From 1dc6e1d5d336da291359bfc82c111d3761b870f4 Mon Sep 17 00:00:00 2001
From: Yage Hu <me@huyage.dev>
Date: Tue, 18 Jun 2024 16:19:07 -0700
Subject: [PATCH] Support absolute Windows path

Signed-off-by: Yage Hu <me@huyage.dev>
---
 src/win/fs.c   | 40 +++++++++++++++++++++++++++++++++-------
 test/test-fs.c | 29 ++++++++++++++++++++++++++---
 2 files changed, 59 insertions(+), 10 deletions(-)

diff --git a/src/win/fs.c b/src/win/fs.c
index 60f49997..1efd04be 100644
--- a/src/win/fs.c
+++ b/src/win/fs.c
@@ -35,6 +35,7 @@
 /* <winioctl.h> requires <windows.h>, included via "uv.h" above, but needs to
    be included before our "winapi.h", included via "internal.h" below. */
 #include <winioctl.h>
+#include <shlwapi.h>
 
 #include "internal.h"
 #include "req-inl.h"
@@ -732,6 +733,7 @@ void fs__openat(uv_fs_t* req) {
   int flags = req->fs.info.file_flags;
   struct uv__fd_info_s fd_info;
   WCHAR * path = req->file.pathw;
+  size_t path_len = wcslen(path);
   struct path rebuilt_path;
   int i;
 
@@ -740,11 +742,23 @@ void fs__openat(uv_fs_t* req) {
     if (path[i] == L'/')
       path[i] = L'\\';
 
-  HANDLE dir_handle = (HANDLE) _get_osfhandle(req->fs.info.fd_out);
-  HANDLE root_dir_handle = dir_handle;
-  if (dir_handle == INVALID_HANDLE_VALUE) {
-    SET_REQ_WIN32_ERROR(req, (DWORD) UV_EBADF);
-    return;
+  HANDLE root_dir_handle = 0;
+  HANDLE dir_handle;
+  BOOL is_absolute = FALSE;
+
+  if (
+    (path_len > 0 && path[0] == L'\\') || 
+    (path_len > 2 && path[1] == L':' && path[2] == L'\\')
+  ) is_absolute = TRUE;
+
+  if (!is_absolute) {
+    dir_handle = (HANDLE) _get_osfhandle(req->fs.info.fd_out);
+    if (dir_handle == INVALID_HANDLE_VALUE) {
+      SET_REQ_WIN32_ERROR(req, (DWORD) UV_EBADF);
+      return;
+    }
+
+    root_dir_handle = dir_handle;
   }
 
   uv__path_init(&rebuilt_path);
@@ -757,7 +771,7 @@ void fs__openat(uv_fs_t* req) {
       // Do nothing.
     } else if (!wcscmp(L"..", token)) {
       // If rebuilt_path is empty, set it to the path of the parent direcotry.
-      if (rebuilt_path.len == 0) {
+      if (rebuilt_path.len == 0 && !is_absolute) {
         DWORD dir_path_len = GetFinalPathNameByHandleW(dir_handle, NULL, 0, VOLUME_NAME_DOS);
         if (dir_path_len == 0) {
           SET_REQ_WIN32_ERROR(req, GetLastError());
@@ -797,7 +811,7 @@ void fs__openat(uv_fs_t* req) {
       }
 
       // Then pop the last component.
-      uv__path_pop(&rebuilt_path);
+      if (rebuilt_path.len > 0) uv__path_pop(&rebuilt_path);
     } else {
       uv__path_push(&rebuilt_path, token);
     }
@@ -805,6 +819,18 @@ void fs__openat(uv_fs_t* req) {
     token = wcstok_s(NULL, L"\\", &next_token);
   }
 
+  if (is_absolute) {
+    // Prepend the path with the NT object directory prefix.
+
+    WCHAR * buf = uv__malloc((rebuilt_path.len + 1) * sizeof(WCHAR));
+    memcpy(buf, rebuilt_path.buf, (rebuilt_path.len + 1) * sizeof(WCHAR));
+    uv__path_set(&rebuilt_path, L"\\??");
+    uv__path_push(&rebuilt_path, buf);
+    uv__free(buf);
+  }
+
+  wprintf(L"%d %s\n", root_dir_handle, rebuilt_path.buf);
+
   /* Adjust flags to be compatible with the memory file mapping. Save the
    * original flags to emulate the correct behavior. */
   if (flags & UV_FS_O_FILEMAP) {
diff --git a/test/test-fs.c b/test/test-fs.c
index b45a453d..b27f9cf0 100644
--- a/test/test-fs.c
+++ b/test/test-fs.c
@@ -3257,6 +3257,32 @@ TEST_IMPL(fs_openat) {
     uv_fs_req_cleanup(&req);
   }
 
+  {
+    r = uv_fs_realpath(NULL, &req, "test/fixtures/file", NULL);
+    ASSERT_OK(r);
+
+    size_t len = strlen(req.ptr);
+    char * abs_path = malloc(len + 1);
+    memcpy(abs_path, req.ptr, len + 1);
+    uv_fs_req_cleanup(&req);
+
+    r = uv_fs_openat(NULL,
+                     &req,
+                     dir,
+                     abs_path,
+                     UV_FS_O_RDONLY,
+                     0,
+                     NULL);
+    ASSERT_GE(r, 0);
+    free(abs_path);
+    fd = (uv_file) req.result;
+    uv_fs_req_cleanup(&req);
+
+    r = uv_fs_close(NULL, &req, fd, NULL);
+    ASSERT_OK(r);
+    uv_fs_req_cleanup(&req);
+  }
+
   r = uv_fs_close(NULL, &req, dir, NULL);
   ASSERT_OK(r);
   uv_fs_req_cleanup(&req);
@@ -3270,10 +3296,7 @@ TEST_IMPL(fs_openat) {
   unlink("test/fixtures/test_dir/test_file");
   unlink("test/fixtures/test_dir/link");
   unlink("test/fixtures/test_dir/nested_dir/file");
-<<<<<<< HEAD
-=======
   unlink("test/fixtures/file");
->>>>>>> 8e91f4974c9681fd1aaf7b42fcb493a3b587ac2f
   rmdir("test/fixtures/test_dir/nested_dir");
   rmdir("test/fixtures/test_dir");