Adding upstream version 255.4.upstream/255.4

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 1635 insertions, 0 deletions

diff --git a/src/shared/copy.c b/src/shared/copy.c
new file mode 100644
index 0000000..c0e30cd
--- /dev/null
+++ b/src/shared/copy.c
@@ -0,0 +1,1635 @@
+/* SPDX-License-Identifier: LGPL-2.1-or-later */
+
+#include <errno.h>
+#include <fcntl.h>
+#include <linux/btrfs.h>
+#include <stddef.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <sys/file.h>
+#include <sys/ioctl.h>
+#include <sys/sendfile.h>
+#include <sys/xattr.h>
+#include <unistd.h>
+
+#include "alloc-util.h"
+#include "btrfs-util.h"
+#include "chattr-util.h"
+#include "copy.h"
+#include "dirent-util.h"
+#include "fd-util.h"
+#include "fileio.h"
+#include "fs-util.h"
+#include "io-util.h"
+#include "macro.h"
+#include "missing_fs.h"
+#include "missing_syscall.h"
+#include "mkdir-label.h"
+#include "mountpoint-util.h"
+#include "nulstr-util.h"
+#include "rm-rf.h"
+#include "selinux-util.h"
+#include "signal-util.h"
+#include "stat-util.h"
+#include "stdio-util.h"
+#include "string-util.h"
+#include "strv.h"
+#include "sync-util.h"
+#include "time-util.h"
+#include "tmpfile-util.h"
+#include "umask-util.h"
+#include "user-util.h"
+#include "xattr-util.h"
+
+#define COPY_BUFFER_SIZE (16U*1024U)
+
+/* A safety net for descending recursively into file system trees to copy. On Linux PATH_MAX is 4096, which means the
+ * deepest valid path one can build is around 2048, which we hence use as a safety net here, to not spin endlessly in
+ * case of bind mount cycles and suchlike. */
+#define COPY_DEPTH_MAX 2048U
+
+static ssize_t try_copy_file_range(
+                int fd_in, loff_t *off_in,
+                int fd_out, loff_t *off_out,
+                size_t len,
+                unsigned flags) {
+
+        static int have = -1;
+        ssize_t r;
+
+        if (have == 0)
+                return -ENOSYS;
+
+        r = copy_file_range(fd_in, off_in, fd_out, off_out, len, flags);
+        if (have < 0)
+                have = r >= 0 || errno != ENOSYS;
+        if (r < 0)
+                return -errno;
+
+        return r;
+}
+
+enum {
+        FD_IS_NO_PIPE,
+        FD_IS_BLOCKING_PIPE,
+        FD_IS_NONBLOCKING_PIPE,
+};
+
+static int fd_is_nonblock_pipe(int fd) {
+        struct stat st;
+        int flags;
+
+        /* Checks whether the specified file descriptor refers to a pipe, and if so if O_NONBLOCK is set. */
+
+        if (fstat(fd, &st) < 0)
+                return -errno;
+
+        if (!S_ISFIFO(st.st_mode))
+                return FD_IS_NO_PIPE;
+
+        flags = fcntl(fd, F_GETFL);
+        if (flags < 0)
+                return -errno;
+
+        return FLAGS_SET(flags, O_NONBLOCK) ? FD_IS_NONBLOCKING_PIPE : FD_IS_BLOCKING_PIPE;
+}
+
+static int look_for_signals(CopyFlags copy_flags) {
+        int r;
+
+        if ((copy_flags & (COPY_SIGINT|COPY_SIGTERM)) == 0)
+                return 0;
+
+        r = pop_pending_signal(copy_flags & COPY_SIGINT ? SIGINT : 0,
+                               copy_flags & COPY_SIGTERM ? SIGTERM : 0);
+        if (r < 0)
+                return r;
+        if (r != 0)
+                return log_debug_errno(SYNTHETIC_ERRNO(EINTR),
+                                       "Got %s, cancelling copy operation.", signal_to_string(r));
+
+        return 0;
+}
+
+static int create_hole(int fd, off_t size) {
+        off_t offset;
+        off_t end;
+
+        offset = lseek(fd, 0, SEEK_CUR);
+        if (offset < 0)
+                return -errno;
+
+        end = lseek(fd, 0, SEEK_END);
+        if (end < 0)
+                return -errno;
+
+        /* If we're not at the end of the target file, try to punch a hole in the existing space using fallocate(). */
+
+        if (offset < end &&
+            fallocate(fd, FALLOC_FL_PUNCH_HOLE | FALLOC_FL_KEEP_SIZE, offset, MIN(size, end - offset)) < 0 &&
+            !ERRNO_IS_NOT_SUPPORTED(errno))
+                return -errno;
+
+        if (end - offset >= size) {
+                /* If we've created the full hole, set the file pointer to the end of the hole we created and exit. */
+                if (lseek(fd, offset + size, SEEK_SET) < 0)
+                        return -errno;
+
+                return 0;
+        }
+
+        /* If we haven't created the full hole, use ftruncate() to grow the file (and the hole) to the
+         * required size and move the file pointer to the end of the file. */
+
+        size -= end - offset;
+
+        if (ftruncate(fd, end + size) < 0)
+                return -errno;
+
+        if (lseek(fd, 0, SEEK_END) < 0)
+                return -errno;
+
+        return 0;
+}
+
+int copy_bytes_full(
+                int fdf, int fdt,
+                uint64_t max_bytes,
+                CopyFlags copy_flags,
+                void **ret_remains,
+                size_t *ret_remains_size,
+                copy_progress_bytes_t progress,
+                void *userdata) {
+
+        _cleanup_close_ int fdf_opened = -EBADF, fdt_opened = -EBADF;
+        bool try_cfr = true, try_sendfile = true, try_splice = true, copied_something = false;
+        int r, nonblock_pipe = -1;
+        size_t m = SSIZE_MAX; /* that is the maximum that sendfile and c_f_r accept */
+
+        assert(fdf >= 0);
+        assert(fdt >= 0);
+        assert(!FLAGS_SET(copy_flags, COPY_LOCK_BSD));
+
+        /* Tries to copy bytes from the file descriptor 'fdf' to 'fdt' in the smartest possible way. Copies a maximum
+         * of 'max_bytes', which may be specified as UINT64_MAX, in which no maximum is applied. Returns negative on
+         * error, zero if EOF is hit before the bytes limit is hit and positive otherwise. If the copy fails for some
+         * reason but we read but didn't yet write some data an ret_remains/ret_remains_size is not NULL, then it will
+         * be initialized with an allocated buffer containing this "remaining" data. Note that these two parameters are
+         * initialized with a valid buffer only on failure and only if there's actually data already read. Otherwise
+         * these parameters if non-NULL are set to NULL. */
+
+        if (ret_remains)
+                *ret_remains = NULL;
+        if (ret_remains_size)
+                *ret_remains_size = 0;
+
+        fdf = fd_reopen_condition(fdf, O_CLOEXEC | O_NOCTTY | O_RDONLY, O_PATH, &fdf_opened);
+        if (fdf < 0)
+                return fdf;
+        fdt = fd_reopen_condition(fdt, O_CLOEXEC | O_NOCTTY | O_RDWR, O_PATH, &fdt_opened);
+        if (fdt < 0)
+                return fdt;
+
+        /* Try btrfs reflinks first. This only works on regular, seekable files, hence let's check the file offsets of
+         * source and destination first. */
+        if ((copy_flags & COPY_REFLINK)) {
+                off_t foffset;
+
+                foffset = lseek(fdf, 0, SEEK_CUR);
+                if (foffset >= 0) {
+                        off_t toffset;
+
+                        toffset = lseek(fdt, 0, SEEK_CUR);
+                        if (toffset >= 0) {
+
+                                if (foffset == 0 && toffset == 0 && max_bytes == UINT64_MAX)
+                                        r = reflink(fdf, fdt); /* full file reflink */
+                                else
+                                        r = reflink_range(fdf, foffset, fdt, toffset, max_bytes == UINT64_MAX ? 0 : max_bytes); /* partial reflink */
+                                if (r >= 0) {
+                                        off_t t;
+
+                                        /* This worked, yay! Now — to be fully correct — let's adjust the file pointers */
+                                        if (max_bytes == UINT64_MAX) {
+
+                                                /* We cloned to the end of the source file, let's position the read
+                                                 * pointer there, and query it at the same time. */
