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package backuptar
import (
"archive/tar"
"fmt"
"strconv"
"strings"
"time"
)
// Functions copied from https://github.com/golang/go/blob/master/src/archive/tar/strconv.go
// as we need to manage the LIBARCHIVE.creationtime PAXRecord manually.
// Idea taken from containerd which did the same thing.
// parsePAXTime takes a string of the form %d.%d as described in the PAX
// specification. Note that this implementation allows for negative timestamps,
// which is allowed for by the PAX specification, but not always portable.
func parsePAXTime(s string) (time.Time, error) {
const maxNanoSecondDigits = 9
// Split string into seconds and sub-seconds parts.
ss, sn := s, ""
if pos := strings.IndexByte(s, '.'); pos >= 0 {
ss, sn = s[:pos], s[pos+1:]
}
// Parse the seconds.
secs, err := strconv.ParseInt(ss, 10, 64)
if err != nil {
return time.Time{}, tar.ErrHeader
}
if len(sn) == 0 {
return time.Unix(secs, 0), nil // No sub-second values
}
// Parse the nanoseconds.
if strings.Trim(sn, "0123456789") != "" {
return time.Time{}, tar.ErrHeader
}
if len(sn) < maxNanoSecondDigits {
sn += strings.Repeat("0", maxNanoSecondDigits-len(sn)) // Right pad
} else {
sn = sn[:maxNanoSecondDigits] // Right truncate
}
nsecs, _ := strconv.ParseInt(sn, 10, 64) // Must succeed
if len(ss) > 0 && ss[0] == '-' {
return time.Unix(secs, -1*nsecs), nil // Negative correction
}
return time.Unix(secs, nsecs), nil
}
// formatPAXTime converts ts into a time of the form %d.%d as described in the
// PAX specification. This function is capable of negative timestamps.
func formatPAXTime(ts time.Time) (s string) {
secs, nsecs := ts.Unix(), ts.Nanosecond()
if nsecs == 0 {
return strconv.FormatInt(secs, 10)
}
// If seconds is negative, then perform correction.
sign := ""
if secs < 0 {
sign = "-" // Remember sign
secs = -(secs + 1) // Add a second to secs
nsecs = -(nsecs - 1e9) // Take that second away from nsecs
}
return strings.TrimRight(fmt.Sprintf("%s%d.%09d", sign, secs, nsecs), "0")
}
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