This is an automated email from the ASF dual-hosted git repository. rohit pushed a commit to branch master in repository https://gitbox.apache.org/repos/asf/cloudstack-cloudmonkey.git
commit 47408438ee3be5095504f740395f85e2e59a76d8 Author: Rohit Yadav <[email protected]> AuthorDate: Mon Oct 22 00:45:58 2018 +0530 cmk: implement file lock for config read/write Signed-off-by: Rohit Yadav <[email protected]> --- config/config.go | 19 ++- go.mod | 1 + go.sum | 2 + vendor/github.com/gofrs/flock/.gitignore | 24 +++ vendor/github.com/gofrs/flock/.travis.yml | 10 ++ vendor/github.com/gofrs/flock/LICENSE | 27 ++++ vendor/github.com/gofrs/flock/README.md | 40 +++++ vendor/github.com/gofrs/flock/appveyor.yml | 25 ++++ vendor/github.com/gofrs/flock/flock.go | 127 ++++++++++++++++ vendor/github.com/gofrs/flock/flock_unix.go | 195 +++++++++++++++++++++++++ vendor/github.com/gofrs/flock/flock_winapi.go | 76 ++++++++++ vendor/github.com/gofrs/flock/flock_windows.go | 140 ++++++++++++++++++ vendor/modules.txt | 2 + 13 files changed, 686 insertions(+), 2 deletions(-) diff --git a/config/config.go b/config/config.go index 0b0ad6b..42af265 100644 --- a/config/config.go +++ b/config/config.go @@ -27,6 +27,7 @@ import ( "strconv" "time" + "github.com/gofrs/flock" "github.com/mitchellh/go-homedir" "gopkg.in/ini.v1" ) @@ -140,6 +141,18 @@ func newHTTPClient(cfg *Config) *http.Client { } func reloadConfig(cfg *Config) *Config { + fileLock := flock.New(path.Join(getDefaultConfigDir(), "lock")) + err := fileLock.Lock() + if err != nil { + fmt.Println("Failed to grab config file lock, please try again") + return cfg + } + cfg = saveConfig(cfg) + fileLock.Unlock() + return cfg +} + +func saveConfig(cfg *Config) *Config { if _, err := os.Stat(cfg.Dir); err != nil { os.Mkdir(cfg.Dir, 0700) } @@ -214,7 +227,7 @@ func reloadConfig(cfg *Config) *Config { } // UpdateConfig updates and saves config -func (c *Config) UpdateConfig(key string, value string) { +func (c *Config) UpdateConfig(key string, value string, update bool) { switch key { case "prompt": c.Core.Prompt = value @@ -246,7 +259,9 @@ func (c *Config) UpdateConfig(key string, value string) { c.Core.VerifyCert = value == "true" } - reloadConfig(c) + if update { + reloadConfig(c) + } } // NewConfig creates or reload config and loads API cache diff --git a/go.mod b/go.mod index ed2a67a..d403cd0 100644 --- a/go.mod +++ b/go.mod @@ -21,6 +21,7 @@ require ( github.com/briandowns/spinner v0.0.0-20181018151057-dd69c579ff20 github.com/c-bata/go-prompt v0.2.2 github.com/fatih/color v1.7.0 // indirect + github.com/gofrs/flock v0.7.0 github.com/google/shlex v0.0.0-20150127133951-6f45313302b9 github.com/gopherjs/gopherjs v0.0.0-20181017120253-0766667cb4d1 // indirect github.com/jtolds/gls v4.2.1+incompatible // indirect diff --git a/go.sum b/go.sum index d7b7057..5bf1766 100644 --- a/go.sum +++ b/go.sum @@ -4,6 +4,8 @@ github.com/c-bata/go-prompt v0.2.2 h1:uyKRz6Z6DUyj49QVijyM339UJV9yhbr70gESwbNU3e github.com/c-bata/go-prompt v0.2.2/go.mod h1:VzqtzE2ksDBcdln8G7mk2RX9QyGjH+OVqOCSiVIqS34= github.com/fatih/color v1.7.0 h1:DkWD4oS2D8LGGgTQ6IvwJJXSL5Vp2ffcQg58nFV38Ys= github.com/fatih/color v1.7.0/go.mod h1:Zm6kSWBoL9eyXnKyktHP6abPY2pDugNf5KwzbycvMj4= +github.com/gofrs/flock v0.7.0 h1:pGFUjl501gafK9HBt1VGL1KCOd/YhIooID+xgyJCf3g= +github.com/gofrs/flock v0.7.0/go.mod h1:F1TvTiK9OcQqauNUHlbJvyl9Qa1QvF/gOUDKA14jxHU= github.com/google/shlex v0.0.0-20150127133951-6f45313302b9 h1:JM174NTeGNJ2m/oLH3UOWOvWQQKd+BoL3hcSCUWFLt0= github.com/google/shlex v0.0.0-20150127133951-6f45313302b9/go.mod h1:RpwtwJQFrIEPstU94h88MWPXP2ektJZ8cZ0YntAmXiE= github.com/gopherjs/gopherjs v0.0.0-20181017120253-0766667cb4d1 h1:EGx4pi6eqNxGaHF6qqu48+N2wcFQ5qg5FXgOdqsJ5d8= diff --git a/vendor/github.com/gofrs/flock/.gitignore b/vendor/github.com/gofrs/flock/.gitignore new file mode 100644 index 0000000..daf913b --- /dev/null +++ b/vendor/github.com/gofrs/flock/.gitignore @@ -0,0 +1,24 @@ +# Compiled Object files, Static and Dynamic libs (Shared Objects) +*.o +*.a +*.so + +# Folders +_obj +_test + +# Architecture specific extensions/prefixes +*.