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Re: svn commit: r1879346 - /httpd/httpd/trunk/server/util_etag.c
On 6/29/20 7:45 PM, minfrin@apache.org wrote:
> Author: minfrin
> Date: Mon Jun 29 17:45:35 2020
> New Revision: 1879346
>
> URL: http://svn.apache.org/viewvc?rev=1879346&view=rev
> Log:
> Use a dedicated constant for the base64 sha1 length.
>
> Modified:
> httpd/httpd/trunk/server/util_etag.c
>
> Modified: httpd/httpd/trunk/server/util_etag.c
> URL: http://svn.apache.org/viewvc/httpd/httpd/trunk/server/util_etag.c?rev=1879346&r1=1879345&r2=1879346&view=diff
> ==============================================================================
> --- httpd/httpd/trunk/server/util_etag.c (original)
> +++ httpd/httpd/trunk/server/util_etag.c Mon Jun 29 17:45:35 2020
> @@ -29,6 +29,8 @@
> #include "http_protocol.h" /* For index_of_response(). Grump. */
> #include "http_request.h"
>
> +#define SHA1_DIGEST_BASE64_LEN 4*(APR_SHA1_DIGESTSIZE/3)

Thanks for the better readability, but using apr_base64_encode_len this would result in

(APR_SHA1_DIGESTSIZE + 2) / 3 * 4) + 1

Why is the calculation different here (Ok I guess '+ 1' in the above is for the final '\0'
which we do not need to take account for here)?

> +
> /* Generate the human-readable hex representation of an apr_uint64_t
> * (basically a faster version of 'sprintf("%llx")')
> */
> @@ -168,7 +170,7 @@ AP_DECLARE(char *) ap_make_etag_ex(reque
> }
>
> etag = apr_palloc(r->pool, weak_len + sizeof("\"\"") +
> - 4*(APR_SHA1_DIGESTSIZE/3) + vlv_len + 4);
> + SHA1_DIGEST_BASE64_LEN + vlv_len + 4);

Tab issue?
And why + 4? I see the need for

- a '\0' at the end
- I assume that vlv contains the closing '"', hence this is accounted for in vlv_len if a vlv is present
- sizeof("\"\"") takes care of the leading '"' (after a possible weak string) and of the closing '"' in case of no vlv
and of the ';' in case of a vlv.

This would result in + 2.


Regards

RĂ¼diger