pkg/compiler: allow specifying static size for filename's

Sometimes filenames are embed into structs and need to take fixed space.

11 files changed, 80 insertions, 16 deletions

diff --git a/docs/syscall_descriptions_syntax.md b/docs/syscall_descriptions_syntax.md
index 42a6439dd..6d3306232 100644
--- a/docs/syscall_descriptions_syntax.md
+++ b/docs/syscall_descriptions_syntax.md
@@ -42,7 +42,9 @@ rest of the type-options are type-specific:
 "stringnoz": a non-zero-terminated memory buffer (no pointer indirection implied), type-options:
 	either a string value in quotes for constant strings (e.g. "foo"),
 	or a reference to string flags,
-"filename": a file/link/dir name, no pointer indirection implied, in most cases you want `ptr[in, filename]`
+"filename": a file/link/dir name, no pointer indirection implied,
+	in most cases you want `ptr[in, filename]`, type-options:
+	static size (optional)
 "fileoff": offset within a file
 "len": length of another field (for array it is number of elements), type-options:
 	argname of the object
diff --git a/executor/syscalls_test.h b/executor/syscalls_test.h
index d5be16213..bea4a537d 100644
--- a/executor/syscalls_test.h
+++ b/executor/syscalls_test.h
@@ -2,11 +2,11 @@
 
 #if 0
 #define GOARCH "32"
-#define SYZ_REVISION "d4cbc2aec52e291fefa8155c6c6ca397ba3c9e49"
+#define SYZ_REVISION "154a7d4ae122c9736177396c2a2e6c0b506b77d2"
 #define SYZ_PAGE_SIZE 8192
 #define SYZ_NUM_PAGES 2048
 #define SYZ_DATA_OFFSET 536870912
-unsigned syscall_count = 92;
+unsigned syscall_count = 93;
 call_t syscalls[] = {
 	{"foo$any0", 0, (syscall_t)foo},
 	{"foo$anyres", 0, (syscall_t)foo},
@@ -69,6 +69,7 @@ call_t syscalls[] = {
 	{"syz_test$length26", 0, (syscall_t)syz_test},
 	{"syz_test$length27", 0, (syscall_t)syz_test},
 	{"syz_test$length28", 0, (syscall_t)syz_test},
+	{"syz_test$length29", 0, (syscall_t)syz_test},
 	{"syz_test$length3", 0, (syscall_t)syz_test},
 	{"syz_test$length4", 0, (syscall_t)syz_test},
 	{"syz_test$length5", 0, (syscall_t)syz_test},
@@ -106,11 +107,11 @@ call_t syscalls[] = {
 
 #if 0
 #define GOARCH "64"
-#define SYZ_REVISION "cabe73c3b49273a8b0cd13bff35d40897dd88138"
+#define SYZ_REVISION "07f96db2fe414280f7b2c908e79f44d3d134b8f8"
 #define SYZ_PAGE_SIZE 4096
 #define SYZ_NUM_PAGES 4096
 #define SYZ_DATA_OFFSET 536870912
-unsigned syscall_count = 92;
+unsigned syscall_count = 93;
 call_t syscalls[] = {
 	{"foo$any0", 0, (syscall_t)foo},
 	{"foo$anyres", 0, (syscall_t)foo},
@@ -173,6 +174,7 @@ call_t syscalls[] = {
 	{"syz_test$length26", 0, (syscall_t)syz_test},
 	{"syz_test$length27", 0, (syscall_t)syz_test},
 	{"syz_test$length28", 0, (syscall_t)syz_test},
+	{"syz_test$length29", 0, (syscall_t)syz_test},
 	{"syz_test$length3", 0, (syscall_t)syz_test},
 	{"syz_test$length4", 0, (syscall_t)syz_test},
 	{"syz_test$length5", 0, (syscall_t)syz_test},
diff --git a/pkg/compiler/types.go b/pkg/compiler/types.go
index a7734262a..f5ec1221e 100644
--- a/pkg/compiler/types.go
+++ b/pkg/compiler/types.go
@@ -264,11 +264,19 @@ var typeArgFlags = &typeArg{
 var typeFilename = &typeDesc{
 	Names:     []string{"filename"},
 	CantBeOpt: true,
+	OptArgs:   1,
+	Args:      []namedArg{{"size", typeArgInt}},
 	Varlen: func(comp *compiler, t *ast.Type, args []*ast.Type) bool {
+		if len(args) >= 1 {
+			return false
+		}
 		return true
 	},
 	Gen: func(comp *compiler, t *ast.Type, args []*ast.Type, base prog.IntTypeCommon) prog.Type {
 		base.TypeSize = 0
+		if len(args) >= 1 {
+			base.TypeSize = args[0].Value
+		}
 		return &prog.BufferType{
 			TypeCommon: base.TypeCommon,
 			Kind:       prog.BufferFilename,
diff --git a/prog/analysis.go b/prog/analysis.go
index 626af7446..7d5cc0099 100644
--- a/prog/analysis.go
+++ b/prog/analysis.go
@@ -73,11 +73,16 @@ func (s *state) analyzeImpl(c *Call, resources bool) {
 		case *BufferType:
 			a := arg.(*DataArg)
 			if typ.Dir() != DirOut && len(a.Data()) != 0 {
+				val := string(a.Data())
+				// Remove trailing zero padding.
+				for len(val) >= 2 && val[len(val)-1] == 0 && val[len(val)-2] == 0 {
+					val = val[:len(val)-1]
+				}
 				switch typ.Kind {
 				case BufferString:
-					s.strings[string(a.Data())] = true
+					s.strings[val] = true
 				case BufferFilename:
-					s.files[string(a.Data())] = true
+					s.files[val] = true
 				}
 			}
 		}
diff --git a/prog/mutation.go b/prog/mutation.go
index dd465cf3d..85a718a80 100644
--- a/prog/mutation.go
+++ b/prog/mutation.go
@@ -194,7 +194,7 @@ func (target *Target) mutateArg(r *randGen, s *state, arg Arg, ctx ArgCtx, updat
 				a.data = r.randString(s, t)
 			}
 		case BufferFilename:
-			a.data = []byte(r.filename(s))
+			a.data = []byte(r.filename(s, t))
 		case BufferText:
 			data := append([]byte{}, a.Data()...)
 			a.data = r.mutateText(t.Text, data)
diff --git a/prog/rand.go b/prog/rand.go
index 97571b7ea..d8ba0f33d 100644
--- a/prog/rand.go
+++ b/prog/rand.go
@@ -150,7 +150,19 @@ func (r *randGen) flags(vv []uint64) (v uint64) {
 	return
 }
 