[568vq] +[568vq].out + +*.cgo1.go +*.cgo2.c +_cgo_defun.c +_cgo_gotypes.go +_cgo_export.* + +_testmain.go + +*.exe +*.test +*.prof diff --git a/vendor/github.com/gofrs/flock/.travis.yml b/vendor/github.com/gofrs/flock/.travis.yml new file mode 100644 index 0000000..b791a74 --- /dev/null +++ b/vendor/github.com/gofrs/flock/.travis.yml @@ -0,0 +1,10 @@ +language: go +go: + - 1.10.x + - 1.11.x +script: go test -v -check.vv -race ./... +sudo: false +notifications: + email: + on_success: never + on_failure: always diff --git a/vendor/github.com/gofrs/flock/LICENSE b/vendor/github.com/gofrs/flock/LICENSE new file mode 100644 index 0000000..aff7d35 --- /dev/null +++ b/vendor/github.com/gofrs/flock/LICENSE @@ -0,0 +1,27 @@ +Copyright (c) 2015, Tim Heckman +All rights reserved. + +Redistribution and use in source and binary forms, with or without +modification, are permitted provided that the following conditions are met: + +* Redistributions of source code must retain the above copyright notice, this + list of conditions and the following disclaimer. + +* Redistributions in binary form must reproduce the above copyright notice, + this list of conditions and the following disclaimer in the documentation + and/or other materials provided with the distribution. + +* Neither the name of linode-netint nor the names of its + contributors may be used to endorse or promote products derived from + this software without specific prior written permission. + +THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" +AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE +IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE +DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE +FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL +DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR +SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER +CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, +OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE +OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. diff --git a/vendor/github.com/gofrs/flock/README.md b/vendor/github.com/gofrs/flock/README.md new file mode 100644 index 0000000..42d580f --- /dev/null +++ b/vendor/github.com/gofrs/flock/README.md @@ -0,0 +1,40 @@ +# flock +[](https://travis-ci.org/gofrs/flock) +[](https://godoc.org/github.com/gofrs/flock) +[](https://github.com/gofrs/flock/blob/master/LICENSE) + +`flock` implements a thread-safe sync.Locker interface for file locking. It also +includes a non-blocking TryLock() function to allow locking without blocking execution. + +## License +`flock` is released under the BSD 3-Clause License. See the `LICENSE` file for more details. + +## Go Compatibility +This package makes use of the `context` package that was introduced in Go 1.7. As such, this +package has an implicit dependency on Go 1.7+. + +## Installation +``` +go get -u github.com/gofrs/flock +``` + +## Usage +```Go +import "github.com/gofrs/flock" + +fileLock := flock.New("/var/lock/go-lock.lock") + +locked, err := fileLock.TryLock() + +if err != nil { + // handle locking error +} + +if locked { + // do work + fileLock.Unlock() +} +``` + +For more detailed usage information take