containerd/fs/path.go

163 lines
3.2 KiB
Go
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package fs
import (
"bytes"
"context"
"io"
"os"
"path/filepath"
"strings"
)
type currentPath struct {
path string
f os.FileInfo
fullPath string
}
func pathChange(lower, upper *currentPath) (ChangeKind, string) {
if lower == nil {
if upper == nil {
panic("cannot compare nil paths")
}
return ChangeKindAdd, upper.path
}
if upper == nil {
return ChangeKindDelete, lower.path
}
// TODO: compare by directory
switch i := strings.Compare(lower.path, upper.path); {
case i < 0:
// File in lower that is not in upper
return ChangeKindDelete, lower.path
case i > 0:
// File in upper that is not in lower
return ChangeKindAdd, upper.path
default:
return ChangeKindModify, upper.path
}
}
func sameFile(f1, f2 *currentPath) (bool, error) {
if os.SameFile(f1.f, f2.f) {
return true, nil
}
equalStat, err := compareSysStat(f1.f.Sys(), f2.f.Sys())
if err != nil || !equalStat {
return equalStat, err
}
if eq, err := compareCapabilities(f1.fullPath, f2.fullPath); err != nil || !eq {
return eq, err
}
// If not a directory also check size, modtime, and content
if !f1.f.IsDir() {
if f1.f.Size() != f2.f.Size() {
return false, nil
}
t1 := f1.f.ModTime()
t2 := f2.f.ModTime()
if t1.Unix() != t2.Unix() {
return false, nil
}
// If the timestamp may have been truncated in one of the
// files, check content of file to determine difference
if t1.Nanosecond() == 0 || t2.Nanosecond() == 0 {
if f1.f.Size() > 0 {
eq, err := compareFileContent(f1.fullPath, f2.fullPath)
if err != nil || !eq {
return eq, err
}
}
} else if t1.Nanosecond() != t2.Nanosecond() {
return false, nil
}
}
return true, nil
}
const compareChuckSize = 32 * 1024
// compareFileContent compares the content of 2 same sized files
// by comparing each byte.
func compareFileContent(p1, p2 string) (bool, error) {
f1, err := os.Open(p1)
if err != nil {
return false, err
}
defer f1.Close()
f2, err := os.Open(p2)
if err != nil {
return false, err
}
defer f2.Close()
b1 := make([]byte, compareChuckSize)
b2 := make([]byte, compareChuckSize)
for {
n1, err1 := f1.Read(b1)
if err1 != nil && err1 != io.EOF {
return false, err1
}
n2, err2 := f2.Read(b2)
if err2 != nil && err2 != io.EOF {
return false, err2
}
if n1 != n2 || !bytes.Equal(b1[:n1], b2[:n2]) {
return false, nil
}
if err1 == io.EOF && err2 == io.EOF {
return true, nil
}
}
}
func pathWalk(ctx context.Context, root string, pathC chan<- *currentPath) error {
return filepath.Walk(root, func(path string, f os.FileInfo, err error) error {
if err != nil {
return err
}
// Rebase path
path, err = filepath.Rel(root, path)
if err != nil {
return err
}
path = filepath.Join(string(os.PathSeparator), path)
// Skip root
if path == string(os.PathSeparator) {
return nil
}
p := &currentPath{
path: path,
f: f,
fullPath: filepath.Join(root, path),
}
select {
case <-ctx.Done():
return ctx.Err()
case pathC <- p:
return nil
}
})
}
func nextPath(ctx context.Context, pathC <-chan *currentPath) (*currentPath, error) {
select {
case <-ctx.Done():
return nil, ctx.Err()
case p := <-pathC:
return p, nil
}
}