pkg/compiler: fix len of parent template struct

Consider the following example:

type len_templ1[DATA1, DATA2] {
	data	DATA1
	inner	len_temp2[DATA2]
}

type len_temp2[DATA] {
	data	DATA
	len	len[len_templ1, int8]
}

Here len refers to a parent struct, but the struct is a template,
so it's actual name is something like "len_templ1[int8, int16]".
Currently this does not work as compiler barks at incorrect
len target.

Make this work.

2 files changed, 26 insertions, 3 deletions

diff --git a/pkg/compiler/check.go b/pkg/compiler/check.go
index eb2a13e19..1954fded5 100644
--- a/pkg/compiler/check.go
+++ b/pkg/compiler/check.go
@@ -7,6 +7,7 @@ package compiler
 
 import (
 	"fmt"
+	"strings"
 
 	"github.com/google/syzkaller/pkg/ast"
 	"github.com/google/syzkaller/prog"
@@ -268,14 +269,15 @@ func (comp *compiler) checkLenType(t *ast.Type, name string, fields []*ast.Field
 	for i, arg := range args {
 		argDesc := desc.Args[i]
 		if argDesc.Type == typeArgLenTarget {
-			comp.checkLenTarget(t, name, arg.Ident, fields, parents)
+			comp.checkLenTarget(t, name, &arg.Ident, fields, parents)
 		} else if argDesc.Type == typeArgType {
 			comp.checkLenType(arg, name, fields, parents, checked, false)
 		}
 	}
 }
 
-func (comp *compiler) checkLenTarget(t *ast.Type, name, target string, fields []*ast.Field, parents []*ast.Struct) {
+func (comp *compiler) checkLenTarget(t *ast.Type, name string, targetp *string, fields []*ast.Field, parents []*ast.Struct) {
+	target := *targetp
 	if target == name {
 		comp.error(t.Pos, "%v target %v refer to itself", t.Ident, target)
 		return
@@ -311,7 +313,14 @@ func (comp *compiler) checkLenTarget(t *ast.Type, name, target string, fields []
 		return
 	}
 	for _, parent := range parents {
-		if target == parent.Name.Name {
+		parentName := parent.Name.Name
+		if pos := strings.IndexByte(parentName, '['); pos != -1 {
+			// For template parents name is "struct_name[ARG1, ARG2]",
+			// strip the part after '[' and update actual len target.
+			parentName = parentName[:pos]
+		}
+		if target == parentName {
+			*targetp = parent.Name.Name
 			return
 		}
 	}
diff --git a/pkg/compiler/testdata/all.txt b/pkg/compiler/testdata/all.txt
index 88e45dba4..8bd81c7d4 100644
--- a/pkg/compiler/testdata/all.txt
+++ b/pkg/compiler/testdata/all.txt
@@ -29,6 +29,20 @@ proc_struct1 {
 	f1	proc[C0, 8, int8]
 }
 
+# Len/bytesize types.
+
+type len_templ1[DATA1, DATA2] {
+	data	DATA1
+	inner	len_temp2[DATA2]
+}
+
+type len_temp2[DATA] {
+	data	DATA
+	len	len[len_templ1, int8]
+}
+
+foo$len_templ(a ptr[in, len_templ1[int8, int16]])
+
 # Void type.
 
 void0 {