a look at the package API docs on +[GoDoc](https://godoc.org/github.com/gofrs/flock). diff --git a/vendor/github.com/gofrs/flock/appveyor.yml b/vendor/github.com/gofrs/flock/appveyor.yml new file mode 100644 index 0000000..6848e94 --- /dev/null +++ b/vendor/github.com/gofrs/flock/appveyor.yml @@ -0,0 +1,25 @@ +version: '{build}' + +build: false +deploy: false + +clone_folder: 'c:\gopath\src\github.com\gofrs\flock' + +environment: + GOPATH: 'c:\gopath' + GOVERSION: '1.11' + +init: + - git config --global core.autocrlf input + +install: + - rmdir c:\go /s /q + - appveyor DownloadFile https://storage.googleapis.com/golang/go%GOVERSION%.windows-amd64.msi + - msiexec /i go%GOVERSION%.windows-amd64.msi /q + - set Path=c:\go\bin;c:\gopath\bin;%Path% + - go version + - go env + +test_script: + - go get -t ./... + - go test -race -v ./... diff --git a/vendor/github.com/gofrs/flock/flock.go b/vendor/github.com/gofrs/flock/flock.go new file mode 100644 index 0000000..5783a49 --- /dev/null +++ b/vendor/github.com/gofrs/flock/flock.go @@ -0,0 +1,127 @@ +// Copyright 2015 Tim Heckman. All rights reserved. +// Use of this source code is governed by the BSD 3-Clause +// license that can be found in the LICENSE file. + +// Package flock implements a thread-safe sync.Locker interface for file locking. +// It also includes a non-blocking TryLock() function to allow locking +// without blocking execution. +// +// Package flock is released under the BSD 3-Clause License. See the LICENSE file +// for more details. +// +// While using this library, remember that the locking behaviors are not +// guaranteed to be the same on each platform. For example, some UNIX-like +// operating systems will transparently convert a shared lock to an exclusive +// lock. If you Unlock() the flock from a location where you believe that you +// have the shared lock, you may accidently drop the exclusive lock. +package flock + +import ( + "context" + "os" + "sync" + "time" +) + +// Flock is the struct type to handle file locking. All fields are unexported, +// with access to some of the fields provided by getter methods (Path() and Locked()). +type Flock struct { + path string + m sync.RWMutex + fh *os.File + l bool + r bool +} + +// New returns a new instance of *Flock. The only parameter +// it takes is the path to the desired lockfile. +func New(path string) *Flock { + return &Flock{path: path} +} + +// NewFlock returns a new instance of *Flock. The only parameter +// it takes is the path to the desired lockfile. +// +// Deprecated: Use New instead. +func NewFlock(path string) *Flock { + return New(path) +} + +// Close is equivalent to calling Unlock. +// +// This will release the lock and close the underlying file descriptor. +// It will not remove the file from disk, that's up to your application. +func (f *Flock) Close() error { + return f.Unlock() +} + +// Path returns the path as provided in NewFlock(). +func (f *Flock) Path() string { + return f.path +} + +// Locked returns the lock state (locked: true, unlocked: false). +// +// Warning: by the time you use the returned value, the state may have changed. +func (f *Flock) Locked() bool { + f.m.RLock() + defer f.m.RUnlock() + return f.l +} + +// RLocked returns the read lock state (locked: true, unlocked: false). +// +// Warning: by the time you use the returned value, the state may have changed. +func (f *Flock) RLocked() bool { + f.m.RLock() + defer f.m.RUnlock() + return f.r +} + +func (f *Flock) String() string { + return f.path +} + +// TryLockContext repeatedly tries to take an exclusive lock until one of the +// conditions is met: TryLock succeeds, TryLock