niceSOFT/systemd: The systemd System and Service Manager

src/shared/fdset.c
362 строки10 KB
Mike Yuan
fdset: do not call fd_get_path() if debug logging is off
21 янв 2026, 17:55
21 янв 2026, 17:5513c0351
/* SPDX-License-Identifier: LGPL-2.1-or-later */

#include <fcntl.h>
#include <unistd.h>

#include "sd-daemon.h"

#include "alloc-util.h"
#include "async.h"
#include "dirent-util.h"
#include "errno-util.h"
#include "fd-util.h"
#include "fdset.h"
#include "log.h"
#include "parse-util.h"
#include "set.h"
#include "stat-util.h"
#include "string-util.h"

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

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

static void fdset_shallow_freep(FDSet **s) {
        /* Destroys the set, but does not free the fds inside, like fdset_free()! */
        set_free(MAKE_SET(*ASSERT_PTR(s)));
}

int fdset_new_array(FDSet **ret, const int fds[], size_t n_fds) {
        _cleanup_(fdset_shallow_freep) FDSet *s = NULL;
        int r;

        assert(ret);
        assert(fds || n_fds == 0);

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

        FOREACH_ARRAY(fd, fds, n_fds) {
                r = fdset_put(s, *fd);
                if (r < 0)
                        return r;
        }

        *ret = TAKE_PTR(s);
        return 0;
}

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

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

        return PTR_TO_FD(p);
}

void fdset_close(FDSet *fds, bool async) {
        int fd;

        while ((fd = fdset_steal_first(fds)) >= 0) {
                /* 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. */

                if (DEBUG_LOGGING) {
                        _cleanup_free_ char *path = NULL;

                        (void) fd_get_path(fd, &path);
                        log_debug("Closing set fd %i (%s)", fd, strna(path));
                }

                if (async)
                        (void) asynchronous_close(fd);
                else
                        (void) close(fd);
        }
}

FDSet* fdset_free(FDSet *s) {
        fdset_close(s, /* async= */ false);
        set_free(MAKE_SET(s));
        return NULL;
}

FDSet* fdset_free_async(FDSet *s) {
        fdset_close(s, /* async= */ true);
        set_free(MAKE_SET(s));
        return NULL;
}

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

        /* Avoid integer overflow in FD_TO_PTR() */
        if (fd == INT_MAX)
                return log_debug_errno(SYNTHETIC_ERRNO(EINVAL), "Refusing invalid fd: %d", fd);

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

int fdset_consume(FDSet *s, int fd) {
        int r;

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

        r = fdset_put(s, fd);
        if (r < 0)
                safe_close(fd);

        return r;
}

int fdset_put_dup(FDSet *s, int fd) {
        _cleanup_close_ int copy = -EBADF;
        int 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)
                return r;

        return TAKE_FD(copy);
}

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

        /* Avoid integer overflow in FD_TO_PTR() */
        if (fd == INT_MAX) {
                log_debug("Refusing invalid fd: %d", fd);
                return false;
        }

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

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

        /* Avoid integer overflow in FD_TO_PTR() */
        if (fd == INT_MAX)
                return log_debug_errno(SYNTHETIC_ERRNO(ENOENT), "Refusing invalid fd: %d", fd);

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

int fdset_new_fill(
                int filter_cloexec, /* if < 0 takes all fds, otherwise only those with O_CLOEXEC set (1) or unset (0) */
                FDSet **ret) {

        _cleanup_(fdset_shallow_freep) FDSet *s = NULL;
        _cleanup_closedir_ DIR *d = NULL;
        int r;

        assert(ret);

