fd_array.cc revision 11856:103e2f92c965 
1/*
2 * Copyright (c) 2016 Advanced Micro Devices, Inc.
3 * All rights reserved.
4 *
5 * For use for simulation and test purposes only
6 *
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions are met:
9 *
10 * 1. Redistributions of source code must retain the above copyright notice,
11 * this list of conditions and the following disclaimer.
12 *
13 * 2. Redistributions in binary form must reproduce the above copyright notice,
14 * this list of conditions and the following disclaimer in the documentation
15 * and/or other materials provided with the distribution.
16 *
17 * 3. Neither the name of the copyright holder nor the names of its
18 * contributors may be used to endorse or promote products derived from this
19 * software without specific prior written permission.
20 *
21 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
22 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
23 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
24 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
25 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
26 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
27 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
28 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
29 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
30 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
31 * POSSIBILITY OF SUCH DAMAGE.
32 *
33 * Author: Brandon Potter
34 */
35
36#include "sim/fd_array.hh"
37
38#include <fcntl.h>
39#include <unistd.h>
40
41#include <array>
42#include <memory>
43#include <string>
44
45#include "base/misc.hh"
46#include "params/Process.hh"
47#include "sim/fd_entry.hh"
48
49FDArray::FDArray(std::string const& input, std::string const& output,
50                 std::string const& errout)
51    : _input(input), _output(output), _errout(errout), _fdArray(),
52      imap {{"",       -1},
53            {"cin",    STDIN_FILENO},
54            {"stdin",  STDIN_FILENO}},
55      oemap{{"",       -1},
56            {"cout",   STDOUT_FILENO},
57            {"stdout", STDOUT_FILENO},
58            {"cerr",   STDERR_FILENO},
59            {"stderr", STDERR_FILENO}}
60{
61    int sim_fd;
62    std::map<std::string, int>::iterator it;
63
64    /**
65     * Search through the input options and setup the default fd if match is
66     * found; otherwise, open an input file and seek to location.
67     */
68    if ((it = imap.find(input)) != imap.end())
69        sim_fd = it->second;
70    else
71        sim_fd = openInputFile(input);
72
73    auto ffd = std::make_shared<FileFDEntry>(sim_fd, O_RDONLY, input, false);
74    _fdArray[STDIN_FILENO] = ffd;
75
76    /**
77     * Search through the output/error options and setup the default fd if
78     * match is found; otherwise, open an output file and seek to location.
79     */
80    if ((it = oemap.find(output)) != oemap.end())
81        sim_fd = it->second;
82    else
83        sim_fd = openOutputFile(output);
84
85    ffd = std::make_shared<FileFDEntry>(sim_fd, O_WRONLY | O_CREAT | O_TRUNC,
86                                        output, false);
87    _fdArray[STDOUT_FILENO] = ffd;
88
89    if (output == errout)
90        ; /* Reuse the same file descriptor if these match. */
91    else if ((it = oemap.find(errout)) != oemap.end())
92        sim_fd = it->second;
93    else
94        sim_fd = openOutputFile(errout);
95
96    ffd = std::make_shared<FileFDEntry>(sim_fd, O_WRONLY | O_CREAT | O_TRUNC,
97                                        errout, false);
98    _fdArray[STDERR_FILENO] = ffd;
99}
100
101void
102FDArray::updateFileOffsets()
103{
104    for (auto& fdp : _fdArray) {
105        /**
106         * It only makes sense to check the offsets if the file descriptor
107         * type is 'File' (which indicates that this file is backed by a
108         * file on the host). If the type is File, then record the offset.
109         */
110        auto ffd = std::dynamic_pointer_cast<FileFDEntry>(fdp);
111
112        if (!ffd)
113            continue;
114
115        /**
116         * Use lseek with SEEK_CUR with offset 0 to figure out where the
117         * offset currently resides and pass that back to our setter.
118         */
119        int sim_fd = ffd->getSimFD();
120        ffd->setFileOffset(lseek(sim_fd, 0, SEEK_CUR));
121    }
122}
123
124void
125FDArray::restoreFileOffsets()
126{
127    /**
128     * Use this lambda to highlight what we mean to do with the seek.
