1/*
2 * Copyright (c) 1997 Shigio Yamaguchi. All rights reserved.
3 * Copyright (c) 1999 Tama Communications Corporation. 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, this list of conditions and the following disclaimer.
10 * 2. Redistributions in binary form must reproduce the above copyright
11 *    notice, this list of conditions and the following disclaimer in the
12 *    documentation and/or other materials provided with the distribution.
13 *
14 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
15 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
16 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
17 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
18 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
19 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
20 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
21 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
22 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
23 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
24 * SUCH DAMAGE.
25 */
26#include <errno.h>
27#include <stdlib.h>
28#include <string.h>
29#include "pathconv.h" /* prototypes */
30/*
31 * rel2abs: convert an relative path name into absolute.
32 *
33 *	i)	path	relative path
34 *	i)	base	base directory (must be absolute path)
35 *	o)	result	result buffer
36 *	i)	size	size of result buffer
37 *	r)		!= NULL: absolute path
38 *			== NULL: error
39 */
40char *
41rel2abs(const char *path, const char *base, char *result, const size_t size)
42{
43	const char *pp, *bp;
44	/*
45	 * endp points the last position which is safe in the result buffer.
46	 */
47	const char *endp = result + size - 1;
48	char *rp;
49	size_t length;
50
51	if (*path == '/') {
52		if (strlen(path) >= size)
53			goto erange;
54		strcpy(result, path);
55		goto finish;
56	} else if (*base != '/' || !size) {
57		errno = EINVAL;
58		return (NULL);
59	} else if (size == 1)
60		goto erange;
61
62	length = strlen(base);
63
64	if (!strcmp(path, ".") || !strcmp(path, "./")) {
65		if (length >= size)
66			goto erange;
67		strcpy(result, base);
68		/*
69		 * rp points the last char.
70		 */
71		rp = result + length - 1;
72		/*
73		 * remove the last '/'.
74		 */
75		if (*rp == '/') {
76			if (length > 1)
77				*rp = 0;
78		} else
79			rp++;
80		/* rp point NULL char */
81		if (*++path == '/') {
82			/*
83			 * Append '/' to the tail of path name.
84			 */
85			*rp++ = '/';
86			if (rp > endp)
87				goto erange;
88			*rp = 0;
89		}
90		goto finish;
91	}
92	bp = base + length;
93	if (*(bp - 1) == '/')
94		--bp;
95	/*
96	 * up to root.
97	 */
98	for (pp = path; *pp && *pp == '.'; ) {
99		if (!strncmp(pp, "../", 3)) {
100			pp += 3;
101			while (bp > base && *--bp != '/')
102				;
103		} else if (!strncmp(pp, "./", 2)) {
104			pp += 2;
105		} else if (!strncmp(pp, "..\0", 3)) {
106			pp += 2;
107			while (bp > base && *--bp != '/')
108				;
109		} else
110			break;
111	}
112	/*
113	 * down to leaf.
114	 */
115	length = bp - base;
116	if (length >= size)
117		goto erange;
118	strncpy(result, base, length);
119	rp = result + length;
120	if (*pp || *(pp - 1) == '/' || length == 0)
121		*rp++ = '/';
122	if (rp + strlen(pp) > endp)
123		goto erange;
124	strcpy(rp, pp);
125finish:
126	return result;
127erange:
128	errno = ERANGE;
129	return (NULL);
130}
131