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// 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"
"sort"
)
func findMachoSymbol(r io.ReaderAt, symbolName string) (uint64, uint64, error) {
machoFile, err := macho.NewFile(r)
if err != nil {
return maxUint64, maxUint64, cantParseError{err}
}
// symbols in macho files seem to be prefixed with an underscore
symbolName = "_" + symbolName
symbols := machoFile.Symtab.Syms
sort.Slice(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
})
for _, symbol := range symbols {
if symbol.Name == symbolName && symbol.Sect != 0 {
// Find the next symbol in the same section with a higher address
n := sort.Search(len(symbols), func(i int) bool {
return symbols[i].Sect == symbol.Sect &&
symbols[i].Value > symbol.Value
})
section := machoFile.Sections[symbol.Sect-1]
var end uint64
if n < len(symbols) {
end = symbols[n].Value
} else {
end = section.Addr + section.Size
}
if end <= symbol.Value && end > symbol.Value+4096 {
return maxUint64, maxUint64, fmt.Errorf("symbol end address does not seem valid, %x:%x", symbol.Value, end)
}
size := end - symbol.Value - 1
offset := uint64(section.Offset) + (symbol.Value - section.Addr)
return offset, size, nil
}
}
return maxUint64, maxUint64, fmt.Errorf("symbol not found")
}
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