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//go:build !windows
// Binary tpm2-nvread reads data from NVRAM at a specified index. The data is
// printed out hex-encoded.
package main
import (
"flag"
"fmt"
"os"
"github.com/google/go-tpm/legacy/tpm2"
"github.com/google/go-tpm/tpmutil"
)
var (
tpmPath = flag.String("tpm-path", "/dev/tpm0", "Path to the TPM device (character device or a Unix socket)")
index = flag.Uint("index", 0, "NVRAM index of read")
)
func main() {
flag.Parse()
if *index == 0 {
fmt.Fprintln(os.Stderr, "--index must be set")
os.Exit(1)
}
val, err := nvRead(*tpmPath, uint32(*index))
if err != nil {
fmt.Fprintf(os.Stderr, "reading from index 0x%x: %v\n", *index, err)
os.Exit(1)
}
fmt.Printf("NVRAM value at index 0x%x (hex encoded):\n%x\n", *index, val)
}
func nvRead(path string, index uint32) ([]byte, error) {
rwc, err := tpm2.OpenTPM(path)
if err != nil {
return nil, fmt.Errorf("can't open TPM at %q: %v", path, err)
}
defer rwc.Close()
return tpm2.NVRead(rwc, tpmutil.Handle(index))
}
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