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      1 /*
      2  * Copyright (C) 2010 Google Inc. All rights reserved.
      3  *
      4  * Redistribution and use in source and binary forms, with or without
      5  * modification, are permitted provided that the following conditions are
      6  * met:
      7  *
      8  *     * Redistributions of source code must retain the above copyright
      9  * notice, this list of conditions and the following disclaimer.
     10  *     * Redistributions in binary form must reproduce the above
     11  * copyright notice, this list of conditions and the following disclaimer
     12  * in the documentation and/or other materials provided with the
     13  * distribution.
     14  *     * Neither the name of Google Inc. nor the names of its
     15  * contributors may be used to endorse or promote products derived from
     16  * this software without specific prior written permission.
     17  *
     18  * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
     19  * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
     20  * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
     21  * A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
     22  * OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
     23  * SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
     24  * LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
     25  * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
     26  * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
     27  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
     28  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
     29  */
     30 
     31 #include "config.h"
     32 #include "modules/filesystem/DOMFilePath.h"
     33 
     34 #include "wtf/Vector.h"
     35 #include "wtf/text/CString.h"
     36 #include "wtf/text/StringBuilder.h"
     37 
     38 namespace WebCore {
     39 
     40 const char DOMFilePath::separator = '/';
     41 const char DOMFilePath::root[] = "/";
     42 
     43 String DOMFilePath::append(const String& base, const String& components)
     44 {
     45     return ensureDirectoryPath(base) + components;
     46 }
     47 
     48 String DOMFilePath::ensureDirectoryPath(const String& path)
     49 {
     50     if (!DOMFilePath::endsWithSeparator(path))
     51         return path + DOMFilePath::separator;
     52     return path;
     53 }
     54 
     55 String DOMFilePath::getName(const String& path)
     56 {
     57     int index = path.reverseFind(DOMFilePath::separator);
     58     if (index != -1)
     59         return path.substring(index + 1);
     60     return path;
     61 }
     62 
     63 String DOMFilePath::getDirectory(const String& path)
     64 {
     65     int index = path.reverseFind(DOMFilePath::separator);
     66     if (!index)
     67         return DOMFilePath::root;
     68     if (index != -1)
     69         return path.substring(0, index);
     70     return ".";
     71 }
     72 
     73 bool DOMFilePath::isParentOf(const String& parent, const String& mayBeChild)
     74 {
     75     ASSERT(DOMFilePath::isAbsolute(parent));
     76     ASSERT(DOMFilePath::isAbsolute(mayBeChild));
     77     if (parent == DOMFilePath::root && mayBeChild != DOMFilePath::root)
     78         return true;
     79     if (parent.length() >= mayBeChild.length() || !mayBeChild.startsWith(parent, false))
     80         return false;
     81     if (mayBeChild[parent.length()] != DOMFilePath::separator)
     82         return false;
     83     return true;
     84 }
     85 
     86 String DOMFilePath::removeExtraParentReferences(const String& path)
     87 {
     88     ASSERT(DOMFilePath::isAbsolute(path));
     89     Vector<String> components;
     90     Vector<String> canonicalized;
     91     path.split(DOMFilePath::separator, components);
     92     for (size_t i = 0; i < components.size(); ++i) {
     93         if (components[i] == ".")
     94             continue;
     95         if (components[i] == "..") {
     96             if (canonicalized.size() > 0)
     97                 canonicalized.removeLast();
     98             continue;
     99         }
    100         canonicalized.append(components[i]);
    101     }
    102     if (canonicalized.isEmpty())
    103         return DOMFilePath::root;
    104     StringBuilder result;
    105     for (size_t i = 0; i < canonicalized.size(); ++i) {
    106         result.append(DOMFilePath::separator);
    107         result.append(canonicalized[i]);
    108     }
    109     return result.toString();
    110 }
    111 
    112 bool DOMFilePath::isValidPath(const String& path)
    113 {
    114     if (path.isEmpty() || path == DOMFilePath::root)
    115         return true;
    116 
    117     // Embedded NULs are not allowed.
    118     if (path.find(static_cast<UChar>(0)) != WTF::kNotFound)
    119         return false;
    120 
    121     // While not [yet] restricted by the spec, '\\' complicates implementation for Chromium.
    122     if (path.find('\\') != WTF::kNotFound)
    123         return false;
    124 
    125     // This method is only called on fully-evaluated absolute paths. Any sign of ".." or "." is likely an attempt to break out of the sandbox.
    126     Vector<String> components;
    127     path.split(DOMFilePath::separator, components);
    128     for (size_t i = 0; i < components.size(); ++i) {
    129         if (components[i] == ".")
    130             return false;
    131         if (components[i] == "..")
    132             return false;
    133     }
    134     return true;
    135 }
    136 
    137 bool DOMFilePath::isValidName(const String& name)
    138 {
    139     if (name.isEmpty())
    140         return true;
    141     // '/' is not allowed in name.
    142     if (name.contains('/'))
    143         return false;
    144     return isValidPath(name);
    145 }
    146 
    147 } // namespace WebCore
    148