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