cmd/go/internal/imports: resolve symlinks in ScanDir

We were using the mode reported by ReadDir to decide whether each
entry is a file, but in the case of symlinks that isn't sufficient: a
symlink could point to either a file or a directory, and if it is a
file we should treat it as such.

Fixes #28107

Change-Id: Icf6e495dce427a7b1124c9cc9f085e40a215c169
Reviewed-on: https://go-review.googlesource.com/c/141097
Run-TryBot: Bryan C. Mills <bcmills@google.com>
TryBot-Result: Gobot Gobot <gobot@golang.org>
Reviewed-by: Russ Cox <rsc@golang.org>

diff --git a/src/cmd/go/internal/imports/scan.go b/src/cmd/go/internal/imports/scan.go
index d944e95724e54244e28f9694e8dbb6780db18f3d..966a38cfef3adf2ad353ba0c6eab85b9493f46a2 100644 (file)
--- a/src/cmd/go/internal/imports/scan.go
+++ b/src/cmd/go/internal/imports/scan.go
@@ -22,6 +22,16 @@ func ScanDir(dir string, tags map[string]bool) ([]string, []string, error) {
        var files []string
        for _, info := range infos {
                name := info.Name()
+
+               // If the directory entry is a symlink, stat it to obtain the info for the
+               // link target instead of the link itself.
+               if info.Mode()&os.ModeSymlink != 0 {
+                       info, err = os.Stat(name)
+                       if err != nil {
+                               continue // Ignore broken symlinks.
+                       }
+               }
+
                if info.Mode().IsRegular() && !strings.HasPrefix(name, "_") && strings.HasSuffix(name, ".go") && MatchFile(name, tags) {
                        files = append(files, filepath.Join(dir, name))
                }

diff --git a/src/cmd/go/testdata/script/mod_symlink.txt b/src/cmd/go/testdata/script/mod_symlink.txt
new file mode 100644 (file)
index 0000000..61da3cc
--- /dev/null
+++ b/src/cmd/go/testdata/script/mod_symlink.txt
@@ -0,0 +1,23 @@
+env GO111MODULE=on
+[!symlink] skip
+
+# 'go list' should resolve modules of imported packages.
+go list -deps -f '{{.Module}}'
+stdout golang.org/x/text
+
+# They should continue to resolve if the importing file is a symlink.
+mkdir links
+cd links
+symlink go.mod -> ../go.mod
+symlink issue.go -> ../issue.go
+
+go list -deps -f '{{.Module}}'
+stdout golang.org/x/text
+
+-- go.mod --
+module golang.org/issue/28107
+
+-- issue.go --
+package issue
+
+import _ "golang.org/x/text/language"