61 lines
1.3 KiB
Go
61 lines
1.3 KiB
Go
package btf
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import (
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"bytes"
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"io"
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"io/ioutil"
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"github.com/pkg/errors"
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)
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type stringTable []byte
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func readStringTable(r io.Reader) (stringTable, error) {
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contents, err := ioutil.ReadAll(r)
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if err != nil {
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return nil, errors.Wrap(err, "can't read string table")
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}
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if len(contents) < 1 {
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return nil, errors.New("string table is empty")
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}
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if contents[0] != '\x00' {
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return nil, errors.New("first item in string table is non-empty")
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}
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if contents[len(contents)-1] != '\x00' {
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return nil, errors.New("string table isn't null terminated")
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}
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return stringTable(contents), nil
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}
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func (st stringTable) Lookup(offset uint32) (string, error) {
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if int64(offset) > int64(^uint(0)>>1) {
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return "", errors.Errorf("offset %d overflows int", offset)
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}
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pos := int(offset)
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if pos >= len(st) {
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return "", errors.Errorf("offset %d is out of bounds", offset)
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}
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if pos > 0 && st[pos-1] != '\x00' {
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return "", errors.Errorf("offset %d isn't start of a string", offset)
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}
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str := st[pos:]
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end := bytes.IndexByte(str, '\x00')
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if end == -1 {
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return "", errors.Errorf("offset %d isn't null terminated", offset)
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}
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return string(str[:end]), nil
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}
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func (st stringTable) LookupName(offset uint32) (Name, error) {
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str, err := st.Lookup(offset)
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return Name(str), err
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}
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