about summary refs log tree commit diff
path: root/src/nix-worker/main.cc
blob: e772421f39bca8548c2604dbfeedfce2787a909e (plain) (blame)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
#include "shared.hh"
#include "local-store.hh"
#include "util.hh"
#include "serialise.hh"
#include "worker-protocol.hh"
#include "archive.hh"
#include "globals.hh"

#include <iostream>
#include <unistd.h>
#include <signal.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <sys/socket.h>
#include <sys/un.h>
#include <fcntl.h>

using namespace nix;


#ifndef SIGPOLL
#define SIGPOLL SIGIO
#endif


static FdSource from(STDIN_FILENO);
static FdSink to(STDOUT_FILENO);

bool canSendStderr;


/* This function is called anytime we want to write something to
   stderr.  If we're in a state where the protocol allows it (i.e.,
   when canSendStderr), send the message to the client over the
   socket. */
static void tunnelStderr(const unsigned char * buf, size_t count)
{
    if (canSendStderr) {
        try {
            writeInt(STDERR_NEXT, to);
            writeString(string((char *) buf, count), to);
        } catch (...) {
            /* Write failed; that means that the other side is
               gone. */
            canSendStderr = false;
            throw;
        }
    }
}


/* A SIGPOLL signal is received when data is available on the client
   communication scoket, or when the client has closed its side of the
   socket.  This handler is enabled at precisely those moments in the
   protocol when we're doing work and the client is supposed to be
   quiet.  Thus, if we get a SIGPOLL signal, it means that the client
   has quit.  So we should quit as well.

   Too bad most operating systems don't support the POLL_HUP value for
   si_code in siginfo_t.  That would make most of the SIGPOLL
   complexity unnecessary, i.e., we could just enable SIGPOLL all the
   time and wouldn't have to worry about races. */
static void sigioHandler(int sigNo)
{
    if (!blockInt) {
        _isInterrupted = 1;
        blockInt = 1;
        canSendStderr = false;
        write(STDERR_FILENO, "SIGPOLL\n", 8);
    }
}


static void setSigPollAction(bool ignore)
{
    struct sigaction act, oact;
    act.sa_handler = ignore ? SIG_IGN : sigioHandler;
    sigfillset(&act.sa_mask);
    act.sa_flags = 0;
    if (sigaction(SIGPOLL, &act, &oact))
        throw SysError("setting handler for SIGPOLL");
}


/* startWork() means that we're starting an operation for which we
   want to send out stderr to the client. */
static void startWork()
{
    canSendStderr = true;

    /* Handle client death asynchronously. */
    setSigPollAction(false);

    /* Of course, there is a race condition here: the socket could
       have closed between when we last read from / wrote to it, and
       between the time we set the handler for SIGPOLL.  In that case
       we won't get the signal.  So do a non-blocking select() to find
       out if any input is available on the socket.  If there is, it
       has to be the 0-byte read that indicates that the socket has
       closed. */
    
    struct timeval timeout;
    timeout.tv_sec = timeout.tv_usec = 0;

    fd_set fds;
    FD_ZERO(&fds);
    FD_SET(from.fd, &fds);
        
    if (select(from.fd + 1, &fds, 0, 0, &timeout) == -1)
        throw SysError("select()");

    if (FD_ISSET(from.fd, &fds)) {
        char c;
        if (read(from.fd, &c, 1) != 0)
            throw Error("EOF expected (protocol error?)");
        _isInterrupted = 1;
        checkInterrupt();
    }
}


/* stopWork() means that we're done; stop sending stderr to the
   client. */
static void stopWork(bool success = true, const string & msg = "")
{
    /* Stop handling async client death; we're going to a state where
       we're either sending or receiving from the client, so we'll be
       notified of client death anyway. */
    setSigPollAction(true);
    
    canSendStderr = false;

    if (success)
        writeInt(STDERR_LAST, to);
    else {
        writeInt(STDERR_ERROR, to);
        writeString(msg, to);
    }
}


static void performOp(Source & from, Sink & to, unsigned int op)
{
    switch (op) {

