xapian-core/common/safesyssocket.h

   1 /** @file
   2  * @brief #include <sys/socket.h> with portability workarounds.
   3  */
   4 /* Copyright (C) 2012,2013,2014,2018,2019 Olly Betts
   5  *
   6  * This program is free software; you can redistribute it and/or
   7  * modify it under the terms of the GNU General Public License as
   8  * published by the Free Software Foundation; either version 2 of the
   9  * License, or (at your option) any later version.
  10  *
  11  * This program is distributed in the hope that it will be useful,
  12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14  * GNU General Public License for more details.
  15  *
  16  * You should have received a copy of the GNU General Public License
  17  * along with this program; if not, write to the Free Software
  18  * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301 USA
  19  */
  20
  21 #ifndef XAPIAN_INCLUDED_SAFESYSSOCKET_H
  22 #define XAPIAN_INCLUDED_SAFESYSSOCKET_H
  23
  24 #ifndef __WIN32__
  25 // Some older BSDs require sys/types.h to be included first.
  26 # include <sys/types.h>
  27 # include <sys/socket.h>
  28 #else
  29 # include "safewinsock2.h"
  30 #endif
  31
  32 #ifdef __WIN32__
  33 # include <type_traits>
  34 # include "xapian/error.h"
  35 # if defined SOCK_CLOEXEC
  36 static_assert(!SOCK_CLOEXEC, "__WIN32__ doesn't support SOCK_CLOEXEC");
  37 # endif
  38 # define SOCK_CLOEXEC 0
  39
  40 static_assert(std::is_unsigned<SOCKET>::value, "SOCKET is unsigned");
  41
  42 inline int socket_(int domain, int type, int protocol) {
  43     // Winsock2's socket() returns the unsigned type SOCKET, which is a 32-bit
  44     // type for WIN32 and a 64-bit type for WIN64.
  45     //
  46     // It seems we can always safely assign SOCKET to an int: failure is indicated
  47     // by INVALID_SOCKET which will cast to -1 as an int, and it seems in
  48     // practice that valid values all fit in 31-bits (and that we're not the
  49     // only code to assume this since it makes it much easier to write code
  50     // that deals with BSD sockets and winsock2's bastardised version of them)
  51     // so Microsoft are unlikely to arbitrarily change that).
  52     //
  53     // But we should check and throw an exception rather than quietly mangling
  54     // the value.
  55     SOCKET sock = socket(domain, type, protocol);
  56     if (rare(sock > SOCKET(0x7fffffff) && sock != INVALID_SOCKET)) {
  57         throw Xapian::NetworkError("socket() returned value > INT_MAX");
  58     }
  59     return int(sock);
  60 }
  61
  62 # ifdef socket
  63 #  undef socket
  64 # endif
  65 # define socket(D,T,P) socket_(D,T,P)
  66
  67 #elif !defined SOCK_CLOEXEC
  68 # define SOCK_CLOEXEC 0
  69 #else
  70 // On Linux at least, sometimes SOCK_CLOEXEC is defined but the kernel doesn't
  71 // handle it in socket() or socketpair():
  72
  73 # include <cerrno>
  74
  75 inline int socket_(int domain, int type, int protocol) {
  76     // Usually type is passed a constant, so we'll collapse to one branch or
  77     // the other here.  The case where SOCK_CLOEXEC == 0 is handled suitably.
  78     if (type & SOCK_CLOEXEC) {
  79         int save_errno = errno;
  80         int r = socket(domain, type, protocol);
  81         if (r < 0 && errno == EINVAL) {
  82             errno = save_errno;
  83             r = socket(domain, type &~ SOCK_CLOEXEC, protocol);
  84         }
  85         return r;
  86     } else {
  87         return socket(domain, type, protocol);
  88     }
  89 }
  90
  91 inline int socketpair_(int domain, int type, int protocol, int *sv) {
  92     // Usually type is passed a constant, so we'll collapse to one branch or
  93     // the other here.  The case where SOCK_CLOEXEC == 0 is handled suitably.
  94     if (type & SOCK_CLOEXEC) {
  95         int save_errno = errno;
  96         int r = socketpair(domain, type, protocol, sv);
  97         if (r != 0 && errno == EINVAL) {
  98             errno = save_errno;
  99             r = socketpair(domain, type &~ SOCK_CLOEXEC, protocol, sv);
 100         }
 101         return r;
 102     } else {
 103         return socketpair(domain, type, protocol, sv);
 104     }
 105 }
 106
 107 # ifdef socket
 108 #  undef socket
 109 # endif
 110 # define socket(D,T,P) socket_(D,T,P)
 111 # ifdef socketpair
 112 #  undef socketpair
 113 # endif
 114 # define socketpair(D,T,P,S) socketpair_(D,T,P,S)
 115 #endif
 116
 117 #endif // XAPIAN_INCLUDED_SAFESYSSOCKET_H