chore: import upstream snapshot with attribution

src/butil/fd_utility.cpp

@@ -0,0 +1,111 @@
+// Licensed to the Apache Software Foundation (ASF) under one
+// or more contributor license agreements.  See the NOTICE file
+// distributed with this work for additional information
+// regarding copyright ownership.  The ASF licenses this file
+// to you under the Apache License, Version 2.0 (the
+// "License"); you may not use this file except in compliance
+// with the License.  You may obtain a copy of the License at
+//
+//   http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing,
+// software distributed under the License is distributed on an
+// "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+// KIND, either express or implied.  See the License for the
+// specific language governing permissions and limitations
+// under the License.
+
+// Date: Mon. Nov 7 14:47:36 CST 2011
+
+#include "butil/build_config.h"
+#include <fcntl.h>                   // fcntl()
+#include <netinet/in.h>              // IPPROTO_TCP
+#include <sys/types.h>
+#include <sys/socket.h>              // setsockopt
+#include <netinet/tcp.h>             // TCP_NODELAY
+#include <netinet/tcp.h>
+#if defined(OS_MACOSX)
+#include <netinet/tcp_fsm.h>        // TCPS_ESTABLISHED, TCP6S_ESTABLISHED
+#endif
+#include "butil/logging.h"
+
+namespace butil {
+
+bool is_blocking(int fd) {
+    const int flags = fcntl(fd, F_GETFL, 0);
+    return flags >= 0 && !(flags & O_NONBLOCK);
+}
+
+int make_non_blocking(int fd) {
+    const int flags = fcntl(fd, F_GETFL, 0);
+    if (flags < 0) {
+        return flags;
+    }
+    if (flags & O_NONBLOCK) {
+        return 0;
+    }
+    return fcntl(fd, F_SETFL, flags | O_NONBLOCK);
+}
+
+int make_blocking(int fd) {
+    const int flags = fcntl(fd, F_GETFL, 0);
+    if (flags < 0) {
+        return flags;
+    }
+    if (flags & O_NONBLOCK) {
+        return fcntl(fd, F_SETFL, flags & ~O_NONBLOCK);
+    }
+    return 0;
+}
+
+int make_close_on_exec(int fd) {
+    return fcntl(fd, F_SETFD, FD_CLOEXEC);
+}
+
+int make_no_delay(int sockfd) {
+    int flag = 1;
+    return setsockopt(sockfd, IPPROTO_TCP, TCP_NODELAY, (char*)&flag, sizeof(flag));
+}
+
+int is_connected(int sockfd) {
+    errno = 0;
+    int err;
+    socklen_t errlen = sizeof(err);
+    if (getsockopt(sockfd, SOL_SOCKET, SO_ERROR, &err, &errlen) < 0) {
+        PLOG(FATAL) << "Fail to getsockopt";
+        return -1;
+    }
+    if (err != 0) {
+        errno = err;
+        return -1;
+    }
+
+#if defined(OS_LINUX)
+    struct tcp_info ti{};
+    socklen_t len = sizeof(ti);
+    if(getsockopt(sockfd, SOL_TCP, TCP_INFO, &ti, &len) < 0) {
+        PLOG(FATAL) << "Fail to getsockopt";
+        return -1;
+    }
+    if (ti.tcpi_state != TCP_ESTABLISHED) {
+        errno = ENOTCONN;
+        return -1;
+    }
+#elif defined(OS_MACOSX)
+    struct tcp_connection_info ti{};
+    socklen_t len = sizeof(ti);
+    if (getsockopt(sockfd, IPPROTO_TCP, TCP_CONNECTION_INFO, &ti, &len) < 0) {
+        PLOG(FATAL) << "Fail to getsockopt";
+        return -1;
+    }
+    if (ti.tcpi_state != TCPS_ESTABLISHED &&
+        ti.tcpi_state != TCP6S_ESTABLISHED) {
+        errno = ENOTCONN;
+        return -1;
+    }
+#endif
+
+    return 0;
+}
+
+}  // namespace butil