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      1 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
      2 // Use of this source code is governed by a BSD-style license that can be
      3 // found in the LICENSE file.
      4 
      5 #include "base/sync_socket.h"
      6 
      7 #include <errno.h>
      8 #include <fcntl.h>
      9 #include <limits.h>
     10 #include <stddef.h>
     11 #include <stdio.h>
     12 #include <sys/ioctl.h>
     13 #include <sys/socket.h>
     14 #include <sys/types.h>
     15 
     16 #if defined(OS_SOLARIS)
     17 #include <sys/filio.h>
     18 #endif
     19 
     20 #include "base/files/file_util.h"
     21 #include "base/logging.h"
     22 #include "base/threading/thread_restrictions.h"
     23 #include "build/build_config.h"
     24 
     25 namespace base {
     26 
     27 namespace {
     28 // To avoid users sending negative message lengths to Send/Receive
     29 // we clamp message lengths, which are size_t, to no more than INT_MAX.
     30 const size_t kMaxMessageLength = static_cast<size_t>(INT_MAX);
     31 
     32 // Writes |length| of |buffer| into |handle|.  Returns the number of bytes
     33 // written or zero on error.  |length| must be greater than 0.
     34 size_t SendHelper(SyncSocket::Handle handle,
     35                   const void* buffer,
     36                   size_t length) {
     37   DCHECK_GT(length, 0u);
     38   DCHECK_LE(length, kMaxMessageLength);
     39   DCHECK_NE(handle, SyncSocket::kInvalidHandle);
     40   const char* charbuffer = static_cast<const char*>(buffer);
     41   return WriteFileDescriptor(handle, charbuffer, length)
     42              ? static_cast<size_t>(length)
     43              : 0;
     44 }
     45 
     46 bool CloseHandle(SyncSocket::Handle handle) {
     47   if (handle != SyncSocket::kInvalidHandle && close(handle) < 0) {
     48     DPLOG(ERROR) << "close";
     49     return false;
     50   }
     51 
     52   return true;
     53 }
     54 
     55 }  // namespace
     56 
     57 const SyncSocket::Handle SyncSocket::kInvalidHandle = -1;
     58 
     59 SyncSocket::SyncSocket() : handle_(kInvalidHandle) {}
     60 
     61 SyncSocket::~SyncSocket() {
     62   Close();
     63 }
     64 
     65 // static
     66 bool SyncSocket::CreatePair(SyncSocket* socket_a, SyncSocket* socket_b) {
     67   DCHECK_NE(socket_a, socket_b);
     68   DCHECK_EQ(socket_a->handle_, kInvalidHandle);
     69   DCHECK_EQ(socket_b->handle_, kInvalidHandle);
     70 
     71 #if defined(OS_MACOSX)
     72   int nosigpipe = 1;
     73 #endif  // defined(OS_MACOSX)
     74 
     75   Handle handles[2] = { kInvalidHandle, kInvalidHandle };
     76   if (socketpair(AF_UNIX, SOCK_STREAM, 0, handles) != 0) {
     77     CloseHandle(handles[0]);
     78     CloseHandle(handles[1]);
     79     return false;
     80   }
     81 
     82 #if defined(OS_MACOSX)
     83   // On OSX an attempt to read or write to a closed socket may generate a
     84   // SIGPIPE rather than returning -1.  setsockopt will shut this off.
     85   if (0 != setsockopt(handles[0], SOL_SOCKET, SO_NOSIGPIPE,
     86                       &nosigpipe, sizeof nosigpipe) ||
     87       0 != setsockopt(handles[1], SOL_SOCKET, SO_NOSIGPIPE,
     88                       &nosigpipe, sizeof nosigpipe)) {
     89     CloseHandle(handles[0]);
     90     CloseHandle(handles[1]);
     91     return false;
     92   }
     93 #endif
     94 
     95   // Copy the handles out for successful return.
     96   socket_a->handle_ = handles[0];
     97   socket_b->handle_ = handles[1];
     98 
     99   return true;
    100 }
    101 
    102 // static
    103 SyncSocket::Handle SyncSocket::UnwrapHandle(
    104     const TransitDescriptor& descriptor) {
    105   return descriptor.fd;
    106 }
    107 
    108 bool SyncSocket::PrepareTransitDescriptor(
    109     ProcessHandle /* peer_process_handle */,
    110     TransitDescriptor* descriptor) {
    111   descriptor->fd = handle();
    112   descriptor->auto_close = false;
    113   return descriptor->fd != kInvalidHandle;
    114 }
    115 
    116 bool SyncSocket::Close() {
    117   const bool retval = CloseHandle(handle_);
    118   handle_ = kInvalidHandle;
    119   return retval;
    120 }
    121 
    122 size_t SyncSocket::Send(const void* buffer, size_t length) {
    123   ThreadRestrictions::AssertIOAllowed();
    124   return SendHelper(handle_, buffer, length);
    125 }
    126 
    127 size_t SyncSocket::Receive(void* buffer, size_t length) {
    128   ThreadRestrictions::AssertIOAllowed();
    129   DCHECK_GT(length, 0u);
    130   DCHECK_LE(length, kMaxMessageLength);
    131   DCHECK_NE(handle_, kInvalidHandle);
    132   char* charbuffer = static_cast<char*>(buffer);
    133   if (ReadFromFD(handle_, charbuffer, length))
    134     return length;
    135   return 0;
    136 }
    137 
    138 size_t SyncSocket::ReceiveWithTimeout(void* buffer,
    139                                       size_t length,
    140                                       TimeDelta timeout) {
    141   ThreadRestrictions::AssertIOAllowed();
    142   DCHECK_GT(length, 0u);
    143   DCHECK_LE(length, kMaxMessageLength);
    144   DCHECK_NE(handle_, kInvalidHandle);
    145 
    146   // TODO(dalecurtis): There's an undiagnosed issue on OSX where we're seeing
    147   // large numbers of open files which prevents select() from being used.  In
    148   // this case, the best we can do is Peek() to see if we can Receive() now or
    149   // return a timeout error (0) if not.  See http://crbug.com/314364.
