Expose ParseStrict to error on too many fields

cronexpr.go

@@ -62,11 +62,22 @@ func MustParse(cronLine string) *Expression {
 /******************************************************************************/
 
 // Parse returns a new Expression pointer. An error is returned if a malformed
-// cron expression is supplied.
+// cron expression is supplied. ParseStrict does the same thing, but unlike
+// Parse, it will return an error if the provided cron line has too many
+// tokens.
 // See <https://github.com/gorhill/cronexpr#implementation> for documentation
 // about what is a well-formed cron expression from this library's point of
 // view.
+
 func Parse(cronLine string) (*Expression, error) {
+	return parse(cronLine, false)
+}
+
+func ParseStrict(cronLine string) (*Expression, error) {
+	return parse(cronLine, true)
+}
+
+func parse(cronLine string, strict bool) (*Expression, error) {
 
 	// Maybe one of the built-in aliases is being used
 	cron := cronNormalizer.Replace(cronLine)
@@ -76,8 +87,14 @@ func Parse(cronLine string) (*Expression, error) {
 	if fieldCount < 5 {
 		return nil, fmt.Errorf("missing field(s)")
 	}
-	// ignore fields beyond 7th
+
 	if fieldCount > 7 {
+		// In strict mode, error out
+		if strict {
+			return nil, fmt.Errorf("too many fields")
+		}
+
+		// In non-strict mode, ignore fields beyond 7th
 		fieldCount = 7
 	}
 

cronexpr/go.mod

@@ -0,0 +1,7 @@
+module github.com/krallin/cronexpr/cronexpr
+
+go 1.14
+
+replace github.com/krallin/cronexpr => ../
+
+require github.com/krallin/cronexpr v0.0.0-00010101000000-000000000000

cronexpr/main.go

@@ -18,7 +18,7 @@ import (
 	"os"
 	"time"
 
-	"github.com/gorhill/cronexpr"
+	"github.com/krallin/cronexpr"
 )
 
 /******************************************************************************/

cronexpr_parse.go

@@ -438,6 +438,9 @@ func genericFieldParse(s string, desc fieldDescriptor) ([]*cronDirective, error)
 			directive.first = desc.atoi(snormal[pairs[2]:pairs[3]])
 			directive.last = desc.atoi(snormal[pairs[4]:pairs[5]])
 			directive.step = 1
+			if directive.last < directive.first {
+				return nil, fmt.Errorf("invalid interval %s (normalized to %d-%d)", snormal, directive.first, directive.last)
+			}
 			directives = append(directives, &directive)
 			continue
 		}

cronexpr_test.go

@@ -305,6 +305,35 @@ func TestInterval_Interval60Issue(t *testing.T) {
 	}
 }
 
+// Issue: https://github.com/aptible/supercronic/issues/63
+func TestRange_OutOfOrder(t *testing.T) {
+	_, err := Parse("45 4 *  *  6-7")
+	if err == nil {
+		t.Errorf("parsing with range 6-7 should return err")
+	}
+
+	_, err = Parse("45 4 *  *  6-5")
+	if err == nil {
+		t.Errorf("parsing with range 6-5 should return err")
+	}
+}
+
+/******************************************************************************/
+
+func TestTooManyFields(t *testing.T) {
+	cronLine := "* * * * * * * foobar"
+
+	_, err := ParseStrict(cronLine)
+	if err == nil {
+		t.Errorf("ParseStrict with too many fields should return err ")
+	}
+
+	_, err = Parse(cronLine)
+	if err != nil {
+		t.Errorf("Parse with too many fields should not return err ")
+	}
+}
+
 /******************************************************************************/
 
 var benchmarkExpressions = []string{

go.mod

@@ -0,0 +1,3 @@
+module github.com/krallin/cronexpr
+
+go 1.14