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