1 files changed, 162 insertions, 0 deletions

diff --git a/src/lib/libc/stdlib/realpath.c b/src/lib/libc/stdlib/realpath.c
new file mode 100644
index 0000000000..1525d0372f
--- /dev/null
+++ b/src/lib/libc/stdlib/realpath.c
@@ -0,0 +1,162 @@
+/*
+ * 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. 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 *rcsid = "$OpenBSD: realpath.c,v 1.10 2003/08/01 21:04:59 millert Exp $";
+#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, needslash, serrno;
+        char *p, *q, wbuf[MAXPATHLEN];
+        int symlinks = 0;
+
+        /* Save the starting point. */
+        if ((fd = open(".", O_RDONLY)) < 0) {
+                (void)strlcpy(resolved, ".", MAXPATHLEN);
+                return (NULL);
+        }
+
+        /* Convert "." -> "" to optimize away a needless lstat() and chdir() */
+        if (path[0] == '.' && path[1] == '\0')
+                path = "";
+
+        /*
+         * 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.
+         */
+        strlcpy(resolved, path, MAXPATHLEN);
+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)) {
+                        if (++symlinks > MAXSYMLINKS) {
+                                errno = ELOOP;
+                                goto err1;
+                        }
+                        n = readlink(p, resolved, MAXPATHLEN-1);
+                        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)strlcpy(wbuf, p, sizeof wbuf);
+        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')
+                needslash = 0;
+        else
+                needslash = 1;
+
+        if (*wbuf) {
+                if (strlen(resolved) + strlen(wbuf) + needslash >= MAXPATHLEN) {
+                        errno = ENAMETOOLONG;
+                        goto err1;
+                }
+                if (needslash)
+                        strlcat(resolved, "/", MAXPATHLEN);
+                strlcat(resolved, wbuf, MAXPATHLEN);
+        }
+
+        /* 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);
+}