Question

我使用新的EventSource类从我的应用程序写入Windows事件日志，到目前为止它非常棒。但是，我观察到有两件事情导致了可能相关的问题：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。

考虑这个块：

[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);
}

发生了一些事情：

如果我尝试将\ n插入到邮件的格式字符串中，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，则会在事件日志中自然打印换行符。
如果签名或homepageAddress字符串包含类似ETW的标记（％1，％2或％3），那么ETW开始用变量本身替换那些伪标记，最后我自己嵌套了变量。< / LI>

我假设如果ETW存在转义字符，它可以用于将换行符放在格式字符串中，并且还允许我预处理我的字符串值以防止这些sql注入样式错误。

是否存在这样的转义字符？这通常是怎么做的？

Answer 1

EventSource清单生成器执行的转换是

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

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

作为参考，转换发生在string EventProviderBase.TranslateToManifestConvention(string)。

然后你最终得到了消息编译器。 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.

转义ETW格式字符串中的字符？

1 个答案: