[libc-commits] [clang] [libc] [libc] Support opaque FILE* on baremetal (PR #168931)

[via libc-commits]

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@@ -0,0 +1,69 @@
+//===-- Baremetal implementation header of vfprintf -------------*- C++ -*-===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_LIBC_SRC_STDIO_BAREMETAL_VFPRINTF_INTERNAL_H
+#define LLVM_LIBC_SRC_STDIO_BAREMETAL_VFPRINTF_INTERNAL_H
+
+#include "hdr/types/FILE.h"
+#include "src/__support/CPP/limits.h"
+#include "src/__support/CPP/string_view.h"
+#include "src/__support/OSUtil/io.h"
+#include "src/__support/arg_list.h"
+#include "src/__support/common.h"
+#include "src/__support/libc_errno.h"
+#include "src/__support/macros/config.h"
+#include "src/stdio/printf_core/core_structs.h"
+#include "src/stdio/printf_core/error_mapper.h"
+#include "src/stdio/printf_core/printf_main.h"
+#include "src/stdio/printf_core/writer.h"
+
+namespace LIBC_NAMESPACE_DECL {
+
+namespace internal {
+
+LIBC_INLINE int write_hook(cpp::string_view str_view, void *cookie) {
+  __llvm_libc_stdio_write(cookie, str_view.data(), str_view.size());
+  return printf_core::WRITE_OK;
+}
+
+} // namespace internal
+
+LIBC_INLINE int vfprintf_internal(::FILE *__restrict stream,
+                                  const char *__restrict format,
+                                  internal::ArgList &args) {
+  static constexpr size_t BUFF_SIZE = 1024;
+  char buffer[BUFF_SIZE];
+
+  printf_core::FlushingBuffer wb(buffer, BUFF_SIZE, &internal::write_hook,
+                                 stream);
+  printf_core::Writer writer(wb);
+
+  auto retval = printf_core::printf_main(&writer, format, args);
+  if (!retval.has_value()) {
+    libc_errno = printf_core::internal_error_to_errno(retval.error());
+    return -1;
+  }
+
+  int flushval = wb.flush_to_stream();
+  if (flushval != printf_core::WRITE_OK) {
+    libc_errno = printf_core::internal_error_to_errno(-flushval);
+    return -1;
+  }
+
+  if (retval.value() > static_cast<size_t>(cpp::numeric_limits<int>::max())) {
+    libc_errno =
+        printf_core::internal_error_to_errno(-printf_core::OVERFLOW_ERROR);
+    return -1;
+  }
+
+  return static_cast<int>(retval.value());
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PiJoules wrote:

Nit: since `retval.value()` is a size_t, do we want to check for overflow here?

https://github.com/llvm/llvm-project/pull/168931