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 Non-Compliant Coding Example

The following non-compliant code example logs the program's state at runtime.

{code

:bgColor

=#ffcccc

void do_stuff(void) {
  FILE *logfile = fopen("log", "a");
  
  /* Check for errors, write logs pertaining to do_stuff(), etc. */
}

int main(void) {
  FILE *logfile = fopen("log", "a");

  /* Check for errors, write logs pertaining to main(), etc. */

  do_stuff();

  /* ... */
}
{null}
However, the file {{log}} is opened twice simultaneously. The result is implementation-defined and potentially dangerous.

h2. Compliant Solution

In this compliant solution, a reference to the file pointer is passed around so that the file does not have to be opened twice separately.

{code

:bgColor

=#ccccff

}
void do_stuff(FILE **file) {
  FILE *logfile = *file;
  
  /* Check for errors, write logs pertaining to do_stuff, etc. */
}

int main(void) {
  FILE *logfile = fopen("log", "a");

  /* Check for errors, write logs pertaining to main, etc. */

  do_stuff(&logfile);

  /* ... */
}
{code}

h2. Risk Assessment

Simultaneously opening a file multiple times could result in abnormal program termination or a data integrity violation.

|| Rule || Severity || Likelihood || Remediation Cost || Priority || Level ||
| FIO31-A | *2* (medium) | *2* (probable) | *2* (medium) | {color:#cc9900}{*}P8{*}{color} | {color:#cc9900}{*}L2{*}{color} |

h2. References

\[[ISO/IEC 9899-1999:TC2|AA. C References#ISO/IEC 9899-1999TC2]\] Section 7.19.3, "Files"