[6.0] 1845b8937 vsl -R: Add strtol underflow/overflow handling

[Dridi Boukelmoune]

commit 1845b8937c45df862bc36138a86b977f058392f8
Author: Dag Haavi Finstad <daghf at varnish-software.com>
Date:   Mon Dec 3 14:31:35 2018 +0100

    vsl -R: Add strtol underflow/overflow handling
    
    Conflicts:
            lib/libvarnishapi/vsl_arg.c
    
    For some reason it was missing errno.h...

diff --git a/lib/libvarnishapi/vsl_arg.c b/lib/libvarnishapi/vsl_arg.c
index 2929b4ccf..25402e583 100644
--- a/lib/libvarnishapi/vsl_arg.c
+++ b/lib/libvarnishapi/vsl_arg.c
@@ -31,6 +31,7 @@
 #include "config.h"
 
 #include <ctype.h>
+#include <errno.h>
 #include <limits.h>
 #include <math.h>
 #include <stdio.h>
@@ -310,7 +311,10 @@ vsl_R_arg(struct VSL_data *vsl, const char *arg)
 	AN(arg);
 	CHECK_OBJ_NOTNULL(vsl, VSL_MAGIC);
 
+	errno = 0;
 	l = strtol(arg, &p, 0);
+	if ((l == LONG_MIN || l == LONG_MAX) && errno == ERANGE)
+		return (vsl_diag(vsl, "-R: Range error"));
 	if (l <= 0 || l > INT_MAX)
 		return (vsl_diag(vsl, "-R: Range error"));
 	vsl->R_opt_l = l;