fails with error, or Context +// Done channel is closed. +func (f *Flock) TryLockContext(ctx context.Context, retryDelay time.Duration) (bool, error) { + return tryCtx(f.TryLock, ctx, retryDelay) +} + +// TryRLockContext repeatedly tries to take a shared lock until one of the +// conditions is met: TryRLock succeeds, TryRLock fails with error, or Context +// Done channel is closed. +func (f *Flock) TryRLockContext(ctx context.Context, retryDelay time.Duration) (bool, error) { + return tryCtx(f.TryRLock, ctx, retryDelay) +} + +func tryCtx(fn func() (bool, error), ctx context.Context, retryDelay time.Duration) (bool, error) { + if ctx.Err() != nil { + return false, ctx.Err() + } + for { + if ok, err := fn(); ok || err != nil { + return ok, err + } + select { + case <-ctx.Done(): + return false, ctx.Err() + case <-time.After(retryDelay): + // try again + } + } +} + +func (f *Flock) setFh() error { + // open a new os.File instance + // create it if it doesn't exist, and open the file read-only. + fh, err := os.OpenFile(f.path, os.O_CREATE|os.O_RDONLY, os.FileMode(0600)) + if err != nil { + return err + } + + // set the filehandle on the struct + f.fh = fh + return nil +} diff --git a/vendor/github.com/gofrs/flock/flock_unix.go b/vendor/github.com/gofrs/flock/flock_unix.go new file mode 100644 index 0000000..45f71a7 --- /dev/null +++ b/vendor/github.com/gofrs/flock/flock_unix.go @@ -0,0 +1,195 @@ +// Copyright 2015 Tim Heckman. All rights reserved. +// Use of this source code is governed by the BSD 3-Clause +// license that can be found in the LICENSE file. + +// +build !windows + +package flock + +import ( + "os" + "syscall" +) + +// Lock is a blocking call to try and take an exclusive file lock. It will wait +// until it is able to obtain the exclusive file lock. It's recommended that +// TryLock() be used over this function. This function may block the ability to +// query the current Locked() or RLocked() status due to a RW-mutex lock. +// +// If we are already exclusive-locked, this function short-circuits and returns +// immediately assuming it can take the mutex lock. +// +// If the *Flock has a shared lock (RLock), this may transparently replace the +// shared lock with an exclusive lock on some UNIX-like operating systems. Be +// careful when using exclusive locks in conjunction with shared locks +// (RLock()), because calling Unlock() may accidentally release the exclusive +// lock that was once a shared lock. +func (f *Flock) Lock() error { + return f.lock(&f.l, syscall.LOCK_EX) +} + +// RLock is a blocking call to try and take a shared file lock. It will wait +// until it is able to obtain the shared file lock. It's recommended that +// TryRLock() be used over this function. This function may block the ability to +// query the current Locked() or RLocked() status due to a RW-mutex lock. +// +// If we are already shared-locked, this function short-circuits and returns +// immediately assuming it can take the mutex lock. +func (f *Flock) RLock() error { + return f.lock(&f.r, syscall.LOCK_SH) +} + +func (f *Flock) lock(locked *bool, flag int) error { + f.m.Lock() + defer f.m.Unlock() + + if *locked { + return nil + } + + if f.fh == nil { + if err := f.setFh(); err != nil { + return err + } + } + + if err := syscall.Flock(int(f.fh.Fd()), flag); err != nil { + shouldRetry, reopenErr := f.reopenFDOnError(err) + if reopenErr != nil { + return reopenErr + } + + if !shouldRetry { + return err + } + + if err = syscall.Flock(int(f.fh.Fd()), flag); err != nil { + return err + } + } + + *locked = true + return nil +} + +// Unlock is a function to unlock the file. This file takes a