[master] ebad1cf Make beresp.filters writable, and test it.

[Poul-Henning Kamp]

commit ebad1cff8a221ef11010f25384b0eaa40c175899
Author: Poul-Henning Kamp <phk at FreeBSD.org>
Date:   Wed Apr 18 07:54:56 2018 +0000

    Make beresp.filters writable, and test it.

diff --git a/bin/varnishd/cache/cache_fetch.c b/bin/varnishd/cache/cache_fetch.c
index 1706c98..b316cec 100644
--- a/bin/varnishd/cache/cache_fetch.c
+++ b/bin/varnishd/cache/cache_fetch.c
@@ -540,9 +540,6 @@ vbf_default_filter_list(const struct busyobj *bo, struct vsb *vsb)
 	if (do_gzip && !is_gunzip)
 		do_gzip = 0;
 
-	/* But we can't do both at the same time */
-	assert(do_gzip == 0 || do_gunzip == 0);
-
 	if (do_gunzip || (is_gzip && bo->do_esi))
 		VSB_cat(vsb, " gunzip");
 
diff --git a/bin/varnishd/cache/cache_vrt_var.c b/bin/varnishd/cache/cache_vrt_var.c
index 0ab6286..52adc63 100644
--- a/bin/varnishd/cache/cache_vrt_var.c
+++ b/bin/varnishd/cache/cache_vrt_var.c
@@ -927,3 +927,21 @@ VRT_r_beresp_filters(VRT_CTX)
 	/* We do not set bo->filter_list yet, things might still change */
 	return (VBF_Get_Filter_List(ctx->bo));
 }
+
+VCL_VOID
+VRT_l_beresp_filters(VRT_CTX, const char *str, ...)
+{
+	va_list ap;
+	const char *b;
+
+	CHECK_OBJ_NOTNULL(ctx, VRT_CTX_MAGIC);
+	CHECK_OBJ_NOTNULL(ctx->bo, BUSYOBJ_MAGIC);
+	va_start(ap, str);
+	b = VRT_String(ctx->bo->ws, NULL, str, ap);
+	va_end(ap);
+	if (b == NULL) {
+		WS_MarkOverflow(ctx->bo->ws);
+		return;
+	}
+	ctx->bo->filter_list = b;
+}
diff --git a/bin/varnishtest/tests/g00003.vtc b/bin/varnishtest/tests/g00003.vtc
index 1ba77ba..74bfa58 100644
--- a/bin/varnishtest/tests/g00003.vtc
+++ b/bin/varnishtest/tests/g00003.vtc
@@ -27,6 +27,12 @@ server s1 {
 	expect req.http.accept-encoding == <undef>
 	txresp -hdr "Vary: Accept-Encoding" \
 	       -body "keep plain real"
+
+	rxreq
+	expect req.url == "/filters"
+	expect req.http.accept-encoding == <undef>
+	txresp -bodylen 78
+
 } -start
 
 varnish v1 -cliok "param.set http_gzip_support true" -vcl+backend {
@@ -36,6 +42,9 @@ varnish v1 -cliok "param.set http_gzip_support true" -vcl+backend {
 		if (bereq.url == "/foobar") {
 			set beresp.do_gzip = true;
 		}
+		if (bereq.url == "/filters") {
+			set beresp.filters = "gzip gunzip gzip gunzip gzip";
+		}
 	}
 } -start
 
@@ -62,6 +71,8 @@ client c1 {
 	expect resp.bodylen == 43
 } -run
 
+varnish v1 -vsl_catchup
+
 varnish v1 -expect n_gzip == 1
 varnish v1 -expect n_gunzip == 2
 varnish v1 -expect n_test_gunzip == 0
@@ -80,3 +91,13 @@ client c1 {
 	expect resp.http.content-encoding == <undef>
 	expect resp.body == "keep plain real"
 } -run
+
+varnish v1 -vsl_catchup
+
+client c1 {
+	txreq -url /filters
+	rxresp
+	expect resp.http.content-encoding == "gzip"
+	gunzip
+	expect resp.bodylen == 78
+} -run
diff --git a/doc/sphinx/reference/vcl_var.rst b/doc/sphinx/reference/vcl_var.rst
index f29a9ed..c1b765c 100644
--- a/doc/sphinx/reference/vcl_var.rst
+++ b/doc/sphinx/reference/vcl_var.rst
@@ -901,6 +901,8 @@ beresp.filters
 
 	Readable from: vcl_backend_response
 
+	Writable from: vcl_backend_response
+
 	List of VFP filters the beresp.body will be pulled through.
 	
 obj