diff options
Diffstat (limited to 'cmd/symbol_inject/macho.go')
-rw-r--r-- | cmd/symbol_inject/macho.go | 65 |
1 files changed, 65 insertions, 0 deletions
diff --git a/cmd/symbol_inject/macho.go b/cmd/symbol_inject/macho.go new file mode 100644 index 00000000..0945293f --- /dev/null +++ b/cmd/symbol_inject/macho.go @@ -0,0 +1,65 @@ +// 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 main + +import ( + "debug/macho" + "fmt" + "io" +) + +func findMachoSymbol(r io.ReaderAt, symbolName string) (uint64, uint64, error) { + machoFile, err := macho.NewFile(r) + if err != nil { + return maxUint64, maxUint64, cantParseError{err} + } + + // TODO(ccross): why? + symbolName = "_" + symbolName + + for i, symbol := range machoFile.Symtab.Syms { + if symbol.Sect == 0 { + continue + } + if symbol.Name == symbolName { + var nextSymbol *macho.Symbol + if i+1 < len(machoFile.Symtab.Syms) { + nextSymbol = &machoFile.Symtab.Syms[i+1] + } + return calculateMachoSymbolOffset(machoFile, symbol, nextSymbol) + } + } + + return maxUint64, maxUint64, fmt.Errorf("symbol not found") +} + +func calculateMachoSymbolOffset(file *macho.File, symbol macho.Symbol, nextSymbol *macho.Symbol) (uint64, uint64, error) { + section := file.Sections[symbol.Sect-1] + + var end uint64 + if nextSymbol != nil && nextSymbol.Sect != symbol.Sect { + nextSymbol = nil + } + if nextSymbol != nil { + end = nextSymbol.Value + } else { + end = section.Addr + section.Size + } + + size := end - symbol.Value - 1 + offset := uint64(section.Offset) + (symbol.Value - section.Addr) + + return offset, size, nil +} |