Update Python/fileutils.c

Co-authored-by: Eryk Sun <[email protected]>

Author: RayyanAnsari

Python/fileutils.c

@@ -1820,19 +1820,25 @@ _Py_write_impl(int fd, const void *buf, size_t count, int gil_held)
     if (hfile == INVALID_HANDLE_VALUE) {
         return -1;
     }
-    DWORD mode, pipe_size;
+    DWORD pipe_mode, pipe_flags, pipe_size, pipe_insize, pipe_outsize;
     if (gil_held) {
         Py_BEGIN_ALLOW_THREADS
         if (GetFileType(hfile) == FILE_TYPE_PIPE &&
-            GetNamedPipeHandleStateW(hfile, &mode, NULL, NULL, NULL,
+            GetNamedPipeHandleStateW(hfile, &pipe_mode, NULL, NULL, NULL,
                                      NULL, 0) &&
-            mode & PIPE_NOWAIT)
+            pipe_mode & PIPE_NOWAIT)
         {
             // GetNamedPipeInfo() requires FILE_READ_ATTRIBUTES access.
             // CreatePipe() includes this access for the write handle.
-            if (!GetNamedPipeInfo(hfile, NULL, NULL, &pipe_size, NULL)) {
+            if (!GetNamedPipeInfo(hfile, &pipe_flags, &pipe_outsize,
+                                  &pipe_insize, NULL))
+            {
                 pipe_size = 4096;
             }
+            else {
+                pipe_size = pipe_flags & PIPE_SERVER_END ? pipe_outsize :
+                                pipe_insize;
+            }
             if (count > pipe_size) {
                 count = pipe_size;
             }
@@ -1841,15 +1847,21 @@ _Py_write_impl(int fd, const void *buf, size_t count, int gil_held)
     }
     else {
         if (GetFileType(hfile) == FILE_TYPE_PIPE &&
-            GetNamedPipeHandleStateW(hfile, &mode, NULL, NULL, NULL,
+            GetNamedPipeHandleStateW(hfile, &pipe_mode, NULL, NULL, NULL,
                                      NULL, 0) &&
-            mode & PIPE_NOWAIT)
+            pipe_mode & PIPE_NOWAIT)
         {
             // GetNamedPipeInfo() requires FILE_READ_ATTRIBUTES access.
             // CreatePipe() includes this access for the write handle.
-            if (!GetNamedPipeInfo(hfile, NULL, NULL, &pipe_size, NULL)) {
+            if (!GetNamedPipeInfo(hfile, &pipe_flags, &pipe_outsize,
+                                  &pipe_insize, NULL))
+            {
                 pipe_size = 4096;
             }
+            else {
+                pipe_size = pipe_flags & PIPE_SERVER_END ? pipe_outsize :
+                                pipe_insize;
+            }
             if (count > pipe_size) {
                 count = pipe_size;
             }