[libc] Implement fopen, fclose, and fread on the GPU

This patch implements the `fopen`, `fclose`, and `fread` functions on
the GPU. These are pretty much re-implemented from what existed but
using the new interface. Having this subset allows us to test the
interface a bit more strenuously since we can write and read to a file.

Reviewed By: sivachandra

Differential Revision: https://reviews.llvm.org/D157622

1 files changed, 32 insertions, 0 deletions

diff --git a/libc/src/stdio/gpu/fopen.cpp b/libc/src/stdio/gpu/fopen.cpp
new file mode 100644
index 0000000..5d88b65
--- /dev/null
+++ b/libc/src/stdio/gpu/fopen.cpp
@@ -0,0 +1,32 @@
+//===-- GPU Implementation of fopen ---------------------------------------===//
+//
+// 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
+//
+//===----------------------------------------------------------------------===//
+
+#include "src/stdio/fopen.h"
+#include "src/__support/CPP/string_view.h"
+#include "src/stdio/gpu/file.h"
+
+#include <stdio.h>
+
+namespace __llvm_libc {
+
+LLVM_LIBC_FUNCTION(::FILE *, fopen,
+                   (const char *__restrict path, const char *__restrict mode)) {
+  uintptr_t file;
+  rpc::Client::Port port = rpc::client.open<RPC_OPEN_FILE>();
+  port.send_n(path, internal::string_length(path) + 1);
+  port.send_and_recv(
+      [=](rpc::Buffer *buffer) {
+        inline_memcpy(buffer->data, mode, internal::string_length(mode) + 1);
+      },
+      [&](rpc::Buffer *buffer) { file = buffer->data[0]; });
+  port.close();
+
+  return reinterpret_cast<FILE *>(file);
+}
+
+} // namespace __llvm_libc