From 504b77b0b9925616be8d080a98f0a4fc04ebe9f2 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?=D0=92=D0=B0=D1=81=D0=B8=D0=BB=D0=B8=D0=B9=20=D0=A7=D0=B0?=
 =?UTF-8?q?=D0=B9?= <basilefff@gmail.com>
Date: Mon, 19 Jun 2023 09:30:55 +0400
Subject: [PATCH] fix: return error when renaming into existing file (#5563)

---
 libtransmission/torrent.cc           | 34 ++++++++++++++++++++++++----
 tests/libtransmission/rename-test.cc |  3 +++
 2 files changed, 33 insertions(+), 4 deletions(-)

diff --git a/libtransmission/torrent.cc b/libtransmission/torrent.cc
index 73a817265..e93371598 100644
--- a/libtransmission/torrent.cc
+++ b/libtransmission/torrent.cc
@@ -2448,10 +2448,36 @@ namespace
 {
 namespace rename_helpers
 {
-bool renameArgsAreValid(std::string_view oldpath, std::string_view newname)
+bool renameArgsAreValid(tr_torrent const* tor, std::string_view oldpath, std::string_view newname)
 {
-    return !std::empty(oldpath) && !std::empty(newname) && newname != "."sv && newname != ".."sv &&
-        !tr_strvContains(newname, TR_PATH_DELIMITER);
+    if (std::empty(oldpath) || std::empty(newname) || newname == "."sv || newname == ".."sv ||
+        tr_strvContains(newname, TR_PATH_DELIMITER))
+    {
+        return false;
+    }
+
+    auto const newpath = tr_strvContains(oldpath, TR_PATH_DELIMITER) ?
+        tr_pathbuf{ tr_sys_path_dirname(oldpath), '/', newname } :
+        tr_pathbuf{ newname };
+
+    if (newpath == oldpath)
+    {
+        return true;
+    }
+
+    auto const newpath_as_dir = tr_pathbuf{ newpath, '/' };
+    auto const n_files = tor->file_count();
+
+    for (tr_file_index_t i = 0; i < n_files; ++i)
+    {
+        auto const& name = tor->file_subpath(i);
+        if (newpath == name || tr_strvStartsWith(name, newpath_as_dir))
+        {
+            return false;
+        }
+    }
+
+    return true;
 }
 
 auto renameFindAffectedFiles(tr_torrent const* tor, std::string_view oldpath)
@@ -2568,7 +2594,7 @@ void torrentRenamePath(
 
     int error = 0;
 
-    if (!renameArgsAreValid(oldpath, newname))
+    if (!renameArgsAreValid(tor, oldpath, newname))
     {
         error = EINVAL;
     }
diff --git a/tests/libtransmission/rename-test.cc b/tests/libtransmission/rename-test.cc
index d038506e5..918133088 100644
--- a/tests/libtransmission/rename-test.cc
+++ b/tests/libtransmission/rename-test.cc
@@ -414,6 +414,9 @@ TEST_F(RenameTest, multifileTorrent)
     EXPECT_EQ(EINVAL, torrentRenameAndWait(tor, "Felidae/FelinaeX", "Genus Felinae"));
     EXPECT_STREQ("Felidae", tr_torrentName(tor));
 
+    // rename filename collision
+    EXPECT_EQ(EINVAL, torrentRenameAndWait(tor, "Felidae/Felinae/Felis/catus/Kyphi", "Saffron"));
+    EXPECT_STREQ("Felidae", tr_torrentName(tor));
     /***
     ****
     ***/