strbuf.c

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

/*
 * Minimal strbuf implementation for standalone graph.c
 */

/* Sentinel buffer for empty strbufs - allows buf to never be NULL */
char strbuf_slopbuf[1];

void strbuf_init(struct strbuf *sb, size_t hint)
{
	sb->alloc = 0;
	sb->len = 0;
	sb->buf = strbuf_slopbuf;
	if (hint)
		strbuf_grow(sb, hint);
}

void strbuf_release(struct strbuf *sb)
{
	if (sb->buf != strbuf_slopbuf)
		free(sb->buf);
	strbuf_init(sb, 0);
}

void strbuf_grow(struct strbuf *sb, size_t extra)
{
	size_t need = sb->len + extra + 1;  /* +1 for NUL */

	if (need <= sb->alloc)
		return;

	/* Grow by at least 64 bytes or double, whichever is more */
	size_t new_alloc = sb->alloc ? sb->alloc * 2 : 64;
	if (new_alloc < need)
		new_alloc = need;

	if (sb->buf == strbuf_slopbuf) {
		sb->buf = malloc(new_alloc);
		sb->buf[0] = '\0';
	} else {
		sb->buf = realloc(sb->buf, new_alloc);
	}

	if (!sb->buf) {
		fprintf(stderr, "strbuf: out of memory\n");
		exit(1);
	}

	sb->alloc = new_alloc;
}

void strbuf_addch(struct strbuf *sb, int c)
{
	strbuf_grow(sb, 1);
	sb->buf[sb->len++] = c;
	sb->buf[sb->len] = '\0';
}

void strbuf_addchars(struct strbuf *sb, int c, size_t n)
{
	strbuf_grow(sb, n);
	memset(sb->buf + sb->len, c, n);
	sb->len += n;
	sb->buf[sb->len] = '\0';
}

void strbuf_add(struct strbuf *sb, const void *data, size_t len)
{
	strbuf_grow(sb, len);
	memcpy(sb->buf + sb->len, data, len);
	sb->len += len;
	sb->buf[sb->len] = '\0';
}

void strbuf_addstr(struct strbuf *sb, const char *s)
{
	strbuf_add(sb, s, strlen(s));
}