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
33 FILE_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
45 void
buffer_init(struct buffer * b,int fd,const struct stat * st,const void * data,size_t len)46 buffer_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
61 void
buffer_fini(struct buffer * b)62 buffer_fini(struct buffer *b)
63 {
64 free(b->ebuf);
65 b->ebuf = NULL;
66 b->elen = 0;
67 }
68
69 int
buffer_fill(const struct buffer * bb)70 buffer_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;
98 out:
99 b->elen = FILE_BADSIZE;
100 return -1;
101 }
102