Merge pull request #73 from xairy/ranged_arrays

Allow range sized arrays

6 files changed, 53 insertions, 28 deletions

diff --git a/prog/mutation.go b/prog/mutation.go
index a00f64e43..a428d27cd 100644
--- a/prog/mutation.go
+++ b/prog/mutation.go
@@ -102,9 +102,19 @@ func (p *Prog) Mutate(rs rand.Source, ncalls int, ct *ChoiceTable) {
 						filename := r.filename(s)
 						arg.Data = []byte(filename)
 					case sys.ArrayType:
-						count := r.rand(6)
-						if count == uintptr(len(arg.Inner)) {
-							count++
+						count := uintptr(0)
+						switch a.Kind {
+						case sys.ArrayRandLen:
+							for count == uintptr(len(arg.Inner)) {
+								count = r.rand(6)
+							}
+						case sys.ArrayRangeLen:
+							if a.RangeBegin == a.RangeEnd {
+								panic("trying to mutate fixed length array")
+							}
+							for count == uintptr(len(arg.Inner)) {
+								count = r.randRange(int(a.RangeBegin), int(a.RangeEnd))
+							}
 						}
 						if count > uintptr(len(arg.Inner)) {
 							var calls []*Call
@@ -344,7 +354,7 @@ func mutationArgs(c *Call) (args, bases []*Arg, parents []*[]*Arg) {
 			// These special structs are mutated as a whole.
 		case sys.ArrayType:
 			// Don't mutate fixed-size arrays.
-			if typ.Len != 0 {
+			if typ.Kind == sys.ArrayRangeLen && typ.RangeBegin == typ.RangeEnd {
 				return
 			}
 		case sys.LenType:
diff --git a/prog/rand.go b/prog/rand.go
index 97033b434..26063b626 100644
--- a/prog/rand.go
+++ b/prog/rand.go
@@ -26,6 +26,10 @@ func (r *randGen) rand(n int) uintptr {
 	return uintptr(r.Intn(n))
 }
 
+func (r *randGen) randRange(begin int, end int) uintptr {
+	return uintptr(begin + r.Intn(end-begin+1))
+}
+
 func (r *randGen) bin() bool {
 	return r.Intn(2) == 0
 }
@@ -770,9 +774,12 @@ func (r *randGen) generateArg(s *state, typ sys.Type, dir ArgDir, sizes map[stri
 		filename := r.filename(s)
 		return dataArg([]byte(filename)), nil, nil
 	case sys.ArrayType:
-		count := a.Len
-		if count == 0 {
+		count := uintptr(0)
+		switch a.Kind {
+		case sys.ArrayRandLen:
 			count = r.rand(6)
+		case sys.ArrayRangeLen:
+			count = r.randRange(int(a.RangeBegin), int(a.RangeEnd))
 		}
 		sz := constArg(count)
 		var inner []*Arg
diff --git a/sys/README.md b/sys/README.md
index 46c0a1a59..1355ad4f8 100644
--- a/sys/README.md
+++ b/sys/README.md
@@ -45,7 +45,7 @@ rest of the type-options are type-specific:
 	"ptr": a pointer to an object, type-options:
 		type of the object; direction (in/out/inout)
 	"array": a variable/fixed-length array, type-options:
-		type of elements, optional size for fixed-length arrays
+		type of elements, optional size (fixed "5", or ranged "5:10", boundaries inclusive)
 	"intN"/"intptr": an integer without a particular meaning, type-options:
 		range of values (e.g. "5:10", or "-100:200", optional)
 ```
diff --git a/sys/align.go b/sys/align.go
index 5e67f6175..4c91c28be 100644
--- a/sys/align.go
+++ b/sys/align.go
@@ -64,7 +64,7 @@ func addAlignment(t *StructType) Type {
 		}
 		off += f.Size()
 		fields = append(fields, f)
-		if at, ok := f.(ArrayType); ok && at.Len == 0 {
+		if at, ok := f.(ArrayType); ok && (at.Kind == ArrayRandLen || (at.Kind == ArrayRangeLen && at.RangeBegin != at.RangeEnd)) {
 			varLen = true
 		}
 		if varLen && i != len(t.Fields)-1 {
diff --git a/sys/decl.go b/sys/decl.go
index a9f9d1ad3..2cc8f22e5 100644
--- a/sys/decl.go
+++ b/sys/decl.go
@@ -236,21 +236,27 @@ func (t FilenameType) Align() uintptr {
 	return 1
 }
 
+type ArrayKind int
+
+const (
+	ArrayRandLen ArrayKind = iota
+	ArrayRangeLen
+)
+
 type ArrayType struct {
 	TypeCommon
-	Type Type
-	Len  uintptr // 0 if variable-length, unused for now
+	Type       Type
+	Kind       ArrayKind
+	RangeBegin uintptr
+	RangeEnd   uintptr
 }
 
 func (t ArrayType) Size() uintptr {
-	if t.Len == 0 {
-		return 0 // for trailing embed arrays
-	}
-	return t.Len * t.Type.Size()
+	panic("should not be called")
 }
 
 func (t ArrayType) Align() uintptr {
-	return t.Type.Align()
+	panic("should not be called")
 }
 
 type PtrType struct {
diff --git a/sysgen/sysgen.go b/sysgen/sysgen.go
index 6d6a75bdc..e7a0fae00 100644
--- a/sysgen/sysgen.go
+++ b/sysgen/sysgen.go
@@ -490,21 +490,23 @@ func generateArg(
 		opt = false
 		fmt.Fprintf(out, "PtrType{%v, Dir: DirIn, Type: FilenameType{%v}}", commonHdr, common())
 	case "array":
-		want := 1
-		if len(a) == 2 {
-			want = 2
-		}
-		if len(a) != want {
-			failf("wrong number of arguments for %v arg %v, want %v, got %v", typ, name, want, len(a))
-		}
-		sz := "0"
-		if len(a) == 2 {
-			sz = a[1]
-			if v, ok := consts[sz]; ok {
-				sz = fmt.Sprint(v)
+		switch len(a) {
+		case 1:
+			fmt.Fprintf(out, "ArrayType{%v, Type: %v, Kind: ArrayRandLen}", common(), generateType(a[0], desc, consts))
+		case 2:
+			var begin, end uintptr
+			sz := a[1]
+			if _, err := fmt.Sscanf(sz, "%d:%d", &begin, &end); err != nil {
+				if v, ok := consts[sz]; ok {
+					sz = fmt.Sprint(v)
+				}
+				fmt.Fprintf(out, "ArrayType{%v, Type: %v, Kind: ArrayRangeLen, RangeBegin: %v, RangeEnd: %v}", common(), generateType(a[0], desc, consts), sz, sz)
+			} else {
+				fmt.Fprintf(out, "ArrayType{%v, Type: %v, Kind: ArrayRangeLen, RangeBegin: %v, RangeEnd: %v}", common(), generateType(a[0], desc, consts), begin, end)
 			}
+		default:
+			failf("wrong number of arguments for %v arg %v, want 1 or 2, got %v", typ, name, len(a))
 		}
-		fmt.Fprintf(out, "ArrayType{%v, Type: %v, Len: %v}", common(), generateType(a[0], desc, consts), sz)
 	case "ptr":
 		canBeArg = true
 		if want := 2; len(a) != want {