From b8a2710a2cefbddc5e6b494db186014b341412e4 Mon Sep 17 00:00:00 2001
From: Aleksei Volkov <volkov.aa@phystech.edu>
Date: Tue, 31 Oct 2023 01:39:43 +0300
Subject: Fix problems in path normalisation algorithm (#1541)

Current implementation of path normalisation contains various flaws:

- Trailing `.` and `..` at the end of path don't get normalised,
- Path `/` turns into an empty string after normalisation.

This patch changes implementation of normalisation to fix these.
---
 spec/dir_spec.lua         |  8 ++++++++
 src/luarocks/core/dir.lua | 11 +++++++----
 2 files changed, 15 insertions(+), 4 deletions(-)

diff --git a/spec/dir_spec.lua b/spec/dir_spec.lua
index 9f05c664..f6ef172e 100644
--- a/spec/dir_spec.lua
+++ b/spec/dir_spec.lua
@@ -52,12 +52,20 @@ describe("luarocks.dir #unit", function()
       it("strips unneeded /../ and /./", function()
          assert.are.same("/some/dir/file.txt", dir.normalize("/../../../some/./foo/bar/.././../dir/bla/../file.txt"))
          assert.are.same("/some/dir/file.txt", dir.normalize("/../../../some/./foo/bar/.././../dir/bla/../file.txt"))
+         assert.are.same("/some/dir", dir.normalize("/../../../some/./foo/bar/.././../dir/./some/subdir/../.."))
+         assert.are.same("/some/dir", dir.normalize("/../../../some/./foo/bar/.././../dir/./."))
       end)
       it("respects relative paths", function()
+         assert.are.same(".", dir.normalize("."))
          assert.are.same("boo", dir.normalize("./boo"))
          assert.are.same("/boo", dir.normalize("/./boo"))
          assert.are.same("../../../../boo", dir.normalize("../../../hello/world/../../../boo"))
       end)
+      it("respects root directory", function()
+         assert.are.same("/", dir.normalize("/"))
+         assert.are.same("/", dir.normalize("/////"))
+         assert.are.same("/", dir.normalize("/a/b/.././../c/./../../"))
+      end)
    end)
 
 end)
diff --git a/src/luarocks/core/dir.lua b/src/luarocks/core/dir.lua
index 0da88997..46dbeafd 100644
--- a/src/luarocks/core/dir.lua
+++ b/src/luarocks/core/dir.lua
@@ -63,6 +63,7 @@ function dir.normalize(name)
    if pathname:match("^.:") then
       drive, pathname = pathname:match("^(.:)(.*)$")
    end
+   pathname = pathname .. "/"
    for piece in pathname:gmatch("(.-)/") do
       if piece == ".." then
          local prev = pieces[#pieces]
@@ -75,11 +76,13 @@ function dir.normalize(name)
          table.insert(pieces, piece)
       end
    end
-   local basename = pathname:match("[^/]+$")
-   if basename then
-      table.insert(pieces, basename)
+   if #pieces == 0 then
+      pathname = drive .. "."
+   elseif #pieces == 1 and pieces[1] == "" then
+      pathname = drive .. "/"
+   else
+      pathname = drive .. table.concat(pieces, "/")
    end
-   pathname = drive .. table.concat(pieces, "/")
    if protocol ~= "file" then pathname = protocol .."://"..pathname end
    return pathname
 end
-- 
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