#include <stdlib.h>
#include <string.h>
#include "buf.h"
#include "err.h"

void buf_init(buf_t *b, size_t n) {
	b->buf = calloc(1, n);
	if (!b->buf) {
		efatal("buf_init");
	}
	b->cap = n;
	b->sz = 0;
}

/* does NOT change sz! just makes room */
void buf_grow(buf_t *b, size_t n) {
	size_t sz = b->sz + n;
	size_t c = b->cap;
	if (sz > c) {
		while (sz > c) c <<= 1;
		char *p = realloc(b->buf, c);
		if (!p) efatal("buf_grow");
		b->buf = p;
		b->cap = c;
	}
}

void buf_cat(buf_t *b, char *src, size_t n) {
	buf_grow(b, n);
	memcpy(&b->buf[b->sz], src, n);
	b->sz += n;
}

void buf_catc(buf_t *b, char c) {
	buf_grow(b, 1);
	b->buf[b->sz++] = c;
}

void buf_free(buf_t *b) {
	free(b->buf);
}