RW-mutex lock, so +// while it is running the Locked() and RLocked() functions will be blocked. +// +// This function short-circuits if we are unlocked already. If not, it calls +// syscall.LOCK_UN on the file and closes the file descriptor. It does not +// remove the file from disk. It's up to your application to do. +// +// Please note, if your shared lock became an exclusive lock this may +// unintentionally drop the exclusive lock if called by the consumer that +// believes they have a shared lock. Please see Lock() for more details. +func (f *Flock) Unlock() error { + f.m.Lock() + defer f.m.Unlock() + + // if we aren't locked or if the lockfile instance is nil + // just return a nil error because we are unlocked + if (!f.l && !f.r) || f.fh == nil { + return nil + } + + // mark the file as unlocked + if err := syscall.Flock(int(f.fh.Fd()), syscall.LOCK_UN); err != nil { + return err + } + + f.fh.Close() + + f.l = false + f.r = false + f.fh = nil + + return nil +} + +// TryLock is the preferred function for taking an exclusive file lock. This +// function takes an RW-mutex lock before it tries to lock the file, so there is +// the possibility that this function may block for a short time if another +// goroutine is trying to take any action. +// +// The actual file lock is non-blocking. If we are unable to get the exclusive +// file lock, the function will return false instead of waiting for the lock. If +// we get the lock, we also set the *Flock instance as being exclusive-locked. +func (f *Flock) TryLock() (bool, error) { + return f.try(&f.l, syscall.LOCK_EX) +} + +// TryRLock is the preferred function for taking a shared file lock. This +// function takes an RW-mutex lock before it tries to lock the file, so there is +// the possibility that this function may block for a short time if another +// goroutine is trying to take any action. +// +// The actual file lock is non-blocking. If we are unable to get the shared file +// lock, the function will return false instead of waiting for the lock. If we +// get the lock, we also set the *Flock instance as being share-locked. +func (f *Flock) TryRLock() (bool, error) { + return f.try(&f.r, syscall.LOCK_SH) +} + +func (f *Flock) try(locked *bool, flag int) (bool, error) { + f.m.Lock() + defer f.m.Unlock() + + if *locked { + return true, nil + } + + if f.fh == nil { + if err := f.setFh(); err != nil { + return false, err + } + } + + var retried bool +retry: + err := syscall.Flock(int(f.fh.Fd()), flag|syscall.LOCK_NB) + + switch err { + case syscall.EWOULDBLOCK: + return false, nil + case nil: + *locked = true + return true, nil + } + if !retried { + if shouldRetry, reopenErr := f.reopenFDOnError(err); reopenErr != nil { + return false, reopenErr + } else if shouldRetry { + retried = true + goto retry + } + } + + return false, err +} + +// reopenFDOnError determines whether we should reopen the file handle +// in readwrite mode and try again. This comes from util-linux/sys-utils/flock.c: +// Since Linux 3.4 (commit 55725513) +// Probably NFSv4 where flock() is emulated by fcntl(). +func (f *Flock) reopenFDOnError(err error) (bool, error) { + if err != syscall.EIO && err != syscall.EBADF { + return false, nil + } + if st, err := f.fh.Stat(); err == nil { + // if the file is able to be read and written + if st.Mode()&0600 == 0600 { + f.fh.Close() + f.fh = nil + + // reopen in read-write mode and set the filehandle + fh, err := os.OpenFile(f.path, os.O_CREATE|os.O_RDWR, os.FileMode(0600)) + if err != nil { + return false, err + } + f.fh = fh + return true, nil + } + } + + return false, nil +} diff --git a/vendor/github.com/gofrs/flock/flock_winapi.go