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-rw-r--r--lib/libpathconv/abs2rel.c111
1 files changed, 111 insertions, 0 deletions
diff --git a/lib/libpathconv/abs2rel.c b/lib/libpathconv/abs2rel.c
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+++ b/lib/libpathconv/abs2rel.c
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+/*
+ * Copyright (c) 1997 Shigio Yamaguchi. All rights reserved.
+ * Copyright (c) 1999 Tama Communications Corporation. All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ * notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ * notice, this list of conditions and the following disclaimer in the
+ * documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+ * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ *
+ * $FreeBSD$
+ */
+#include <errno.h>
+#include <stdlib.h>
+#include <string.h>
+#include "pathconv.h" /* prototypes */
+/*
+ * abs2rel: convert an absolute path name into relative.
+ *
+ * i) path absolute path
+ * i) base base directory (must be absolute path)
+ * o) result result buffer
+ * i) size size of result buffer
+ * r) != NULL: relative path
+ * == NULL: error
+ */
+char *
+abs2rel(const char *path, const char *base, char *result, const size_t size)
+{
+ const char *pp, *bp, *branch;
+ /*
+ * endp points the last position which is safe in the result buffer.
+ */
+ const char *endp = result + size - 1;
+ char *rp;
+
+ if (*path != '/') {
+ if (strlen(path) >= size)
+ goto erange;
+ strcpy(result, path);
+ goto finish;
+ } else if (*base != '/' || !size) {
+ errno = EINVAL;
+ return (NULL);
+ } else if (size == 1)
+ goto erange;
+ /*
+ * seek to branched point.
+ */
+ branch = path;
+ for (pp = path, bp = base; *pp && *bp && *pp == *bp; pp++, bp++)
+ if (*pp == '/')
+ branch = pp;
+ if ((*pp == 0 || (*pp == '/' && *(pp + 1) == 0)) &&
+ (*bp == 0 || (*bp == '/' && *(bp + 1) == 0))) {
+ rp = result;
+ *rp++ = '.';
+ if (*pp == '/' || *(pp - 1) == '/')
+ *rp++ = '/';
+ if (rp > endp)
+ goto erange;
+ *rp = 0;
+ goto finish;
+ }
+ if ((*pp == 0 && *bp == '/') || (*pp == '/' && *bp == 0))
+ branch = pp;
+ /*
+ * up to root.
+ */
+ rp = result;
+ for (bp = base + (branch - path); *bp; bp++)
+ if (*bp == '/' && *(bp + 1) != 0) {
+ if (rp + 3 > endp)
+ goto erange;
+ *rp++ = '.';
+ *rp++ = '.';
+ *rp++ = '/';
+ }
+ if (rp > endp)
+ goto erange;
+ *rp = 0;
+ /*
+ * down to leaf.
+ */
+ if (*branch) {
+ if (rp + strlen(branch + 1) > endp)
+ goto erange;
+ strcpy(rp, branch + 1);
+ } else
+ *--rp = 0;
+finish:
+ return result;
+erange:
+ errno = ERANGE;
+ return (NULL);
+}