Re: svn commit: r1879346 - /httpd/httpd/trunk/server/util_etag.c

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Re: svn commit: r1879346 - /httpd/httpd/trunk/server/util_etag.c

Ruediger Pluem


On 6/29/20 7:45 PM, [hidden email] 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