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This compliant solution eliminates the NULL return and simply returns the item array, even if it is zero-length. The main function can effectively handle this situation without exhibiting erroneous behavior. Since the array lives on the stack, it must prevent returning a value in the stack frame (as mandated by DCL30-C. Declare objects with appropriate storage durations). So the getStack() function also takes a pointer to Inventory, so that it can return a pointer to its contents safely.

Code Block

bgColor	#ccccff
lang	c

#include <stdio.h>

enum { INV_SIZE=20 };

typedef struct {
  size_t stockOfItem[INV_SIZE];
  size_t length;
} Inventory;

size_t *getStock(Inventory* iv);

int main(void) {
  Inventory iv;
  size_t i;
  size_t *item;

  iv.length = 0;
  
  /*
   * Other code that might modify the inventory but still
   * leave no items in it upon completion.
    */
  
  item = getStock(&iv);

  if (iv.length != 0) {
    printf("Stock of first item in inventory: %zd\n", item[0]);
  }
  
  return 0;
}

size_t *getStock(Inventory* iv) {
  return iv.stockOfItem->stockOfItem;
}

Noncompliant Code Example (Sentinel Value)

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Code Block

bgColor	#FFCCCC
lang	c

#include <stdio.h>
#include <stdint.h>
#include <malloc<stdlib.h>

enum { FINAL_ITEM=SIZE_MAX, INV_SIZE=20 };

size_t *arraySort(size_t *array);

int main(void) {
  size_t i;
  size_t stockOfItem[INV_SIZE];
  size_t *sortedArray;

  /* Other code that might use stockarray but leaves it empty */

  sortedArray = arraySort(stockOfItem);
  
  for (i = 0; sortedArray[i] != FINAL_ITEM; i++) {
	printf("Item stock: %zd", sortedArray[i]);
  }
  
  return 0;
}

/* Create new sorted array */
size_t *arraySort(size_t *array) {
  size_t i;
  size_t *sortedArray;

  for(i = 0; array[i] != FINAL_ITEM; i++);
  
  if (i == 0) {
    return NULL;
  }

  sortedArray = (size_t*) malloc(sizeof(size_t)*i);
  if (sortedArray == NULL) {
    /* Handle memory error */
  }

  /* Add sorted data to array */

  return sortedArray;
}

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Tool

Version

Checker

Description

Parasoft C/C++test

Include Page

	Parasoft_V
	Parasoft_V

CERT_C-MSC19-a
CERT_C-MSC19-b

Avoid accessing arrays out of bounds
Avoid null pointer dereferencing

PC-lint Plus

Include Page

	PC-lint Plus_V
	PC-lint Plus_V

413, 418, 419, 420, 473,
613, 661, 662, 668, 669,
670

Partially supported

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Key

Noncompliant Code Example (Sentinel Value)

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