mod_rewrite:为什么不能使用环境变量来防止递归？

Question

为什么我不能使用mod_rewrite与此类似的规则:

RewriteEngine On
RewriteCond %{ENV:did_rewrite} !=true
RewriteCond %{REQUEST_URI} ^(.*)/
RewriteRule (.*) %1/foo.php?original=$1 [E=did_rewrite:true]

为了防止递归？

当我转过身时RewriteLogLevel,我看到:

[.../initial] (3) [perdir /.../test/] strip per-dir prefix: /.../test/stuff -> stuff
[.../initial] (3) [perdir /.../test/] applying pattern '(.*)' to uri 'stuff'
[.../initial] (4) [perdir /.../test/] RewriteCond: input='' pattern='!=true' => matched
[.../initial] (4) [perdir /.../test/] RewriteCond: input='/test/stuff' pattern='(.*)/' => matched
[.../initial] (2) [perdir /.../test/] rewrite 'stuff' -> '/test/foo.php?original=stuff'
[.../initial] (5) setting env variable 'did_rewrite' to 'true'
[.../initial] (3) split uri=/test/foo.php?original=stuff -> uri=/test/foo.php, args=original=stuff
[.../initial] (1) [perdir /.../test/] internal redirect with /test/foo.php [INTERNAL REDIRECT]
[.../initial/redir#1] (3) [perdir /.../test/] strip per-dir prefix: /.../test/foo.php -> foo.php
[.../initial/redir#1] (3) [perdir /.../test/] applying pattern '(.*)' to uri 'foo.php'
[.../initial/redir#1] (4) [perdir /.../test/] RewriteCond: input='' pattern='!=true' => matched
[.../initial/redir#1] (4) [perdir /.../test/] RewriteCond: input='/test/foo.php' pattern='(.*)/' => matched
[.../initial/redir#1] (2) [perdir /.../test/] rewrite 'foo.php' -> '/test/foo.php?original=foo.php'
...

看起来,在"递归"调用中,环境变量以某种方式变得未设置......但我无法弄清楚为什么会发生这种情况.

要明确:我知道有很多方法可以防止这种递归.我想了解为什么这种特殊方式不起作用.

Answer 1

我认为这篇博文可能有你的答案.总之,当Apache执行内部重定向时,它会重命名所有环境变量:

static apr_table_t *rename_original_env(apr_pool_t *p, apr_table_t *t)
{
    const apr_array_header_t *env_arr = apr_table_elts(t);
    const apr_table_entry_t *elts = (const apr_table_entry_t *) env_arr->elts;
    apr_table_t *new = apr_table_make(p, env_arr->nalloc);
    int i;

    for (i = 0; i < env_arr->nelts; ++i) {
        if (!elts[i].key)
            continue;
        apr_table_setn(new, apr_pstrcat(p, "REDIRECT_", elts[i].key, NULL),
                  elts[i].val);
    }

    return new;
}

不幸的是,这似乎没有在任何地方记录.