ngx_int_t
ngx_regex_compile(ngx_regex_compile_t *rc)
{
    int               n, erroff;
    char             *p;
    pcre             *re;
    const char       *errstr;
    ngx_regex_elt_t  *elt;

    ngx_regex_malloc_init(rc->pool);

    re = pcre_compile((const char *) rc->pattern.data, (int) rc->options,
                      &errstr, &erroff, NULL);

    /* ensure that there is no current pool */
    ngx_regex_malloc_done();

    if (re == NULL) {
        if ((size_t) erroff == rc->pattern.len) {
           rc->err.len = ngx_snprintf(rc->err.data, rc->err.len,
                              "pcre_compile() failed: %s in \"%V\"",
                               errstr, &rc->pattern)
                      - rc->err.data;

        } else {
           rc->err.len = ngx_snprintf(rc->err.data, rc->err.len,
                              "pcre_compile() failed: %s in \"%V\" at \"%s\"",
                               errstr, &rc->pattern, rc->pattern.data + erroff)
                      - rc->err.data;
        }

        return NGX_ERROR;
    }

    rc->regex = ngx_pcalloc(rc->pool, sizeof(ngx_regex_t));
    if (rc->regex == NULL) {
        goto nomem;
    }

    rc->regex->code = re;

    /* do not study at runtime */

    if (ngx_pcre_studies != NULL) {
        elt = ngx_list_push(ngx_pcre_studies);
        if (elt == NULL) {
            goto nomem;
        }

        elt->regex = rc->regex;
        elt->name = rc->pattern.data;
    }

    n = pcre_fullinfo(re, NULL, PCRE_INFO_CAPTURECOUNT, &rc->captures);
    if (n < 0) {
        p = "pcre_fullinfo(\"%V\", PCRE_INFO_CAPTURECOUNT) failed: %d";
        goto failed;
    }

    if (rc->captures == 0) {
        return NGX_OK;
    }

    n = pcre_fullinfo(re, NULL, PCRE_INFO_NAMECOUNT, &rc->named_captures);
    if (n < 0) {
        p = "pcre_fullinfo(\"%V\", PCRE_INFO_NAMECOUNT) failed: %d";
        goto failed;
    }

    if (rc->named_captures == 0) {
        return NGX_OK;
    }

    n = pcre_fullinfo(re, NULL, PCRE_INFO_NAMEENTRYSIZE, &rc->name_size);
    if (n < 0) {
        p = "pcre_fullinfo(\"%V\", PCRE_INFO_NAMEENTRYSIZE) failed: %d";
        goto failed;
    }

    n = pcre_fullinfo(re, NULL, PCRE_INFO_NAMETABLE, &rc->names);
    if (n < 0) {
        p = "pcre_fullinfo(\"%V\", PCRE_INFO_NAMETABLE) failed: %d";
        goto failed;
    }

    return NGX_OK;

failed:

    rc->err.len = ngx_snprintf(rc->err.data, rc->err.len, p, &rc->pattern, n)
                  - rc->err.data;
    return NGX_ERROR;

nomem:

    rc->err.len = ngx_snprintf(rc->err.data, rc->err.len,
                               "regex \"%V\" compilation failed: no memory",
                               &rc->pattern)
                  - rc->err.data;
    return NGX_ERROR;
}