+                                                t = lseek(fdf, 0, SEEK_END);
+                                                if (t < 0)
+                                                        return -errno;
+                                                if (t < foffset)
+                                                        return -ESPIPE;
+
+                                                /* Let's adjust the destination file write pointer by the same number
+                                                 * of bytes. */
+                                                t = lseek(fdt, toffset + (t - foffset), SEEK_SET);
+                                                if (t < 0)
+                                                        return -errno;
+
+                                                return 0; /* we copied the whole thing, hence hit EOF, return 0 */
+                                        } else {
+                                                t = lseek(fdf, foffset + max_bytes, SEEK_SET);
+                                                if (t < 0)
+                                                        return -errno;
+
+                                                t = lseek(fdt, toffset + max_bytes, SEEK_SET);
+                                                if (t < 0)
+                                                        return -errno;
+
+                                                return 1; /* we copied only some number of bytes, which worked, but this means we didn't hit EOF, return 1 */
+                                        }
+                                }
+                        }
+                }
+        }
+
+        for (;;) {
+                ssize_t n;
+
+                if (max_bytes <= 0)
+                        break;
+
+                r = look_for_signals(copy_flags);
+                if (r < 0)
+                        return r;
+
+                if (max_bytes != UINT64_MAX && m > max_bytes)
+                        m = max_bytes;
+
+                if (copy_flags & COPY_HOLES) {
+                        off_t c, e;
+
+                        c = lseek(fdf, 0, SEEK_CUR);
+                        if (c < 0)
+                                return -errno;
+
+                        /* To see if we're in a hole, we search for the next data offset. */
+                        e = lseek(fdf, c, SEEK_DATA);
+                        if (e < 0 && errno == ENXIO)
+                                /* If errno == ENXIO, that means we've reached the final hole of the file and
+                                * that hole isn't followed by more data. */
+                                e = lseek(fdf, 0, SEEK_END);
+                        if (e < 0)
+                                return -errno;
+
+                        /* If we're in a hole (current offset is not a data offset), create a hole of the
+                         * same size in the target file. */
+                        if (e > c) {
+                                /* Make sure our new hole doesn't go over the maximum size we're allowed to copy. */
+                                n = MIN(max_bytes, (uint64_t) e - c);
+                                r = create_hole(fdt, n);
+                                if (r < 0)
+                                        return r;
+
+                                /* Make sure holes are taken into account in the maximum size we're supposed to copy. */
+                                if (max_bytes != UINT64_MAX) {
+                                        max_bytes -= n;
+                                        if (max_bytes <= 0)
+                                                break;
+                                }
+
+                                /* Update the size we're supposed to copy in this iteration if needed. */
+                                if (m > max_bytes)
+                                        m = max_bytes;
+                        }
+
+                        c = e; /* Set c to the start of the data segment. */
+
+                        /* After copying a potential hole, find the end of the data segment by looking for
+                         * the next hole. If we get ENXIO, we're at EOF. */
+                        e = lseek(fdf, c, SEEK_HOLE);
+                        if (e < 0) {
+                                if (errno == ENXIO)
+                                        break;
+                                return -errno;
+                        }
+
+                        /* SEEK_HOLE modifies the file offset so we need to move back to the initial offset. */
+                        if (lseek(fdf, c, SEEK_SET) < 0)
+                                return -errno;
+
+                        /* Make sure we're not copying more than the current data segment. */
+                        m = MIN(m, (size_t) e - c);
+                }
+
+                /* First try copy_file_range(), unless we already tried */
+                if (try_cfr) {
+                        n = try_copy_file_range(fdf, NULL, fdt, NULL, m, 0u);
+                        if (n < 0) {
+                                if (!IN_SET(n, -EINVAL, -ENOSYS, -EXDEV, -EBADF))
+                                        return n;
+
+                                try_cfr = false;
+                                /* use fallback below */
+                        } else if (n == 0) { /* likely EOF */
+
+                                if (copied_something)
+                                        break;
+
+                                /* So, we hit EOF immediately, without having copied a single byte. This
+                                 * could indicate two things: the file is actually empty, or we are on some
+                                 * virtual file system such as procfs/sysfs where the syscall actually
+                                 * doesn't work but doesn't return an error. Try to handle that, by falling
+                                 * back to simple read()s in case we encounter empty files.
+                                 *
+                                 * See: https://lwn.net/Articles/846403/ */
+                                try_cfr = try_sendfile = try_splice = false;
+                        } else
+                                /* Success! */
+                                goto next;
+                }
+
+                /* First try sendfile(), unless we already tried */
+                if (try_sendfile) {
+                        n = sendfile(fdt, fdf, NULL, m);
+                        if (n < 0) {
+                                if (!IN_SET(errno, EINVAL, ENOSYS))
+                                        return -errno;
+
+                                try_sendfile = false;
+                                /* use fallback below */
+                        } else if (n == 0) { /* likely EOF */
+
+                                if (copied_something)
+                                        break;
+
+                                try_sendfile = try_splice = false; /* same logic as above for copy_file_range() */
+                        } else
+                                /* Success! */
+                                goto next;
+                }
+
+                /* Then try splice, unless we already tried. */
+                if (try_splice) {
+
+                        /* splice()'s asynchronous I/O support is a bit weird. When it encounters a pipe file
+                         * descriptor, then it will ignore its O_NONBLOCK flag and instead only honour the
+                         * SPLICE_F_NONBLOCK flag specified in its flag parameter. Let's hide this behaviour
+                         * here, and check if either of the specified fds are a pipe, and if so, let's pass
+                         * the flag automatically, depending on O_NONBLOCK being set.
