[dev.power64] code review 160200044: build: merge default into dev.power64

src/cmd/internal/objfile/plan9obj.go

+// Copyright 2014 The Go Authors.  All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+// Parsing of Plan 9 a.out executables.
+
+package objfile
+
+import (
+        "debug/plan9obj"
+        "fmt"
+        "os"
+        "sort"
+)
+
+var validSymType = map[rune]bool{
+        'T': true,
+        't': true,
+        'D': true,
+        'd': true,
+        'B': true,
+        'b': true,
+}
+
+type plan9File struct {
+        plan9 *plan9obj.File
+}
+
+func openPlan9(r *os.File) (rawFile, error) {
+        f, err := plan9obj.NewFile(r)
+        if err != nil {
+                return nil, err
+        }
+        return &plan9File{f}, nil
+}
+
+func (f *plan9File) symbols() ([]Sym, error) {
+        plan9Syms, err := f.plan9.Symbols()
+        if err != nil {
+                return nil, err
+        }
+
+        // Build sorted list of addresses of all symbols.
+        // We infer the size of a symbol by looking at where the next symbol begins.
+        var addrs []uint64
+        for _, s := range plan9Syms {
+                if !validSymType[s.Type] {
+                        continue
+                }
+                addrs = append(addrs, s.Value)
+        }
+        sort.Sort(uint64s(addrs))
+
+        var syms []Sym
+
+        for _, s := range plan9Syms {
+                if !validSymType[s.Type] {
+                        continue
+                }
+                sym := Sym{Addr: s.Value, Name: s.Name, Code: rune(s.Type)}
+                i := sort.Search(len(addrs), func(x int) bool { return addrs[x] > s.Value })
+                if i < len(addrs) {
+                        sym.Size = int64(addrs[i] - s.Value)
+                }
+                syms = append(syms, sym)
+        }
+
+        return syms, nil
+}
+
+func (f *plan9File) pcln() (textStart uint64, symtab, pclntab []byte, err error) {
+        textStart = f.plan9.LoadAddress + f.plan9.HdrSize
+        if pclntab, err = loadPlan9Table(f.plan9, "runtime.pclntab", "runtime.epclntab"); err != nil {
+                // We didn't find the symbols, so look for the names used in 1.3 and earlier.
+                // TODO: Remove code looking for the old symbols when we no longer care about 1.3.
+                var err2 error
+                if pclntab, err2 = loadPlan9Table(f.plan9, "pclntab", "epclntab"); err2 != nil {
+                        return 0, nil, nil, err
+                }
+        }
+        if symtab, err = loadPlan9Table(f.plan9, "runtime.symtab", "runtime.esymtab"); err != nil {
+                // Same as above.
+                var err2 error
+                if symtab, err2 = loadPlan9Table(f.plan9, "symtab", "esymtab"); err2 != nil {
+                        return 0, nil, nil, err
+                }
+        }
+        return textStart, symtab, pclntab, nil
+}
+
+func findPlan9Symbol(f *plan9obj.File, name string) (*plan9obj.Sym, error) {
+        syms, err := f.Symbols()
+        if err != nil {
+                return nil, err
+        }
+        for _, s := range syms {
+                if s.Name != name {
+                        continue
+                }
+                return &s, nil
+        }
+        return nil, fmt.Errorf("no %s symbol found", name)
+}
+
+func loadPlan9Table(f *plan9obj.File, sname, ename string) ([]byte, error) {
+        ssym, err := findPlan9Symbol(f, sname)
+        if err != nil {
+                return nil, err
+        }
+        esym, err := findPlan9Symbol(f, ename)
+        if err != nil {
+                return nil, err
+        }
+        sect := f.Section("text")
+        if sect == nil {
+                return nil, err
+        }
+        data, err := sect.Data()
+        if err != nil {
+                return nil, err
+        }
+        textStart := f.LoadAddress + f.HdrSize
+        return data[ssym.Value-textStart : esym.Value-textStart], nil
+}