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 * $FreeBSD$
27 */
28#include <errno.h>
29#include <stdlib.h>
30#include <string.h>
31#include "pathconv.h" /* prototypes */
32/*
33 * rel2abs: convert an relative path name into absolute.
34 *
35 *	i)	path	relative path
36 *	i)	base	base directory (must be absolute path)
37 *	o)	result	result buffer
38 *	i)	size	size of result buffer
39 *	r)		!= NULL: absolute path
40 *			== NULL: error
41 */
42char *
43rel2abs(const char *path, const char *base, char *result, const size_t size)
44{
45	const char *pp, *bp;
46	/*
47	 * endp points the last position which is safe in the result buffer.
48	 */
49	const char *endp = result + size - 1;
50	char *rp;
51	size_t length;
52
53	if (*path == '/') {
54		if (strlen(path) >= size)
55			goto erange;
56		strcpy(result, path);
57		goto finish;
58	} else if (*base != '/' || !size) {
59		errno = EINVAL;
60		return (NULL);
61	} else if (size == 1)
62		goto erange;
63
64	length = strlen(base);
65
66	if (!strcmp(path, ".") || !strcmp(path, "./")) {
67		if (length >= size)
68			goto erange;
69		strcpy(result, base);
70		/*
71		 * rp points the last char.
72		 */
73		rp = result + length - 1;
74		/*
75		 * remove the last '/'.
76		 */
77		if (*rp == '/') {
78			if (length > 1)
79				*rp = 0;
80		} else
81			rp++;
82		/* rp point NULL char */
83		if (*++path == '/') {
84			/*
85			 * Append '/' to the tail of path name.
86			 */
87			*rp++ = '/';
88			if (rp > endp)
89				goto erange;
90			*rp = 0;
91		}
92		goto finish;
93	}
94	bp = base + length;
95	if (*(bp - 1) == '/')
96		--bp;
97	/*
98	 * up to root.
99	 */
100	for (pp = path; *pp && *pp == '.'; ) {
101		if (!strncmp(pp, "../", 3)) {
102			pp += 3;
103			while (bp > base && *--bp != '/')
104				;
105		} else if (!strncmp(pp, "./", 2)) {
106			pp += 2;
107		} else if (!strncmp(pp, "..\0", 3)) {
108			pp += 2;
109			while (bp > base && *--bp != '/')
110				;
111		} else
112			break;
113	}
114	/*
115	 * down to leaf.
116	 */
117	length = bp - base;
118	if (length >= size)
119		goto erange;
120	strncpy(result, base, length);
121	rp = result + length;
122	if (*pp || *(pp - 1) == '/' || length == 0)
123		*rp++ = '/';
124	if (rp + strlen(pp) > endp)
125		goto erange;
126	strcpy(rp, pp);
127finish:
128	return result;
129erange:
130	errno = ERANGE;
131	return (NULL);
132}
133