+                         *
+                         * Here's a twist though: when we use it to move data between two pipes of which one
+                         * has O_NONBLOCK set and the other has not, then we have no individual control over
+                         * O_NONBLOCK behaviour. Hence in that case we can't use splice() and still guarantee
+                         * systematic O_NONBLOCK behaviour, hence don't. */
+
+                        if (nonblock_pipe < 0) {
+                                int a, b;
+
+                                /* Check if either of these fds is a pipe, and if so non-blocking or not */
+                                a = fd_is_nonblock_pipe(fdf);
+                                if (a < 0)
+                                        return a;
+
+                                b = fd_is_nonblock_pipe(fdt);
+                                if (b < 0)
+                                        return b;
+
+                                if ((a == FD_IS_NO_PIPE && b == FD_IS_NO_PIPE) ||
+                                    (a == FD_IS_BLOCKING_PIPE && b == FD_IS_NONBLOCKING_PIPE) ||
+                                    (a == FD_IS_NONBLOCKING_PIPE && b == FD_IS_BLOCKING_PIPE))
+
+                                        /* splice() only works if one of the fds is a pipe. If neither is,
+                                         * let's skip this step right-away. As mentioned above, if one of the
+                                         * two fds refers to a blocking pipe and the other to a non-blocking
+                                         * pipe, we can't use splice() either, hence don't try either. This
+                                         * hence means we can only use splice() if either only one of the two
+                                         * fds is a pipe, or if both are pipes with the same nonblocking flag
+                                         * setting. */
+
+                                        try_splice = false;
+                                else
+                                        nonblock_pipe = a == FD_IS_NONBLOCKING_PIPE || b == FD_IS_NONBLOCKING_PIPE;
+                        }
+                }
+
+                if (try_splice) {
+                        n = splice(fdf, NULL, fdt, NULL, m, nonblock_pipe ? SPLICE_F_NONBLOCK : 0);
+                        if (n < 0) {
+                                if (!IN_SET(errno, EINVAL, ENOSYS))
+                                        return -errno;
+
+                                try_splice = false;
+                                /* use fallback below */
+                        } else if (n == 0) { /* likely EOF */
+
+                                if (copied_something)
+                                        break;
+
+                                try_splice = false; /* same logic as above for copy_file_range() + sendfile() */
+                        } else
+                                /* Success! */
+                                goto next;
+                }
+
+                /* As a fallback just copy bits by hand */
+                {
+                        uint8_t buf[MIN(m, COPY_BUFFER_SIZE)], *p = buf;
+                        ssize_t z;
+
+                        n = read(fdf, buf, sizeof buf);
+                        if (n < 0)
+                                return -errno;
+                        if (n == 0) /* EOF */
+                                break;
+
+                        z = (size_t) n;
+                        do {
+                                ssize_t k;
+
+                                k = write(fdt, p, z);
+                                if (k < 0) {
+                                        r = -errno;
+
+                                        if (ret_remains) {
+                                                void *copy;
+
+                                                copy = memdup(p, z);
+                                                if (!copy)
+                                                        return -ENOMEM;
+
+                                                *ret_remains = copy;
+                                        }
+
+                                        if (ret_remains_size)
+                                                *ret_remains_size = z;
+
+                                        return r;
+                                }
+
+                                assert(k <= z);
+                                z -= k;
+                                p += k;
+                        } while (z > 0);
+                }
+
+        next:
+                if (progress) {
+                        r = progress(n, userdata);
+                        if (r < 0)
+                                return r;
+                }
+
+                if (max_bytes != UINT64_MAX) {
+                        assert(max_bytes >= (uint64_t) n);
+                        max_bytes -= n;
+                }
+
+                /* sendfile accepts at most SSIZE_MAX-offset bytes to copy, so reduce our maximum by the
+                 * amount we already copied, but don't go below our copy buffer size, unless we are close the
+                 * limit of bytes we are allowed to copy. */
+                m = MAX(MIN(COPY_BUFFER_SIZE, max_bytes), m - n);
+
+                copied_something = true;
+        }
+
+        if (copy_flags & COPY_TRUNCATE) {
+                off_t off = lseek(fdt, 0, SEEK_CUR);
+                if (off < 0)
+                        return -errno;
+
+                if (ftruncate(fdt, off) < 0)
+                        return -errno;
+        }
+
+        return max_bytes <= 0; /* return 0 if we hit EOF earlier than the size limit */
+}
+
+static int fd_copy_symlink(
+                int df,
+                const char *from,
+                const struct stat *st,
+                int dt,
+                const char *to,
+                uid_t override_uid,
+                gid_t override_gid,
+                CopyFlags copy_flags) {
+
+        _cleanup_free_ char *target = NULL;
+        int r;
+
+        assert(from);
+        assert(st);
+        assert(to);
+
+        r = readlinkat_malloc(df, from, &target);
+        if (r < 0)
+                return r;
+
+        if (copy_flags & COPY_MAC_CREATE) {
+                r = mac_selinux_create_file_prepare_at(dt, to, S_IFLNK);
+                if (r < 0)
+                        return r;
+        }
+        r = RET_NERRNO(symlinkat(target, dt, to));
+        if (copy_flags & COPY_MAC_CREATE)
+                mac_selinux_create_file_clear();
+        if (r < 0) {
+                if (FLAGS_SET(copy_flags, COPY_GRACEFUL_WARN) && (ERRNO_IS_PRIVILEGE(r) || ERRNO_IS_NOT_SUPPORTED(r))) {
+                        log_notice_errno(r, "Failed to copy symlink '%s', ignoring: %m", from);
+                        return 0;
+                }
+
+                return r;
+        }
+
+        if (fchownat(dt, to,
+                     uid_is_valid(override_uid) ? override_uid : st->st_uid,
+                     gid_is_valid(override_gid) ? override_gid : st->st_gid,
+                     AT_SYMLINK_NOFOLLOW) < 0)
+                r = -errno;
+
+        (void) copy_xattr(df, from, dt, to, copy_flags);
+        (void) utimensat(dt, to, (struct timespec[]) { st->st_atim, st->st_mtim }, AT_SYMLINK_NOFOLLOW);
+        return r;
+}
+
+/* Encapsulates the database we store potential hardlink targets in */
+typedef struct HardlinkContext {
+        int dir_fd;    /* An fd to the directory we use as lookup table. Never AT_FDCWD. Lazily created, when
+                        * we add the first entry. */
+
+        /* These two fields are used to create the hardlink repository directory above — via
+         * mkdirat(parent_fd, subdir) — and are kept so that we can automatically remove the directory again
+         * when we are done. */
+        int parent_fd; /* Possibly AT_FDCWD */
+        char *subdir;
+} HardlinkContext;
+
+static int hardlink_context_setup(
+                HardlinkContext *c,
+                int dt,
+                const char *to,
+                CopyFlags copy_flags) {
+
+        _cleanup_close_ int dt_copy = -EBADF;
+        int r;
+
+        assert(c);
+        assert(c->dir_fd < 0 && c->dir_fd != AT_FDCWD);
+        assert(c->parent_fd < 0);
+        assert(!c->subdir);
+
+        /* If hardlink recreation is requested we have to maintain a database of inodes that are potential
+         * hardlink sources. Given that generally disk sizes have to be assumed to be larger than what fits
+         * into physical RAM we cannot maintain that database in dynamic memory alone. Here we opt to
+         * maintain it on disk, to simplify things: inside the destination directory we'll maintain a
+         * temporary directory consisting of hardlinks of every inode we copied that might be subject of
+         * hardlinks. We can then use that as hardlink source later on. Yes, this means additional disk IO
+         * but thankfully Linux is optimized for this kind of thing. If this ever becomes a performance
+         * bottleneck we can certainly place an in-memory hash table in front of this, but for the beginning,
+         * let's keep things simple, and just use the disk as lookup table for inodes.
