vsl: Write to stdout when opening "-"

Just like the file cursor reads from stdin when opening "-". And in
addition, teach varnishlog to also write to stdout when it is opening
the file directly. Likewise, put varnishncsa on par with varnishlog in
that regard.

It is now possible to compress binary VSL on the fly without taking
a detour to the file system, see u00019.vtc for an example.

Considering how VUT daemonizes, a "-w -" option in daemon mode becomes
an error as well.

Refs #3740

bin/varnishlog/varnishlog.c

@@ -72,9 +72,12 @@ openout(int append)
 {
 
 	AN(LOG.w_arg);
-	if (LOG.A_opt)
-		LOG.fo = fopen(LOG.w_arg, append ? "a" : "w");
-	else
+	if (LOG.A_opt) {
+		if (!strcmp(LOG.w_arg, "-"))
+			LOG.fo = stdout;
+		else
+			LOG.fo = fopen(LOG.w_arg, append ? "a" : "w");
+	} else
 		LOG.fo = VSL_WriteOpen(vut->vsl, LOG.w_arg, append, LOG.u_opt);
 	if (LOG.fo == NULL)
 		VUT_Error(vut, 2, "Cannot open output file (%s)",
@@ -148,6 +151,9 @@ main(int argc, char * const *argv)
 	if (vut->D_opt && !LOG.w_arg)
 		VUT_Error(vut, 1, "Missing -w option");
 
+	if (vut->D_opt && !strcmp(LOG.w_arg, "-"))
+		VUT_Error(vut, 1, "Daemon cannot write to stdout");
+
 	/* Setup output */
 	if (LOG.A_opt || !LOG.w_arg) {
 		vut->dispatch_f = VSL_PrintTransactions;

bin/varnishlog/varnishlog_options.h

@@ -58,7 +58,9 @@
 	    " reopened allowing the old one to be rotated away. The"	\
 	    " file can then be read by varnishlog and other tools with"	\
 	    " the -r option, unless the -A option was specified. This"	\
-	    " option is required when running in daemon mode."		\
+	    " option is required when running in daemon mode. If the"	\
+	    " filename is -, varnishlog writes to the standard output"	\
+	    " and cannot work as a daemon."				\
 	)
 
 LOG_OPT_a

bin/varnishncsa/varnishncsa.c

@@ -167,7 +167,10 @@ openout(int append)
 {
 
 	AN(CTX.w_arg);
-	CTX.fo = fopen(CTX.w_arg, append ? "a" : "w");
+	if (!strcmp(CTX.w_arg, "-"))
+		CTX.fo = stdout;
+	else
+		CTX.fo = fopen(CTX.w_arg, append ? "a" : "w");
 	if (CTX.fo == NULL)
 		VUT_Error(vut, 1, "Can't open output file (%s)",
 		    strerror(errno));
@@ -1217,6 +1220,9 @@ main(int argc, char * const *argv)
 	if (vut->D_opt && !CTX.w_arg)
 		VUT_Error(vut, 1, "Missing -w option");
 
+	if (vut->D_opt && !strcmp(CTX.w_arg, "-"))
+		VUT_Error(vut, 1, "Daemon cannot write to stdout");
+
 	/* Check for valid grouping mode */
 	assert(vut->g_arg < VSL_g__MAX);
 	if (vut->g_arg != VSL_g_vxid && vut->g_arg != VSL_g_request)

bin/varnishncsa/varnishncsa_options.h

@@ -34,7 +34,8 @@
 #define NCSA_OPT_a							\
 	VOPT("a", "[-a]", "Append to file",				\
 	    "When writing output to a file, append to it rather than"	\
-	    " overwrite it."						\
+	    " overwrite it. This option has no effect without the -w"	\
+	    " option."							\
 	)
 
 #define NCSA_OPT_F							\
@@ -62,7 +63,9 @@
 	    " unless the -a option was specified. If the application"	\
 	    " receives a SIGHUP in daemon mode the file will be"	\
 	    " reopened allowing the old one to be rotated away. This"	\
-	    " option is required when running in daemon mode."		\
+	    " option is required when running in daemon mode. If the"	\
+	    " filename is -, varnishncsa writes to the standard output"	\
+	    " and cannot work as a daemon."				\
 	)
 #define NCSA_OPT_b							\
 	VOPT("b", "[-b]", "Backend mode",				\

bin/varnishtest/tests/u00003.vtc

@@ -69,6 +69,8 @@ shell -expect "Copyright (c) 2006 Verdens Gang AS" \
 	"varnishncsa -V"
 shell -err -expect "Missing -w option" \
 	{varnishncsa -D}
+shell -err -expect "Daemon cannot write to stdout" \
+	"varnishlog -D -w -"
 shell -err -expect "Unknown format specifier at: %{foo}A" \
 	{varnishncsa -F "%{foo}A"}
 shell -err -expect "Unknown format specifier at: %A" \

bin/varnishtest/tests/u00006.vtc

@@ -26,6 +26,8 @@ shell -err -match "Usage: .*varnishlog <options>" \
 	"varnishlog extra"
 shell -err -expect "Missing -w option" \
 	"varnishlog -D"
+shell -err -expect "Daemon cannot write to stdout" \
+	"varnishlog -D -w -"
 shell -err -expect "Ambiguous grouping type: r" \
 	"varnishlog -g r"
 shell -err -expect "Unknown grouping type: foo" \

bin/varnishtest/tests/u00019.vtc

+varnishtest "varnishlog write vsl to stdout"
+
+feature cmd "command -v gzip"
+feature cmd "command -v zcat"
+
+varnish v1 -vcl {
+	backend be none;
+} -start
+
+client c1 {
+	txreq
+	rxresp
+	expect resp.status == 503
+} -run
+
+shell {varnishlog -d -w - -n ${v1_name} | gzip >vsl.gz}
+shell {ls -l}
+shell -match "RespStatus +503" {zcat vsl.gz | varnishlog -r -}

lib/libvarnishapi/vsl.c

@@ -413,14 +413,17 @@ VSL_WriteOpen(struct VSL_data *vsl, const char *name, int append, int unbuf)
 {
 	const char head[] = VSL_FILE_ID;
 	FILE* f;
-	f = fopen(name, append ? "a" : "w");
+	if (!strcmp(name, "-"))
+		f = stdout;
+	else
+		f = fopen(name, append ? "a" : "w");
 	if (f == NULL) {
 		vsl_diag(vsl, "%s", strerror(errno));
 		return (NULL);
 	}
 	if (unbuf)
 		setbuf(f, NULL);
-	if (0 == ftell(f)) {
+	if (ftell(f) == 0 || f == stdout) {
 		if (fwrite(head, 1, sizeof head, f) != sizeof head) {
 			vsl_diag(vsl, "%s", strerror(errno));
 			(void)fclose(f);