Finish updating README.

README.rst

@@ -1023,13 +1023,31 @@ as workspace exhaustion.
 LOGGING
 =======
 
-XXX ...
+Both of ``.match()`` and ``.hasprefix()`` return ``false`` when the
+string to be matched is NULL, typically because an unset header was
+specified. Such usage may be deliberate; you might intend VCL logic to
+depend on whether a header either doesn't match or does not exist. But
+it may be an error, for example due to misspelling the header name.
+
+When the string to be matched is NULL, the VMOD emits a warning to the
+log with the tag ``Notice``, in this format::
+
+  vmod_selector: <obj>.<method>(): subject string is NULL
+
+... where ``<obj>`` is the object name and ``<method>`` is either
+``match`` or ``hasprefix``.
+
+As noted above, VCL failure during request/response transactions
+(after successful VCL load) is logged with an error message using the
+``VCL_Error`` tag. These messages begin with the prefix ``vmod
+selector failure``.
 
 REQUIREMENTS
 ============
 
-The VMOD requires Varnish since version 6.0.0, or the current master
-branch.
+The VMOD requires Varnish since version 6.5.0, or the current master
+branch. See the source repository for versions of the VMOD that are
+compatible with other versions of Varnish.
 
 INSTALLATION
 ============
@@ -1049,6 +1067,10 @@ The VMOD uses workspace for two purposes:
 * A copy of the string to be matched for case insensitive matches (the
   copy is set to all one case).
 
+The default workspace sizes are usually more than large enough for
+typical usages, but that depends on workspace consumption for other
+purposes.
+
 If you find that methods are failing with ``VCL_Error`` messages
 indicating "out of space", consider increasing the varnishd parameters
 ``workspace_client`` and/or ``workspace_backend`` (see varnishd(1)).
@@ -1064,13 +1086,6 @@ and ``pcre_match_limit_recursion``, in which case they emit the same
 ``VCL_Error`` messages as the native operations. If necessary, adjust
 these parameters as advised in varnishd(1).
 
-AUTHOR
-======
-
-* Geoffrey Simmons <geoff@uplex.de>
-
-UPLEX Nils Goroll Systemoptimierung
-
 SEE ALSO
 ========
 

src/vmod_selector.vcc

@@ -911,13 +911,31 @@ as workspace exhaustion.
 LOGGING
 =======
 
-XXX ...
+Both of ``.match()`` and ``.hasprefix()`` return ``false`` when the
+string to be matched is NULL, typically because an unset header was
+specified. Such usage may be deliberate; you might intend VCL logic to
+depend on whether a header either doesn't match or does not exist. But
+it may be an error, for example due to misspelling the header name.
+
+When the string to be matched is NULL, the VMOD emits a warning to the
+log with the tag ``Notice``, in this format::
+
+  vmod_selector: <obj>.<method>(): subject string is NULL
+
+... where ``<obj>`` is the object name and ``<method>`` is either
+``match`` or ``hasprefix``.
+
+As noted above, VCL failure during request/response transactions
+(after successful VCL load) is logged with an error message using the
+``VCL_Error`` tag. These messages begin with the prefix ``vmod
+selector failure``.
 
 REQUIREMENTS
 ============
 
-The VMOD requires Varnish since version 6.0.0, or the current master
-branch.
+The VMOD requires Varnish since version 6.5.0, or the current master
+branch. See the source repository for versions of the VMOD that are
+compatible with other versions of Varnish.
 
 INSTALLATION
 ============
@@ -937,6 +955,10 @@ The VMOD uses workspace for two purposes:
 * A copy of the string to be matched for case insensitive matches (the
   copy is set to all one case).
 
+The default workspace sizes are usually more than large enough for
+typical usages, but that depends on workspace consumption for other
+purposes.
+
 If you find that methods are failing with ``VCL_Error`` messages
 indicating "out of space", consider increasing the varnishd parameters
 ``workspace_client`` and/or ``workspace_backend`` (see varnishd(1)).
@@ -952,13 +974,6 @@ and ``pcre_match_limit_recursion``, in which case they emit the same
 ``VCL_Error`` messages as the native operations. If necessary, adjust
 these parameters as advised in varnishd(1).
 
-AUTHOR
-======
-
-* Geoffrey Simmons <geoff@uplex.de>
-
-UPLEX Nils Goroll Systemoptimierung
-
 SEE ALSO
 ========