129     * Notice that this either seeks correctly (sets the file location on the
130     * host) or it fails with a fatal. The error is fatal because it's not
131     * possible to guarantee that the simulation will proceed as it should
132     * have in the same way that it would have proceeded sans checkpoints.
133     */
134    void (*seek)(std::shared_ptr<FileFDEntry>)
135        = [] (std::shared_ptr<FileFDEntry> ffd)
136    {
137        if (lseek(ffd->getSimFD(), ffd->getFileOffset(), SEEK_SET) < 0)
138            fatal("Unable to seek to location in %s", ffd->getFileName());
139    };
140
141    std::map<std::string, int>::iterator it;
142
143    /**
144     * Search through the input options and set fd if match is found;
145     * otherwise, open an input file and seek to location.
146     * Check if user has specified a different input file, and if so, use it
147     * instead of the file specified in the checkpoint. This also resets the
148     * file offset from the checkpointed value
149     */
150    std::shared_ptr<FDEntry> stdin_fde = _fdArray[STDIN_FILENO];
151    auto stdin_ffd = std::dynamic_pointer_cast<FileFDEntry>(stdin_fde);
152
153    if (_input != stdin_ffd->getFileName()) {
154        warn("Using new input file (%s) rather than checkpointed (%s)\n",
155             _input, stdin_ffd->getFileName());
156        stdin_ffd->setFileName(_input);
157        stdin_ffd->setFileOffset(0);
158    }
159
160    if ((it = imap.find(stdin_ffd->getFileName())) != imap.end()) {
161        stdin_ffd->setSimFD(it->second);
162    } else {
163        stdin_ffd->setSimFD(openInputFile(stdin_ffd->getFileName()));
164        seek(stdin_ffd);
165    }
166
167    /**
168     * Search through the output options and set fd if match is found;
169     * otherwise, open an output file and seek to location.
170     * Check if user has specified a different output file, and if so, use it
171     * instead of the file specified in the checkpoint. This also resets the
172     * file offset from the checkpointed value
173     */
174    std::shared_ptr<FDEntry> stdout_fde = _fdArray[STDOUT_FILENO];
175    auto stdout_ffd = std::dynamic_pointer_cast<FileFDEntry>(stdout_fde);
176
177    if (_output != stdout_ffd->getFileName()) {
178        warn("Using new output file (%s) rather than checkpointed (%s)\n",
179             _output, stdout_ffd->getFileName());
180        stdout_ffd->setFileName(_output);
181        stdout_ffd->setFileOffset(0);
182    }
183
184    if ((it = oemap.find(stdout_ffd->getFileName())) != oemap.end()) {
185        stdout_ffd->setSimFD(it->second);
186    } else {
187        stdout_ffd->setSimFD(openOutputFile(stdout_ffd->getFileName()));
188        seek(stdout_ffd);
189    }
190
191    /**
192     * Search through the error options and set fd if match is found;
193     * otherwise, open an error file and seek to location.
194     * Check if user has specified a different error file, and if so, use it
195     * instead of the file specified in the checkpoint. This also resets the
196     * file offset from the checkpointed value
197     */
198    std::shared_ptr<FDEntry> stderr_fde = _fdArray[STDERR_FILENO];
199    auto stderr_ffd = std::dynamic_pointer_cast<FileFDEntry>(stderr_fde);
200
201    if (_errout != stderr_ffd->getFileName()) {
202        warn("Using new error file (%s) rather than checkpointed (%s)\n",
203             _errout, stderr_ffd->getFileName());
204        stderr_ffd->setFileName(_errout);
205        stderr_ffd->setFileOffset(0);
206    }
207
208    if (stdout_ffd->getFileName() == stderr_ffd->getFileName()) {
209        /* Reuse the same sim_fd file descriptor if these match. */
210        stderr_ffd->setSimFD(stdout_ffd->getSimFD());
211    } else if ((it = oemap.find(stderr_ffd->getFileName())) != oemap.end()) {
212        stderr_ffd->setSimFD(it->second);
213    } else {
214        stderr_ffd->setSimFD(openOutputFile(stderr_ffd->getFileName()));
215        seek(stderr_ffd);
216    }
217
218    for (int tgt_fd = 3; tgt_fd < _fdArray.size(); tgt_fd++) {
219        std::shared_ptr<FDEntry> fdp = _fdArray[tgt_fd];
220        if (!fdp)
221            continue;
222
223        /* Need to reconnect pipe ends. */
224        if (auto pfd = std::dynamic_pointer_cast<PipeFDEntry>(fdp)) {
225            /**
226             * Check which end of the pipe we are looking at; we only want
227             * to setup the pipe once so we arbitrarily choose the read
228             * end to be the end that sets up the pipe.