        /* Creates an fdset and fills in all currently open file descriptors. Also set all collected fds
         * to CLOEXEC. */

        d = opendir("/proc/self/fd");
        if (!d) {
                if (errno == ENOENT && proc_mounted() == 0)
                        return log_debug_errno(SYNTHETIC_ERRNO(ENOSYS),
                                               "Failed to open /proc/self/fd/, /proc/ is not mounted.");

                return log_debug_errno(errno, "Failed to open /proc/self/fd/: %m");
        }

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

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

                if (!IN_SET(de->d_type, DT_LNK, DT_UNKNOWN))
                        continue;

                fd = parse_fd(de->d_name);
                if (fd < 0)
                        return fd;

                if (fd < 3)
                        continue;
                if (fd == dirfd(d))
                        continue;

                if (filter_cloexec >= 0) {
                        int fl;

                        /* If user asked for that filter by O_CLOEXEC. This is useful so that fds that have
                         * been passed in can be collected and fds which have been created locally can be
                         * ignored, under the assumption that only the latter have O_CLOEXEC set. */

                        fl = RET_NERRNO(fcntl(fd, F_GETFD));
                        if (fl < 0) {
                                if (DEBUG_LOGGING) {
                                        _cleanup_free_ char *path = NULL;
                                        (void) fd_get_path(fd, &path);
                                        log_debug_errno(fl, "Failed to get flags of fd=%d (%s): %m",
                                                        fd, strna(path));
                                }

                                return fl;
                        }

                        if (FLAGS_SET(fl, FD_CLOEXEC) != !!filter_cloexec)
                                continue;
                }

                /* We need to set CLOEXEC manually only if we're collecting non-CLOEXEC fds. */
                if (filter_cloexec <= 0) {
                        r = fd_cloexec(fd, true);
                        if (r < 0) {
                                if (DEBUG_LOGGING) {
                                        _cleanup_free_ char *path = NULL;
                                        (void) fd_get_path(fd, &path);
                                        log_debug_errno(r, "Failed to set CLOEXEC flag on fd=%d (%s): %m",
                                                        fd, strna(path));
                                }

                                return r;
                        }
                }

                r = fdset_put(s, fd);
                if (r < 0) {
                        if (DEBUG_LOGGING) {
                                _cleanup_free_ char *path = NULL;
                                (void) fd_get_path(fd, &path);
                                log_debug_errno(r, "Failed to put fd=%d (%s) into fdset: %m",
                                                fd, strna(path));
                        }

                        return r;
                }
        }

        *ret = TAKE_PTR(s);
        return 0;
}

int fdset_cloexec(FDSet *fds, bool b) {
        int r;

        assert(fds);

        int fd;
        FDSET_FOREACH(fd, fds) {
                r = fd_cloexec(fd, b);
                if (r < 0)
                        return r;
        }

        return 0;
}

int fdset_new_listen_fds(FDSet **ret, bool unset) {
        _cleanup_(fdset_shallow_freep) FDSet *s = NULL;
        int n, r;

        assert(ret);

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

        n = sd_listen_fds(unset);
        if (n < 0)
                return n;
        if (n == 0) {
                *ret = NULL;
                return 0;
        }

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

        for (int fd = SD_LISTEN_FDS_START; fd < SD_LISTEN_FDS_START + n; fd++) {
                r = fdset_put(s, fd);
                if (r < 0)
                        return r;
        }

        *ret = TAKE_PTR(s);
        return n;
}

int fdset_to_array(FDSet *fds, int **ret) {
        unsigned j = 0, m;
        int *a;

        assert(ret);

        m = fdset_size(fds);
        if (m > INT_MAX) /* We want to be able to return an "int" */
                return -ENOMEM;
        if (m == 0) {
                *ret = NULL; /* suppress array allocation if empty */
                return 0;
        }

        a = new(int, m);
        if (!a)
                return -ENOMEM;

        int fd;
        FDSET_FOREACH(fd, fds)
                a[j++] = fd;

        assert(j == m);

        *ret = TAKE_PTR(a);
        return (int) m;
}

int fdset_close_others(FDSet *fds) {
        _cleanup_free_ int *a = NULL;
        int n;

        n = fdset_to_array(fds, &a);
        if (n < 0)
                return n;

        return close_all_fds(a, n);
}

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);
}