Sanfoundry (Interview Question) INTERNSHIP

/*

 * Sanfoundry.com Memory Leak Program – India Internship Bangalore

 * Author: Manish Kumar Bhojasia, Location: Bangalore, India

 */

#include <stdio.h>

#include <stdlib.h>

#include <string.h>

#define KB1     1024

#define MEMSIZE (4 * KB1)

char *string = "IDENTIFY 10 ISSUES IN THIS MEMLEAK PROGRAM";

char *gstring = "IDENTIFY 10 ISSUES IN THIS MEMLEAK PROGRAM";

char *gptr;

int num;

char * f1_alloc(void);

char * f2_copyme(void);

void   f3_free(char *);

main()

{

    srand((int)getpid());

    while (1) {

        gptr = f1_alloc();

        strcpy(gptr, string);

        f2_copyme();

        f3_free(gptr);

    }

}

char *f1_alloc()

{

    return (malloc(MEMSIZE));

}

char *f2_copyme()

{

    static int len, i = 0;

    char *s;

    len = strlen(string);

    s = (char *)malloc(len);

    strncpy(s, string, len);

    i++;

    if (!(i % MEMSIZE))

        printf("i=%d, %s\n", i, s);

}

void f3_free(char *p)

{

    num = rand() % 3;

    if (!num)

        free(p);

}

This program will hang your computer or forcibly terminated.

Error’s in this program are::

1.       LINE No 11-> the program has used macro’s to define MEMSIZE (4*KB) which is a very large value and in whole program it will not be utilised and it just a wastage of memory.

2.       LINE No 13-> char * string is initialized with a string but this is not a good practice to store a address of a string in a pointer without declaring the size of the pointer and it can cause overwriting of memory.

3.       LINE No 14-> char * string is initialized with a string but this is not a good practice to store a address of a string in a pointer without declaring the size of the pointer and it can cause overwriting of memory.

4.       LINE No15-> will show a logical error as loop is declared for infinite times.

5.       LINE No35->Memory allocating many numbers of times but de allocation is very rarely.

6.        LINE No 39-> “len” is declared as static and its value is overwrite again and again which is not required when we had declared it as static.

7.       LINE No43-> in this “s” is allocated with memory every time the function is called but de allocation is not there.

8.       “MEMSIZE” is replaced by a huge memory “4 * KB” but most of the memory is wasted.

9.       Program generally shows “segmentation error” because de allocation and allocation are not parallel.

10.   LINE 37-> In function “f2_copyme() has a return type but function does not return any thing which can also be considered as an error. http://www.sanfoundry.com/internship/