1/*	$NetBSD: buffer.c,v 1.1.1.5 2023/08/18 18:36:49 christos Exp $	*/
2
3/*
4 * Copyright (c) Christos Zoulas 2017.
5 * All Rights Reserved.
6 *
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions
9 * are met:
10 * 1. Redistributions of source code must retain the above copyright
11 *    notice immediately at the beginning of the file, without modification,
12 *    this list of conditions, and the following disclaimer.
13 * 2. Redistributions in binary form must reproduce the above copyright
14 *    notice, this list of conditions and the following disclaimer in the
15 *    documentation and/or other materials provided with the distribution.
16 *
17 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
18 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
19 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
20 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE FOR
21 * ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
22 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
23 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
24 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
25 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
26 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
27 * SUCH DAMAGE.
28 */
29#include "file.h"
30
31#ifndef	lint
32#if 0
33FILE_RCSID("@(#)$File: buffer.c,v 1.13 2023/07/02 12:48:39 christos Exp $")
34#else
35__RCSID("$NetBSD: buffer.c,v 1.1.1.5 2023/08/18 18:36:49 christos Exp $");
36#endif
37#endif	/* lint */
38
39#include "magic.h"
40#include <unistd.h>
41#include <string.h>
42#include <stdlib.h>
43#include <sys/stat.h>
44
45void
46buffer_init(struct buffer *b, int fd, const struct stat *st, const void *data,
47    size_t len)
48{
49	b->fd = fd;
50	if (st)
51		memcpy(&b->st, st, sizeof(b->st));
52	else if (b->fd == -1 || fstat(b->fd, &b->st) == -1)
53		memset(&b->st, 0, sizeof(b->st));
54	b->fbuf = data;
55	b->flen = len;
56	b->eoff = 0;
57	b->ebuf = NULL;
58	b->elen = 0;
59}
60
61void
62buffer_fini(struct buffer *b)
63{
64	free(b->ebuf);
65	b->ebuf = NULL;
66	b->elen = 0;
67}
68
69int
70buffer_fill(const struct buffer *bb)
71{
72	struct buffer *b = CCAST(struct buffer *, bb);
73
74	if (b->elen != 0)
75		return b->elen == FILE_BADSIZE ? -1 : 0;
76
77	if (!S_ISREG(b->st.st_mode))
78		goto out;
79
80	b->elen = CAST(size_t, b->st.st_size) < b->flen ?
81	    CAST(size_t, b->st.st_size) : b->flen;
82	if (b->elen == 0) {
83		free(b->ebuf);
84		b->ebuf = NULL;
85		return 0;
86	}
87	if ((b->ebuf = malloc(b->elen)) == NULL)
88		goto out;
89
90	b->eoff = b->st.st_size - b->elen;
91	if (pread(b->fd, b->ebuf, b->elen, b->eoff) == -1) {
92		free(b->ebuf);
93		b->ebuf = NULL;
94		goto out;
95	}
96
97	return 0;
98out:
99	b->elen = FILE_BADSIZE;
100	return -1;
101}
102