1// Copyright 2019 Google Inc. All rights reserved.
2//
3// Licensed under the Apache License, Version 2.0 (the "License");
4// you may not use this file except in compliance with the License.
5// You may obtain a copy of the License at
6//
7//     http://www.apache.org/licenses/LICENSE-2.0
8//
9// Unless required by applicable law or agreed to in writing, software
10// distributed under the License is distributed on an "AS IS" BASIS,
11// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
12// See the License for the specific language governing permissions and
13// limitations under the License.
14
15package main
16
17import (
18	"bytes"
19	"fmt"
20)
21
22// compareTargetFiles takes two ZipArtifacts and compares the files they contain by examining
23// the path, size, and CRC of each file.
24func compareTargetFiles(priZip, refZip ZipArtifact, artifact string, allowLists []allowList, filters []string) (zipDiff, error) {
25	priZipFiles, err := priZip.Files()
26	if err != nil {
27		return zipDiff{}, fmt.Errorf("error fetching target file lists from primary zip %v", err)
28	}
29
30	refZipFiles, err := refZip.Files()
31	if err != nil {
32		return zipDiff{}, fmt.Errorf("error fetching target file lists from reference zip %v", err)
33	}
34
35	priZipFiles, err = filterTargetZipFiles(priZipFiles, artifact, filters)
36	if err != nil {
37		return zipDiff{}, err
38	}
39
40	refZipFiles, err = filterTargetZipFiles(refZipFiles, artifact, filters)
41	if err != nil {
42		return zipDiff{}, err
43	}
44
45	// Compare the file lists from both builds
46	diff := diffTargetFilesLists(refZipFiles, priZipFiles)
47
48	return applyAllowLists(diff, allowLists)
49}
50
51// zipDiff contains the list of files that differ between two zip files.
52type zipDiff struct {
53	modified         [][2]*ZipArtifactFile
54	onlyInA, onlyInB []*ZipArtifactFile
55}
56
57// String pretty-prints the list of files that differ between two zip files.
58func (d *zipDiff) String() string {
59	buf := &bytes.Buffer{}
60
61	must := func(n int, err error) {
62		if err != nil {
63			panic(err)
64		}
65	}
66
67	var sizeChange int64
68
69	if len(d.modified) > 0 {
70		must(fmt.Fprintln(buf, "files modified:"))
71		for _, f := range d.modified {
72			must(fmt.Fprintf(buf, "   %v (%v bytes -> %v bytes)\n", f[0].Name, f[0].UncompressedSize64, f[1].UncompressedSize64))
73			sizeChange += int64(f[1].UncompressedSize64) - int64(f[0].UncompressedSize64)
74		}
75	}
76
77	if len(d.onlyInA) > 0 {
78		must(fmt.Fprintln(buf, "files removed:"))
79		for _, f := range d.onlyInA {
80			must(fmt.Fprintf(buf, " - %v (%v bytes)\n", f.Name, f.UncompressedSize64))
81			sizeChange -= int64(f.UncompressedSize64)
82		}
83	}
84
85	if len(d.onlyInB) > 0 {
86		must(fmt.Fprintln(buf, "files added:"))
87		for _, f := range d.onlyInB {
88			must(fmt.Fprintf(buf, " + %v (%v bytes)\n", f.Name, f.UncompressedSize64))
89			sizeChange += int64(f.UncompressedSize64)
90		}
91	}
92
93	if len(d.modified) > 0 || len(d.onlyInA) > 0 || len(d.onlyInB) > 0 {
94		must(fmt.Fprintf(buf, "total size change: %v bytes\n", sizeChange))
95	}
96
97	return buf.String()
98}
99
100func diffTargetFilesLists(a, b []*ZipArtifactFile) zipDiff {
101	i := 0
102	j := 0
103
104	diff := zipDiff{}
105
106	for i < len(a) && j < len(b) {
107		if a[i].Name == b[j].Name {
108			if a[i].UncompressedSize64 != b[j].UncompressedSize64 || a[i].CRC32 != b[j].CRC32 {
109				diff.modified = append(diff.modified, [2]*ZipArtifactFile{a[i], b[j]})
110			}
111			i++
112			j++
113		} else if a[i].Name < b[j].Name {
114			// a[i] is not present in b
115			diff.onlyInA = append(diff.onlyInA, a[i])
116			i++
117		} else {
118			// b[j] is not present in a
119			diff.onlyInB = append(diff.onlyInB, b[j])
120			j++
121		}
122	}
123	for i < len(a) {
124		diff.onlyInA = append(diff.onlyInA, a[i])
125		i++
126	}
127	for j < len(b) {
128		diff.onlyInB = append(diff.onlyInB, b[j])
129		j++
130	}
131
132	return diff
133}
134