ for AIX Fix Pack 8 (August 2016 PTF) for 13.1
XL C/C++ for AIX Fix Pack 9 (June 2017 PTF) for 13.1
XL C/C++ for AIX Fix Pack 10 (February 2018 PTF) for 13.1
XL C/C++ for AIX Fix Pack 11 (November 2018 PTF) for 13.1

APAR status

• Closed as program error.

Error description

• An invalid FILE descriptor is kept by an ofstream object after
  encountering an ENOSPC 'No space left on device' error.
  
  The issue occurs when the ofstream close() function is called
  when the file system being written to is full.  The system
  fclose() function is called, which in turn calls fflush() to
  write out any remaining data.  The fflush() fails with an ENOSPC
  error due to the full filesystem, and fclose() returns -1.  Even
  though -1 is returned, the fclose() function releases the FILE
  descriptor.
  
  Because -1 is returned from fclose(), the ofstream close() sets
  the ofstream failbit to 1, however is_open is still 1, and the
  FILE descriptor associated with the ofstream object is still
  treated as active.
  
  If the ofstream object is used again, it will be acting upon an
  inactive, invalid FILE descriptor, and undefined behaviour may
  be seen.
  

Local fix

Problem summary

• PROBLEM DESCRIPTION:
  The C++ runtime incorrectly keeps the file descriptor alive
  after fclose() failed and the is_open flag remains true. This
  allows the second fclose() to close the file but the file
  descriptor has been freed by the first fclose() and reused by
  the system for another file.  As a result, the second fclose()
  closes a different stream.
  
  USERS AFFECTED:
  Users who close a file stream twice because the first attempt
  failed with an error such as no space left on device.
  

Problem conclusion

• The C++ runtime behavior does not comply with the C++ standard
  and has now been fixed.
  

Temporary fix

Comments

APAR Information

• APAR is sysrouted FROM one or more of the following:

  IV73852

• APAR is sysrouted TO one or more of the following:

Fix information

• Fixed component name

  XL C/C++ RUNTIM

• Fixed component ID

  5725C7201

Applicable component levels

• RD10 PSY

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