xapian-core  1.4.19
safesyssocket.h
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1 
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
#define rare(COND)
Definition: config.h:543
#define SOCK_CLOEXEC
Definition: safesyssocket.h:68
Hierarchy of classes which Xapian can throw as exceptions.
include <winsock2.h> but working around problems.
Indicates a problem communicating with a remote database.
Definition: error.h:803