Benchmarking tool for sort function

gistfile1.c

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

void sort(const char **strings, size_t count, const char **out);

/* Macros grabbed from my darray module:
 *     http://ccan.ozlabs.org/info/darray.html */
#define darray(type) struct {type *item; size_t size; size_t alloc;}
#define darray_new() {0,0,0}
#define darray_append(arr, ...) do { \
		darray_resize(arr, (arr).size+1); \
		(arr).item[(arr).size-1] = (__VA_ARGS__); \
	} while(0)
#define darray_resize(arr, newSize) darray_growalloc(arr, (arr).size = (newSize))
#define darray_realloc(arr, newAlloc) do { \
		(arr).item = realloc((arr).item, ((arr).alloc = (newAlloc)) * sizeof(*(arr).item)); \
	} while(0)
#define darray_growalloc(arr, need) do { \
		size_t __need = (need); \
		if (__need > (arr).alloc) \
			darray_realloc(arr, darray_next_alloc((arr).alloc, __need)); \
	} while(0)
static inline size_t darray_next_alloc(size_t alloc, size_t need)
{
	if (alloc == 0)
		alloc = 1;
	while (alloc < need)
		alloc *= 2;
	return alloc;
}

static char *chomp(const char *str)
{
	size_t len;
	char *ret;
	
	len = strlen(str);
	if (len > 0 && str[len-1] == '\n')
		len--;
	
	ret = malloc(len + 1);
	memcpy(ret, str, len);
	ret[len] = '\0';
	
	return ret;
}

char **get_lines(size_t *count)
{
	darray(char*) arr = darray_new();
	char buffer[1024];
	
	while (fgets(buffer, sizeof(buffer), stdin) != NULL)
		darray_append(arr, chomp(buffer));
	
	*count = arr.size;
	return arr.item;
}

int main(int argc, char *argv[])
{
	char **lines;
	const char **sorted;
	size_t count;
	size_t i;
	int sort_count;
	int j;
	
	if (argc > 1)
		sort_count = atoi(argv[1]);
	else
		sort_count = 1;
	
	fprintf(stderr, "Reading lines\n");
	lines = get_lines(&count);
	sorted = malloc(count * sizeof(*sorted));
	
	fprintf(stderr, "Sorting\n");
	for (j = 0; j < sort_count; j++)
		sort((const char **)lines, count, sorted);
	
	fprintf(stderr, "Printing\n");
	for (i = 0; i < count; i++)
		puts(sorted[i]);
	
	fprintf(stderr, "Freeing\n");
	for (i = 0; i < count; i++)
		free(lines[i]);
	free(lines);
	free(sorted);
	
	fprintf(stderr, "Done.\n");
	
	return 0;
}