1 files changed, 158 insertions, 0 deletions

diff --git a/lib/libc/stdlib/realpath.c b/lib/libc/stdlib/realpath.c
new file mode 100644
index 000000000000..28380d72183a
--- /dev/null
+++ b/lib/libc/stdlib/realpath.c
@@ -0,0 +1,158 @@
+/*
+ * Copyright (c) 1994
+ *	The Regents of the University of California.  All rights reserved.
+ *
+ * This code is derived from software contributed to Berkeley by
+ * Jan-Simon Pendry.
+ *
+ * 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.
+ * 3. All advertising materials mentioning features or use of this software
+ *    must display the following acknowledgement:
+ *	This product includes software developed by the University of
+ *	California, Berkeley and its contributors.
+ * 4. Neither the name of the University nor the names of its contributors
+ *    may be used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE REGENTS 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 REGENTS 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.
+ */
+
+#if defined(LIBC_SCCS) && !defined(lint)
+static char sccsid[] = "@(#)realpath.c	8.1 (Berkeley) 2/16/94";
+#endif /* LIBC_SCCS and not lint */
+
+#include <sys/param.h>
+#include <sys/stat.h>
+
+#include <errno.h>
+#include <fcntl.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+
+/*
+ * char *realpath(const char *path, char resolved_path[MAXPATHLEN]);
+ *
+ * Find the real name of path, by removing all ".", ".." and symlink
+ * components.  Returns (resolved) on success, or (NULL) on failure,
+ * in which case the path which caused trouble is left in (resolved).
+ */
+char *
+realpath(path, resolved)
+	const char *path;
+	char *resolved;
+{
+	struct stat sb;
+	int fd, n, rootd, serrno;
+	char *p, *q, wbuf[MAXPATHLEN];
+
+	/* Save the starting point. */
+	if ((fd = open(".", O_RDONLY)) < 0) {
+		(void)strcpy(resolved, ".");
+		return (NULL);
+	}
+
+	/*
+	 * Find the dirname and basename from the path to be resolved.
+	 * Change directory to the dirname component.
+	 * lstat the basename part.
+	 *     if it is a symlink, read in the value and loop.
+	 *     if it is a directory, then change to that directory.
+	 * get the current directory name and append the basename.
+	 */
+	(void)strncpy(resolved, path, MAXPATHLEN - 1);
+	resolved[MAXPATHLEN - 1] = '\0';
+loop:
+	q = strrchr(resolved, '/');
+	if (q != NULL) {
+		p = q + 1;
+		if (q == resolved)
+			q = "/";
+		else {
+			do {
+				--q;
+			} while (q > resolved && *q == '/');
+			q[1] = '\0';
+			q = resolved;
+		}
+		if (chdir(q) < 0)
+			goto err1;
+	} else
+		p = resolved;
+
+	/* Deal with the last component. */
+	if (*p != '\0' && lstat(p, &sb) == 0) {
+		if (S_ISLNK(sb.st_mode)) {
+			n = readlink(p, resolved, MAXPATHLEN);
+			if (n < 0)
+				goto err1;
+			resolved[n] = '\0';
+			goto loop;
+		}
+		if (S_ISDIR(sb.st_mode)) {
+			if (chdir(p) < 0)
+				goto err1;
+			p = "";
+		}
+	}
+
+	/*
+	 * Save the last component name and get the full pathname of
+	 * the current directory.
+	 */
+	(void)strcpy(wbuf, p);
+	if (getcwd(resolved, MAXPATHLEN) == 0)
+		goto err1;
+
+	/*
+	 * Join the two strings together, ensuring that the right thing
+	 * happens if the last component is empty, or the dirname is root.
+	 */
+	if (resolved[0] == '/' && resolved[1] == '\0')
+		rootd = 1;
+	else
+		rootd = 0;
+
+	if (*wbuf) {
+		if (strlen(resolved) + strlen(wbuf) + rootd + 1 > MAXPATHLEN) {
+			errno = ENAMETOOLONG;
+			goto err1;
+		}
+		if (rootd == 0)
+			(void)strcat(resolved, "/");
+		(void)strcat(resolved, wbuf);
+	}
+
+	/* Go back to where we came from. */
+	if (fchdir(fd) < 0) {
+		serrno = errno;
+		goto err2;
+	}
+
+	/* It's okay if the close fails, what's an fd more or less? */
+	(void)close(fd);
+	return (resolved);
+
+err1:	serrno = errno;
+	(void)fchdir(fd);
+err2:	(void)close(fd);
+	errno = serrno;
+	return (NULL);
+}