b/vendor/github.com/gofrs/flock/flock_winapi.go new file mode 100644 index 0000000..fe405a2 --- /dev/null +++ b/vendor/github.com/gofrs/flock/flock_winapi.go @@ -0,0 +1,76 @@ +// Copyright 2015 Tim Heckman. All rights reserved. +// Use of this source code is governed by the BSD 3-Clause +// license that can be found in the LICENSE file. + +// +build windows + +package flock + +import ( + "syscall" + "unsafe" +) + +var ( + kernel32, _ = syscall.LoadLibrary("kernel32.dll") + procLockFileEx, _ = syscall.GetProcAddress(kernel32, "LockFileEx") + procUnlockFileEx, _ = syscall.GetProcAddress(kernel32, "UnlockFileEx") +) + +const ( + winLockfileFailImmediately = 0x00000001 + winLockfileExclusiveLock = 0x00000002 + winLockfileSharedLock = 0x00000000 +) + +// Use of 0x00000000 for the shared lock is a guess based on some the MS Windows +// `LockFileEX` docs, which document the `LOCKFILE_EXCLUSIVE_LOCK` flag as: +// +// > The function requests an exclusive lock. Otherwise, it requests a shared +// > lock. +// +// https://msdn.microsoft.com/en-us/library/windows/desktop/aa365203(v=vs.85).aspx + +func lockFileEx(handle syscall.Handle, flags uint32, reserved uint32, numberOfBytesToLockLow uint32, numberOfBytesToLockHigh uint32, offset *syscall.Overlapped) (bool, syscall.Errno) { + r1, _, errNo := syscall.Syscall6( + uintptr(procLockFileEx), + 6, + uintptr(handle), + uintptr(flags), + uintptr(reserved), + uintptr(numberOfBytesToLockLow), + uintptr(numberOfBytesToLockHigh), + uintptr(unsafe.Pointer(offset))) + + if r1 != 1 { + if errNo == 0 { + return false, syscall.EINVAL + } + + return false, errNo + } + + return true, 0 +} + +func unlockFileEx(handle syscall.Handle, reserved uint32, numberOfBytesToLockLow uint32, numberOfBytesToLockHigh uint32, offset *syscall.Overlapped) (bool, syscall.Errno) { + r1, _, errNo := syscall.Syscall6( + uintptr(procUnlockFileEx), + 5, + uintptr(handle), + uintptr(reserved), + uintptr(numberOfBytesToLockLow), + uintptr(numberOfBytesToLockHigh), + uintptr(unsafe.Pointer(offset)), + 0) + + if r1 != 1 { + if errNo == 0 { + return false, syscall.EINVAL + } + + return false, errNo + } + + return true, 0 +} diff --git a/vendor/github.com/gofrs/flock/flock_windows.go b/vendor/github.com/gofrs/flock/flock_windows.go new file mode 100644 index 0000000..9f4a5f1 --- /dev/null +++ b/vendor/github.com/gofrs/flock/flock_windows.go @@ -0,0 +1,140 @@ +// Copyright 2015 Tim Heckman. All rights reserved. +// Use of this source code is governed by the BSD 3-Clause +// license that can be found in the LICENSE file. + +package flock + +import ( + "syscall" +) + +// ErrorLockViolation is the error code returned from the Windows syscall when a +// lock would block and you ask to fail immediately. +const ErrorLockViolation syscall.Errno = 0x21 // 33 + +// Lock is a blocking call to try and take an exclusive file lock. It will wait +// until it is able to obtain the exclusive file lock. It's recommended that +// TryLock() be used over this function. This function may block the ability to +// query the current Locked() or RLocked() status due to a RW-mutex lock. +// +// If we are already locked, this function short-circuits and returns +// immediately assuming it can take the mutex lock. +func (f *Flock) Lock() error { + return f.lock(&f.l, winLockfileExclusiveLock) +} + +// RLock is a blocking call to try and take a shared file lock. It will wait +// until it is able to obtain the shared file lock. It's recommended that +// TryRLock() be used over this function. This function may block the ability to +// query the current Locked() or RLocked() status due to a RW-mutex