#if 0        
    case wopQuit: {
        /* Close the database. */
        store.reset((StoreAPI *) 0);
        writeInt(1, to);
        break;
    }
#endif

    case wopIsValidPath: {
        Path path = readStorePath(from);
        startWork();
        bool result = store->isValidPath(path);
        stopWork();
        writeInt(result, to);
        break;
    }

    case wopHasSubstitutes: {
        Path path = readStorePath(from);
        startWork();
        bool result = store->hasSubstitutes(path);
        stopWork();
        writeInt(result, to);
        break;
    }

    case wopQueryPathHash: {
        Path path = readStorePath(from);
        startWork();
        Hash hash = store->queryPathHash(path);
        stopWork();
        writeString(printHash(hash), to);
        break;
    }

    case wopQueryReferences:
    case wopQueryReferrers: {
        Path path = readStorePath(from);
        startWork();
        PathSet paths;
        if (op == wopQueryReferences)
            store->queryReferences(path, paths);
        else
            store->queryReferrers(path, paths);
        stopWork();
        writeStringSet(paths, to);
        break;
    }

    case wopAddToStore: {
        /* !!! uberquick hack */
        string baseName = readString(from);
        bool fixed = readInt(from) == 1;
        bool recursive = readInt(from) == 1;
        string hashAlgo = readString(from);
        
        Path tmp = createTempDir();
        Path tmp2 = tmp + "/" + baseName;
        restorePath(tmp2, from);

        startWork();
        Path path = store->addToStore(tmp2, fixed, recursive, hashAlgo);
        stopWork();
        
        writeString(path, to);
            
        deletePath(tmp);
        break;
    }

    case wopAddTextToStore: {
        string suffix = readString(from);
        string s = readString(from);
        PathSet refs = readStorePaths(from);
        startWork();
        Path path = store->addTextToStore(suffix, s, refs);
        stopWork();
        writeString(path, to);
        break;
    }

    case wopBuildDerivations: {
        PathSet drvs = readStorePaths(from);
        startWork();
        store->buildDerivations(drvs);
        stopWork();
        writeInt(1, to);
        break;
    }

    case wopEnsurePath: {
        Path path = readStorePath(from);
        startWork();
        store->ensurePath(path);
        stopWork();
        writeInt(1, to);
        break;
    }

    case wopAddTempRoot: {
        Path path = readStorePath(from);
        startWork();
        store->addTempRoot(path);
        stopWork();
        writeInt(1, to);
        break;
    }

    case wopAddIndirectRoot: {
        Path path = absPath(readString(from));
        startWork();
        store->addIndirectRoot(path);
        stopWork();
        writeInt(1, to);
        break;
    }

    case wopSyncWithGC: {
        startWork();
        store->syncWithGC();
        stopWork();
        writeInt(1, to);
        break;
    }

    case wopFindRoots: {
        startWork();
        Roots roots = store->findRoots();
        stopWork();
        writeInt(roots.size(), to);
        for (Roots::iterator i = roots.begin(); i != roots.end(); ++i) {
            writeString(i->first, to);
            writeString(i->second, to);
        }
        break;
    }

    default:
        throw Error(format("invalid operation %1%") % op);
    }
}


static void processConnection()
{
    canSendStderr = false;
    writeToStderr = tunnelStderr;

    /* Allow us to receive SIGPOLL for events on the client socket. */
    setSigPollAction(true);
    if (fcntl(from.fd, F_SETOWN, getpid()) == -1)
        throw SysError("F_SETOWN");
    if (fcntl(from.fd, F_SETFL, fcntl(from.fd, F_GETFL, 0) | FASYNC) == -1)
        throw SysError("F_SETFL");

    /* Exchange the greeting. */
    unsigned int magic = readInt(from);
    if (magic != WORKER_MAGIC_1) throw Error("protocol mismatch");
    verbosity = (Verbosity) readInt(from);
    writeInt(WORKER_MAGIC_2, to);

    /* Send startup error messages to the client. */
    startWork();

    try {

        /* Prevent users from doing something very dangerous. */
        if (setuidMode && geteuid() == 0 &&
            querySetting("build-users", Strings()).size() == 0)
            throw Error("if you run `nix-worker' setuid root, then you MUST set `build-users'!");

        /* Open the store. */
        store = boost::shared_ptr<StoreAPI>(new LocalStore(true));

        stopWork();
        
