Don't yell at me.

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107KB, 792x1023px

I am not an expert with C by any means and I need some assistance.
When I run this code it crashes and says that realloc has an invalid next size.
This issue is most likely related to the new_command function but I cant figure it out.
Please help me /g/ I need to learn (I would post in wsr but they dont have code tags)
Pls no bully.

#define _GNU_SOURCE
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

typedef struct 
{
    char* alias;
    void (*function)();
}command;

command* global_commands;
int total_commands = 0;

void echo()
{
    puts("hello");
}

void execute(char* command_alias)
{
    for(int current_command = 0; current_command < total_commands; current_command++)
    {
        if(!strcmp(global_commands[current_command].alias, command_alias))
        {
            puts("Exists, running...");
            global_commands[current_command].function();
            break;
        }
    }
}

void new_command(char* new_alias, void* new_function)
{
    command new_command = {new_alias, new_function};
    if(!(global_commands = realloc(global_commands, sizeof(global_commands) + sizeof(new_command))))
    {
        puts("Unable to add command!");
        return;
    }
    global_commands[total_commands] = new_command;
    total_commands++;
}

char* getstr()
{
    char* str = calloc(sizeof(char), 1);
    char character;
    while((character = getchar()) != '\n')
        asprintf(&str, "%s%c", str, character);
    return str;
}

int main()
{
    if(!(global_commands = malloc(sizeof(command))))
    {
        puts("Failed to allocate space for command list!");
        return 1;
    }
    fprintf(stdout, "> ");
    new_command("exit", echo);
    new_command("test", echo);
    new_command("cd", echo);
    for(;;)
    {
        char* command_alias = getstr();        
        execute(command_alias);
        free(command_alias);
        fprintf(stdout, "> ");
    }
}