+         *
+         * Note that this should have zero performance impact as long as .n_link of all files copied remains
+         * <= 0, because in that case we will not actually allocate the hardlink inode lookup table directory
+         * on disk (we do so lazily, when the first candidate with .n_link > 1 is seen). This means, in the
+         * common case where hardlinks are not used at all or only for few files the fact that we store the
+         * table on disk shouldn't matter perfomance-wise. */
+
+        if (!FLAGS_SET(copy_flags, COPY_HARDLINKS))
+                return 0;
+
+        if (dt == AT_FDCWD)
+                dt_copy = AT_FDCWD;
+        else if (dt < 0)
+                return -EBADF;
+        else {
+                dt_copy = fcntl(dt, F_DUPFD_CLOEXEC, 3);
+                if (dt_copy < 0)
+                        return -errno;
+        }
+
+        r = tempfn_random_child(to, "hardlink", &c->subdir);
+        if (r < 0)
+                return r;
+
+        c->parent_fd = TAKE_FD(dt_copy);
+
+        /* We don't actually create the directory we keep the table in here, that's done on-demand when the
+         * first entry is added, using hardlink_context_realize() below. */
+        return 1;
+}
+
+static int hardlink_context_realize(HardlinkContext *c) {
+        if (!c)
+                return 0;
+
+        if (c->dir_fd >= 0) /* Already realized */
+                return 1;
+
+        if (c->parent_fd < 0 && c->parent_fd != AT_FDCWD) /* Not configured */
+                return 0;
+
+        assert(c->subdir);
+
+        c->dir_fd = open_mkdir_at(c->parent_fd, c->subdir, O_EXCL|O_CLOEXEC, 0700);
+        if (c->dir_fd < 0)
+                return c->dir_fd;
+
+        return 1;
+}
+
+static void hardlink_context_destroy(HardlinkContext *c) {
+        int r;
+
+        assert(c);
+
+        /* Automatically remove the hardlink lookup table directory again after we are done. This is used via
+         * _cleanup_() so that we really delete this, even on failure. */
+
+        if (c->dir_fd >= 0) {
+                /* <dir_fd> might be have already been used for reading, so we need to rewind it. */
+                if (lseek(c->dir_fd, 0, SEEK_SET) < 0)
+                        log_debug_errno(errno, "Failed to lseek on file descriptor, ignoring: %m");
+
+                r = rm_rf_children(TAKE_FD(c->dir_fd), REMOVE_PHYSICAL, NULL); /* consumes dir_fd in all cases, even on failure */
+                if (r < 0)
+                        log_debug_errno(r, "Failed to remove hardlink store (%s) contents, ignoring: %m", c->subdir);
+
+                assert(c->parent_fd >= 0 || c->parent_fd == AT_FDCWD);
+                assert(c->subdir);
+
+                if (unlinkat(c->parent_fd, c->subdir, AT_REMOVEDIR) < 0)
+                        log_debug_errno(errno, "Failed to remove hardlink store (%s) directory, ignoring: %m", c->subdir);
+        }
+
+        assert_cc(AT_FDCWD < 0);
+        c->parent_fd = safe_close(c->parent_fd);
+
+        c->subdir = mfree(c->subdir);
+}
+
+static int try_hardlink(
+                HardlinkContext *c,
+                const struct stat *st,
+                int dt,
+                const char *to) {
+
+        char dev_ino[DECIMAL_STR_MAX(dev_t)*2 + DECIMAL_STR_MAX(uint64_t) + 4];
+
+        assert(st);
+        assert(dt >= 0 || dt == AT_FDCWD);
+        assert(to);
+
+        if (!c) /* No temporary hardlink directory, don't bother */
+                return 0;
+
+        if (st->st_nlink <= 1) /* Source not hardlinked, don't bother */
+                return 0;
+
+        if (c->dir_fd < 0) /* not yet realized, hence empty */
+                return 0;
+
+        xsprintf(dev_ino, "%u:%u:%" PRIu64, major(st->st_dev), minor(st->st_dev), (uint64_t) st->st_ino);
+        if (linkat(c->dir_fd, dev_ino, dt, to, 0) < 0)  {
+                if (errno != ENOENT) /* doesn't exist in store yet */
+                        log_debug_errno(errno, "Failed to hardlink %s to %s, ignoring: %m", dev_ino, to);
+                return 0;
+        }
+
+        return 1;
+}
+
+static int memorize_hardlink(
+                HardlinkContext *c,
+                const struct stat *st,
+                int dt,
+                const char *to) {
+
+        char dev_ino[DECIMAL_STR_MAX(dev_t)*2 + DECIMAL_STR_MAX(uint64_t) + 4];
+        int r;
+
+        assert(st);
+        assert(dt >= 0 || dt == AT_FDCWD);
+        assert(to);
+
+        if (!c) /* No temporary hardlink directory, don't bother */
+                return 0;
+
+        if (st->st_nlink <= 1) /* Source not hardlinked, don't bother */
+                return 0;
+
+        r = hardlink_context_realize(c); /* Create the hardlink store lazily */
+        if (r < 0)
+                return r;
+
+        xsprintf(dev_ino, "%u:%u:%" PRIu64, major(st->st_dev), minor(st->st_dev), (uint64_t) st->st_ino);
+        if (linkat(dt, to, c->dir_fd, dev_ino, 0) < 0) {
+                log_debug_errno(errno, "Failed to hardlink %s to %s, ignoring: %m", to, dev_ino);
+                return 0;
+        }
+
+        return 1;
+}
+
+static int fd_copy_tree_generic(
+                int df,
+                const char *from,
+                const struct stat *st,
+                int dt,
+                const char *to,
+                dev_t original_device,
+                unsigned depth_left,
+                uid_t override_uid,
+                gid_t override_gid,
+                CopyFlags copy_flags,
+                Hashmap *denylist,
+                Set *subvolumes,
+                HardlinkContext *hardlink_context,
+                const char *display_path,
+                copy_progress_path_t progress_path,
+                copy_progress_bytes_t progress_bytes,
+                void *userdata);
+
+static int fd_copy_regular(
+                int df,
+                const char *from,
+                const struct stat *st,
+                int dt,
+                const char *to,
+                uid_t override_uid,
+                gid_t override_gid,
+                CopyFlags copy_flags,
+                HardlinkContext *hardlink_context,
+                copy_progress_bytes_t progress,
+                void *userdata) {
+
+        _cleanup_close_ int fdf = -EBADF, fdt = -EBADF;
+        int r, q;
+
+        assert(from);
+        assert(st);
+        assert(to);
+
+        r = try_hardlink(hardlink_context, st, dt, to);
+        if (r < 0)
+                return r;
+        if (r > 0) /* worked! */
+                return 0;
+
+        fdf = openat(df, from, O_RDONLY|O_CLOEXEC|O_NOCTTY|O_NOFOLLOW);
+        if (fdf < 0)
+                return -errno;
+
+        if (copy_flags & COPY_MAC_CREATE) {
+                r = mac_selinux_create_file_prepare_at(dt, to, S_IFREG);
+                if (r < 0)
+                        return r;
+        }
