[libc-commits] [libc] [libc] Support _IONBF buffering for read_unlocked (PR #120677)

[Jack Huang via libc-commits]

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@@ -209,12 +220,22 @@ FileIOResult File::read_unlocked(void *data, size_t len) {
   for (size_t i = 0; i < available_data; ++i)
     dataref[i] = bufref[i + pos];
   read_limit = pos = 0; // Reset the pointers.
+
+  return available_data;
+}
+
+FileIOResult File::read_unlocked_fbf(uint8_t *data, size_t len) {
+  // Read data from the buffer first.
+  size_t available_data = copy_data_from_buf(data, len);
+  if (available_data == len)
+    return available_data;
+
   // Update the dataref to reflect that fact that we have already
   // copied |available_data| into |data|.
-  dataref = cpp::span<uint8_t>(dataref.data() + available_data,
-                               dataref.size() - available_data);
-
   size_t to_fetch = len - available_data;
+  cpp::span<uint8_t> dataref(static_cast<uint8_t *>(data) + available_data,
+                             to_fetch);
+
   if (to_fetch > bufsize) {
     auto result = platform_read(this, dataref.data(), to_fetch);
     size_t fetched_size = result.value;
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jackhong12 wrote:

Got it. I also change the line 286 from `result.has_error()` to `result.error`. I think it has the same problem.

https://github.com/llvm/llvm-project/pull/120677