-func (r *randGen) filename(s *state) string {
+func (r *randGen) filename(s *state, typ *BufferType) string {
+	fn := r.filenameImpl(s)
+	if !typ.Varlen() {
+		size := typ.Size()
+		if uint64(len(fn)) < size {
+			fn += string(make([]byte, size-uint64(len(fn))))
+		}
+		fn = fn[:size]
+	}
+	return fn
+}
+
+func (r *randGen) filenameImpl(s *state) string {
 	dir := "."
 	if r.oneOf(2) && len(s.files) != 0 {
 		files := make([]string, 0, len(s.files))
@@ -540,18 +552,20 @@ func (r *randGen) generateArgImpl(s *state, typ Type, ignoreSpecial bool) (arg A
 			return MakeDataArg(a, data), nil
 		case BufferFilename:
 			if a.Dir() == DirOut {
-				sz := 0
+				var sz uint64
 				switch {
+				case !a.Varlen():
+					sz = a.Size()
 				case r.nOutOf(1, 3):
-					sz = r.Intn(100)
+					sz = r.rand(100)
 				case r.nOutOf(1, 2):
 					sz = 108 // UNIX_PATH_MAX
 				default:
 					sz = 4096 // PATH_MAX
 				}
-				return MakeOutDataArg(a, uint64(sz)), nil
+				return MakeOutDataArg(a, sz), nil
 			}
-			return MakeDataArg(a, []byte(r.filename(s))), nil
+			return MakeDataArg(a, []byte(r.filename(s, a))), nil
 		case BufferText:
 			if a.Dir() == DirOut {
 				return MakeOutDataArg(a, uint64(r.Intn(100))), nil
diff --git a/prog/size_test.go b/prog/size_test.go
index 08b7cba92..8ce368d09 100644
--- a/prog/size_test.go
+++ b/prog/size_test.go
@@ -146,6 +146,10 @@ func TestAssignSize(t *testing.T) {
 			"syz_test$length28(&(0x7f0000000000), 0x0)",
 			"syz_test$length28(&(0x7f0000000000)=@f1, 0x2a)",
 		},
+		{
+			"syz_test$length29(&(0x7f0000000000)={'./a\\x00', './b/c\\x00', 0x0, 0x0, 0x0})",
+			"syz_test$length29(&(0x7f0000000000)={'./a\\x00', './b/c\\x00', 0xa, 0x14, 0x21})",
+		},
 	}
 