    150   if (handle_ >= FD_SETSIZE)
    151     return Peek() < length ? 0 : Receive(buffer, length);
    152 
    153   // Only timeouts greater than zero and less than one second are allowed.
    154   DCHECK_GT(timeout.InMicroseconds(), 0);
    155   DCHECK_LT(timeout.InMicroseconds(),
    156             base::TimeDelta::FromSeconds(1).InMicroseconds());
    157 
    158   // Track the start time so we can reduce the timeout as data is read.
    159   TimeTicks start_time = TimeTicks::Now();
    160   const TimeTicks finish_time = start_time + timeout;
    161 
    162   fd_set read_fds;
    163   size_t bytes_read_total;
    164   for (bytes_read_total = 0;
    165        bytes_read_total < length && timeout.InMicroseconds() > 0;
    166        timeout = finish_time - base::TimeTicks::Now()) {
    167     FD_ZERO(&read_fds);
    168     FD_SET(handle_, &read_fds);
    169 
    170     // Wait for data to become available.
    171     struct timeval timeout_struct =
    172         { 0, static_cast<suseconds_t>(timeout.InMicroseconds()) };
    173     const int select_result =
    174         select(handle_ + 1, &read_fds, NULL, NULL, &timeout_struct);
    175     // Handle EINTR manually since we need to update the timeout value.
    176     if (select_result == -1 && errno == EINTR)
    177       continue;
    178     if (select_result <= 0)
    179       return bytes_read_total;
    180 
    181     // select() only tells us that data is ready for reading, not how much.  We
    182     // must Peek() for the amount ready for reading to avoid blocking.
    183     DCHECK(FD_ISSET(handle_, &read_fds));
    184     const size_t bytes_to_read = std::min(Peek(), length - bytes_read_total);
    185 
    186     // There may be zero bytes to read if the socket at the other end closed.
    187     if (!bytes_to_read)
    188       return bytes_read_total;
    189 
    190     const size_t bytes_received =
    191         Receive(static_cast<char*>(buffer) + bytes_read_total, bytes_to_read);
    192     bytes_read_total += bytes_received;
    193     if (bytes_received != bytes_to_read)
    194       return bytes_read_total;
    195   }
    196 
    197   return bytes_read_total;
    198 }
    199 
    200 size_t SyncSocket::Peek() {
    201   DCHECK_NE(handle_, kInvalidHandle);
    202   int number_chars = 0;
    203   if (ioctl(handle_, FIONREAD, &number_chars) == -1) {
    204     // If there is an error in ioctl, signal that the channel would block.
    205     return 0;
    206   }
    207   DCHECK_GE(number_chars, 0);
    208   return number_chars;
    209 }
    210 
    211 CancelableSyncSocket::CancelableSyncSocket() {}
    212 CancelableSyncSocket::CancelableSyncSocket(Handle handle)
    213     : SyncSocket(handle) {
    214 }
    215 
    216 bool CancelableSyncSocket::Shutdown() {
    217   DCHECK_NE(handle_, kInvalidHandle);
    218   return HANDLE_EINTR(shutdown(handle_, SHUT_RDWR)) >= 0;
    219 }
    220 
    221 size_t CancelableSyncSocket::Send(const void* buffer, size_t length) {
    222   DCHECK_GT(length, 0u);
    223   DCHECK_LE(length, kMaxMessageLength);
    224   DCHECK_NE(handle_, kInvalidHandle);
    225 
    226   const long flags = fcntl(handle_, F_GETFL, NULL);
    227   if (flags != -1 && (flags & O_NONBLOCK) == 0) {
    228     // Set the socket to non-blocking mode for sending if its original mode
    229     // is blocking.
    230     fcntl(handle_, F_SETFL, flags | O_NONBLOCK);
    231   }
    232 
    233   const size_t len = SendHelper(handle_, buffer, length);
    234 
    235   if (flags != -1 && (flags & O_NONBLOCK) == 0) {
    236     // Restore the original flags.
    237     fcntl(handle_, F_SETFL, flags);
    238   }
    239 
    240   return len;
    241 }
    242 
    243 // static
    244 bool CancelableSyncSocket::CreatePair(CancelableSyncSocket* socket_a,
    245                                       CancelableSyncSocket* socket_b) {
    246   return SyncSocket::CreatePair(socket_a, socket_b);
    247 }
    248 
    249 }  // namespace base
    250