xref: /PHP-8.4/ext/fileinfo/libmagic/buffer.c (revision b7c5813c)
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
30 FILE_RCSID("@(#)$File: buffer.c,v 1.13 2023/07/02 12:48:39 christos Exp $")
31 #endif	/* lint */
32 
33 #include "magic.h"
34 #ifdef HAVE_UNISTD_H
35 #include <unistd.h>
36 #endif
37 #include <string.h>
38 #include <stdlib.h>
39 #include <sys/stat.h>
40 
41 void
buffer_init(struct buffer * b,int fd,const zend_stat_t * st,const void * data,size_t len)42 buffer_init(struct buffer *b, int fd, const zend_stat_t *st, const void *data,
43     size_t len)
44 {
45 	b->fd = fd;
46 	if (st)
47 		memcpy(&b->st, st, sizeof(b->st));
48 	else if (b->fd == -1 || zend_fstat(b->fd, &b->st) == -1)
49 		memset(&b->st, 0, sizeof(b->st));
50 	b->fbuf = data;
51 	b->flen = len;
52 	b->eoff = 0;
53 	b->ebuf = NULL;
54 	b->elen = 0;
55 }
56 
57 void
buffer_fini(struct buffer * b)58 buffer_fini(struct buffer *b)
59 {
60 	efree(b->ebuf);
61 	b->ebuf = NULL;
62 	b->elen = 0;
63 }
64 
65 int
buffer_fill(const struct buffer * bb)66 buffer_fill(const struct buffer *bb)
67 {
68 	struct buffer *b = CCAST(struct buffer *, bb);
69 
70 	if (b->elen != 0)
71 		return b->elen == FILE_BADSIZE ? -1 : 0;
72 
73 	if (!S_ISREG(b->st.st_mode))
74 		goto out;
75 
76 	b->elen = CAST(size_t, b->st.st_size) < b->flen ?
77 	    CAST(size_t, b->st.st_size) : b->flen;
78 	if (b->elen == 0) {
79 		efree(b->ebuf);
80 		b->ebuf = NULL;
81 		return 0;
82 	}
83 	if ((b->ebuf = emalloc(b->elen)) == NULL)
84 		goto out;
85 
86 	b->eoff = b->st.st_size - b->elen;
87 	if (FINFO_LSEEK_FUNC(b->fd, b->eoff, SEEK_SET) == (zend_off_t)-1 ||
88 		FINFO_READ_FUNC(b->fd, b->ebuf, b->elen) != (ssize_t)b->elen)
89 	{
90 		efree(b->ebuf);
91 		b->ebuf = NULL;
92 		goto out;
93 	}
94 
95 	return 0;
96 out:
97 	b->elen = FILE_BADSIZE;
98 	return -1;
99 }
100