1 files changed, 125 insertions, 0 deletions
diff --git a/luni/src/main/native/realpath.cpp b/luni/src/main/native/realpath.cpp
new file mode 100644
index 0000000..d1960a4
--- /dev/null
+++ b/luni/src/main/native/realpath.cpp
@@ -0,0 +1,125 @@
+/*
+ * Copyright (c) 2003 Constantin S. Svintsoff <kostik@iclub.nsu.ru>
+ *
+ * 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. The names of the authors may not be used to endorse or promote
+ *    products derived from this software without specific prior written
+ *    permission.
+ *
+ * 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.
+ */
+
+#include "readlink.h"
+
+#include <string>
+
+#include <errno.h>
+#include <sys/param.h>
+#include <sys/stat.h>
+#include <unistd.h>
+
+/**
+ * This differs from realpath(3) mainly in its behavior when a path element does not exist or can
+ * not be searched. realpath(3) treats that as an error and gives up, but we have Java-compatible
+ * behavior where we just assume the path element was not a symbolic link. This leads to a textual
+ * treatment of ".." from that point in the path, which may actually lead us back to a path we
+ * can resolve (as in "/tmp/does-not-exist/../blah.txt" which would be an error for realpath(3)
+ * but "/tmp/blah.txt" under the traditional Java interpretation).
+ *
+ * This implementation also removes all the fixed-length buffers of the C original.
+ */
+bool realpath(const char* path, std::string& resolved) {
+    // 'path' must be an absolute path.
+    if (path[0] != '/') {
+        errno = EINVAL;
+        return false;
+    }
+
+    resolved = "/";
+    if (path[1] == '\0') {
+        return true;
+    }
+
+    // Iterate over path components in 'left'.
+    int symlinkCount = 0;
+    std::string left(path + 1);
+    while (!left.empty()) {
+        // Extract the next path component.
+        size_t nextSlash = left.find('/');
+        std::string nextPathComponent = left.substr(0, nextSlash);
+        if (nextSlash != std::string::npos) {
+            left.erase(0, nextSlash + 1);
+        } else {
+            left.clear();
+        }
+        if (nextPathComponent.empty()) {
+            continue;
+        } else if (nextPathComponent == ".") {
+            continue;
+        } else if (nextPathComponent == "..") {
+            // Strip the last path component except when we have single "/".
+            if (resolved.size() > 1) {
+                resolved.erase(resolved.rfind('/'));
+            }
+            continue;
+        }
+
+        // Append the next path component.
+        if (resolved[resolved.size() - 1] != '/') {
+            resolved += '/';
+        }
+        resolved += nextPathComponent;
+
+        // See if we've got a symbolic link, and resolve it if so.
+        struct stat sb;
+        if (lstat(resolved.c_str(), &sb) == 0 && S_ISLNK(sb.st_mode)) {
+            if (symlinkCount++ > MAXSYMLINKS) {
+                errno = ELOOP;
+                return false;
+            }
+
+            std::string symlink;
+            if (!readlink(resolved.c_str(), symlink)) {
+                return false;
+            }
+            if (symlink[0] == '/') {
+                // The symbolic link is absolute, so we need to start from scratch.
+                resolved = "/";
+            } else if (resolved.size() > 1) {
+                // The symbolic link is relative, so we just lose the last path component (which
+                // was the link).
+                resolved.erase(resolved.rfind('/'));
+            }
+
+            if (!left.empty()) {
+                const char* maybeSlash = (symlink[symlink.size() - 1] != '/') ? "/" : "";
+                left = symlink + maybeSlash + left;
+            } else {
+                left = symlink;
+            }
+        }
+    }
+
+    // Remove trailing slash except when the resolved pathname is a single "/".
+    if (resolved.size() > 1 && resolved[resolved.size() - 1] == '/') {
+        resolved.erase(resolved.size() - 1, 1);
+    }
+    return true;
+}