#include "pathlocks.hh"
#include "util.hh"

#include <cerrno>
#include <cstdlib>

#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>


namespace nix {


int openLockFile(const Path & path, bool create)
{
    AutoCloseFD fd;

    fd = open(path.c_str(), O_RDWR | (create ? O_CREAT : 0), 0600);
    if (fd == -1 && (create || errno != ENOENT))
        throw SysError(format("opening lock file `%1%'") % path);

    closeOnExec(fd);

    return fd.borrow();
}


void deleteLockFile(const Path & path, int fd)
{
    /* Get rid of the lock file.  Have to be careful not to introduce
       races.  Write a (meaningless) token to the file to indicate to
       other processes waiting on this lock that the lock is stale
       (deleted). */
    unlink(path.c_str());
    writeFull(fd, "d");
    /* Note that the result of unlink() is ignored; removing the lock
       file is an optimisation, not a necessity. */
}


bool lockFile(int fd, LockType lockType, bool wait)
{
    struct flock lock;
    if (lockType == ltRead) lock.l_type = F_RDLCK;
    else</td></tr></table>
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<td class='lines'><pre><code># This is a "service unit file" for the systemd init system to launch
# 'guix publish'.  Drop it in /etc/systemd/system or similar to have
# 'guix publish' automatically started.

[Unit]
Description=Publish the GNU Guix store
Requires=guix-daemon.service
PartOf=guix-daemon.service
After=guix-daemon.service

[Service]
ExecStart=@localstatedir@/guix/profiles/per-user/root/current-guix/bin/guix publish --user=nobody --port=8181
Environment='GUIX_LOCPATH=@localstatedir@/guix/profiles/per-user/root/guix-profile/lib/locale' LC_ALL=en_US.utf8
StandardOutput=journal
StandardError=journal

# Despite the name, this is rate-limited: a broken daemon will eventually fail.
Restart=always

# See &lt;https://lists.gnu.org/archive/html/guix-devel/2016-04/msg00608.html&gt;.
TasksMax=1024

[Install]
WantedBy=multi-user.target
</code></pre></td></tr></table>
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PathLocks()
{
    try {
        unlock();
    } catch (...) {
        ignoreException();
    }
}


void PathLocks::unlock()
{
    foreach (list<FDPair>::iterator, i, fds) {
        if (deletePaths) deleteLockFile(i->second, i->first);

        lockedPaths.erase(i->second);
        if (close(i->first) == -1)
            printMsg(lvlError,
                format("error (ignored): cannot close lock file on `%1%'") % i->second);

        debug(format("lock released on `%1%'") % i->second);
    }

    fds.clear();
}


void PathLocks::setDeletion(bool deletePaths)
{
    this->deletePaths = deletePaths;
}


bool pathIsLockedByMe(const Path & path)
{
    Path lockPath = path + ".lock";
    return lockedPaths.find(lockPath) != lockedPaths.end();
}

 
}