+        fdt = openat(dt, to, O_WRONLY|O_CREAT|O_EXCL|O_CLOEXEC|O_NOCTTY|O_NOFOLLOW, st->st_mode & 07777);
+        if (copy_flags & COPY_MAC_CREATE)
+                mac_selinux_create_file_clear();
+        if (fdt < 0)
+                return -errno;
+
+        r = copy_bytes_full(fdf, fdt, UINT64_MAX, copy_flags, NULL, NULL, progress, userdata);
+        if (r < 0)
+                goto fail;
+
+        if (fchown(fdt,
+                   uid_is_valid(override_uid) ? override_uid : st->st_uid,
+                   gid_is_valid(override_gid) ? override_gid : st->st_gid) < 0)
+                r = -errno;
+
+        if (fchmod(fdt, st->st_mode & 07777) < 0)
+                r = -errno;
+
+        (void) futimens(fdt, (struct timespec[]) { st->st_atim, st->st_mtim });
+        (void) copy_xattr(fdf, NULL, fdt, NULL, copy_flags);
+
+        if (copy_flags & COPY_FSYNC) {
+                if (fsync(fdt) < 0) {
+                        r = -errno;
+                        goto fail;
+                }
+        }
+
+        q = close_nointr(TAKE_FD(fdt)); /* even if this fails, the fd is now invalidated */
+        if (q < 0) {
+                r = q;
+                goto fail;
+        }
+
+        (void) memorize_hardlink(hardlink_context, st, dt, to);
+        return r;
+
+fail:
+        (void) unlinkat(dt, to, 0);
+        return r;
+}
+
+static int fd_copy_fifo(
+                int df,
+                const char *from,
+                const struct stat *st,
+                int dt,
+                const char *to,
+                uid_t override_uid,
+                gid_t override_gid,
+                CopyFlags copy_flags,
+                HardlinkContext *hardlink_context) {
+        int r;
+
+        assert(from);
+        assert(st);
+        assert(to);
+
+        r = try_hardlink(hardlink_context, st, dt, to);
+        if (r < 0)
+                return r;
+        if (r > 0) /* worked! */
+                return 0;
+
+        if (copy_flags & COPY_MAC_CREATE) {
+                r = mac_selinux_create_file_prepare_at(dt, to, S_IFIFO);
+                if (r < 0)
+                        return r;
+        }
+        r = RET_NERRNO(mkfifoat(dt, to, st->st_mode & 07777));
+        if (copy_flags & COPY_MAC_CREATE)
+                mac_selinux_create_file_clear();
+        if (FLAGS_SET(copy_flags, COPY_GRACEFUL_WARN) && (ERRNO_IS_NEG_PRIVILEGE(r) || ERRNO_IS_NEG_NOT_SUPPORTED(r))) {
+                log_notice_errno(r, "Failed to copy fifo '%s', ignoring: %m", from);
+                return 0;
+        } else if (r < 0)
+                return r;
+
+        if (fchownat(dt, to,
+                     uid_is_valid(override_uid) ? override_uid : st->st_uid,
+                     gid_is_valid(override_gid) ? override_gid : st->st_gid,
+                     AT_SYMLINK_NOFOLLOW) < 0)
+                r = -errno;
+
+        if (fchmodat(dt, to, st->st_mode & 07777, 0) < 0)
+                r = -errno;
+
+        (void) utimensat(dt, to, (struct timespec[]) { st->st_atim, st->st_mtim }, AT_SYMLINK_NOFOLLOW);
+
+        (void) memorize_hardlink(hardlink_context, st, dt, to);
+        return r;
+}
+
+static int fd_copy_node(
+                int df,
+                const char *from,
+                const struct stat *st,
+                int dt,
+                const char *to,
+                uid_t override_uid,
+                gid_t override_gid,
+                CopyFlags copy_flags,
+                HardlinkContext *hardlink_context) {
+        int r;
+
+        assert(from);
+        assert(st);
+        assert(to);
+
+        r = try_hardlink(hardlink_context, st, dt, to);
+        if (r < 0)
+                return r;
+        if (r > 0) /* worked! */
+                return 0;
+
+        if (copy_flags & COPY_MAC_CREATE) {
+                r = mac_selinux_create_file_prepare_at(dt, to, st->st_mode & S_IFMT);
+                if (r < 0)
+                        return r;
+        }
+        r = RET_NERRNO(mknodat(dt, to, st->st_mode, st->st_rdev));
+        if (copy_flags & COPY_MAC_CREATE)
+                mac_selinux_create_file_clear();
+        if (FLAGS_SET(copy_flags, COPY_GRACEFUL_WARN) && (ERRNO_IS_NEG_PRIVILEGE(r) || ERRNO_IS_NEG_NOT_SUPPORTED(r))) {
+                log_notice_errno(r, "Failed to copy node '%s', ignoring: %m", from);
+                return 0;
+        } else if (r < 0)
+                return r;
+
+        if (fchownat(dt, to,
+                     uid_is_valid(override_uid) ? override_uid : st->st_uid,
+                     gid_is_valid(override_gid) ? override_gid : st->st_gid,
+                     AT_SYMLINK_NOFOLLOW) < 0)
+                r = -errno;
+
+        if (fchmodat(dt, to, st->st_mode & 07777, 0) < 0)
+                r = -errno;
+
+        (void) utimensat(dt, to, (struct timespec[]) { st->st_atim, st->st_mtim }, AT_SYMLINK_NOFOLLOW);
+
+        (void) memorize_hardlink(hardlink_context, st, dt, to);
+        return r;
+}
+
+static int fd_copy_directory(
+                int df,
+                const char *from,
+                const struct stat *st,
+                int dt,
+                const char *to,
+                dev_t original_device,
+                unsigned depth_left,
+                uid_t override_uid,
+                gid_t override_gid,
+                CopyFlags copy_flags,
+                Hashmap *denylist,
+                Set *subvolumes,
+                HardlinkContext *hardlink_context,
+                const char *display_path,
+                copy_progress_path_t progress_path,
+                copy_progress_bytes_t progress_bytes,
+                void *userdata) {
+
+        _cleanup_(hardlink_context_destroy) HardlinkContext our_hardlink_context = {
+                .dir_fd = -EBADF,
+                .parent_fd = -EBADF,
+        };
+
+        _cleanup_close_ int fdf = -EBADF, fdt = -EBADF;
+        _cleanup_closedir_ DIR *d = NULL;
+        bool exists;
+        int r;
+
+        assert(st);
+        assert(to);
+
+        if (depth_left == 0)
+                return -ENAMETOOLONG;
+
+        if (from)
+                fdf = openat(df, from, O_RDONLY|O_DIRECTORY|O_CLOEXEC|O_NOCTTY|O_NOFOLLOW);
+        else
+                fdf = fcntl(df, F_DUPFD_CLOEXEC, 3);
+        if (fdf < 0)
+                return -errno;
+
+        if (!hardlink_context) {
+                /* If recreating hardlinks is requested let's set up a context for that now. */
+                r = hardlink_context_setup(&our_hardlink_context, dt, to, copy_flags);
+                if (r < 0)
+                        return r;
+                if (r > 0) /* It's enabled and allocated, let's now use the same context for all recursive
+                            * invocations from here down */
+                        hardlink_context = &our_hardlink_context;
+        }
+
+        d = take_fdopendir(&fdf);
+        if (!d)
+                return -errno;
+
