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 inline int accept_(int sockfd, struct sockaddr* addr, SOCKLEN_T* addrlen) {
  68     // Winsock2's accept() returns the unsigned type SOCKET, which is a 32-bit
  69     // type for WIN32 and a 64-bit type for WIN64.
  70     //
  71     // It seems we can always safely assign SOCKET to an int: failure is indicated
  72     // by INVALID_SOCKET which will cast to -1 as an int, and it seems in
  73     // practice that valid values all fit in 31-bits (and that we're not the
  74     // only code to assume this since it makes it much easier to write code
  75     // that deals with BSD sockets and winsock2's bastardised version of them)
  76     // so Microsoft are unlikely to arbitrarily change that).
  77     //
  78     // But we should check and throw an exception rather than quietly mangling
  79     // the value.
  80     SOCKET sock = accept(sockfd, addr, addrlen);
  81     if (rare(sock > SOCKET(0x7fffffff) && sock != INVALID_SOCKET)) {
  82         throw Xapian::NetworkError("accept() returned value > INT_MAX");
  83     }
  84     return int(sock);
  85 }
  86
  87 # ifdef accept
  88 #  undef accept
  89 # endif
  90 # define accept(S,A,L) accept_(S,A,L)
  91
  92 #elif !defined SOCK_CLOEXEC
  93 # define SOCK_CLOEXEC 0
  94 #else
  95 // On Linux at least, sometimes SOCK_CLOEXEC is defined but the kernel doesn't
  96 // handle it in socket() or socketpair():
  97
  98 # include <cerrno>
  99
 100 inline int socket_(int domain, int type, int protocol) {
 101     // Usually type is passed a constant, so we'll collapse to one branch or
 102     // the other here.  The case where SOCK_CLOEXEC == 0 is handled suitably.
 103     if (type & SOCK_CLOEXEC) {
 104         int save_errno = errno;
 105         int r = socket(domain, type, protocol);
 106         if (r < 0 && errno == EINVAL) {
 107             errno = save_errno;
 108             r = socket(domain, type &~ SOCK_CLOEXEC, protocol);
 109         }
 110         return r;
 111     } else {
 112         return socket(domain, type, protocol);
 113     }
 114 }
 115
 116 inline int socketpair_(int domain, int type, int protocol, int *sv) {
 117     // Usually type is passed a constant, so we'll collapse to one branch or
 118     // the other here.  The case where SOCK_CLOEXEC == 0 is handled suitably.
 119     if (type & SOCK_CLOEXEC) {
 120         int save_errno = errno;
 121         int r = socketpair(domain, type, protocol, sv);
 122         if (r != 0 && errno == EINVAL) {
 123             errno = save_errno;
 124             r = socketpair(domain, type &~ SOCK_CLOEXEC, protocol, sv);
 125         }
 126         return r;
 127     } else {
 128         return socketpair(domain, type, protocol, sv);
 129     }
 130 }
 131
 132 # ifdef socket
 133 #  undef socket
 134 # endif
 135 # define socket(D,T,P) socket_(D,T,P)
 136 # ifdef socketpair
 137 #  undef socketpair
 138 # endif
 139 # define socketpair(D,T,P,S) socketpair_(D,T,P,S)
 140 #endif
 141
 142 #endif // XAPIAN_INCLUDED_SAFESYSSOCKET_H