sys: support recursive structs

A struct can have a pointer to itself directly or indirectly.
Currently it leads to inifinite recursion when generating descriptions.
Fix this.

3 files changed, 30 insertions, 16 deletions

diff --git a/sys/align.go b/sys/align.go
index fdcbb5444..5e67f6175 100644
--- a/sys/align.go
+++ b/sys/align.go
@@ -17,12 +17,12 @@ func initAlign() {
 		case ArrayType:
 			t1.Type = rec(t1.Type)
 			t = t1
-		case StructType:
+		case *StructType:
 			for i, f := range t1.Fields {
 				t1.Fields[i] = rec(f)
 			}
 			t = addAlignment(t1)
-		case UnionType:
+		case *UnionType:
 			opts := make(map[string]bool)
 			for i, opt := range t1.Options {
 				if opts[opt.Name()] {
@@ -44,7 +44,7 @@ func initAlign() {
 	}
 }
 
-func addAlignment(t StructType) Type {
+func addAlignment(t *StructType) Type {
 	if t.packed {
 		t.padded = true
 		return t
diff --git a/sys/decl.go b/sys/decl.go
index 41527e91f..a447948bc 100644
--- a/sys/decl.go
+++ b/sys/decl.go
@@ -275,7 +275,7 @@ type StructType struct {
 	align  uintptr
 }
 
-func (t StructType) Size() uintptr {
+func (t *StructType) Size() uintptr {
 	if !t.padded {
 		panic("struct is not padded yet")
 	}
@@ -286,7 +286,7 @@ func (t StructType) Size() uintptr {
 	return size
 }
 
-func (t StructType) Align() uintptr {
+func (t *StructType) Align() uintptr {
 	if t.align != 0 {
 		return t.align // overrided by user attribute
 	}
@@ -305,7 +305,7 @@ type UnionType struct {
 	varlen  bool
 }
 
-func (t UnionType) Size() uintptr {
+func (t *UnionType) Size() uintptr {
 	if t.varlen {
 		panic("union size is not statically known")
 	}
@@ -318,7 +318,7 @@ func (t UnionType) Size() uintptr {
 	return size
 }
 
-func (t UnionType) Align() uintptr {
+func (t *UnionType) Align() uintptr {
 	var align uintptr
 	for _, opt := range t.Options {
 		if a1 := opt.Align(); align < a1 {
@@ -353,6 +353,7 @@ func resourceCtors(kind []string, precise bool) []*Call {
 	// Find calls that produce the necessary resources.
 	var metas []*Call
 	// Recurse into arguments to see if there is an out/inout arg of necessary type.
+	seen := make(map[Type]bool)
 	var checkArg func(typ Type, dir Dir) bool
 	checkArg = func(typ Type, dir Dir) bool {
 		if resarg, ok := typ.(ResourceType); ok && dir != DirIn && isCompatibleResource(kind, resarg.Desc.Kind, precise) {
@@ -363,13 +364,21 @@ func resourceCtors(kind []string, precise bool) []*Call {
 			if checkArg(typ1.Type, dir) {
 				return true
 			}
-		case StructType:
+		case *StructType:
+			if seen[typ1] {
+				return false // prune recursion via pointers to structs/unions
+			}
+			seen[typ1] = true
 			for _, fld := range typ1.Fields {
 				if checkArg(fld, dir) {
 					return true
 				}
 			}
-		case UnionType:
+		case *UnionType:
+			if seen[typ1] {
+				return false // prune recursion via pointers to structs/unions
+			}
+			seen[typ1] = true
 			for _, opt := range typ1.Options {
 				if checkArg(opt, dir) {
 					return true
@@ -438,6 +447,7 @@ func isCompatibleResource(dst, src []string, precise bool) bool {
 
 func (c *Call) InputResources() []ResourceType {
 	var resources []ResourceType
+	seen := make(map[Type]bool)
 	var checkArg func(typ Type, dir Dir)
 	checkArg = func(typ Type, dir Dir) {
 		switch typ1 := typ.(type) {
@@ -449,11 +459,19 @@ func (c *Call) InputResources() []ResourceType {
 			checkArg(typ1.Type, dir)
 		case PtrType:
 			checkArg(typ1.Type, typ1.Dir)
-		case StructType:
+		case *StructType:
+			if seen[typ1] {
+				return // prune recursion via pointers to structs/unions
+			}
+			seen[typ1] = true
 			for _, fld := range typ1.Fields {
 				checkArg(fld, dir)
 			}
-		case UnionType:
+		case *UnionType:
+			if seen[typ1] {
+				return // prune recursion via pointers to structs/unions
+			}
+			seen[typ1] = true
 			for _, opt := range typ1.Options {
 				checkArg(opt, dir)
 			}
diff --git a/sys/sndseq.txt b/sys/sndseq.txt
index 551e736ef..cffc3ae93 100644
--- a/sys/sndseq.txt
+++ b/sys/sndseq.txt
@@ -210,7 +210,6 @@ snd_seq_event_data [
 	quote	snd_seq_ev_quote
 ]
 
-
 snd_seq_ev_note {
 	chan	int8
 	note	int8
@@ -256,10 +255,7 @@ snd_seq_result {
 snd_seq_ev_quote {
 	origin	snd_seq_addr
 	val	int16
-# TODO: this should be:
-#	event	ptr[in, snd_seq_event, opt]
-# but sysgen goes into inifite recursion.
-	event	buffer[in]
+	event	ptr[in, snd_seq_event, opt]
 } [packed]
 
 snd_seq_queue_skew {