55 lines
1.1 KiB
Go
55 lines
1.1 KiB
Go
package btf
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import (
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"bytes"
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"errors"
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"fmt"
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"io"
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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 := io.ReadAll(r)
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if err != nil {
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return nil, fmt.Errorf("can't read string table: %v", err)
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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 "", fmt.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 "", fmt.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 "", fmt.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 "", fmt.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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