From b2344b83ed0bbbd1f8e3ec5efdf09c81ad169941 Mon Sep 17 00:00:00 2001 From: "W. Trevor King" Date: Thu, 5 Jul 2018 10:57:39 -0700 Subject: pkg/ctime: Factor libpod/finished* into a separate package This removes some boilerplate from the libpod package, so we can focus on container stuff there. And it gives us a tidy sub-package for focusing on ctime extraction, so we can focus on unit testing and portability of the extraction utility there. For the unsupported implementation, I'm falling back to Go's ModTime [1]. That's obviously not the creation time, but it's likely to be closer than the uninitialized Time structure from cc6f0e85 (more changes to compile darwin, 2018-07-04, #1047). Especially for our use case in libpod/oci, where we're looking at write-once exit files. The test is more complicated than I initially expected, because on Linux filesystem timestamps come from a truncated clock without interpolation [2] (and network filesystems can be completely decoupled [3]). So even for local disks, creation times can be up to a jiffie earlier than 'before'. This test ensures at least monotonicity by creating two files and ensuring the reported creation time for the second is greater than or equal to the reported creation time for the first. It also checks that both creation times are within the window from one second earlier than 'before' through 'after'. That should be enough of a window for local disks, even if the kernel for those systems has an abnormally large jiffie. It might be ok on network filesystems, although it will not be very resilient to network clock lagging behind the local system clock. [1]: https://golang.org/pkg/os/#FileInfo [2]: https://groups.google.com/d/msg/linux.kernel/mdeXx2TBYZA/_4eJEuJoAQAJ Subject: Re: Apparent backward time travel in timestamps on file creation Date: Thu, 30 Mar 2017 20:20:02 +0200 Message-ID: [3]: https://groups.google.com/d/msg/linux.kernel/mdeXx2TBYZA/cTKj4OBuAQAJ Subject: Re: Apparent backward time travel in timestamps on file creation Date: Thu, 30 Mar 2017 22:10:01 +0200 Message-ID: Signed-off-by: W. Trevor King Closes: #1050 Approved by: mheon --- pkg/ctime/ctime.go | 12 ++++++++ pkg/ctime/ctime_linux_32.go | 14 ++++++++++ pkg/ctime/ctime_linux_64.go | 14 ++++++++++ pkg/ctime/ctime_test.go | 63 ++++++++++++++++++++++++++++++++++++++++++ pkg/ctime/ctime_unsupported.go | 12 ++++++++ 5 files changed, 115 insertions(+) create mode 100644 pkg/ctime/ctime.go create mode 100644 pkg/ctime/ctime_linux_32.go create mode 100644 pkg/ctime/ctime_linux_64.go create mode 100644 pkg/ctime/ctime_test.go create mode 100644 pkg/ctime/ctime_unsupported.go (limited to 'pkg') diff --git a/pkg/ctime/ctime.go b/pkg/ctime/ctime.go new file mode 100644 index 000000000..f5c69c7e3 --- /dev/null +++ b/pkg/ctime/ctime.go @@ -0,0 +1,12 @@ +// Package ctime includes a utility for determining file-creation times. +package ctime + +import ( + "os" + "time" +) + +// Created returns the file-creation time. +func Created(fi os.FileInfo) time.Time { + return created(fi) +} diff --git a/pkg/ctime/ctime_linux_32.go b/pkg/ctime/ctime_linux_32.go new file mode 100644 index 000000000..00c1a9a8e --- /dev/null +++ b/pkg/ctime/ctime_linux_32.go @@ -0,0 +1,14 @@ +// +build arm,linux 386,linux + +package ctime + +import ( + "os" + "syscall" + "time" +) + +func created(fi os.FileInfo) time.Time { + st := fi.Sys().(*syscall.Stat_t) + return time.Unix(int64(st.Ctim.Sec), int64(st.Ctim.Nsec)) +} diff --git a/pkg/ctime/ctime_linux_64.go b/pkg/ctime/ctime_linux_64.go new file mode 100644 index 000000000..1251c1ded --- /dev/null +++ b/pkg/ctime/ctime_linux_64.go @@ -0,0 +1,14 @@ +// +build !arm,!386,linux + +package ctime + +import ( + "os" + "syscall" + "time" +) + +func created(fi os.FileInfo) time.Time { + st := fi.Sys().(*syscall.Stat_t) + return time.Unix(st.Ctim.Sec, st.Ctim.Nsec) +} diff --git a/pkg/ctime/ctime_test.go b/pkg/ctime/ctime_test.go new file mode 100644 index 000000000..abfc627da --- /dev/null +++ b/pkg/ctime/ctime_test.go @@ -0,0 +1,63 @@ +package ctime + +import ( + "io/ioutil" + "os" + "testing" + "time" +) + +func TestCreated(t *testing.T) { + before := time.Now() + + fileA, err := ioutil.TempFile("", "ctime-test-") + if err != nil { + t.Error(err) + } + defer os.Remove(fileA.Name()) + + fileB, err := ioutil.TempFile("", "ctime-test-") + if err != nil { + t.Error(err) + } + defer os.Remove(fileB.Name()) + + after := time.Now() + + infoA, err := fileA.Stat() + if err != nil { + t.Error(err) + } + + err = fileA.Close() + if err != nil { + t.Error(err) + } + + infoB, err := fileB.Stat() + if err != nil { + t.Error(err) + } + + err = fileB.Close() + if err != nil { + t.Error(err) + } + + createdA := Created(infoA) + beforeToCreateA := createdA.Sub(before) + if beforeToCreateA.Nanoseconds() < -1000000000 { + t.Errorf("created file A %s is %v nanoseconds before %s", createdA, -beforeToCreateA.Nanoseconds(), before) + } + + createdB := Created(infoB) + createAToCreateB := createdB.Sub(createdA) + if createAToCreateB.Nanoseconds() < 0 { + t.Errorf("created file B %s is %v nanoseconds before file A %s", createdB, -createAToCreateB.Nanoseconds(), createdA) + } + + createBToAfter := after.Sub(createdB) + if createBToAfter.Nanoseconds() < 0 { + t.Errorf("created file B %s is %v nanoseconds after %s", createdB, -createBToAfter.Nanoseconds(), after) + } +} diff --git a/pkg/ctime/ctime_unsupported.go b/pkg/ctime/ctime_unsupported.go new file mode 100644 index 000000000..325731353 --- /dev/null +++ b/pkg/ctime/ctime_unsupported.go @@ -0,0 +1,12 @@ +// +build !linux + +package ctime + +import ( + "os" + "time" +) + +func created(fi os.FileInfo) time.Time { + return fi.ModTime() +} -- cgit v1.2.3-54-g00ecf