+        r = dir_is_empty_at(dt, to, /* ignore_hidden_or_backup= */ false);
+        if (r < 0 && r != -ENOENT)
+                return r;
+        if ((r > 0 && !(copy_flags & (COPY_MERGE|COPY_MERGE_EMPTY))) || (r == 0 && !FLAGS_SET(copy_flags, COPY_MERGE)))
+                return -EEXIST;
+
+        exists = r >= 0;
+
+        fdt = xopenat_lock(dt, to,
+                           O_RDONLY|O_DIRECTORY|O_CLOEXEC|O_NOCTTY|O_NOFOLLOW|(exists ? 0 : O_CREAT|O_EXCL),
+                           (copy_flags & COPY_MAC_CREATE ? XO_LABEL : 0)|(set_contains(subvolumes, st) ? XO_SUBVOLUME : 0),
+                           st->st_mode & 07777,
+                           copy_flags & COPY_LOCK_BSD ? LOCK_BSD : LOCK_NONE,
+                           LOCK_EX);
+        if (fdt < 0)
+                return fdt;
+
+        r = 0;
+
+        if (PTR_TO_INT(hashmap_get(denylist, st)) == DENY_CONTENTS) {
+                log_debug("%s is in the denylist, not recursing", from);
+                goto finish;
+        }
+
+        FOREACH_DIRENT_ALL(de, d, return -errno) {
+                const char *child_display_path = NULL;
+                _cleanup_free_ char *dp = NULL;
+                struct stat buf;
+                int q;
+
+                if (dot_or_dot_dot(de->d_name))
+                        continue;
+
+                r = look_for_signals(copy_flags);
+                if (r < 0)
+                        return r;
+
+                if (fstatat(dirfd(d), de->d_name, &buf, AT_SYMLINK_NOFOLLOW) < 0) {
+                        r = -errno;
+                        continue;
+                }
+
+                if (progress_path) {
+                        if (display_path)
+                                child_display_path = dp = path_join(display_path, de->d_name);
+                        else
+                                child_display_path = de->d_name;
+
+                        r = progress_path(child_display_path, &buf, userdata);
+                        if (r < 0)
+                                return r;
+                }
+
+                if (PTR_TO_INT(hashmap_get(denylist, &buf)) == DENY_INODE) {
+                        log_debug("%s/%s is in the denylist, ignoring", from, de->d_name);
+                        continue;
+                }
+
+                if (S_ISDIR(buf.st_mode)) {
+                        /*
+                         * Don't descend into directories on other file systems, if this is requested. We do a simple
+                         * .st_dev check here, which basically comes for free. Note that we do this check only on
+                         * directories, not other kind of file system objects, for two reason:
+                         *
+                         * • The kernel's overlayfs pseudo file system that overlays multiple real file systems
+                         *   propagates the .st_dev field of the file system a file originates from all the way up
+                         *   through the stack to stat(). It doesn't do that for directories however. This means that
+                         *   comparing .st_dev on non-directories suggests that they all are mount points. To avoid
+                         *   confusion we hence avoid relying on this check for regular files.
+                         *
+                         * • The main reason we do this check at all is to protect ourselves from bind mount cycles,
+                         *   where we really want to avoid descending down in all eternity. However the .st_dev check
+                         *   is usually not sufficient for this protection anyway, as bind mount cycles from the same
+                         *   file system onto itself can't be detected that way. (Note we also do a recursion depth
+                         *   check, which is probably the better protection in this regard, which is why
+                         *   COPY_SAME_MOUNT is optional).
+                         */
+
+                        if (FLAGS_SET(copy_flags, COPY_SAME_MOUNT)) {
+                                if (buf.st_dev != original_device)
+                                        continue;
+
+                                r = fd_is_mount_point(dirfd(d), de->d_name, 0);
+                                if (r < 0)
+                                        return r;
+                                if (r > 0)
+                                        continue;
+                        }
+                }
+
+                q = fd_copy_tree_generic(dirfd(d), de->d_name, &buf, fdt, de->d_name, original_device,
+                                         depth_left-1, override_uid, override_gid, copy_flags & ~COPY_LOCK_BSD,
+                                         denylist, subvolumes, hardlink_context, child_display_path, progress_path,
+                                         progress_bytes, userdata);
+
+                if (q == -EINTR) /* Propagate SIGINT/SIGTERM up instantly */
+                        return q;
+                if (q == -EEXIST && (copy_flags & COPY_MERGE))
+                        q = 0;
+                if (q < 0)
+                        r = q;
+        }
+
+finish:
+        if (!exists) {
+                if (fchown(fdt,
+                           uid_is_valid(override_uid) ? override_uid : st->st_uid,
+                           gid_is_valid(override_gid) ? override_gid : st->st_gid) < 0)
+                        r = -errno;
+
+                if (fchmod(fdt, st->st_mode & 07777) < 0)
+                        r = -errno;
+
+                (void) copy_xattr(dirfd(d), NULL, fdt, NULL, copy_flags);
+                (void) futimens(fdt, (struct timespec[]) { st->st_atim, st->st_mtim });
+        }
+
+        if (copy_flags & COPY_FSYNC_FULL) {
+                if (fsync(fdt) < 0)
+                        return -errno;
+        }
+
+        if (r < 0)
+                return r;
+
+        return copy_flags & COPY_LOCK_BSD ? TAKE_FD(fdt) : 0;
+}
+
+static int fd_copy_leaf(
+                int df,
+                const char *from,
+                const struct stat *st,
+                int dt,
+                const char *to,
+                uid_t override_uid,
+                gid_t override_gid,
+                CopyFlags copy_flags,
+                HardlinkContext *hardlink_context,
+                const char *display_path,
+                copy_progress_bytes_t progress_bytes,
+                void *userdata) {
+        int r;
+
+        if (S_ISREG(st->st_mode))
+                r = fd_copy_regular(df, from, st, dt, to, override_uid, override_gid, copy_flags, hardlink_context, progress_bytes, userdata);
+        else if (S_ISLNK(st->st_mode))
+                r = fd_copy_symlink(df, from, st, dt, to, override_uid, override_gid, copy_flags);
+        else if (S_ISFIFO(st->st_mode))
+                r = fd_copy_fifo(df, from, st, dt, to, override_uid, override_gid, copy_flags, hardlink_context);
