Add a -N option for use with utilities. This takes a VSM filename as argument,...

Add a -N option for use with utilities. This takes a VSM filename as argument, and will also disable the abandonment checks.

This allows reading a stale VSM file (e.g. _VSM.keep saved from a
panic) for forensics gathering.

doc/sphinx/reference/varnishstat.rst

@@ -19,7 +19,7 @@ Varnish Cache statistics
 SYNOPSIS
 ========
 
-varnishstat [-1] [-x] [-j] [-f field_list] [-l] [-n varnish_name] [-V] [-w delay]
+varnishstat [-1] [-x] [-j] [-f field_list] [-l] [-n varnish_name] [-N filename] [-V] [-w delay]
 
 DESCRIPTION
 ===========
@@ -38,6 +38,9 @@ The following options are available:
 -n          Specifies the name of the varnishd instance to get logs from.  If -n is not specified, the host name
 	    is used.
 
+-N          Specify a the filename of a stale VSM instance. When using this
+            option the abandonment checking is disabled.
+
 -V          Display the version number and exit.
 
 -w delay    Wait delay seconds between updates.  The default is 1. Can also be used with -1, -x or -j for repeated output.

include/vapi/vsc.h

@@ -44,8 +44,8 @@ struct VSM_fantom;
  * VSC level access functions
  */
 
-#define VSC_ARGS	"f:n:"
-#define VSC_n_USAGE	VSM_n_USAGE
+#define VSC_ARGS	"f:n:N:"
+#define VSC_n_USAGE	VSM_n_USAGE " " VSM_N_USAGE
 #define VSC_f_USAGE	"[-f field_name,...]"
 #define VSC_USAGE	VSC_n_USAGE \
 			VSC_f_USAGE

include/vapi/vsm.h

@@ -96,6 +96,20 @@ int VSM_n_Arg(struct VSM_data *vd, const char *n_arg);
 	 *	 <0 on failure, VSM_Error() returns diagnostic string
 	 */
 
+#define VSM_N_USAGE	"[-N filename]"
+
+int VSM_N_Arg(struct VSM_data *vd, const char *N_arg);
+	/*
+	 * Configure the library to use the specified VSM file name. This
+	 * bypasses abandonment checks and allows looking at stale VSM
+	 * files without a running Varnish instance.
+	 *
+	 * Can also be, and normally is done through VSC_Arg()/VSL_Arg().
+	 *
+	 * Returns:
+	 *	1 on success
+	 */
+
 const char *VSM_Name(const struct VSM_data *vd);
 	/*
 	 * Return the instance name.

lib/libvarnishapi/vsc.c

@@ -253,6 +253,7 @@ VSC_Arg(struct VSM_data *vd, int arg, const char *opt)
 	switch (arg) {
 	case 'f': return (vsc_f_arg(vd, opt));
 	case 'n': return (VSM_n_Arg(vd, opt));
+	case 'N': return (VSM_N_Arg(vd, opt));
 	default:
 		return (0);
 	}

lib/libvarnishapi/vsm.c

@@ -141,6 +141,20 @@ VSM_n_Arg(struct VSM_data *vd, const char *opt)
 
 /*--------------------------------------------------------------------*/
 
+int
+VSM_N_Arg(struct VSM_data *vd, const char *opt)
+{
+
+	CHECK_OBJ_NOTNULL(vd, VSM_MAGIC);
+	AN(opt);
+
+	REPLACE(vd->fname, opt);
+	vd->N_opt = 1;
+	return (1);
+}
+
+/*--------------------------------------------------------------------*/
+
 const char *
 VSM_Name(const struct VSM_data *vd)
 {
@@ -191,7 +205,7 @@ VSM_Open(struct VSM_data *vd)
 		/* Already open */
 		return (0);
 
-	if (!vd->n_opt)
+	if (!vd->n_opt && !vd->N_opt)
 		(void)VSM_n_Arg(vd, "");
 
 	AZ(vd->head);
@@ -224,7 +238,7 @@ VSM_Open(struct VSM_data *vd)
 		return (vsm_diag(vd, "Not a VSM file %s\n", vd->fname));
 	}
 
-	if (slh.alloc_seq == 0) {
+	if (!vd->N_opt && slh.alloc_seq == 0) {
 		AZ(close(vd->vsm_fd));
 		vd->vsm_fd = -1;
 		return (vsm_diag(vd,
@@ -282,6 +296,9 @@ VSM_Abandoned(struct VSM_data *vd)
 	if (vd->head == NULL)
 		/* Not open */
 		return (1);
+	if (vd->N_opt)
+		/* No abandonment check should be done */
+		return (0);
 	if (!vd->head->alloc_seq)
 		/* Flag of abandonment set by mgt */
 		return (1);
@@ -328,11 +345,11 @@ VSM__itern(const struct VSM_data *vd, struct VSM_fantom *vf)
 
 	if (!vd->head)
 		return (0);	/* Not open */
-	if (vd->head->alloc_seq == 0)
+	if (!vd->N_opt && vd->head->alloc_seq == 0)
 		return (0);	/* abandoned VSM */
-	else if (vf->priv != 0) {
+	else if (vf->chunk != NULL) {
 		/* get next chunk */
-		if (vf->priv != vd->head->alloc_seq)
+		if (!vd->N_opt && vf->priv != vd->head->alloc_seq)
 			return (0); /* changes during iteration */
 		if (vf->chunk->len == 0)
 			return (0); /* free'd during iteration */
@@ -376,7 +393,9 @@ VSM_StillValid(const struct VSM_data *vd, struct VSM_fantom *vf)
 	AN(vf);
 	if (!vd->head)
 		return (VSM_invalid);
-	if (!vd->head->alloc_seq)
+	if (!vd->N_opt && !vd->head->alloc_seq)
+		return (VSM_invalid);
+	if (vf->chunk == NULL)
 		return (VSM_invalid);
 	if (vf->priv == vd->head->alloc_seq)
 		return (VSM_valid);

lib/libvarnishapi/vsm_api.h

@@ -39,6 +39,7 @@ struct VSM_data {
 
 	char			*n_opt;
 	char			*fname;
+	int			N_opt;
 
 	struct stat		fstat;