Merge lp:~chipaca/snappy/touch into lp:~snappy-dev/snappy/snappy-moved-to-github

[John Lenton]

Added helpers.Touch, for `touch -c -h` functionality.

[Michael Vogt (mvo)]

The code is nice but whats the use-case :) ?

review: Needs Information

[John Lenton (chipaca)]

Moved to WIP so I can refactor to follow jodh's approach wrt isatty.

[John Lenton (chipaca)]

Use case is to touch the security symlinks before calling aa-clickwhatsit to regenerate & reload the security thingiemabobs.

[John Lenton (chipaca)]

Changed my mind, keeping as is.

[lp:~chipaca/snappy/touch]

327. By John Lenton on 2015-04-09

Check for dependents on framework remove. by chipaca approved by mvo

328. By John Lenton on 2015-04-09

merged trunk

[Michael Vogt (mvo)]

Its very nice, one minor comment on the naming.

[John Lenton (chipaca)]

I know how bad I am at naming things, so all naming suggestions are accepted :)

Unless I think they're worse, of course :-p

[lp:~chipaca/snappy/touch]

329. By John Lenton on 2015-04-13

renamed helpers.Touch to helpers.UpdateTimestamp

[John Lenton (chipaca)]

Done.

[Sergio Schvezov (sergiusens)]

one minor thing

review: Needs Fixing

[Sergio Schvezov (sergiusens)]

sorry, wrong mind set when looking at this.

review: Approve

=== added file 'helpers/touch.go'
--- helpers/touch.go	1970-01-01 00:00:00 +0000
+++ helpers/touch.go	2015-04-13 17:01:37 +0000
@@ -0,0 +1,57 @@
+/*
+ * Copyright (C) 2014-2015 Canonical Ltd
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 3 as
+ * published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ */
+
+package helpers
+
+/*
+#include <fcntl.h> // for AT_*
+#include <sys/stat.h>
+#include <stdlib.h> // for free()
+
+int touch(const char *pathname) {
+    // the first 0 is the dirfd, which is ignored if pathname is absolute
+    // the second 0 is a null pointer => use current time
+    return utimensat(0, pathname, 0, AT_SYMLINK_NOFOLLOW);
+}
+*/
+import "C"
+
+import (
+	"errors"
+	"path/filepath"
+	"unsafe"
+)
+
+var ErrNotAbsPath = errors.New("not an absolute path")
+
+// UpdateTimestamp updates the timestamp of the file at pathname. It does not
+// create it if it does not exist. It does not dereference it if it is a
+// symlink. It's like `touch -c -h pathname`.
+//
+// pathname must be absolute.
+func UpdateTimestamp(pathname string) error {
+	if !filepath.IsAbs(pathname) {
+		return ErrNotAbsPath
+	}
+
+	p := C.CString(pathname)
+	defer C.free(unsafe.Pointer(p))
+
+	_, e := C.touch(p)
+
+	return e
+}

=== added file 'helpers/touch_test.go'
--- helpers/touch_test.go	1970-01-01 00:00:00 +0000
+++ helpers/touch_test.go	2015-04-13 17:01:37 +0000
@@ -0,0 +1,74 @@
+/*
+ * Copyright (C) 2014-2015 Canonical Ltd
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License version 3 as
+ * published by the Free Software Foundation.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <http://www.gnu.org/licenses/>.
+ *
+ */
+
+package helpers
+
+import (
+	"os"
+	"path/filepath"
+	"time"
+
+	. "launchpad.net/gocheck"
+)
+
+func (ts *HTestSuite) TestUpdateTimestamp(c *C) {
+	// empirical
+	minRes := 25 * time.Millisecond
+
+	d := c.MkDir()
+	foo := filepath.Join(d, "foo")
+	bar := filepath.Join(d, "bar")
+	c.Assert(os.Symlink(foo, bar), IsNil)
+	time.Sleep(minRes)
+	c.Assert(os.Mkdir(foo, 0755), IsNil)
+	// so now foo (the dir) has a timestamp after bar's (the symlink)
+	// let's check that:
+	fifoo, err := os.Lstat(foo)
+	c.Assert(err, IsNil)
+	fibar, err := os.Lstat(bar)
+	c.Assert(err, IsNil)
+	c.Assert(fifoo.ModTime().After(fibar.ModTime()), Equals, true)
+	// and bar is a symlink to foo
+	fifoox, err := os.Stat(bar)
+	c.Assert(err, IsNil)
+	c.Assert(fifoo.ModTime(), Equals, fifoox.ModTime())
+	// ok.
+	time.Sleep(minRes)
+
+	// this should update bar's timestamp to be newer than foo's
+	// (even though bar is a symlink to foo)
+	c.Assert(UpdateTimestamp(bar), IsNil)
+
+	fifoo, err = os.Lstat(foo)
+	c.Assert(err, IsNil)
+	fibar, err = os.Lstat(bar)
+	c.Assert(err, IsNil)
+	c.Assert(fifoo.ModTime().Before(fibar.ModTime()), Equals, true)
+}
+
+func (ts *HTestSuite) TestUpdateTimestampDoesNotCreate(c *C) {
+	d := c.MkDir()
+	foo := filepath.Join(d, "foo")
+
+	c.Check(UpdateTimestamp(foo), NotNil)
+	_, err := os.Stat(foo)
+	c.Check(os.IsNotExist(err), Equals, true)
+}
+
+func (ts *HTestSuite) TestUpdateTimestampBailsOnRelative(c *C) {
+	c.Check(UpdateTimestamp("./foo"), Equals, ErrNotAbsPath)
+}