PM98899: __IOLBF LINE BUFFERING IN AN ENHANCED ASCII PROGRAM DOES NOT RESULT IN THE BUFFER BEING FLUSHED AT EACH NEWLINE

Obtain the fix for this APAR.

APAR status

• Closed as program error.

Error description

• #include <stdio.h>
  #include <time.h>
  The following small C program compiled in Enhanced ASCII mode
  produces output that immediately follows the program source:-
  -----
  #include <unistd.h>
  
  int main( void ) {
      int I;
      time_t clock;
  
  if ( 1 ) {
   if ( setvbuf( stdout, NULL, _IOLBF, 36 ) ) perror( "stdout");
   if ( setvbuf( stderr, NULL, _IOLBF, 36 ) ) perror( "stderr");
       }
      for ( I = 0; I<5; I++ ) {
          fprintf( stdout, "Record %2d to stdout \t%s\n", I,
              ctime( ( time( &clock ), &clock ) ) );
          sleep( 1 );
          fprintf( stderr, "Record %2d to stderr \t%s\n", I,
              ctime( ( time( &clock ), &clock ) ) );
          sleep( 1 ); }
  
      return( 0 ); }
  ---
  Record  0 to stderr     Mon Aug 19 12:20:51 2013
  Record  1 to stderr     Mon Aug 19 12:20:53 2013
  Record  2 to stderr     Mon Aug 19 12:20:55 2013
  Record  3 to stderr     Mon Aug 19 12:20:57 2013
  Record  4 to stderr     Mon Aug 19 12:20:59 2013
  Record  0 to stdout     Mon Aug 19 12:20:50 2013
  Record  1 to stdout     Mon Aug 19 12:20:52 2013
  Record  2 to stdout     Mon Aug 19 12:20:54 2013
  Record  3 to stdout     Mon Aug 19 12:20:56 2013
  
  The above indicates the buffer is not being flushed at each
  newline. The program works correctly in EBCDIC mode and inorder
  to obtain comparable output for the ASCII program, the \n in the
  source needed to be changed to \025
  

Local fix

• use fflush() as a bypass
  

Problem summary

• ****************************************************************
  * USERS AFFECTED: Users of z/OS C/C++ Enhanced ASCII I/O       *
  *                 applications that also use any of the        *
  *                 printf family of functions as well as line   *
  *                 buffering mode.                              *
  ****************************************************************
  * PROBLEM DESCRIPTION: For Enhanced ASCII applications that    *
  *                      also use line buffering mode (__IOLBF), *
  *                      the new-line character in a printf()    *
  *                      may not cause the I/O buffer to be      *
  *                      flushed properly.                       *
  ****************************************************************
  * RECOMMENDATION:                                              *
  ****************************************************************
  See problem description.
  

Problem conclusion

• The code was corrected to fix the problem.
  

Temporary fix

Comments

APAR Information

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

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

  UI14146 UI14147 UI14148

Modules/Macros

• CELHBFMT CELHDFMA CELHDFME CELHDFMT CELHDFM2
  CELHFPRT CELHPRTA CELHPRTF CELHSPRT CELHSPTA CELHVFPR CELHVPRT
  CELHVPR2 CELHVSPR CELHXFMT CELJDFME CELJDFMT CELJDFM2 CELJFPRT
  CELJPRTF CELJSPRT CELJVFPR CELJVPRT CELJVPR2 CELJVSPR CELJXFMT
  CELQDFME CELQDFMT CELQDFM2 CELQFPRT CELQPRTF CELQSPRT CELQVFPR
  CELQVPRT CELQVPR2 CELQVSPR CELQXFMT CELZDFME CELZDFMT CELZDFM2
  CELZFPRT CELZPRTF CELZSPRT CELZVFPR CELZVPRT CELZVPR2 CELZVSPR
  CELZXFMT EDC4001B EDC40096 EDC401A5 EDC401A6 EDC401A7 EDC4014F
  EDC40173 EDC403BF EDC403C0 EDC4045D EDC4045E EDC40473 EDC40474
  EDC40475 EDC40476
  

Fix information

• Fixed component name

  LE C LIBRARY

• Fixed component ID

  568819805

Applicable component levels

• R770 PSY UI14146

     UP14/01/22 P F401

• R780 PSY UI14147

     UP14/01/22 P F401

• R790 PSY UI14148

     UP14/01/22 P F401

Fix is available

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