229             */
230            if (pfd->getEndType() == PipeFDEntry::EndType::write)
231                continue;
232
233            /* Setup the pipe or fatal out of the simulation. */
234            int fd_pair[2];
235            if (pipe(fd_pair) < 0)
236                fatal("Unable to create new pipe");
237
238            /**
239             * Reconstruct the ends of the pipe by reassigning the pipe
240             * that we created on the host. This one is the read end.
241             */
242            pfd->setSimFD(fd_pair[0]);
243
244            /**
245             * Grab the write end by referencing the read ends source and
246             * using that tgt_fd to index the array.
247             */
248            int prs = pfd->getPipeReadSource();
249            std::shared_ptr<FDEntry> write_fdp = _fdArray[prs];
250
251            /* Now cast it and make sure that we are still sane. */
252            auto write_pfd = std::dynamic_pointer_cast<PipeFDEntry>(write_fdp);
253
254            /* Hook up the write end back to the right side of the pipe. */
255            write_pfd->setSimFD(fd_pair[1]);
256        }
257
258        /* Need to reassign 'driver'. */
259        if (auto dfd = std::dynamic_pointer_cast<DeviceFDEntry>(fdp)) {
260            /**
261             * Yeah, how does one retain the entire driver state from this
262             * particular set of code? If you figure it out, add some code
263             * here to rectify the issue.
264             */
265            fatal("Unable to restore checkpoints with emulated drivers");
266        }
267
268        /* Need to open files and seek. */
269        if (auto ffd = std::dynamic_pointer_cast<FileFDEntry>(fdp)) {
270            /**
271             * Assume that this has the mode of an output file so there's no
272             * need to worry about properly recording the mode. If you're
273             * reading this and this happens to be your issue, at least be
274             * happy that you've discovered the issue (and not mad at me).
275             * Onward ho!
276             */
277            int sim_fd = openFile(ffd->getFileName(), ffd->getFlags(), 0664);
278            ffd->setSimFD(sim_fd);
279            seek(ffd);
280        }
281    }
282}
283
284int
285FDArray::allocFD(std::shared_ptr<FDEntry> in)
286{
287    for (int i = 0; i < _fdArray.size(); i++) {
288        std::shared_ptr<FDEntry> fdp = _fdArray[i];
289        if (!fdp) {
290            _fdArray[i] = in;
291            return i;
292        }
293    }
294    fatal("Out of target file descriptors");
295}
296
297int
298FDArray::openFile(std::string const& filename, int flags, mode_t mode) const
299{
300    int sim_fd = open(filename.c_str(), flags, mode);
301    if (sim_fd != -1)
302        return sim_fd;
303    fatal("Unable to open %s with mode %O", filename, mode);
304}
305
306int
307FDArray::openInputFile(std::string const& filename) const
308{
309    return openFile(filename, O_RDONLY, 00);
310}
311
312int
313FDArray::openOutputFile(std::string const& filename) const
314{
315    return openFile(filename, O_WRONLY | O_CREAT | O_TRUNC, 0664);
316}
317
318std::shared_ptr<FDEntry>
319FDArray::getFDEntry(int tgt_fd)
320{
321    assert(0 <= tgt_fd && tgt_fd < _fdArray.size());
322    return _fdArray[tgt_fd];
323}
324
325int
326FDArray::closeFDEntry(int tgt_fd)
327{
328    if (tgt_fd >= _fdArray.size() || tgt_fd < 0)
329        return -EBADF;
330
331    int sim_fd = -1;
332    auto hbfdp = std::dynamic_pointer_cast<HBFDEntry>(_fdArray[tgt_fd]);
333    if (hbfdp)
334        sim_fd = hbfdp->getSimFD();
335
336    int status = 0;
337    if (sim_fd > 2)
338        status = close(sim_fd);
339
340    if (status == 0)
341        _fdArray[tgt_fd] = nullptr;
342
343    return status;
344}
345