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/*
* 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 (
"bytes"
"io"
"os"
"path/filepath"
)
const bufsz = 16 * 1024
// FilesAreEqual compares the two files' contents and returns whether
// they are the same.
func FilesAreEqual(a, b string) bool {
fa, err := os.Open(a)
if err != nil {
return false
}
defer fa.Close()
fb, err := os.Open(b)
if err != nil {
return false
}
defer fb.Close()
fia, err := fa.Stat()
if err != nil {
return false
}
fib, err := fb.Stat()
if err != nil {
return false
}
if fia.Size() != fib.Size() {
return false
}
return streamsEqual(fa, fb)
}
func streamsEqual(fa, fb io.Reader) bool {
bufa := make([]byte, bufsz)
bufb := make([]byte, bufsz)
for {
ra, erra := io.ReadAtLeast(fa, bufa, bufsz)
rb, errb := io.ReadAtLeast(fb, bufb, bufsz)
if erra == io.EOF && errb == io.EOF {
return true
}
if erra != nil || errb != nil {
// if both files finished in the middle of a
// ReadAtLeast, (returning io.ErrUnexpectedEOF), then we
// still need to check what was read to know whether
// they're equal. Otherwise, we know they're not equal
// (because we count any read error as a being non-equal
// also).
tailMightBeEqual := erra == io.ErrUnexpectedEOF && errb == io.ErrUnexpectedEOF
if !tailMightBeEqual {
return false
}
}
if !bytes.Equal(bufa[:ra], bufb[:rb]) {
return false
}
}
}
// DirUpdated compares two directories, and returns which files present in both
// have been updated, with the given prefix prepended.
//
// Subdirectories are ignored.
//
// This function is to compare the policies and templates in a (framework) click
// to be installed, against the policies and templates of one already installed,
// to then determine what changed. The prefix is because policies and templates
// are specified with the framework name.
func DirUpdated(dirA, dirB, pfx string) map[string]bool {
filesA, _ := filepath.Glob(filepath.Join(dirA, "*"))
updated := make(map[string]bool)
for _, fileA := range filesA {
if IsDirectory(fileA) {
continue
}
name := filepath.Base(fileA)
fileB := filepath.Join(dirB, name)
if FileExists(fileB) && !FilesAreEqual(fileA, fileB) {
updated[pfx+name] = true
}
}
return updated
}
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