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These examples also assume that errno is set if fopen() or malloc() fail. These are guaranteed by POSIX but not by C11. See ERR30-C. Set errno to zero before calling a library function known to set errno, and check errno only after the function returns a value indicating failureTake care when reading errno for more details.

Code Block
bgColor#FFCCCC
langc
typedef struct object {  /* Generic struct: contents don't matter */
  int propertyA, propertyB, propertyC;
} object_t;

errno_t do_something(void){
  FILE *fin1, *fin2;
  object_t *obj;
  errno_t ret_val;
  
  fin1 = fopen("some_file", "r");
  if (fin1 == NULL) {
    return errno;
  }

  fin2 = fopen("some_other_file", "r");
  if (fin2 == NULL) {
    fclose(fin1);
    return errno;
  }

  obj = malloc(sizeof(object_t));
  if (obj == NULL) {
    ret_val = errno;
    fclose(fin1);
    return ret_val;  /* Forgot to close fin2!! */
  }

  /* ... More code ... */

  fclose(fin1);
  fclose(fin2);
  free(obj);
  return NOERR;
}

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Tool

Version

Checker

Description

Klocwork
Include Page
Klocwork_V
Klocwork_V
MLK.MIGHT
MLK.MUST
MLK.RET.MIGHT
MLK.RET.MUST
RH.LEAK

LDRA tool suite
Include Page
LDRA_V
LDRA_V
50 DPartially implemented
Parasoft C/C++test
Include Page
Parasoft_V
Parasoft_V

CERT_C-MEM12-a

Ensure resources are freed

PC-lint Plus

Include Page
PC-lint Plus_V
PC-lint Plus_V

429

Assistance provided

Polyspace Bug Finder

Include Page
Polyspace Bug Finder_V
Polyspace Bug Finder_V

Memory leak

Missing unlock

Resource leak

CERT C: Rec. MEM12-C


Checks for memory leak and resource leak (rec. partially covered)

Memory allocated dynamically not freed

Lock function without unlock function

File stream not closed before FILE pointer scope ends or pointer is reassigned

Bibliography


 Dijkstra, Edgar, "Go To Statement Considered Harmful.", 1968
Linux Kernel Sourcecode (v2.6.xx)2.6.29, kernel/fork.c, the copy_process() Function
[Seacord 2013]Chapter 4, "Dynamic Memory Management"

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