tree_entry: fix CommitsInfo messed up with entries have the same SHA1

[manfer]

to fix gogs/gogs#6186
to fix gogs/gogs#6235
to fix gogs/gogs#6240

The problem is on git-module

git-module/tree_entry.go

Lines 261 to 270 in cf0a6d7

	infos := make(map[[20]byte]*EntryCommitInfo, len(es))
	for info := range results {
	infos[info.Entry.id.bytes] = info
	}
	commitsInfo := make([]*EntryCommitInfo, len(es))
	for i, e := range es {
	commitsInfo[i] = infos[e.id.bytes]
	}
	return commitsInfo, nil

An entry id is not unique so it should not be used as map key. When on a tree there is a file or folder with same contents its SHA1 hash is equal. This can be tested in any repo with two files with same content executing git ls-tree HEAD

$ mkdir testrepo; cd testrepo
$ git init
$ echo "this is a test" > test1
$ git add .
$ git commit -m "adding test1 file"
$ echo "this is a test" > test2
$ git add .
$ git commit -m "adding test2 file"
$ git ls-tree HEAD
100644 blob 90bfcb510602aa11ae53a42dcec18ea39fbd8cec    test1
100644 blob 90bfcb510602aa11ae53a42dcec18ea39fbd8cec    test2

Maybe a solution is using name as the key as I bet entry name is unique in any tree.

	infos := make(map[string]*EntryCommitInfo, len(es))
	for info := range results {
		infos[info.Entry.name] = info
	}


	commitsInfo := make([]*EntryCommitInfo, len(es))
	for i, e := range es {
		commitsInfo[i] = infos[e.name]
	}
	return commitsInfo, nil

Or maybe just including entry index on info so later only one loop is needed to fill commitsInfo.

// EntryCommitInfo contains a tree entry with its commit information.
type EntryCommitInfo struct {
	Entry     *TreeEntry
        Index     int
	Commit    *Commit
	Submodule *Submodule
}

        ...
			go func(e *TreeEntry, i int) {
				defer func() {
					wg.Done()
        ...

				info := &EntryCommitInfo{
					Entry: e,
                                        Index: i,
				}

        ...

				results <- info
			}(e, i)
		}
	}()

        ...

	commitsInfo := make([]*EntryCommitInfo, len(es))
	for info := range results {
		commitsInfo[info.Index] = info
	}
	return commitsInfo, nil

[codecov]

Codecov Report

Merging #59 into master will decrease coverage by 0.01%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##           master      #59      +/-   ##
==========================================
- Coverage   83.58%   83.56%   -0.02%     
==========================================
  Files          24       24              
  Lines        1998     1996       -2     
==========================================
- Hits         1670     1668       -2     
  Misses        236      236              
  Partials       92       92              

Impacted Files	Coverage Δ
tree_entry.go	75.38% <100.00%> (-0.38%)	⬇️

[unknwon]

@manfer: Wow, thanks a lot for the great details! LGTM at first glance, I'll take a deeper look later this week.

[unknwon]

I'm merging it as-is, then add a test case later.

[unknwon]

https://github.com/gogs/git-module/releases/tag/v1.1.2 has tagged for this merge.

[xZero707]

@manfer Amazing work. Thank you!