+        else if (S_ISBLK(st->st_mode) || S_ISCHR(st->st_mode) || S_ISSOCK(st->st_mode))
+                r = fd_copy_node(df, from, st, dt, to, override_uid, override_gid, copy_flags, hardlink_context);
+        else
+                r = -EOPNOTSUPP;
+
+        return r;
+}
+
+static int fd_copy_tree_generic(
+                int df,
+                const char *from,
+                const struct stat *st,
+                int dt,
+                const char *to,
+                dev_t original_device,
+                unsigned depth_left,
+                uid_t override_uid,
+                gid_t override_gid,
+                CopyFlags copy_flags,
+                Hashmap *denylist,
+                Set *subvolumes,
+                HardlinkContext *hardlink_context,
+                const char *display_path,
+                copy_progress_path_t progress_path,
+                copy_progress_bytes_t progress_bytes,
+                void *userdata) {
+
+        int r;
+
+        assert(!FLAGS_SET(copy_flags, COPY_LOCK_BSD));
+
+        if (S_ISDIR(st->st_mode))
+                return fd_copy_directory(df, from, st, dt, to, original_device, depth_left-1, override_uid,
+                                         override_gid, copy_flags, denylist, subvolumes, hardlink_context,
+                                         display_path, progress_path, progress_bytes, userdata);
+
+        DenyType t = PTR_TO_INT(hashmap_get(denylist, st));
+        if (t == DENY_INODE) {
+                log_debug("%s is in the denylist, ignoring", from);
+                return 0;
+        } else if (t == DENY_CONTENTS)
+                log_debug("%s is configured to have its contents excluded, but is not a directory", from);
+
+        r = fd_copy_leaf(df, from, st, dt, to, override_uid, override_gid, copy_flags, hardlink_context, display_path, progress_bytes, userdata);
+        /* We just tried to copy a leaf node of the tree. If it failed because the node already exists *and* the COPY_REPLACE flag has been provided, we should unlink the node and re-copy. */
+        if (r == -EEXIST && (copy_flags & COPY_REPLACE)) {
+                /* This codepath is us trying to address an error to copy, if the unlink fails, lets just return the original error. */
+                if (unlinkat(dt, to, 0) < 0)
+                        return r;
+
+                r = fd_copy_leaf(df, from, st, dt, to, override_uid, override_gid, copy_flags, hardlink_context, display_path, progress_bytes, userdata);
+        }
+
+        return r;
+}
+
+int copy_tree_at_full(
+                int fdf,
+                const char *from,
+                int fdt,
+                const char *to,
+                uid_t override_uid,
+                gid_t override_gid,
+                CopyFlags copy_flags,
+                Hashmap *denylist,
+                Set *subvolumes,
+                copy_progress_path_t progress_path,
+                copy_progress_bytes_t progress_bytes,
+                void *userdata) {
+
+        struct stat st;
+        int r;
+
+        assert(from);
+        assert(to);
+        assert(!FLAGS_SET(copy_flags, COPY_LOCK_BSD));
+
+        if (fstatat(fdf, from, &st, AT_SYMLINK_NOFOLLOW) < 0)
+                return -errno;
+
+        r = fd_copy_tree_generic(fdf, from, &st, fdt, to, st.st_dev, COPY_DEPTH_MAX, override_uid,
+                                 override_gid, copy_flags, denylist, subvolumes, NULL, NULL, progress_path,
+                                 progress_bytes, userdata);
+        if (r < 0)
+                return r;
+
+        if (S_ISDIR(st.st_mode) && (copy_flags & COPY_SYNCFS)) {
+                /* If the top-level inode is a directory run syncfs() now. */
+                r = syncfs_path(fdt, to);
+                if (r < 0)
+                        return r;
+        } else if ((copy_flags & (COPY_FSYNC_FULL|COPY_SYNCFS)) != 0) {
+                /* fsync() the parent dir of what we just copied if COPY_FSYNC_FULL is set. Also do this in
+                 * case COPY_SYNCFS is set but the top-level inode wasn't actually a directory. We do this so that
+                 * COPY_SYNCFS provides reasonable synchronization semantics on any kind of inode: when the
+                 * copy operation is done the whole inode — regardless of its type — and all its children
+                 * will be synchronized to disk. */
+                r = fsync_parent_at(fdt, to);
+                if (r < 0)
+                        return r;
+        }
+
+        return 0;
+}
+
+static int sync_dir_by_flags(int dir_fd, const char *path, CopyFlags copy_flags) {
+        assert(dir_fd >= 0 || dir_fd == AT_FDCWD);
+        assert(path);
+
+        if (copy_flags & COPY_SYNCFS)
+                return syncfs_path(dir_fd, path);
+        if (copy_flags & COPY_FSYNC_FULL)
+                return fsync_parent_at(dir_fd, path);
+
+        return 0;
+}
+
+int copy_directory_at_full(
+                int dir_fdf,
+                const char *from,
+                int dir_fdt,
+                const char *to,
+                CopyFlags copy_flags,
+                copy_progress_path_t progress_path,
+                copy_progress_bytes_t progress_bytes,
+                void *userdata) {
+
+        _cleanup_close_ int fdt = -EBADF;
+        struct stat st;
+        int r;
+
+        assert(dir_fdf >= 0 || dir_fdf == AT_FDCWD);
+        assert(dir_fdt >= 0 || dir_fdt == AT_FDCWD);
+        assert(to);
+
+        if (fstatat(dir_fdf, strempty(from), &st, AT_SYMLINK_NOFOLLOW|(isempty(from) ? AT_EMPTY_PATH : 0)) < 0)
+                return -errno;
+
+        r = stat_verify_directory(&st);
+        if (r < 0)
+                return r;
+
+        r = fd_copy_directory(
+                        dir_fdf, from,
+                        &st,
+                        dir_fdt, to,
+                        st.st_dev,
+                        COPY_DEPTH_MAX,
+                        UID_INVALID, GID_INVALID,
+                        copy_flags,
+                        NULL, NULL, NULL, NULL,
+                        progress_path,
+                        progress_bytes,
+                        userdata);
+        if (r < 0)
+                return r;
+
+        if (FLAGS_SET(copy_flags, COPY_LOCK_BSD))
+                fdt = r;
+
+        r = sync_dir_by_flags(dir_fdt, to, copy_flags);
+        if (r < 0)
+                return r;
+
+        return FLAGS_SET(copy_flags, COPY_LOCK_BSD) ? TAKE_FD(fdt) : 0;
+}
+
+int copy_file_fd_at_full(
+                int dir_fdf,
+                const char *from,
+                int fdt,
+                CopyFlags copy_flags,
+                copy_progress_bytes_t progress_bytes,
+                void *userdata) {
+
+        _cleanup_close_ int fdf = -EBADF;
+        struct stat st;
+        int r;
+
+        assert(dir_fdf >= 0 || dir_fdf == AT_FDCWD);
