forked from lix-project/lix
570 lines
15 KiB
C++
570 lines
15 KiB
C++
#include "shared.hh"
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#include "local-store.hh"
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#include "util.hh"
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#include "serialise.hh"
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#include "worker-protocol.hh"
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#include "archive.hh"
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#include "globals.hh"
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#include <iostream>
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#include <unistd.h>
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#include <signal.h>
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#include <sys/types.h>
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#include <sys/wait.h>
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#include <sys/stat.h>
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#include <sys/socket.h>
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#include <sys/un.h>
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#include <fcntl.h>
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#include <errno.h>
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using namespace nix;
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#ifndef SIGPOLL
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#define SIGPOLL SIGIO
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#endif
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static FdSource from(STDIN_FILENO);
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static FdSink to(STDOUT_FILENO);
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bool canSendStderr;
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pid_t myPid;
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/* This function is called anytime we want to write something to
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stderr. If we're in a state where the protocol allows it (i.e.,
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when canSendStderr), send the message to the client over the
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socket. */
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static void tunnelStderr(const unsigned char * buf, size_t count)
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{
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/* Don't send the message to the client if we're a child of the
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process handling the connection. Otherwise we could screw up
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the protocol. It's up to the parent to redirect stderr and
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send it to the client somehow (e.g., as in build.cc). */
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if (canSendStderr && myPid == getpid()) {
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try {
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writeInt(STDERR_NEXT, to);
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writeString(string((char *) buf, count), to);
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} catch (...) {
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/* Write failed; that means that the other side is
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gone. */
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canSendStderr = false;
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throw;
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}
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} else
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writeFull(STDERR_FILENO, buf, count);
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}
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/* Return true if the remote side has closed its end of the
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connection, false otherwise. Should not be called on any socket on
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which we expect input! */
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static bool isFarSideClosed(int socket)
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{
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struct timeval timeout;
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timeout.tv_sec = timeout.tv_usec = 0;
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fd_set fds;
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FD_ZERO(&fds);
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FD_SET(socket, &fds);
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if (select(socket + 1, &fds, 0, 0, &timeout) == -1)
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throw SysError("select()");
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if (!FD_ISSET(socket, &fds)) return false;
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/* Destructive read to determine whether the select() marked the
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socket as readable because there is actual input or because
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we've reached EOF (i.e., a read of size 0 is available). */
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char c;
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if (read(socket, &c, 1) != 0)
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throw Error("EOF expected (protocol error?)");
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return true;
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}
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/* A SIGPOLL signal is received when data is available on the client
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communication scoket, or when the client has closed its side of the
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socket. This handler is enabled at precisely those moments in the
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protocol when we're doing work and the client is supposed to be
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quiet. Thus, if we get a SIGPOLL signal, it means that the client
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has quit. So we should quit as well.
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Too bad most operating systems don't support the POLL_HUP value for
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si_code in siginfo_t. That would make most of the SIGPOLL
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complexity unnecessary, i.e., we could just enable SIGPOLL all the
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time and wouldn't have to worry about races. */
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static void sigPollHandler(int sigNo)
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{
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try {
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/* Check that the far side actually closed. We're still
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getting spurious signals every once in a while. I.e.,
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there is no input available, but we get a signal with
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POLL_IN set. Maybe it's delayed or something. */
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if (isFarSideClosed(from.fd)) {
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if (!blockInt) {
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_isInterrupted = 1;
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blockInt = 1;
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canSendStderr = false;
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write(STDERR_FILENO, "SIGPOLL\n", 8);
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}
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} else {
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string s = "spurious SIGPOLL\n";
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write(STDERR_FILENO, s.c_str(), s.size());
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}
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}
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catch (Error & e) {
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/* Shouldn't happen. */
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write(STDERR_FILENO, e.msg().c_str(), e.msg().size());
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abort();
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}
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}
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static void setSigPollAction(bool enable)
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{
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struct sigaction act, oact;
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act.sa_handler = enable ? sigPollHandler : SIG_IGN;
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sigfillset(&act.sa_mask);
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act.sa_flags = 0;
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if (sigaction(SIGPOLL, &act, &oact))
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throw SysError("setting handler for SIGPOLL");
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}
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/* startWork() means that we're starting an operation for which we
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want to send out stderr to the client. */
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static void startWork()
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{
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canSendStderr = true;
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/* Handle client death asynchronously. */
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setSigPollAction(true);
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/* Of course, there is a race condition here: the socket could
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have closed between when we last read from / wrote to it, and
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between the time we set the handler for SIGPOLL. In that case
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we won't get the signal. So do a non-blocking select() to find
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out if any input is available on the socket. If there is, it
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has to be the 0-byte read that indicates that the socket has
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closed. */
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if (isFarSideClosed(from.fd)) {
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_isInterrupted = 1;
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checkInterrupt();
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}
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}
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/* stopWork() means that we're done; stop sending stderr to the
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client. */
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static void stopWork(bool success = true, const string & msg = "")
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{
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/* Stop handling async client death; we're going to a state where
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we're either sending or receiving from the client, so we'll be
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notified of client death anyway. */
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setSigPollAction(false);
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canSendStderr = false;
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if (success)
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writeInt(STDERR_LAST, to);
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else {
