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IAR Embedded Workbench for RX 5.20

PTR-arith-field

In this section:
Synopsis

Direct access to a field of a struct, using an offset from the address of the struct.

Enabled by default

Yes

Severity/Certainty

Medium/High

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Full description

A field of a struct is accessed directly, using an offset from the address of the struct. Because a struct might in some cases be padded to maintain proper alignment of its fields, it can be very dangerous to access fields using only an offset from the address of the struct itself. This check is identical to MISRAC2004-17.1_a.

Coding standards
CERT ARR37-C

Do not add or subtract an integer to a pointer to a non-array object

CWE 188

Reliance on Data/Memory Layout

MISRA C:2004 17.1

(Required) Pointer arithmetic shall only be applied to pointers that address an array or array element.

Code examples

The following code example fails the check and will give a warning:

struct S{
  char c;
  int x;
};

void main(void) {
  struct S s;
  *(&s.c+1) = 10;
}

The following code example passes the check and will not give a warning about this issue:

struct S{
  char c;
  int x;
};

void example(void) {
  struct S s;
  s.x = 10;
}