Turn symbol_inject into a reusable package

Bug: 31559095
Test: m blueprint_tools
Change-Id: I0f7a9f14111af26d753db547c6de313a7079658a

1 files changed, 97 insertions, 0 deletions

diff --git a/symbol_inject/macho.go b/symbol_inject/macho.go
new file mode 100644
index 000000000..6ee3f4fbd
--- /dev/null
+++ b/symbol_inject/macho.go
@@ -0,0 +1,97 @@
+// Copyright 2018 Google Inc. All rights reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package symbol_inject
+
+import (
+	"debug/macho"
+	"fmt"
+	"io"
+	"sort"
+	"strings"
+)
+
+func machoSymbolsFromFile(r io.ReaderAt) (*File, error) {
+	machoFile, err := macho.NewFile(r)
+	if err != nil {
+		return nil, cantParseError{err}
+	}
+
+	return extractMachoSymbols(machoFile)
+}
+
+func extractMachoSymbols(machoFile *macho.File) (*File, error) {
+	symbols := machoFile.Symtab.Syms
+	sort.SliceStable(symbols, func(i, j int) bool {
+		if symbols[i].Sect != symbols[j].Sect {
+			return symbols[i].Sect < symbols[j].Sect
+		}
+		return symbols[i].Value < symbols[j].Value
+	})
+
+	file := &File{}
+
+	for _, section := range machoFile.Sections {
+		file.Sections = append(file.Sections, &Section{
+			Name:   section.Name,
+			Addr:   section.Addr,
+			Offset: uint64(section.Offset),
+			Size:   section.Size,
+		})
+	}
+
+	for _, symbol := range symbols {
+		if symbol.Sect > 0 {
+			section := file.Sections[symbol.Sect-1]
+			file.Symbols = append(file.Symbols, &Symbol{
+				// symbols in macho files seem to be prefixed with an underscore
+				Name: strings.TrimPrefix(symbol.Name, "_"),
+				// MachO symbol value is virtual address of the symbol, convert it to offset into the section.
+				Addr: symbol.Value - section.Addr,
+				// MachO symbols don't have size information.
+				Size:    0,
+				Section: section,
+			})
+		}
+	}
+
+	return file, nil
+}
+
+func dumpMachoSymbols(r io.ReaderAt) error {
+	machoFile, err := macho.NewFile(r)
+	if err != nil {
+		return cantParseError{err}
+	}
+
+	fmt.Println("&macho.File{")
+
+	fmt.Println("\tSections: []*macho.Section{")
+	for _, section := range machoFile.Sections {
+		fmt.Printf("\t\t&macho.Section{SectionHeader: %#v},\n", section.SectionHeader)
+	}
+	fmt.Println("\t},")
+
+	fmt.Println("\tSymtab: &macho.Symtab{")
+	fmt.Println("\t\tSyms: []macho.Symbol{")
+	for _, symbol := range machoFile.Symtab.Syms {
+		fmt.Printf("\t\t\t%#v,\n", symbol)
+	}
+	fmt.Println("\t\t},")
+	fmt.Println("\t},")
+
+	fmt.Println("}")
+
+	return nil
+}