bes  Updated for version 3.20.5
BESStreamResponseHandler.cc
1 // BESStreamResponseHandler.cc
2 
3 // This file is part of bes, A C++ back-end server implementation framework
4 // for the OPeNDAP Data Access Protocol.
5 
6 // Copyright (c) 2004-2009 University Corporation for Atmospheric Research
7 // Author: Patrick West <pwest@ucar.edu> and Jose Garcia <jgarcia@ucar.edu>
8 //
9 // This library is free software; you can redistribute it and/or
10 // modify it under the terms of the GNU Lesser General Public
11 // License as published by the Free Software Foundatiion; either
12 // version 2.1 of the License, or (at your option) any later version.
13 //
14 // This library is distributed in the hope that it will be useful,
15 // but WITHOUT ANY WARRANTY; without even the implied warranty of
16 // MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
17 // Lesser General Public License for more details.
18 //
19 // You should have received a copy of the GNU Lesser General Public
20 // License along with this library; if not, write to the Free Software
21 // Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
22 //
23 // You can contact University Corporation for Atmospheric Research at
24 // 3080 Center Green Drive, Boulder, CO 80301
25 
26 // (c) COPYRIGHT University Corporation for Atmospheric Research 2004-2005
27 // Please read the full copyright statement in the file COPYRIGHT_UCAR.
28 //
29 // Authors:
30 // pwest Patrick West <pwest@ucar.edu>
31 // jgarcia Jose Garcia <jgarcia@ucar.edu>
32 
33 #include <unistd.h>
34 
35 #include <cerrno>
36 #include <iostream>
37 #include <fstream>
38 #include <string>
39 #include <cstring>
40 
41 using std::ifstream;
42 using std::ios;
43 using std::endl;
44 using std::string;
45 
46 #include "BESStreamResponseHandler.h"
47 #include "BESRequestHandlerList.h"
48 #include "BESForbiddenError.h"
49 #include "BESNotFoundError.h"
50 #include "BESInternalError.h"
51 #include "BESDataNames.h"
52 #include "BESContainer.h"
53 #include "BESDataHandlerInterface.h"
54 
55 #define BES_STREAM_BUFFER_SIZE 4096
56 
57 BESStreamResponseHandler::BESStreamResponseHandler(const string &name) :
58  BESResponseHandler(name)
59 {
60 }
61 
62 BESStreamResponseHandler::~BESStreamResponseHandler()
63 {
64 }
65 
66 extern volatile int bes_timeout; // defined in BESInterface. jhrg 1/24/17
67 
79 {
80  d_response_object = 0;
81 
82  // Hack. We put this here because the bes timeout period should not
83  // include the time it takes to send data for a file transfer response.
84  //
85  // An alternative would be to implement a BESTransmitter for the "get stream"
86  // operation and have that run from the call to BESInterface::transmist_data().
87  // pcw talks about that below.
88  // jhrg 1/24/17
89  if (bes_timeout != 0) {
90  bes_timeout = 0;
91  alarm(bes_timeout);
92  }
93 
94  // What if there is a special way to stream back a data file?
95  // Should we pass this off to the request handlers and put
96  // this code into a different class for reuse? For now
97  // just keep it here. pcw 10/11/06
98 
99  // I thought about putting this in the transmit method below
100  // but decided that this is like executing a non-buffered
101  // request, so kept it here. Plus the idea expressed above
102  // led me to leave the code in the execute method.
