Q69539: _cexit() Does Not Close Files Correctly

Article: Q69539
Product(s): See article
Version(s): 6.00 6.00a | 6.00 6.00a
Operating System(s): MS-DOS | OS/2
Keyword(s): ENDUSER | s_quickc buglist6.00 buglist6.00a | mspl13_c
Last Modified: 25-FEB-1991

As stated in the online help, the _cexit() function performs clean-up
operations and returns without terminating the process. The _cexit()
function first calls the functions registered by the atexit() and
onexit() routines, and then it should flush all I/O buffers and close
all open files before returning.

The _cexit() function works as described except that it does not close
all the open files. The sample code below demonstrates this problem.

Microsoft has confirmed this to be a problem in C versions 6.00 and
6.00a. We are researching this problem and will post new information
here as it becomes available.

Sample Code
-----------

*\

#include<stdio.h>
#include<stdlib.h>
#include<process.h>

void foo(void);

void main(void)
{
    FILE *outfile;
    int   retval;

    atexit(foo);    /* set up function to invoke on exit */

    if ( (outfile = fopen("TEST.TXT", "w")) == NULL )
        {
        printf("Could not open test file TEST.TXT");
        exit(-1);
        }

    retval = fprintf(outfile, "This is line 1.\n");
    if ( retval >= 0 )
        printf("\nFirst line written successfully to file.\n");
    else
        printf("\nFile write failed on first attempt!\n");

    _cexit();   /* Call _cexit() -- files should all be closed */

    retval = fprintf(outfile, "This line should not be written!\n");
    if ( retval >= 0 )
        printf("Error - Write to file succeeded for file that should"
               " have been closed!\n");
    else
        printf("File write failed on second attempt as expected!\n");

    fclose(outfile);
}

void foo(void)
{
    printf("\nThis is the exit function code.\n\n");
}

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