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writeInt(STDERR_ERROR, to);
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writeString(msg, to);
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}
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}
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static void performOp(Source & from, Sink & to, unsigned int op)
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{
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switch (op) {
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#if 0
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case wopQuit: {
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/* Close the database. */
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store.reset((StoreAPI *) 0);
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writeInt(1, to);
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break;
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}
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#endif
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case wopIsValidPath: {
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Path path = readStorePath(from);
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startWork();
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bool result = store->isValidPath(path);
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stopWork();
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writeInt(result, to);
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break;
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}
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case wopHasSubstitutes: {
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Path path = readStorePath(from);
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startWork();
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bool result = store->hasSubstitutes(path);
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stopWork();
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writeInt(result, to);
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break;
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}
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case wopQueryPathHash: {
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Path path = readStorePath(from);
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startWork();
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Hash hash = store->queryPathHash(path);
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stopWork();
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writeString(printHash(hash), to);
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break;
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}
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case wopQueryReferences:
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case wopQueryReferrers: {
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Path path = readStorePath(from);
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startWork();
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PathSet paths;
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if (op == wopQueryReferences)
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store->queryReferences(path, paths);
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else
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store->queryReferrers(path, paths);
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stopWork();
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writeStringSet(paths, to);
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break;
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}
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case wopAddToStore: {
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/* !!! uberquick hack */
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string baseName = readString(from);
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bool fixed = readInt(from) == 1;
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bool recursive = readInt(from) == 1;
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string hashAlgo = readString(from);
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Path tmp = createTempDir();
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Path tmp2 = tmp + "/" + baseName;
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restorePath(tmp2, from);
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startWork();
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Path path = store->addToStore(tmp2, fixed, recursive, hashAlgo);
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stopWork();
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writeString(path, to);
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deletePath(tmp);
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break;
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}
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case wopAddTextToStore: {
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string suffix = readString(from);
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string s = readString(from);
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PathSet refs = readStorePaths(from);
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startWork();
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Path path = store->addTextToStore(suffix, s, refs);
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stopWork();
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writeString(path, to);
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break;
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}
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case wopBuildDerivations: {
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PathSet drvs = readStorePaths(from);
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startWork();
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store->buildDerivations(drvs);
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stopWork();
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writeInt(1, to);
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break;
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}
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case wopEnsurePath: {
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Path path = readStorePath(from);
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startWork();
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store->ensurePath(path);
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stopWork();
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writeInt(1, to);
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break;
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}
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case wopAddTempRoot: {
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Path path = readStorePath(from);
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startWork();
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store->addTempRoot(path);
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stopWork();
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writeInt(1, to);
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break;
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}
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case wopAddIndirectRoot: {
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Path path = absPath(readString(from));
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startWork();
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store->addIndirectRoot(path);
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stopWork();
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writeInt(1, to);
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break;
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}
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case wopSyncWithGC: {
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startWork();
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store->syncWithGC();
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stopWork();
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writeInt(1, to);
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break;
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}
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case wopFindRoots: {
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startWork();
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Roots roots = store->findRoots();
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stopWork();
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writeInt(roots.size(), to);
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for (Roots::iterator i = roots.begin(); i != roots.end(); ++i) {
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writeString(i->first, to);
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writeString(i->second, to);
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}
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break;
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}
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case wopCollectGarbage: {
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GCAction action = (GCAction) readInt(from);
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PathSet pathsToDelete = readStorePaths(from);
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bool ignoreLiveness = readInt(from);
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PathSet result;
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unsigned long long bytesFreed;
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startWork();
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if (ignoreLiveness)
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throw Error("you are not allowed to ignore liveness");
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store->collectGarbage(action, pathsToDelete, ignoreLiveness,
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result, bytesFreed);
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stopWork();
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writeStringSet(result, to);
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writeInt(bytesFreed & 0xffffffff, to);
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writeInt(bytesFreed >> 32, to);
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break;
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}
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default:
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throw Error(format("invalid operation %1%") % op);
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}
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}
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static void processConnection()
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{
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canSendStderr = false;
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myPid = getpid();
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writeToStderr = tunnelStderr;
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/* Allow us to receive SIGPOLL for events on the client socket. */
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setSigPollAction(false);
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if (fcntl(from.fd, F_SETOWN, getpid()) == -1)
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throw SysError("F_SETOWN");
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if (fcntl(from.fd, F_SETFL, fcntl(from.fd, F_GETFL, 0) | FASYNC) == -1)
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throw SysError("F_SETFL");
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/* Exchange the greeting. */
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unsigned int magic = readInt(from);
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if (magic != WORKER_MAGIC_1) throw Error("protocol mismatch");
