Should verify that the max value is not too big

When parsing the ulimit, we should check if the ulimit max value is greater then
the processes max value.  If yes then we should return an error.

Signed-off-by: Daniel J Walsh <dwalsh@redhat.com>

ulimit.go

@@ -4,6 +4,7 @@ import (
 	"fmt"
 	"strconv"
 	"strings"
+	"syscall"
 )
 
 // Ulimit is a human friendly version of Rlimit.
@@ -69,10 +70,10 @@ func ParseUlimit(val string) (*Ulimit, error) {
 		return nil, fmt.Errorf("invalid ulimit argument: %s", val)
 	}
 
-	if _, exists := ulimitNameMapping[parts[0]]; !exists {
+	limitType, exists := ulimitNameMapping[parts[0]]
+	if !exists {
 		return nil, fmt.Errorf("invalid ulimit type: %s", parts[0])
 	}
-
 	var (
 		soft int64
 		hard = &soft // default to soft in case no hard was set
@@ -103,6 +104,13 @@ func ParseUlimit(val string) (*Ulimit, error) {
 		if soft > *hard {
 			return nil, fmt.Errorf("ulimit soft limit must be less than or equal to hard limit: %d > %d", soft, *hard)
 		}
+		var rlimit syscall.Rlimit
+		if err := syscall.Getrlimit(limitType, &rlimit); err == nil {
+			if *hard > int64(rlimit.Max) {
+				return nil, fmt.Errorf("ulimit hard limit must be less than or equal to hard limit for the current process, hard: %d", *hard)
+			}
+		}
+
 	}
 
 	return &Ulimit{Name: parts[0], Soft: soft, Hard: *hard}, nil

ulimit_test.go

@@ -21,6 +21,12 @@ func TestParseUlimitValid(t *testing.T) {
 	}
 }
 
+func TestParseUlimitTooBig(t *testing.T) {
+	if _, err := ParseUlimit("nofile=512:1000024"); err == nil {
+		t.Fatalf("expected invalid value got %q", err)
+	}
+}
+
 func TestParseUlimitInvalidLimitType(t *testing.T) {
 	if _, err := ParseUlimit("notarealtype=1024:1024"); err == nil {
 		t.Fatalf("expected error on invalid ulimit type")