 	for i, test := range tests {
diff --git a/prog/types.go b/prog/types.go
index cdf1a0863..1dee2015b 100644
--- a/prog/types.go
+++ b/prog/types.go
@@ -259,7 +259,7 @@ const (
 type BufferType struct {
 	TypeCommon
 	Kind       BufferKind
-	RangeBegin uint64   // for BufferBlobRange kind
+	RangeBegin uint64   // for BufferBlobRange kind, or static size for BufferFilename
 	RangeEnd   uint64   // for BufferBlobRange kind
 	Text       TextKind // for BufferText
 	SubKind    string
diff --git a/sys/test/32.go b/sys/test/32.go
index 7425c8bd9..50611b0dd 100644
--- a/sys/test/32.go
+++ b/sys/test/32.go
@@ -93,6 +93,13 @@ var structDescs_32 = []*KeyedStruct{
 		&BufferType{TypeCommon: TypeCommon{TypeName: "string", FldName: "a", TypeSize: 10}, Kind: 2, SubKind: "serialize_strings", Values: []string{"aaa\x00\x00\x00\x00\x00\x00\x00", "bbb\x00\x00\x00\x00\x00\x00\x00"}},
 		&BufferType{TypeCommon: TypeCommon{TypeName: "string", FldName: "b", TypeSize: 5}, Kind: 2, SubKind: "serialize_strings", Values: []string{"aaa\x00\x00", "bbb\x00\x00"}},
 	}}},
+	{Key: StructKey{Name: "static_filename"}, Desc: &StructDesc{TypeCommon: TypeCommon{TypeName: "static_filename", TypeSize: 33}, Fields: []Type{
+		&BufferType{TypeCommon: TypeCommon{TypeName: "filename", FldName: "f1", TypeSize: 10}, Kind: 3},
+		&BufferType{TypeCommon: TypeCommon{TypeName: "filename", FldName: "f2", TypeSize: 20}, Kind: 3},
+		&LenType{IntTypeCommon: IntTypeCommon{TypeCommon: TypeCommon{TypeName: "bytesize", FldName: "f3", TypeSize: 1}}, BitSize: 8, Buf: "f1"},
+		&LenType{IntTypeCommon: IntTypeCommon{TypeCommon: TypeCommon{TypeName: "bytesize", FldName: "f4", TypeSize: 1}}, BitSize: 8, Buf: "f2"},
+		&LenType{IntTypeCommon: IntTypeCommon{TypeCommon: TypeCommon{TypeName: "bytesize", FldName: "f5", TypeSize: 1}}, BitSize: 8, Buf: "parent"},
+	}}},
 	{Key: StructKey{Name: "syz_align0"}, Desc: &StructDesc{TypeCommon: TypeCommon{TypeName: "syz_align0", TypeSize: 24}, Fields: []Type{
 		&IntType{IntTypeCommon: IntTypeCommon{TypeCommon: TypeCommon{TypeName: "int16", FldName: "f0", TypeSize: 2}}},
 		&ConstType{IntTypeCommon: IntTypeCommon{TypeCommon: TypeCommon{TypeName: "pad", TypeSize: 2}}, IsPad: true},
@@ -690,6 +697,9 @@ var syscalls_32 = []*Syscall{
 		&PtrType{TypeCommon: TypeCommon{TypeName: "ptr", FldName: "a0", TypeSize: 4}, Type: &UnionType{Key: StructKey{Name: "explicitly_sized_union"}}},
 		&LenType{IntTypeCommon: IntTypeCommon{TypeCommon: TypeCommon{TypeName: "len", FldName: "a1", TypeSize: 4}}, Buf: "a0"},
 	}},
+	{Name: "syz_test$length29", CallName: "syz_test", Args: []Type{
+		&PtrType{TypeCommon: TypeCommon{TypeName: "ptr", FldName: "a", TypeSize: 4}, Type: &StructType{Key: StructKey{Name: "static_filename"}}},
+	}},
 	{Name: "syz_test$length3", CallName: "syz_test", Args: []Type{
 		&PtrType{TypeCommon: TypeCommon{TypeName: "ptr", FldName: "a0", TypeSize: 4}, Type: &StructType{Key: StructKey{Name: "syz_length_len_struct"}}},
 	}},
@@ -797,4 +807,4 @@ var consts_32 = []ConstValue{
 	{Name: "ONLY_32BITS_CONST", Value: 1},
 }
 