    } catch (Error & e) {
        stopWork(false, e.msg());
        return;
    }

    /* Process client requests. */
    unsigned int opCount = 0;
    
    while (true) {
        WorkerOp op;
        try {
            op = (WorkerOp) readInt(from);
        } catch (EndOfFile & e) {
            break;
        }

        opCount++;

        try {
            performOp(from, to, op);
        } catch (Error & e) {
            stopWork(false, e.msg());
        }

        assert(!canSendStderr);
    };

    printMsg(lvlError, format("%1% worker operations") % opCount);
}


static void setSigChldAction(bool ignore)
{
    struct sigaction act, oact;
    act.sa_handler = ignore ? SIG_IGN : SIG_DFL;
    sigfillset(&act.sa_mask);
    act.sa_flags = 0;
    if (sigaction(SIGCHLD, &act, &oact))
        throw SysError("setting SIGCHLD handler");
}


static void daemonLoop()
{
    /* Get rid of children automatically; don't let them become
       zombies. */
    setSigChldAction(true);
    
    /* Create and bind to a Unix domain socket. */
    AutoCloseFD fdSocket = socket(PF_UNIX, SOCK_STREAM, 0);
    if (fdSocket == -1)
        throw SysError("cannot create Unix domain socket");

    string socketPath = nixStateDir + DEFAULT_SOCKET_PATH;

    struct sockaddr_un addr;
    addr.sun_family = AF_UNIX;
    if (socketPath.size() >= sizeof(addr.sun_path))
        throw Error(format("socket path `%1%' is too long") % socketPath);
    strcpy(addr.sun_path, socketPath.c_str());

    unlink(socketPath.c_str());

    /* Make sure that the socket is created with 0666 permission
       (everybody can connect). */
    mode_t oldMode = umask(0111);
    int res = bind(fdSocket, (struct sockaddr *) &addr, sizeof(addr));
    umask(oldMode);
    if (res == -1)
        throw SysError(format("cannot bind to socket `%1%'") % socketPath);

    if (listen(fdSocket, 5) == -1)
        throw SysError(format("cannot listen on socket `%1%'") % socketPath);

    /* Loop accepting connections. */
    while (1) {

        try {
            /* Important: the server process *cannot* open the
               Berkeley DB environment, because it doesn't like forks
               very much. */
            assert(!store);
            
            /* Accept a connection. */
            struct sockaddr_un remoteAddr;
            socklen_t remoteAddrLen = sizeof(remoteAddr);

            AutoCloseFD remote = accept(fdSocket,
                (struct sockaddr *) &remoteAddr, &remoteAddrLen);
            checkInterrupt();
            if (remote == -1)
                throw SysError("accepting connection");

            printMsg(lvlInfo, format("accepted connection %1%") % remote);

            /* Fork a child to handle the connection. */
            pid_t child;
            child = fork();
    
            switch (child) {
        
            case -1:
                throw SysError("unable to fork");

            case 0:
                try { /* child */
                    
                    /* Background the worker. */
                    if (setsid() == -1)
                        throw SysError(format("creating a new session"));

                    /* Restore normal handling of SIGCHLD. */
                    setSigChldAction(false);
                    
                    /* Handle the connection. */
                    from.fd = remote;
                    to.fd = remote;
                    processConnection();
                    
                } catch (std::exception & e) {
                    std::cerr << format("child error: %1%\n") % e.what();
                }
                exit(0);
            }

        } catch (Interrupted & e) {
            throw;
        } catch (Error & e) {
            printMsg(lvlError, format("error processing connection: %1%") % e.msg());
        }
    }
}


void run(Strings args)
{
    bool slave = false;
    bool daemon = false;
    
    for (Strings::iterator i = args.begin(); i != args.end(); ) {
        string arg = *i++;
        if (arg == "--slave") slave = true;
        if (arg == "--daemon") daemon = true;
    }

    if (slave) {
        /* This prevents us from receiving signals from the terminal
           when we're running in setuid mode. */
        if (setsid() == -1)
            throw SysError(format("creating a new session"));

        processConnection();
    }

    else if (daemon) {
        if (setuidMode)
            throw Error("daemon cannot be started in setuid mode");
        chdir("/");
        daemonLoop();
    }

    else
        throw Error("must be run in either --slave or --daemon mode");
}


#include "help.txt.hh"

void printHelp()
{
    std::cout << string((char *) helpText, sizeof helpText);
}


string programId = "nix-worker";