aspnetcore/shared/ArgumentEscaper.cs

107 lines
3.5 KiB
C#

// Copyright (c) .NET Foundation. All rights reserved.
// Licensed under the Apache License, Version 2.0. See License.txt in the project root for license information.
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
namespace Microsoft.Extensions.Tools.Internal
{
public static class ArgumentEscaper
{
/// <summary>
/// Undo the processing which took place to create string[] args in Main, so that the next process will
/// receive the same string[] args.
/// </summary>
/// <remarks>
/// See https://blogs.msdn.microsoft.com/twistylittlepassagesallalike/2011/04/23/everyone-quotes-command-line-arguments-the-wrong-way/
/// </remarks>
/// <param name="args"></param>
/// <returns></returns>
public static string EscapeAndConcatenate(IEnumerable<string> args)
=> string.Join(" ", args.Select(EscapeSingleArg));
private static string EscapeSingleArg(string arg)
{
var sb = new StringBuilder();
var needsQuotes = ShouldSurroundWithQuotes(arg);
var isQuoted = needsQuotes || IsSurroundedWithQuotes(arg);
if (needsQuotes)
{
sb.Append('"');
}
for (int i = 0; i < arg.Length; ++i)
{
var backslashes = 0;
// Consume all backslashes
while (i < arg.Length && arg[i] == '\\')
{
backslashes++;
i++;
}
if (i == arg.Length && isQuoted)
{
// Escape any backslashes at the end of the arg when the argument is also quoted.
// This ensures the outside quote is interpreted as an argument delimiter
sb.Append('\\', 2 * backslashes);
}
else if (i == arg.Length)
{
// At then end of the arg, which isn't quoted,
// just add the backslashes, no need to escape
sb.Append('\\', backslashes);
}
else if (arg[i] == '"')
{
// Escape any preceding backslashes and the quote
sb.Append('\\', (2 * backslashes) + 1);
sb.Append('"');
}
else
{
// Output any consumed backslashes and the character
sb.Append('\\', backslashes);
sb.Append(arg[i]);
}
}
if (needsQuotes)
{
sb.Append('"');
}
return sb.ToString();
}
private static bool ShouldSurroundWithQuotes(string argument)
{
// Don't quote already quoted strings
if (IsSurroundedWithQuotes(argument))
{
return false;
}
// Only quote if whitespace exists in the string
return ContainsWhitespace(argument);
}
private static bool IsSurroundedWithQuotes(string argument)
{
if (argument.Length <= 1)
{
return false;
}
return argument[0] == '"' && argument[argument.Length - 1] == '"';
}
private static bool ContainsWhitespace(string argument)
=> argument.IndexOfAny(new [] { ' ', '\t', '\n' }) >= 0;
}
}