Issue #13772: Restored directory detection of targets in os.symlink on Windows, which was temporarily removed in Python 3.2.3 due to an incomplete implementation. The implementation now works even if the symlink is created in a location other than the current directory.

Modules/posixmodule.c

@@ -7200,6 +7200,124 @@ check_CreateSymbolicLink()
     return (Py_CreateSymbolicLinkW && Py_CreateSymbolicLinkA);
 }
 
+void _dirnameW(WCHAR *path) {
+    /* Remove the last portion of the path */
+
+    WCHAR *ptr;
+
+    /* walk the path from the end until a backslash is encountered */
+    for(ptr = path + wcslen(path); ptr != path; ptr--)
+    {
+        if(*ptr == *L"\\" || *ptr == *L"/") {
+            break;
+        }
+    }
+    *ptr = 0;
+}
+
+void _dirnameA(char *path) {
+    /* Remove the last portion of the path */
+
+    char *ptr;
+
+    /* walk the path from the end until a backslash is encountered */
+    for(ptr = path + strlen(path); ptr != path; ptr--)
+    {
+        if(*ptr == '\\' || *ptr == '/') {
+            break;
+        }
+    }
+    *ptr = 0;
+}
+
+int _is_absW(WCHAR *path) {
+    /* Is this path absolute? */
+
+    return path[0] == L'\\' || path[0] == L'/' || path[1] == L':';
+
+}
+
+int _is_absA(char *path) {
+    /* Is this path absolute? */
+
+    return path[0] == '\\' || path[0] == '/' || path[1] == ':';
+
+}
+
+void _joinW(WCHAR *dest_path, const WCHAR *root, const WCHAR *rest) {
+    /* join root and rest with a backslash */
+    int root_len;
+
+    if(_is_absW(rest)) {
+        wcscpy(dest_path, rest);
+        return;
+    }
+
+    root_len = wcslen(root);
+
+    wcscpy(dest_path, root);
+    if(root_len) {
+        dest_path[root_len] = *L"\\";
+        root_len += 1;
+    }
+    wcscpy(dest_path+root_len, rest);
+}
+
+void _joinA(char *dest_path, const char *root, const char *rest) {
+    /* join root and rest with a backslash */
+    int root_len;
+
+    if(_is_absA(rest)) {
+        strcpy(dest_path, rest);
+        return;
+    }
+
+    root_len = strlen(root);
+
+    strcpy(dest_path, root);
+    if(root_len) {
+        dest_path[root_len] = '\\';
+        root_len += 1;
+    }
+    strcpy(dest_path+root_len, rest);
+}
+
+int _check_dirW(WCHAR *src, WCHAR *dest)
+{
+    /* Return True if the path at src relative to dest is a directory */
+    WIN32_FILE_ATTRIBUTE_DATA src_info;
+    WCHAR dest_parent[MAX_PATH];
+    WCHAR src_resolved[MAX_PATH] = L"";
+
+    /* dest_parent = os.path.dirname(dest) */
+    wcscpy(dest_parent, dest);
+    _dirnameW(dest_parent);
+    /* src_resolved = os.path.join(dest_parent, src) */
+    _joinW(src_resolved, dest_parent, src);
+    return (
+        GetFileAttributesExW(src_resolved, GetFileExInfoStandard, &src_info)
+        && src_info.dwFileAttributes & FILE_ATTRIBUTE_DIRECTORY
+    );
+}
+
+int _check_dirA(char *src, char *dest)
+{
+    /* Return True if the path at src relative to dest is a directory */
+    WIN32_FILE_ATTRIBUTE_DATA src_info;
+    char dest_parent[MAX_PATH];
+    char src_resolved[MAX_PATH] = "";
+
+    /* dest_parent = os.path.dirname(dest) */
+    strcpy(dest_parent, dest);
+    _dirnameW(dest_parent);
+    /* src_resolved = os.path.join(dest_parent, src) */
+    _joinW(src_resolved, dest_parent, src);
+    return (
+        GetFileAttributesExA(src_resolved, GetFileExInfoStandard, &src_info)
+        && src_info.dwFileAttributes & FILE_ATTRIBUTE_DIRECTORY
+    );
+}
+
 #endif
 
 static PyObject *
@@ -7256,13 +7374,20 @@ posix_symlink(PyObject *self, PyObject *args, PyObject *kwargs)
     }
 
 #ifdef MS_WINDOWS
+
     Py_BEGIN_ALLOW_THREADS
-    if (dst.wide)
+    if (dst.wide) {
+        /* if src is a directory, ensure target_is_directory==1 */
+        target_is_directory |= _check_dirW(src.wide, dst.wide);
         result = Py_CreateSymbolicLinkW(dst.wide, src.wide,
                                         target_is_directory);
-    else
+    }
+    else {
+        /* if src is a directory, ensure target_is_directory==1 */
+        target_is_directory |= _check_dirA(src.narrow, dst.narrow);
         result = Py_CreateSymbolicLinkA(dst.narrow, src.narrow,
                                         target_is_directory);
+    }
     Py_END_ALLOW_THREADS
 
     if (!result) {