From a61bdc24dab160aba1a72e976334bf99b8cfe151 Mon Sep 17 00:00:00 2001
From: Charles Kerr <charles@charleskerr.com>
Date: Fri, 30 Jan 2026 08:55:37 -0600
Subject: [PATCH] refactor: use std::filesystem for tr_sys_path_resolve()
 (#8282)

---
 libtransmission/file-posix.cc | 18 ---------------
 libtransmission/file-win32.cc | 42 -----------------------------------
 libtransmission/file.cc       | 21 ++++++++++++++++++
 3 files changed, 21 insertions(+), 60 deletions(-)

diff --git a/libtransmission/file-posix.cc b/libtransmission/file-posix.cc
index 6b99615ef..d2049c20b 100644
--- a/libtransmission/file-posix.cc
+++ b/libtransmission/file-posix.cc
@@ -226,24 +226,6 @@ bool tr_sys_path_is_same(std::string_view const path1, std::string_view const pa
     return ret;
 }
 
-std::string tr_sys_path_resolve(std::string_view path, tr_error* error)
-{
-    auto const szpath = tr_pathbuf{ path };
-    auto buf = std::array<char, PATH_MAX>{};
-
-    if (auto const* const ret = realpath(szpath, std::data(buf)); ret != nullptr)
-    {
-        return ret;
-    }
-
-    if (error != nullptr)
-    {
-        error->set_from_errno(errno);
-    }
-
-    return {};
-}
-
 std::string_view tr_sys_path_basename(std::string_view path, tr_error* /*error*/)
 {
     // As per the basename() manpage:
diff --git a/libtransmission/file-win32.cc b/libtransmission/file-win32.cc
index 3a49e1405..76857e8ef 100644
--- a/libtransmission/file-win32.cc
+++ b/libtransmission/file-win32.cc
@@ -488,48 +488,6 @@ bool tr_sys_path_is_same(std::string_view const path1, std::string_view const pa
         fi1->nFileIndexLow == fi2->nFileIndexLow;
 }
 
-std::string tr_sys_path_resolve(std::string_view path, tr_error* error)
-{
-    auto ret = std::string{};
-
-    if (auto const wide_path = path_to_native_path(path); !std::empty(wide_path))
-    {
-        if (auto const handle = CreateFileW(
-                wide_path.c_str(),
-                FILE_READ_EA,
-                FILE_SHARE_READ | FILE_SHARE_WRITE | FILE_SHARE_DELETE,
-                nullptr,
-                OPEN_EXISTING,
-                FILE_FLAG_BACKUP_SEMANTICS,
-                nullptr);
-            handle != INVALID_HANDLE_VALUE)
-        {
-            if (auto const wide_ret_size = GetFinalPathNameByHandleW(handle, nullptr, 0, 0); wide_ret_size != 0)
-            {
-                auto wide_ret = std::wstring{};
-                wide_ret.resize(wide_ret_size);
-                if (GetFinalPathNameByHandleW(handle, std::data(wide_ret), wide_ret_size, 0) == wide_ret_size - 1)
-                {
-                    // `wide_ret_size` includes the terminating '\0'; remove it from `wide_ret`
-                    wide_ret.resize(std::size(wide_ret) - 1);
-                    TR_ASSERT(tr_strv_starts_with(wide_ret, NativeLocalPathPrefix));
-                    ret = native_path_to_path(wide_ret);
-                }
-            }
-
-            CloseHandle(handle);
-        }
-    }
-
-    if (!std::empty(ret))
-    {
-        return ret;
-    }
-
-    set_system_error(error, GetLastError());
-    return {};
-}
-
 std::string_view tr_sys_path_basename(std::string_view path, tr_error* error)
 {
     if (std::empty(path))
diff --git a/libtransmission/file.cc b/libtransmission/file.cc
index 4f2d6a867..d6dcbfd70 100644
--- a/libtransmission/file.cc
+++ b/libtransmission/file.cc
@@ -3,6 +3,8 @@
 // or any future license endorsed by Mnemosyne LLC.
 // License text can be found in the licenses/ folder.
 
+#include <filesystem>
+#include <system_error>
 #include <string>
 #include <string_view>
 #include <vector>
@@ -11,6 +13,25 @@
 #include "libtransmission/file.h"
 #include "libtransmission/tr-assert.h"
 
+std::string tr_sys_path_resolve(std::string_view path, tr_error* error)
+{
+    auto ec = std::error_code{};
+    auto const canonical_path = std::filesystem::canonical(tr_u8path(path), ec);
+
+    if (ec)
+    {
+        if (error != nullptr)
+        {
+            error->set(ec.value(), ec.message());
+        }
+
+        return {};
+    }
+
+    auto const u8_path = canonical_path.u8string();
+    return { std::begin(u8_path), std::end(u8_path) };
+}
+
 std::vector<std::string> tr_sys_dir_get_files(
     std::string_view folder,
     std::function<bool(std::string_view)> const& test,