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Lock around reading as well as connecting & disconnecting so we don't start reading after 

someone has set our file descriptor to -1 and crash in FD_SET...
<rdar://problem/11653966>

llvm-svn: 160336
This commit is contained in:
Jim Ingham 2012-07-17 01:47:11 +00:00
parent b21dd02e61
commit ab728678ee
2 changed files with 81 additions and 37 deletions
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8
lldb/include/lldb/Core/ConnectionFileDescriptor.h
View File

@ -112,9 +112,11 @@ protected:
SocketAddress m_udp_send_sockaddr;
bool m_should_close_fd; // True if this class should close the file descriptor when it goes away.
uint32_t m_socket_timeout_usec;
int m_command_fd_send; // A pipe that we select on the reading end of along with
int m_command_fd_receive; // m_fd_recv so we can force ourselves out of the select.
Mutex m_mutex;
int m_command_fd_send; // A pipe that we select on the reading end of along with
int m_command_fd_receive; // m_fd_recv so we can force ourselves out of the select.
Mutex m_mutex;
bool m_shutting_down; // This marks that we are shutting down so if we get woken up from BytesAvailable
// to disconnect, we won't try to read again.
static in_port_t
GetSocketPort (int fd);

110
lldb/source/Core/ConnectionFileDescriptor.cpp
View File

@ -77,7 +77,8 @@ ConnectionFileDescriptor::ConnectionFileDescriptor () :
m_socket_timeout_usec(0),
m_command_fd_send(-1),
m_command_fd_receive(-1),
m_mutex (Mutex::eMutexTypeRecursive)
m_mutex (Mutex::eMutexTypeRecursive),
m_shutting_down (false)
{
LogSP log(lldb_private::GetLogIfAnyCategoriesSet (LIBLLDB_LOG_CONNECTION | LIBLLDB_LOG_OBJECT));
if (log)
@ -95,7 +96,8 @@ ConnectionFileDescriptor::ConnectionFileDescriptor (int fd, bool owns_fd) :
m_socket_timeout_usec(0),
m_command_fd_send(-1),
m_command_fd_receive(-1),
m_mutex (Mutex::eMutexTypeRecursive)
m_mutex (Mutex::eMutexTypeRecursive),
m_shutting_down (false)
{
LogSP log(lldb_private::GetLogIfAnyCategoriesSet (LIBLLDB_LOG_CONNECTION | LIBLLDB_LOG_OBJECT));
if (log)
@ -282,50 +284,72 @@ ConnectionFileDescriptor::Connect (const char *s, Error *error_ptr)
ConnectionStatus
ConnectionFileDescriptor::Disconnect (Error *error_ptr)
{
Mutex::Locker locker (m_mutex);
LogSP log(lldb_private::GetLogIfAnyCategoriesSet (LIBLLDB_LOG_CONNECTION));
if (log)
log->Printf ("%p ConnectionFileDescriptor::Disconnect ()", this);
ConnectionStatus status = eConnectionStatusSuccess;
if (m_fd_send >= 0 || m_fd_recv >= 0)
if (m_fd_send < 0 && m_fd_recv < 0)
{
if (log)
log->Printf ("%p ConnectionFileDescriptor::Disconnect(): Nothing to disconnect", this);
return eConnectionStatusSuccess;
}
// Try to get the ConnectionFileDescriptor's mutex. If we fail, that is quite likely
// because somebody is doing a blocking read on our file descriptor. If that's the case,
// then send the "q" char to the command file channel so the read will wake up and the connection
// will then know to shut down.
m_shutting_down = true;
Mutex::Locker locker;
bool got_lock= locker.TryLock (m_mutex);
if (!got_lock)
{
if (m_should_close_fd == false)
{
m_fd_send = m_fd_recv = -1;
}
else
{
if (m_fd_send == m_fd_recv)
{
// Both file descriptors are the same, only close one
m_fd_recv = -1;
status = Close (m_fd_send, error_ptr);
}
else
{
// File descriptors are the different, close both if needed
if (m_fd_send >= 0)
status = Close (m_fd_send, error_ptr);
if (m_fd_recv >= 0)
{
ConnectionStatus recv_status = Close (m_fd_recv, error_ptr);
if (status == eConnectionStatusSuccess)
status = recv_status;
}
}
}
// Now write a byte to the command pipe to wake our Reader if it is stuck in read.
if (m_command_fd_send != -1 )
{
write (m_command_fd_send, "q", 1);
close (m_command_fd_send);
m_command_fd_send = -1;
}
locker.Lock (m_mutex);
}
return status;
if (m_should_close_fd == true)
{
if (m_fd_send == m_fd_recv)
{
status = Close (m_fd_send, error_ptr);
}
else
{
// File descriptors are the different, close both if needed
if (m_fd_send >= 0)
status = Close (m_fd_send, error_ptr);
if (m_fd_recv >= 0)
{
ConnectionStatus recv_status = Close (m_fd_recv, error_ptr);
if (status == eConnectionStatusSuccess)
status = recv_status;
}
}
}
// Now set all our descriptors to invalid values.
m_fd_send = m_fd_recv = -1;
if (status != eConnectionStatusSuccess)
{
return status;
}
m_shutting_down = false;
return eConnectionStatusSuccess;
}
size_t
@ -340,6 +364,22 @@ ConnectionFileDescriptor::Read (void *dst,
log->Printf ("%p ConnectionFileDescriptor::Read () ::read (fd = %i, dst = %p, dst_len = %zu)...",
this, m_fd_recv, dst, dst_len);
Mutex::Locker locker;
bool got_lock = locker.TryLock (m_mutex);
if (!got_lock)
{
if (log)
log->Printf ("%p ConnectionFileDescriptor::Read () failed to get the connection lock.",
this);
if (error_ptr)
error_ptr->SetErrorString ("failed to get the connection lock for read.");
status = eConnectionStatusTimedOut;
return 0;
}
else if (m_shutting_down)
return eConnectionStatusError;
ssize_t bytes_read = 0;
status = BytesAvailable (timeout_usec, error_ptr);
@ -542,7 +582,6 @@ ConnectionFileDescriptor::Write (const void *src, size_t src_len, ConnectionStat
break; // Break to close....
}
//Disconnect (NULL);
return 0;
}
@ -553,6 +592,9 @@ ConnectionFileDescriptor::Write (const void *src, size_t src_len, ConnectionStat
ConnectionStatus
ConnectionFileDescriptor::BytesAvailable (uint32_t timeout_usec, Error *error_ptr)
{
// Don't need to take the mutex here separately since we are only called from Read. If we
// ever get used more generally we will need to lock here as well.
LogSP log(lldb_private::GetLogIfAnyCategoriesSet (LIBLLDB_LOG_CONNECTION));
if (log)
log->Printf("%p ConnectionFileDescriptor::BytesAvailable (timeout_usec = %u)", this, timeout_usec);
@ -641,7 +683,7 @@ ConnectionFileDescriptor::BytesAvailable (uint32_t timeout_usec, Error *error_pt
if (log)
log->Printf("%p ConnectionFileDescriptor::BytesAvailable() got data: %*s from the command channel.",
this, (int) bytes_read, buffer);
return eConnectionStatusEndOfFile;
}
else