Resources.cs

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using System;
using System.IO;
 
namespace IKVM.CoreLib.Modules
{
 
    static class Resources
    {
 
        public static string ToPackageName(string name)
        {
            int index = name.LastIndexOf('/');
            if (index == -1 || index == name.Length - 1)
            {
                return "";
            }
            else
            {
                return name.Substring(0, index).Replace('/', '.');
            }
        }
 
        public static string ToResourceName(string dir, string file)
        {
            // full dir path, with ending separator
            dir = Path.GetFullPath(dir);
            if (dir.EndsWith(Path.DirectorySeparatorChar) == false)
                dir += Path.DirectorySeparatorChar;
 
            // normalize relative path off of dir
            file = Path.Combine(dir, file);
            if (file.StartsWith(dir) == false)
                throw new InvalidOperationException("Resource file does not exist in directory.");
 
            // cut directory off of file path
            file = file[dir.Length..];
            if (Path.DirectorySeparatorChar != '/')
                file = file.Replace(Path.DirectorySeparatorChar, '/');
 
            // ensure directory path ends with separator
            if (file != "" && Directory.Exists(file))
                file += "/";
 
            return file;
        }
 
        public static string? ToFilePath(string dir, string name)
        {
            var expectDirectory = name.EndsWith('/');
            if (expectDirectory)
                name = name.TrimEnd('/');
 
            var path = ToSafeFilePath(name);
            if (path is not null)
            {
                var file = Path.Combine(dir, path);
                if (Directory.Exists(file) || (Directory.Exists(file) == false && expectDirectory == false))
                    return file;
            }
 
            return null;
        }
 
        static string? ToSafeFilePath(string name)
        {
            // scan elements of resource name
            int next;
            int off = 0;
            while ((next = name.IndexOf('/', off)) != -1)
            {
                int len = next - off;
                if (MayTranslate(name, off, len) == false)
                    return null;
 
                off = next + 1;
            }
 
            int rem = name.Length - off;
            if (MayTranslate(name, off, rem) == false)
                return null;
 
            // map resource name to a file path string
            string path;
            if (Path.DirectorySeparatorChar == '/')
            {
                path = name;
            }
            else
            {
                // not allowed to embed file separators
                if (name.Contains(Path.DirectorySeparatorChar))
                    return null;
 
                // convert to native separator
                path = name.Replace('/', Path.DirectorySeparatorChar);
            }
 
            // file path not allowed to have root component
            return Path.IsPathRooted(path) == false ? path : null;
        }
 
        static bool MayTranslate(string name, int off, int len)
        {
            if (len <= 2)
            {
                if (len == 0)
                    return false;
 
                var starsWithDot = (name[off] == '.');
                if (len == 1 && starsWithDot)
                    return false;
                if (len == 2 && starsWithDot && (name[off + 1] == '.'))
                    return false;
            }
 
            return true;
        }
 
    }
 
}