forked from cerc-io/ipld-eth-server
77 lines
1.9 KiB
Go
77 lines
1.9 KiB
Go
package fslock
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import (
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"fmt"
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"io"
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"os"
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"path"
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"strings"
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"syscall"
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"github.com/ipfs/go-ipfs-util"
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logging "github.com/ipfs/go-log"
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lock "go4.org/lock"
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)
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// log is the fsrepo logger
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var log = logging.Logger("lock")
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func errPerm(path string) error {
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return fmt.Errorf("failed to take lock at %s: permission denied", path)
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}
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// Lock creates the lock.
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func Lock(confdir, lockFile string) (io.Closer, error) {
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return lock.Lock(path.Join(confdir, lockFile))
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}
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// Locked checks if there is a lock already set.
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func Locked(confdir, lockFile string) (bool, error) {
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log.Debugf("Checking lock")
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if !util.FileExists(path.Join(confdir, lockFile)) {
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log.Debugf("File doesn't exist: %s", path.Join(confdir, lockFile))
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return false, nil
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}
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lk, err := Lock(confdir, lockFile)
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if err != nil {
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// EAGAIN == someone else has the lock
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if err == syscall.EAGAIN {
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log.Debugf("Someone else has the lock: %s", path.Join(confdir, lockFile))
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return true, nil
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}
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if strings.Contains(err.Error(), "resource temporarily unavailable") {
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log.Debugf("Can't lock file: %s.\n reason: %s", path.Join(confdir, lockFile), err.Error())
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return true, nil
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}
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// we hold the lock ourselves
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if strings.Contains(err.Error(), "already locked") {
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log.Debugf("Lock is already held by us: %s", path.Join(confdir, lockFile))
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return true, nil
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}
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// lock fails on permissions error
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if os.IsPermission(err) {
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log.Debugf("Lock fails on permissions error")
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return false, errPerm(confdir)
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}
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if isLockCreatePermFail(err) {
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log.Debugf("Lock fails on permissions error")
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return false, errPerm(confdir)
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}
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// otherwise, we cant guarantee anything, error out
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return false, err
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}
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log.Debugf("No one has a lock")
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lk.Close()
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return false, nil
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}
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func isLockCreatePermFail(err error) bool {
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s := err.Error()
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return strings.Contains(s, "Lock Create of") && strings.Contains(s, "permission denied")
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}
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