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Programmers should exercise caution if the second operand contains side effects because it may not be apparent whether the side effects actually occur.

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Noncompliant Code Example

In this noncompliant code example, the second operand of the logical OR operator invokes a function that results in side effects:

char *p = /* Initialize; may or may not be NULL */

if (p || (p = (char *) malloc(BUF_SIZE)) ) {
  /* Perform some Docomputation stuffbased withon p */
  free(p);
  p = NULL;
} else {
  /* Handle malloc() error */
  return;
}

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char *p = /* Initialize; may or may not be NULL */
char *q = NULL;
if (p == NULL) {
  q = (char *) malloc(BUF_SIZE);
  p = q;
}
if (p == NULL) {
  /* Handle malloc() error */
  return;
}

/* Perform some Docomputation stuffbased withon p */
free(q);
q = NULL;

Risk Assessment

Failing to understand the short-circuit behavior of the logical OR or AND operator may cause unintended program behavior.

Automated Detection

Related Vulnerabilities

Search for vulnerabilities resulting from the violation of this rule on the CERT website.

Related Guidelines

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