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verbosity = (Verbosity) readInt(from);
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writeInt(WORKER_MAGIC_2, to);
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/* Send startup error messages to the client. */
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startWork();
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try {
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/* Prevent users from doing something very dangerous. */
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if (geteuid() == 0 &&
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querySetting("build-users-group", "") == "")
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throw Error("if you run `nix-worker' as root, then you MUST set `build-users-group'!");
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/* Open the store. */
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store = boost::shared_ptr<StoreAPI>(new LocalStore(true));
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stopWork();
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} catch (Error & e) {
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stopWork(false, e.msg());
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return;
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}
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/* Process client requests. */
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unsigned int opCount = 0;
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while (true) {
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WorkerOp op;
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try {
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op = (WorkerOp) readInt(from);
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} catch (EndOfFile & e) {
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break;
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}
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opCount++;
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try {
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performOp(from, to, op);
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} catch (Error & e) {
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stopWork(false, e.msg());
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}
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assert(!canSendStderr);
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};
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printMsg(lvlError, format("%1% worker operations") % opCount);
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}
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static void sigChldHandler(int sigNo)
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{
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/* Reap all dead children. */
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while (waitpid(-1, 0, WNOHANG) == 0) ;
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}
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static void setSigChldAction(bool autoReap)
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{
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struct sigaction act, oact;
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act.sa_handler = autoReap ? sigChldHandler : SIG_DFL;
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sigfillset(&act.sa_mask);
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act.sa_flags = 0;
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if (sigaction(SIGCHLD, &act, &oact))
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throw SysError("setting SIGCHLD handler");
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}
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static void daemonLoop()
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{
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/* Get rid of children automatically; don't let them become
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zombies. */
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setSigChldAction(true);
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/* Create and bind to a Unix domain socket. */
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AutoCloseFD fdSocket = socket(PF_UNIX, SOCK_STREAM, 0);
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if (fdSocket == -1)
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throw SysError("cannot create Unix domain socket");
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string socketPath = nixStateDir + DEFAULT_SOCKET_PATH;
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struct sockaddr_un addr;
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addr.sun_family = AF_UNIX;
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if (socketPath.size() >= sizeof(addr.sun_path))
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throw Error(format("socket path `%1%' is too long") % socketPath);
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strcpy(addr.sun_path, socketPath.c_str());
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unlink(socketPath.c_str());
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/* Make sure that the socket is created with 0666 permission
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(everybody can connect). */
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mode_t oldMode = umask(0111);
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int res = bind(fdSocket, (struct sockaddr *) &addr, sizeof(addr));
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umask(oldMode);
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if (res == -1)
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throw SysError(format("cannot bind to socket `%1%'") % socketPath);
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if (listen(fdSocket, 5) == -1)
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throw SysError(format("cannot listen on socket `%1%'") % socketPath);
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/* Loop accepting connections. */
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while (1) {
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try {
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/* Important: the server process *cannot* open the
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Berkeley DB environment, because it doesn't like forks
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very much. */
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assert(!store);
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/* Accept a connection. */
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struct sockaddr_un remoteAddr;
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socklen_t remoteAddrLen = sizeof(remoteAddr);
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AutoCloseFD remote = accept(fdSocket,
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(struct sockaddr *) &remoteAddr, &remoteAddrLen);
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checkInterrupt();
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if (remote == -1)
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if (errno == EINTR)
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continue;
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else
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throw SysError("accepting connection");
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printMsg(lvlInfo, format("accepted connection %1%") % remote);
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/* Fork a child to handle the connection. */
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pid_t child;
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child = fork();
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switch (child) {
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case -1:
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throw SysError("unable to fork");
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case 0:
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try { /* child */
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/* Background the worker. */
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if (setsid() == -1)
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throw SysError(format("creating a new session"));
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/* Restore normal handling of SIGCHLD. */
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setSigChldAction(false);
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/* Handle the connection. */
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from.fd = remote;
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to.fd = remote;
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processConnection();
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} catch (std::exception & e) {
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std::cerr << format("child error: %1%\n") % e.what();
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}
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exit(0);
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}
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} catch (Interrupted & e) {
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throw;
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} catch (Error & e) {
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printMsg(lvlError, format("error processing connection: %1%") % e.msg());
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}
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}
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}
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void run(Strings args)
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{
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bool slave = false;
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bool daemon = false;
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for (Strings::iterator i = args.begin(); i != args.end(); ) {
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string arg = *i++;
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if (arg == "--slave") slave = true;
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if (arg == "--daemon") daemon = true;
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}
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if (slave) {
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/* This prevents us from receiving signals from the terminal
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when we're running in setuid mode. */
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if (setsid() == -1)
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throw SysError(format("creating a new session"));
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processConnection();
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}
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else if (daemon) {
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if (setuidMode)
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throw Error("daemon cannot be started in setuid mode");
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chdir("/");
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daemonLoop();
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}
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else
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throw Error("must be run in either --slave or --daemon mode");
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}
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#include "help.txt.hh"
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void printHelp()
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{
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std::cout << string((char *) helpText, sizeof helpText);
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}
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string programId = "nix-worker";
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