netstack: Refactor tcpip.Endpoint.Read

Read now takes a destination io.Writer, count, options. Keeping the method name
Read, in contrast to the Write method.

This enables:
* direct transfer of views under VV
* zero copy

It also eliminates the need for sentry to keep a slice of view because
userspace had requested a read that is smaller than the view returned, removing
the complexity there.

Read/Peek/ReadPacket are now consolidated together and some duplicate code is
removed.

PiperOrigin-RevId: 350636322

1 files changed, 9 insertions, 0 deletions

diff --git a/test/syscalls/linux/socket_generic.cc b/test/syscalls/linux/socket_generic.cc
index a28ee2233..de0b8bb11 100644
--- a/test/syscalls/linux/socket_generic.cc
+++ b/test/syscalls/linux/socket_generic.cc
@@ -43,6 +43,15 @@ TEST_P(AllSocketPairTest, BasicReadWrite) {
   EXPECT_EQ(data, absl::string_view(buf, 3));
 }
 
+TEST_P(AllSocketPairTest, BasicReadWriteBadBuffer) {
+  auto sockets = ASSERT_NO_ERRNO_AND_VALUE(NewSocketPair());
+  const std::string data = "abc";
+  ASSERT_THAT(WriteFd(sockets->first_fd(), data.c_str(), 3),
+              SyscallSucceedsWithValue(3));
+  ASSERT_THAT(ReadFd(sockets->second_fd(), nullptr, 3),
+              SyscallFailsWithErrno(EFAULT));
+}
+
 TEST_P(AllSocketPairTest, BasicSendRecv) {
   auto sockets = ASSERT_NO_ERRNO_AND_VALUE(NewSocketPair());
   char sent_data[512];