Función readLine() en C

readline.c

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

char* readLine(void);

int main(void)
{
	char* buf;
	printf("Ingrese un nombre:\n");
	buf = readLine();
	if(buf == NULL)
	{
		printf("No se puso asignar memoria dinamica!");
		return 1;
	}
	printf("String: %s, length: %d\n", buf, strlen(buf));
	free(buf);
    return 0;
}

char* readLine()
{
	int i = 0;
	int ch;
	char* aux;
	char* buf;
	buf = malloc(sizeof(char));
	if(buf == NULL)
		return NULL;
	while((ch = getchar()) != '\n')
	{
		buf[i++] = ch;
		aux = buf;
		buf = realloc(buf, (i+1)* sizeof(char));
		if(buf == NULL)
		{
			free(aux);
			return NULL;
		}
	}
	buf[i] = '\0';
	return buf;
}