lock. +// +// If we are already locked, this function short-circuits and returns +// immediately assuming it can take the mutex lock. +func (f *Flock) RLock() error { + return f.lock(&f.r, winLockfileSharedLock) +} + +func (f *Flock) lock(locked *bool, flag uint32) error { + f.m.Lock() + defer f.m.Unlock() + + if *locked { + return nil + } + + if f.fh == nil { + if err := f.setFh(); err != nil { + return err + } + } + + if _, errNo := lockFileEx(syscall.Handle(f.fh.Fd()), flag, 0, 1, 0, &syscall.Overlapped{}); errNo > 0 { + return errNo + } + + *locked = true + return nil +} + +// Unlock is a function to unlock the file. This file takes a RW-mutex lock, so +// while it is running the Locked() and RLocked() functions will be blocked. +// +// This function short-circuits if we are unlocked already. If not, it calls +// UnlockFileEx() on the file and closes the file descriptor. It does not remove +// the file from disk. It's up to your application to do. +func (f *Flock) Unlock() error { + f.m.Lock() + defer f.m.Unlock() + + // if we aren't locked or if the lockfile instance is nil + // just return a nil error because we are unlocked + if (!f.l && !f.r) || f.fh == nil { + return nil + } + + // mark the file as unlocked + if _, errNo := unlockFileEx(syscall.Handle(f.fh.Fd()), 0, 1, 0, &syscall.Overlapped{}); errNo > 0 { + return errNo + } + + f.fh.Close() + + f.l = false + f.r = false + f.fh = nil + + return nil +} + +// TryLock is the preferred function for taking an exclusive file lock. This +// function does take a RW-mutex lock before it tries to lock the file, so there +// is the possibility that this function may block for a short time if another +// goroutine is trying to take any action. +// +// The actual file lock is non-blocking. If we are unable to get the exclusive +// file lock, the function will return false instead of waiting for the lock. If +// we get the lock, we also set the *Flock instance as being exclusive-locked. +func (f *Flock) TryLock() (bool, error) { + return f.try(&f.l, winLockfileExclusiveLock) +} + +// TryRLock is the preferred function for taking a shared file lock. This +// function does take a RW-mutex lock before it tries to lock the file, so there +// is the possibility that this function may block for a short time if another +// goroutine is trying to take any action. +// +// The actual file lock is non-blocking. If we are unable to get the shared file +// lock, the function will return false instead of waiting for the lock. If we +// get the lock, we also set the *Flock instance as being shared-locked. +func (f *Flock) TryRLock() (bool, error) { + return f.try(&f.r, winLockfileSharedLock) +} + +func (f *Flock) try(locked *bool, flag uint32) (bool, error) { + f.m.Lock() + defer f.m.Unlock() + + if *locked { + return true, nil + } + + if f.fh == nil { + if err := f.setFh(); err != nil { + return false, err + } + } + + _, errNo := lockFileEx(syscall.Handle(f.fh.Fd()), flag|winLockfileFailImmediately, 0, 1, 0, &syscall.Overlapped{}) + + if errNo > 0 { + if errNo == ErrorLockViolation || errNo == syscall.ERROR_IO_PENDING { + return false, nil + } + + return false, errNo + } + + *locked = true + + return true, nil +} diff --git a/vendor/modules.txt b/vendor/modules.txt index d15237f..b2fda38 100644 --- a/vendor/modules.txt +++ b/vendor/modules.txt @@ -4,6 +4,8 @@ github.com/briandowns/spinner github.com/c-bata/go-prompt # github.com/fatih/color v1.7.0 github.com/fatih/color +# github.com/gofrs/flock v0.7.0 +github.com/gofrs/flock # github.com/google/shlex v0.0.0-20150127133951-6f45313302b9 github.com/google/shlex # github.com/mattn/go-colorable v0.0.9
