memory management using malloc while running-CodePudding

Below is my C program:

When I run "leaks -atExit -- ./test" there are no memory leaks.
But when I run "./test" i get the below error.

malloc: *** error for object 0x7f95324059c8: pointer being freed was not allocated

Where am I going wrong here in my memory allocation?

CodePudding user response：

**args is not the number of arguments that were passed to free_args. You're using a NULL sentinel to indicate the end of the arguments, so you should check for that.

Also, the types of the arguments are char**, not char*.

When looping over the arguments, you need to start with args, then use va_arg to get the additional arguments.

void free_args(char **args, ...){
    va_list arg;
    
    va_start(arg, args);
    for (char **ar = args; ar != NULL; ar = va_arg(arg, char**)) {
        free(ar);
    }   
    va_end(arg);
}

Note that this does have a memory leak. You're freeing the upArgs and lowArgs arrays, but not freeing all the strings that they point to. I'm not showing how to fix that, I assume it was intention so that leak would report the problem.

When I use

leaks --atExit -- ./testleaks a Bcd EF

I get the following leak report:

Process 30435: 8 leaks for 128 total leaked bytes.

    8 (128 bytes) << TOTAL >>
      1 (16 bytes) ROOT LEAK: 0x13f606880 [16]
      1 (16 bytes) ROOT LEAK: 0x13f606890 [16]
      1 (16 bytes) ROOT LEAK: 0x13f6068a0 [16]
      1 (16 bytes) ROOT LEAK: 0x13f6068b0 [16]
      1 (16 bytes) ROOT LEAK: 0x13f6068f0 [16]
      1 (16 bytes) ROOT LEAK: 0x13f606900 [16]
      1 (16 bytes) ROOT LEAK: 0x13f606910 [16]
      1 (16 bytes) ROOT LEAK: 0x13f606920 [16]