ruby 64位aix编译中的正则表达式限制 [英] Regex limit in ruby 64 bit aix compilation

问题描述

我在 AIX Box 上编译了 ruby​​ 64 位.似乎没有任何问题，除非我在代码中使用了一些特定的正则表达式.下面是一个例子:

I have compiled ruby 64 bit on an AIX Box. There doesn't seem to be any issue except when I use some specific regular expressions in my code. Here is an example:

/([0-9]){1000}/.match("2")

结果:

RegexpError: too big quantifier in {,}: /([0-9]*){1000}/

当我尝试减少重复次数时，它似乎奏效了.

When I try reducing the number of repetitions, it seems to work.

我尝试深入研究 ruby​​ 代码.但无法理解其中的原因.这是我们在 AIX/64 位 ruby​​ 中的某种依赖或限制吗?

I tried digging into the ruby code. But could not understand the reason. Is this some dependency or restriction that we have in AIX/64 bit ruby?

提前致谢:)

推荐答案

我几乎立即找到了答案.

I almost immediately found the answer.

我做的第一件事是在 ruby​​ 源代码中搜索抛出的错误.我发现 regex.h 对此负责.

The first thing I did was to search in the ruby source code for the error being thrown. I found that regex.h was responsible for this.

在regex.h中，代码流程是这样的:

In regex.h, the code flow is something like this:

/* Maximum number of duplicates an interval can allow.  */
#ifndef RE_DUP_MAX
#define RE_DUP_MAX  ((1 << 15) - 1)
#endif

现在这里的问题是 RE_DUP_MAX.在 AIX 机器上，在/usr/include 中的某处定义了相同的常量.我搜索它并在

Now the problem here is RE_DUP_MAX. On AIX box, the same constant has been defined somewhere in /usr/include. I searched for it and found in

/usr/include/NLregexp.h
/usr/include/sys/limits.h
/usr/include/unistd.h

我不确定正在使用这三个中的哪一个(很可能是 NLregexp.h).在这些标头中，RE_DUP_MAX 的值已设置为 255！所以正则表达式的重复次数是有上限的！

I am not sure which of the three is being used(most probably NLregexp.h). In these headers, the value of RE_DUP_MAX has been set to 255! So there is a cap placed on the number of repetitions of a regex!

简而言之，原因是编译采用了系统定义的值，而不是我们在regex.h中定义的值！

In short, the reason is the compilation taking the system defined value than that we define in regex.h!

因此通过在 regex.h 中重新分配 RE_DUP_MAX 的值解决了问题即

Hence the issue was solved by reassigning the value of RE_DUP_MAX in regex.h i.e

# ifdef RE_DUP_MAX
# undef RE_DUP_MAX                                                                                            
# endif

# define RE_DUP_MAX ((1 << 15) - 1)

干杯！

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