src/shared/fdset.c

/* SPDX-License-Identifier: LGPL-2.1+ */
/***
  This file is part of systemd.

  Copyright 2010 Lennart Poettering

  systemd is free software; you can redistribute it and/or modify it
  under the terms of the GNU Lesser General Public License as published by
  the Free Software Foundation; either version 2.1 of the License, or
  (at your option) any later version.

  systemd is distributed in the hope that it will be useful, but
  WITHOUT ANY WARRANTY; without even the implied warranty of
  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
  Lesser General Public License for more details.

  You should have received a copy of the GNU Lesser General Public License
  along with systemd; If not, see <http://www.gnu.org/licenses/>.
***/

#include <alloca.h>
#include <errno.h>
#include <fcntl.h>
#include <stddef.h>

#include "sd-daemon.h"

#include "dirent-util.h"
#include "fd-util.h"
#include "fdset.h"
#include "log.h"
#include "macro.h"
#include "parse-util.h"
#include "path-util.h"
#include "set.h"

#define MAKE_SET(s) ((Set*) s)
#define MAKE_FDSET(s) ((FDSet*) s)

FDSet *fdset_new(void) {
        return MAKE_FDSET(set_new(NULL));
}

int fdset_new_array(FDSet **ret, const int *fds, unsigned n_fds) {
        unsigned i;
        FDSet *s;
        int r;

        assert(ret);

        s = fdset_new();
        if (!s)
                return -ENOMEM;

        for (i = 0; i < n_fds; i++) {

                r = fdset_put(s, fds[i]);
                if (r < 0) {
                        set_free(MAKE_SET(s));
                        return r;
                }
        }

        *ret = s;
        return 0;
}

FDSet* fdset_free(FDSet *s) {
        void *p;

        while ((p = set_steal_first(MAKE_SET(s)))) {
                /* Valgrind's fd might have ended up in this set here,
                 * due to fdset_new_fill(). We'll ignore all failures
                 * here, so that the EBADFD that valgrind will return
                 * us on close() doesn't influence us */

                /* When reloading duplicates of the private bus
                 * connection fds and suchlike are closed here, which
                 * has no effect at all, since they are only
                 * duplicates. So don't be surprised about these log
                 * messages. */

                log_debug("Closing left-over fd %i", PTR_TO_FD(p));
                close_nointr(PTR_TO_FD(p));
        }

        set_free(MAKE_SET(s));
        return NULL;
}

int fdset_put(FDSet *s, int fd) {
        assert(s);
        assert(fd >= 0);

        return set_put(MAKE_SET(s), FD_TO_PTR(fd));
}

int fdset_put_dup(FDSet *s, int fd) {
        int copy, r;

        assert(s);
        assert(fd >= 0);

        copy = fcntl(fd, F_DUPFD_CLOEXEC, 3);
        if (copy < 0)
                return -errno;

        r = fdset_put(s, copy);
        if (r < 0) {
                safe_close(copy);
                return r;
        }

        return copy;
}

bool fdset_contains(FDSet *s, int fd) {
        assert(s);
        assert(fd >= 0);

        return !!set_get(MAKE_SET(s), FD_TO_PTR(fd));
}

int fdset_remove(FDSet *s, int fd) {
        assert(s);
        assert(fd >= 0);

        return set_remove(MAKE_SET(s), FD_TO_PTR(fd)) ? fd : -ENOENT;
}

int fdset_new_fill(FDSet **_s) {
        _cleanup_closedir_ DIR *d = NULL;
        struct dirent *de;
        int r = 0;
        FDSet *s;

        assert(_s);

        /* Creates an fdset and fills in all currently open file
         * descriptors. */

        d = opendir("/proc/self/fd");
        if (!d)
                return -errno;

        s = fdset_new();
        if (!s) {
                r = -ENOMEM;
                goto finish;
        }

        FOREACH_DIRENT(de, d, return -errno) {
                int fd = -1;

                r = safe_atoi(de->d_name, &fd);
                if (r < 0)
                        goto finish;

                if (fd < 3)
                        continue;

                if (fd == dirfd(d))
                        continue;

                r = fdset_put(s, fd);
                if (r < 0)
                        goto finish;
        }

        r = 0;
        *_s = s;
        s = NULL;

finish:
        /* We won't close the fds here! */
        if (s)
                set_free(MAKE_SET(s));

        return r;
}

int fdset_cloexec(FDSet *fds, bool b) {
        Iterator i;
        void *p;
        int r;

        assert(fds);

        SET_FOREACH(p, MAKE_SET(fds), i) {
                r = fd_cloexec(PTR_TO_FD(p), b);
                if (r < 0)
                        return r;
        }

        return 0;
}

int fdset_new_listen_fds(FDSet **_s, bool unset) {
        int n, fd, r;
        FDSet *s;

        assert(_s);

        /* Creates an fdset and fills in all passed file descriptors */

        s = fdset_new();
        if (!s) {
                r = -ENOMEM;
                goto fail;
        }

        n = sd_listen_fds(unset);
        for (fd = SD_LISTEN_FDS_START; fd < SD_LISTEN_FDS_START + n; fd ++) {
                r = fdset_put(s, fd);
                if (r < 0)
                        goto fail;
        }

        *_s = s;
        return 0;


fail:
        if (s)
                set_free(MAKE_SET(s));

        return r;
}

int fdset_close_others(FDSet *fds) {
        void *e;
        Iterator i;
        int *a;
        unsigned j, m;

        j = 0, m = fdset_size(fds);
        a = alloca(sizeof(int) * m);
        SET_FOREACH(e, MAKE_SET(fds), i)
                a[j++] = PTR_TO_FD(e);

        assert(j == m);

        return close_all_fds(a, j);
}

unsigned fdset_size(FDSet *fds) {
        return set_size(MAKE_SET(fds));
}

bool fdset_isempty(FDSet *fds) {
        return set_isempty(MAKE_SET(fds));
}

int fdset_iterate(FDSet *s, Iterator *i) {
        void *p;

        if (!set_iterate(MAKE_SET(s), i, &p))
                return -ENOENT;

        return PTR_TO_FD(p);
}

int fdset_steal_first(FDSet *fds) {
        void *p;

        p = set_steal_first(MAKE_SET(fds));
        if (!p)
                return -ENOENT;

        return PTR_TO_FD(p);
}