c# - ETW 格式字符串中的转义字符？

Question

我正在使用新的 EventSource 类从我的应用程序写入 Windows 事件日志，到目前为止它很棒。但是，我观察到有两件事会导致可能相关的问题:传递给 Event 属性的格式字符串在写入事件日志之前似乎没有经过正常的 string.Format 处理。

考虑这个 block :

[Event((int)LogEvent.UserCreated, Keywords=Keywords.Directory, Channel=EventChannel.Operational,
Message="Created username {0} with forum post signature {1} and homepage {2}.")]
public void UserCreated(string username, string signature, string homepageAddress)
{
    WriteEvent((int)LogEvent.UserCreated, username, signature, homepageAddress);
}

会发生一些事情:

如果我尝试在消息的格式字符串中插入\n，则事件日志中不会打印换行符。

如果签名字符串包含换行符，则换行符会自然地打印在事件日志中。

如果签名或 homepageAddress 字符串包含类似 ETW 的标记(%1、%2 或 %3)，则 ETW 开始将这些伪标记替换为变量本身，并且最终得到嵌套在它们自身中的变量。

我假设如果 ETW 有一个转义字符，它可以用来在格式字符串中添加换行符，并且还允许我预处理我的字符串值以防止这些 sql 注入(inject)样式错误。

这样的转义字符是否存在？这通常是怎么做的？

Answer 1

EventSource list 生成器执行的翻译是

{0} -> %1
...
{n} -> %(n+1)

&   -> &
<   -> &lt;
>   -> &gt;
'   -> &apos;
"   -> &quot;

作为引用，转换发生在 string EventProviderBase.TranslateToManifestConvention(string) .

然后你最终得到消息编译器。 Escapes are as follows :

%n[!format_specifier!]  Describes an insert. Each insert is an entry in the 
    Arguments array in the FormatMessage function. The value of n can be a number 
    between 1 and 99. The format specifier is optional. If no value is specified, 
    the default is !s!. For information about the format specifier, see wsprintf. 
    The format specifier can use * for either the precision or the width. When 
    specified, they consume inserts numbered n+1 and n+2.

%0  Terminates a message text line without a trailing newline character. This can 
    be used to build a long line or terminate a prompt message without a trailing 
    newline character.

%.  Generates a single period. This can be used to display a period at the 
    beginning of a line, which would otherwise terminate the message text.

%!  Generates a single exclamation point. This can be used to specify an 
    exclamation point immediately after an insert.

%%  Generates a single percent sign.

%n  Generates a hard line break when it occurs at the end of a line. This can be 
    used with FormatMessage to ensure that the message fits a certain width.

%b  Generates a space character. This can be used to ensure an appropriate number 
    of trailing spaces on a line.

%r  Generates a hard carriage return without a trailing newline character.