Apply suggestions from code review

RayyanAnsari · eryksun · web-flow · commit fdef371afd98 · 2023-02-16T11:05:44.000Z
Co-authored-by: Eryk Sun &lt;eryksun@gmail.com&gt;
diff --git a/Python/fileutils.c b/Python/fileutils.c
@@ -1813,61 +1813,6 @@ _Py_write_impl(int fd, const void *buf, size_t count, int gil_held)
         }
     }
 
-    // In non-blocking mode, a write that exceeds the available size of a pipe
-    // fails without writing anything. Limiting writes to the pipe size allows
-    // a buffered write to succeed eventually, as the pipe is read.
-    HANDLE hfile = _Py_get_osfhandle(fd);
-    if (hfile == INVALID_HANDLE_VALUE) {
-        return -1;
-    }
-    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, &pipe_mode, NULL, NULL, NULL,
-                                     NULL, 0) &&
-            pipe_mode & PIPE_NOWAIT)
-        {
-            // GetNamedPipeInfo() requires FILE_READ_ATTRIBUTES access.
-            // CreatePipe() includes this access for the write handle.
-            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;
-            }
-        }
-        Py_END_ALLOW_THREADS
-    }
-    else {
-        if (GetFileType(hfile) == FILE_TYPE_PIPE &&
-            GetNamedPipeHandleStateW(hfile, &pipe_mode, NULL, NULL, NULL,
-                                     NULL, 0) &&
-            pipe_mode & PIPE_NOWAIT)
-        {
-            // GetNamedPipeInfo() requires FILE_READ_ATTRIBUTES access.
-            // CreatePipe() includes this access for the write handle.
-            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;
-            }
-        }
-    }
-
 #endif
     if (count > _PY_WRITE_MAX) {
         count = _PY_WRITE_MAX;
@@ -1878,13 +1823,18 @@ _Py_write_impl(int fd, const void *buf, size_t count, int gil_held)
             Py_BEGIN_ALLOW_THREADS
             errno = 0;
 #ifdef MS_WINDOWS
-            _doserrno = 0;
-            n = write(fd, buf, (int)count);
             // write() on a non-blocking pipe fails with ENOSPC on Windows if
             // the pipe lacks available space for the entire buffer.
-            if (n < 0 && errno == ENOSPC && _doserrno == 0) {
+            int c = (int)count;
+            do {
+                _doserrno = 0;
+                n = write(fd, buf, c);
+                if (n >= 0 || errno != ENOSPC || _doserrno != 0) {
+                    break;
+                }
                 errno = EAGAIN;
-            }
+                c /= 2;
+            } while (c > 0);
 #else
             n = write(fd, buf, count);
 #endif
@@ -1899,13 +1849,18 @@ _Py_write_impl(int fd, const void *buf, size_t count, int gil_held)
         do {
             errno = 0;
 #ifdef MS_WINDOWS
-            _doserrno = 0;
-            n = write(fd, buf, (int)count);
             // write() on a non-blocking pipe fails with ENOSPC on Windows if
             // the pipe lacks available space for the entire buffer.
-            if (n < 0 && errno == ENOSPC && _doserrno == 0) {
+            int c = (int)count;
+            do {
+                _doserrno = 0;
+                n = write(fd, buf, c);
+                if (n >= 0 || errno != ENOSPC || _doserrno != 0) {
+                    break;
+                }
                 errno = EAGAIN;
-            }
+                c /= 2;
+            } while (c > 0);
 #else
             n = write(fd, buf, count);
 #endif
