x/debug: support getting values of slice type.
The type program.Slice that the user gets for slice variables just
embeds a program.Array and adds a capacity field.
The DWARF information for slices doesn't include stride, so the stride
is computed with the size of the element type.
Change-Id: I69c60998abd1b48b1986522f60f93ddcad0c155e
Reviewed-on: https://go-review.googlesource.com/12831
Reviewed-by: Rob Pike <r@golang.org>
diff --git a/ogle/demo/ogler/ogler_test.go b/ogle/demo/ogler/ogler_test.go
index 3b9e35b..b2ba5d7 100644
--- a/ogle/demo/ogler/ogler_test.go
+++ b/ogle/demo/ogler/ogler_test.go
@@ -414,4 +414,23 @@
}
return nil
})
+
+ checkValue("main.Z_slice", func(val program.Value) error {
+ s, ok := val.(program.Slice)
+ if !ok {
+ return fmt.Errorf("got %T(%v) expected Slice", val, val)
+ }
+ if s.Len() != 5 {
+ return fmt.Errorf("got slice length %d expected 5", s.Len())
+ }
+ expected := []uint8{115, 108, 105, 99, 101}
+ for i := uint64(0); i < 5; i++ {
+ if v, err := prog.Value(s.Element(i)); err != nil {
+ return fmt.Errorf("reading element %d: %s", i, err)
+ } else if v != expected[i] {
+ return fmt.Errorf("element %d: got %T(%v) want %T(%d)", i, v, v, expected[i], expected[i])
+ }
+ }
+ return nil
+ })
}
diff --git a/ogle/program/program.go b/ogle/program/program.go
index 24619aa..9e45c26 100644
--- a/ogle/program/program.go
+++ b/ogle/program/program.go
@@ -123,6 +123,12 @@
}
}
+// Slice is a Var representing a slice.
+type Slice struct {
+ Array
+ Capacity uint64
+}
+
// Struct is a Var representing a struct.
type Struct struct {
Fields []StructField
diff --git a/ogle/program/proxyrpc/proxyrpc.go b/ogle/program/proxyrpc/proxyrpc.go
index 91bb49e..568fdea 100644
--- a/ogle/program/proxyrpc/proxyrpc.go
+++ b/ogle/program/proxyrpc/proxyrpc.go
@@ -17,6 +17,7 @@
gob.Register(program.Pointer{})
gob.Register(program.Array{})
gob.Register(program.Struct{})
+ gob.Register(program.Slice{})
}
// For regularity, each method has a unique Request and a Response type even
diff --git a/ogle/program/server/value.go b/ogle/program/server/value.go
index d457b92..bbb1e4e 100644
--- a/ogle/program/server/value.go
+++ b/ogle/program/server/value.go
@@ -118,6 +118,32 @@
TypeID: uint64(t.Type.Common().Offset),
Address: uint64(s.arch.Uintptr(buf)),
}, nil
+ case *dwarf.SliceType:
+ ptr, err := s.peekPtrStructField(&t.StructType, addr, "array")
+ if err != nil {
+ return nil, fmt.Errorf("reading slice location: %s", err)
+ }
+ length, err := s.peekUintOrIntStructField(&t.StructType, addr, "len")
+ if err != nil {
+ return nil, fmt.Errorf("reading slice length: %s", err)
+ }
+ capacity, err := s.peekUintOrIntStructField(&t.StructType, addr, "cap")
+ if err != nil {
+ return nil, fmt.Errorf("reading slice capacity: %s", err)
+ }
+ if capacity < length {
+ return nil, fmt.Errorf("slice's capacity %d is less than its length %d", capacity, length)
+ }
+
+ return program.Slice{
+ program.Array{
+ ElementTypeID: uint64(t.ElemType.Common().Offset),
+ Address: uint64(ptr),
+ Length: length,
+ StrideBits: uint64(t.ElemType.Common().ByteSize) * 8,
+ },
+ capacity,
+ }, nil
case *dwarf.ArrayType:
length := t.Count
stride := t.StrideBitSize