103  // pcw 10/11/06
104  if (dhi.containers.size() != 1) {
105  string err = (string) "Unable to stream file: " + "no container specified";
106  throw BESInternalError(err, __FILE__, __LINE__);
107  }
108 
109  dhi.first_container();
110  BESContainer *container = dhi.container;
111  string filename = container->access();
112  if (filename.empty()) {
113  string err = (string) "Unable to stream file: " + "filename not specified";
114  throw BESInternalError(err, __FILE__, __LINE__);
115  }
116 
117  int bytes = 0;
118  ifstream os;
119  os.open(filename.c_str(), ios::in);
120  int myerrno = errno;
121  if (!os) {
122  string serr = (string) "Unable to stream file because it cannot be opened. file: '" + filename + "' msg: ";
123  char *err = strerror(myerrno);
124  if (err)
125  serr += err;
126  else
127  serr += "Unknown error";
128 
129  // ENOENT means that the node wasn't found.
130  // On some systems a file that doesn't exist returns ENOTDIR because: w.f.t?
131  // Otherwise, access is being denied for some other reason
132  if (myerrno == ENOENT || myerrno == ENOTDIR) {
133  // On some systems a file that doesn't exist returns ENOTDIR because: w.f.t?
134  throw BESNotFoundError(serr, __FILE__, __LINE__);
135  }
136  // Not a 404? Then we'll go with the forbidden fruit theory...
137  throw BESForbiddenError(serr, __FILE__, __LINE__);
138  }
139 
140  int nbytes;
141  char block[BES_STREAM_BUFFER_SIZE];
142  os.read(block, sizeof block);
143  nbytes = os.gcount();
144  while (nbytes) {
145  bytes += nbytes;
146  dhi.get_output_stream().write((char*) block, nbytes);
147 
148  os.read(block, sizeof block);
149  nbytes = os.gcount();
150  }
151 
152  os.close();
153 }
154 
163 {
164  // The Data is transmitted when it is read, dumped to stdout, so there is nothing
165  // to transmit here.
166 }
167 
174 void BESStreamResponseHandler::dump(ostream &strm) const
175 {
176  strm << BESIndent::LMarg << "BESStreamResponseHandler::dump - (" << (void *) this << ")" << endl;
177  BESIndent::Indent();
179  BESIndent::UnIndent();
180 }
181 
183 BESStreamResponseHandler::BESStreamResponseBuilder(const string &name)
184 {
185  return new BESStreamResponseHandler(name);
186 }
187 
BESDataHandlerInterface::container
BESContainer * container
pointer to current container in this interface
Definition: BESDataHandlerInterface.h:79
BESNotFoundError
error thrown if the resource requested cannot be found
Definition: BESNotFoundError.h:40
BESContainer::access
virtual string access()=0
returns the true name of this container
BESStreamResponseHandler::dump
virtual void dump(ostream &strm) const
dumps information about this object
Definition: BESStreamResponseHandler.cc:174
BESResponseHandler::dump
virtual void dump(std::ostream &strm) const
dumps information about this object
Definition: BESResponseHandler.cc:98
BESStreamResponseHandler::transmit
virtual void transmit(BESTransmitter *transmitter, BESDataHandlerInterface &r)
transmit the file, streaming it back to the client
Definition: BESStreamResponseHandler.cc:162
BESStreamResponseHandler::execute
virtual void execute(BESDataHandlerInterface &r)
executes the command 'get file <filename>;' by streaming the specified file
Definition: BESStreamResponseHandler.cc:78
BESForbiddenError
error thrown if the BES is not allowed to access the resource requested
Definition: BESForbiddenError.h:40
BESInternalError
exception thrown if inernal error encountered
Definition: BESInternalError.h:43
BESResponseHandler
handler object that knows how to create a specific response object
Definition: BESResponseHandler.h:77
BESTransmitter
Definition: BESTransmitter.h:47
BESContainer
A container is something that holds data. E.G., a netcdf file or a database entry.
Definition: BESContainer.h:68
BESDataHandlerInterface::first_container
void first_container()
set the container pointer to the first container in the containers list
Definition: BESDataHandlerInterface.h:139
BESStreamResponseHandler
Definition: BESStreamResponseHandler.h:38
BESDataHandlerInterface
Structure storing information used by the BES to handle the request.
Definition: BESDataHandlerInterface.h:60