CodeQL library for C/C++
codeql/cpp-all 0.3.5 (changelog, source)
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Member predicate AliasFunction::parameterNeverEscapes

Holds if the address passed to the parameter at the specified index is never retained after the function returns.

Example:

int* g;
int* func(int* p, int* q, int* r, int* s, int n) {
  *s = 1;  // `s` does not escape.
  g = p;  // Stored in global. `p` escapes.
  if (rand()) {
    return q;  // `q` escapes via the return value.
  }
  else {
    return r + n;  // `r` escapes via the return value, even though an offset has been added.
  }
}

For the above function, the following terms hold:

  • parameterEscapesOnlyViaReturn(1)
  • parameterEscapesOnlyViaReturn(2)
  • parameterNeverEscapes(3)
predicate parameterNeverEscapes(int index)