-const revision_32 = "d4cbc2aec52e291fefa8155c6c6ca397ba3c9e49"
+const revision_32 = "154a7d4ae122c9736177396c2a2e6c0b506b77d2"
diff --git a/sys/test/64.go b/sys/test/64.go
index 4b48d9b05..3c4cf8281 100644
--- a/sys/test/64.go
+++ b/sys/test/64.go
@@ -93,6 +93,13 @@ var structDescs_64 = []*KeyedStruct{
 		&BufferType{TypeCommon: TypeCommon{TypeName: "string", FldName: "a", TypeSize: 10}, Kind: 2, SubKind: "serialize_strings", Values: []string{"aaa\x00\x00\x00\x00\x00\x00\x00", "bbb\x00\x00\x00\x00\x00\x00\x00"}},
 		&BufferType{TypeCommon: TypeCommon{TypeName: "string", FldName: "b", TypeSize: 5}, Kind: 2, SubKind: "serialize_strings", Values: []string{"aaa\x00\x00", "bbb\x00\x00"}},
 	}}},
+	{Key: StructKey{Name: "static_filename"}, Desc: &StructDesc{TypeCommon: TypeCommon{TypeName: "static_filename", TypeSize: 33}, Fields: []Type{
+		&BufferType{TypeCommon: TypeCommon{TypeName: "filename", FldName: "f1", TypeSize: 10}, Kind: 3},
+		&BufferType{TypeCommon: TypeCommon{TypeName: "filename", FldName: "f2", TypeSize: 20}, Kind: 3},
+		&LenType{IntTypeCommon: IntTypeCommon{TypeCommon: TypeCommon{TypeName: "bytesize", FldName: "f3", TypeSize: 1}}, BitSize: 8, Buf: "f1"},
+		&LenType{IntTypeCommon: IntTypeCommon{TypeCommon: TypeCommon{TypeName: "bytesize", FldName: "f4", TypeSize: 1}}, BitSize: 8, Buf: "f2"},
+		&LenType{IntTypeCommon: IntTypeCommon{TypeCommon: TypeCommon{TypeName: "bytesize", FldName: "f5", TypeSize: 1}}, BitSize: 8, Buf: "parent"},
+	}}},
 	{Key: StructKey{Name: "syz_align0"}, Desc: &StructDesc{TypeCommon: TypeCommon{TypeName: "syz_align0", TypeSize: 24}, Fields: []Type{
 		&IntType{IntTypeCommon: IntTypeCommon{TypeCommon: TypeCommon{TypeName: "int16", FldName: "f0", TypeSize: 2}}},
 		&ConstType{IntTypeCommon: IntTypeCommon{TypeCommon: TypeCommon{TypeName: "pad", TypeSize: 2}}, IsPad: true},
@@ -689,6 +696,9 @@ var syscalls_64 = []*Syscall{
 		&PtrType{TypeCommon: TypeCommon{TypeName: "ptr", FldName: "a0", TypeSize: 8}, Type: &UnionType{Key: StructKey{Name: "explicitly_sized_union"}}},
 		&LenType{IntTypeCommon: IntTypeCommon{TypeCommon: TypeCommon{TypeName: "len", FldName: "a1", TypeSize: 8}}, Buf: "a0"},
 	}},
+	{Name: "syz_test$length29", CallName: "syz_test", Args: []Type{
+		&PtrType{TypeCommon: TypeCommon{TypeName: "ptr", FldName: "a", TypeSize: 8}, Type: &StructType{Key: StructKey{Name: "static_filename"}}},
+	}},
 	{Name: "syz_test$length3", CallName: "syz_test", Args: []Type{
 		&PtrType{TypeCommon: TypeCommon{TypeName: "ptr", FldName: "a0", TypeSize: 8}, Type: &StructType{Key: StructKey{Name: "syz_length_len_struct"}}},
 	}},
@@ -795,4 +805,4 @@ var consts_64 = []ConstValue{
 	{Name: "IPPROTO_UDP", Value: 17},
 }
 
-const revision_64 = "cabe73c3b49273a8b0cd13bff35d40897dd88138"
+const revision_64 = "07f96db2fe414280f7b2c908e79f44d3d134b8f8"
diff --git a/sys/test/test.txt b/sys/test/test.txt
index ca548d073..9c074d217 100644
--- a/sys/test/test.txt
+++ b/sys/test/test.txt
@@ -409,11 +409,20 @@ explicitly_sized_union [
 	f1	int8
 ] [size[42]]
 
+static_filename {
+	f1	filename[10]
+	f2	filename[20]
+	f3	bytesize[f1, int8]
+	f4	bytesize[f2, int8]
+	f5	bytesize[parent, int8]
+}
+
 syz_test$length24(a ptr[in, len_nontemp5])
 syz_test$length25(a0 ptr[in, array[array[int8]]], a1 len[a0])
 syz_test$length26(a ptr[in, len_unaligned], b bytesize[a])
 syz_test$length27(a0 ptr[in, explicitly_sized], a1 len[a0])
 syz_test$length28(a0 ptr[in, explicitly_sized_union], a1 len[a0])
+syz_test$length29(a ptr[in, static_filename])
 
 # Big endian