Apache'if'指令中的正则表达式...这里出了什么问题? [英] Regex in Apache 'if' directive ... what's wrong here?

问题描述

(现在怀疑是Apache中的一个可能的错误...请参阅下文.)

以下是这些语句:(Apache 2.4)

<IfDefine !SERVER_TYPE>
    Define SERVER_TYPE prod
</IfDefine>
<If "${SERVER_TYPE} !~ /prod|demo|test/">   <===error here===
    Error "Define 'SERVER_TYPE' is hosed'"
</If>

Apache抱怨IF:

Apache complains about the IF:

Cannot parse condition clause: syntax error, unexpected T_OP_NRE, expecting '('

我可以猜到T_OP_NRE是指否定的正则表达式".即！〜"，但是我一生都无法弄清楚该语句中的语法错误是什么！ (而且，偶然地，"=〜"会产生[几乎]相同的消息.)

I can guess that T_OP_NRE refers to "negated regular-expression" i.e. "!~" but I can't for the life of me figure out what's the syntax-error in that statement! (And, incidentally, "=~" produces [almost] the same message.)

Apache可以识别$ {SERVER_TYPE}语法，因为我可以确认是否拼写错误的标识符. < DEFINE>的文档明确指出，应该像我一样使用"$ {ident}"而不是％{ident}"语法.

Apache is recognizing the ${SERVER_TYPE} syntax as I can confirm if I misspell the identifier. The documentation for <DEFINE> expressly states that "${ident}" not "%{ident}" syntax should be used, as I have done.

我的语法有什么问题，为什么Apache期望使用左括号?

What's wrong with my syntax, and why does Apache expect a left-parenthesis?

我开始谨慎地认为这实际上是Apache/2.4.12中的 BUG(！)，因为仅当使用"$ {DEFINED_SYMBOL}"时才会发生解析错误.如果未定义该符号，它将抱怨并做所有正确的事情(因此，它知道它在看什么...)，但是它给出了一个荒谬的(对我...)消息，如下所示: -仅当此结构位于左侧时显示.

I am cautiously beginning to believe that this is actually a BUG(!) in Apache/2.4.12 because the parse-error only occurs when "${DEFINED_SYMBOL}" is used. It will complain and do all the right things if the symbol is not defined (so, it knows what it's looking at ...), but it gives a nonsensical (to me ...) message as-shown if, and only if, this construct is on the left-hand side.

一个明显的解决方法是将符号放在单引号中，例如:

An apparent workaround is to put the symbol in single quotes, e.g.:

<If "'${SERVER_TYPE}' != /prod/demo/test/">

...但是到目前为止，在我的测试中，我认为它与正则表达式不正确匹配.实际上，我不确定发生什么，因为以下内容被认为是非匹配("true"):

... but so-far in my testing I don't think that it is matching the regex correctly. In fact, I'm not yet sure what is going on, because the following is considered to be a non-match ("true"):

<If "'prod' !~ /prod|demo|test/">

通过以下Perl单行代码，可以证明正则表达式的语法是正确的:

The regex syntax can be shown to be correct via this Perl one-liner:

perl -e 'my $var = "prod"; if ($var =~ /prod|demo|test/) {print "yes\n";}'

...显示是".

P.S.对于已定义符号，"$ {IDENT}"语法 是正确的(与％{}"相反).

P.S. The "${IDENT}" syntax is correct (versus "%{}", which is not) in the case of a Defined symbol.

推荐答案

尝试以下语法:

<If "'${SERVER_TYPE}' !~ m#(prod|demo|test)#">
    #Error "Define 'SERVER_TYPE' is hosed"
    RedirectMatch /old /new/
</If>

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