+        assert(from);
+        assert(fdt >= 0);
+        assert(!FLAGS_SET(copy_flags, COPY_LOCK_BSD));
+
+        fdf = openat(dir_fdf, from, O_RDONLY|O_CLOEXEC|O_NOCTTY);
+        if (fdf < 0)
+                return -errno;
+
+        r = fd_verify_regular(fdf);
+        if (r < 0)
+                return r;
+
+        if (fstat(fdt, &st) < 0)
+                return -errno;
+
+        r = copy_bytes_full(fdf, fdt, UINT64_MAX, copy_flags, NULL, NULL, progress_bytes, userdata);
+        if (r < 0)
+                return r;
+
+        /* Make sure to copy file attributes only over if target is a regular
+         * file (so that copying a file to /dev/null won't alter the access
+         * mode/ownership of that device node...) */
+        if (S_ISREG(st.st_mode)) {
+                (void) copy_times(fdf, fdt, copy_flags);
+                (void) copy_xattr(fdf, NULL, fdt, NULL, copy_flags);
+        }
+
+        if (copy_flags & COPY_FSYNC_FULL) {
+                r = fsync_full(fdt);
+                if (r < 0)
+                        return r;
+        } else if (copy_flags & COPY_FSYNC) {
+                if (fsync(fdt) < 0)
+                        return -errno;
+        }
+
+        return 0;
+}
+
+int copy_file_at_full(
+                int dir_fdf,
+                const char *from,
+                int dir_fdt,
+                const char *to,
+                int flags,
+                mode_t mode,
+                unsigned chattr_flags,
+                unsigned chattr_mask,
+                CopyFlags copy_flags,
+                copy_progress_bytes_t progress_bytes,
+                void *userdata) {
+
+        _cleanup_close_ int fdf = -EBADF, fdt = -EBADF;
+        struct stat st;
+        int r;
+
+        assert(dir_fdf >= 0 || dir_fdf == AT_FDCWD);
+        assert(dir_fdt >= 0 || dir_fdt == AT_FDCWD);
+        assert(from);
+        assert(to);
+
+        fdf = openat(dir_fdf, from, O_RDONLY|O_CLOEXEC|O_NOCTTY);
+        if (fdf < 0)
+                return -errno;
+
+        if (fstat(fdf, &st) < 0)
+                return -errno;
+
+        r = stat_verify_regular(&st);
+        if (r < 0)
+                return r;
+
+        WITH_UMASK(0000) {
+                fdt = xopenat_lock(dir_fdt, to,
+                                   flags|O_WRONLY|O_CREAT|O_CLOEXEC|O_NOCTTY,
+                                   (copy_flags & COPY_MAC_CREATE ? XO_LABEL : 0),
+                                   mode != MODE_INVALID ? mode : st.st_mode,
+                                   copy_flags & COPY_LOCK_BSD ? LOCK_BSD : LOCK_NONE, LOCK_EX);
+                if (fdt < 0)
+                        return fdt;
+        }
+
+        if (!FLAGS_SET(flags, O_EXCL)) { /* if O_EXCL was used we created the thing as regular file, no need to check again */
+                r = fd_verify_regular(fdt);
+                if (r < 0)
+                        goto fail;
+        }
+
+        if (chattr_mask != 0)
+                (void) chattr_fd(fdt, chattr_flags, chattr_mask & CHATTR_EARLY_FL, NULL);
+
+        r = copy_bytes_full(fdf, fdt, UINT64_MAX, copy_flags & ~COPY_LOCK_BSD, NULL, NULL, progress_bytes, userdata);
+        if (r < 0)
+                goto fail;
+
+        (void) copy_times(fdf, fdt, copy_flags);
+        (void) copy_xattr(fdf, NULL, fdt, NULL, copy_flags);
+
+        if (chattr_mask != 0)
+                (void) chattr_fd(fdt, chattr_flags, chattr_mask & ~CHATTR_EARLY_FL, NULL);
+
+        if (copy_flags & (COPY_FSYNC|COPY_FSYNC_FULL)) {
+                if (fsync(fdt) < 0) {
+                        r = -errno;
+                        goto fail;
+                }
+        }
+
+        if (!FLAGS_SET(copy_flags, COPY_LOCK_BSD)) {
+                r = close_nointr(TAKE_FD(fdt)); /* even if this fails, the fd is now invalidated */
+                if (r < 0)
+                        goto fail;
+        }
+
+        if (copy_flags & COPY_FSYNC_FULL) {
+                r = fsync_parent_at(dir_fdt, to);
+                if (r < 0)
+                        goto fail;
+        }
+
+        return copy_flags & COPY_LOCK_BSD ? TAKE_FD(fdt) : 0;
+
+fail:
+        /* Only unlink if we definitely are the ones who created the file */
+        if (FLAGS_SET(flags, O_EXCL))
+                (void) unlinkat(dir_fdt, to, 0);
+
+        return r;
+}
+
+int copy_file_atomic_at_full(
+                int dir_fdf,
+                const char *from,
+                int dir_fdt,
+                const char *to,
+                mode_t mode,
+                unsigned chattr_flags,
+                unsigned chattr_mask,
+                CopyFlags copy_flags,
+                copy_progress_bytes_t progress_bytes,
+                void *userdata) {
+
+        _cleanup_(unlink_and_freep) char *t = NULL;
+        _cleanup_close_ int fdt = -EBADF;
+        int r;
+
+        assert(from);
+        assert(to);
+        assert(!FLAGS_SET(copy_flags, COPY_LOCK_BSD));
+
+        if (copy_flags & COPY_MAC_CREATE) {
+                r = mac_selinux_create_file_prepare_at(dir_fdt, to, S_IFREG);
+                if (r < 0)
+                        return r;
+        }
+        fdt = open_tmpfile_linkable_at(dir_fdt, to, O_WRONLY|O_CLOEXEC, &t);
+        if (copy_flags & COPY_MAC_CREATE)
+                mac_selinux_create_file_clear();
+        if (fdt < 0)
+                return fdt;
+
+        if (chattr_mask != 0)
+                (void) chattr_fd(fdt, chattr_flags, chattr_mask & CHATTR_EARLY_FL, NULL);
+
+        r = copy_file_fd_at_full(dir_fdf, from, fdt, copy_flags, progress_bytes, userdata);
+        if (r < 0)
+                return r;
+
+        if (fchmod(fdt, mode) < 0)
+                return -errno;
+
+        if ((copy_flags & (COPY_FSYNC|COPY_FSYNC_FULL))) {
+                /* Sync the file */
+                if (fsync(fdt) < 0)
+                        return -errno;
+        }
+
+        r = link_tmpfile_at(fdt, dir_fdt, t, to, (copy_flags & COPY_REPLACE) ? LINK_TMPFILE_REPLACE : 0);
+        if (r < 0)
+                return r;
+
+        t = mfree(t);
+
+        if (chattr_mask != 0)
+                (void) chattr_fd(fdt, chattr_flags, chattr_mask & ~CHATTR_EARLY_FL, NULL);
+
+        r = close_nointr(TAKE_FD(fdt)); /* even if this fails, the fd is now invalidated */
+        if (r < 0)
+                goto fail;
+
+        if (copy_flags & COPY_FSYNC_FULL) {
+                /* Sync the parent directory */
+                r = fsync_parent_at(dir_fdt, to);
+                if (r < 0)
+                        goto fail;
+        }
+
+        return 0;
+
+fail:
+        (void) unlinkat(dir_fdt, to, 0);
+        return r;
+}
+
+int copy_times(int fdf, int fdt, CopyFlags flags) {
+        struct stat st;
+
+        assert(fdf >= 0);
+        assert(fdt >= 0);
+
+        if (fstat(fdf, &st) < 0)
+                return -errno;
+
+        if (futimens(fdt, (struct timespec[2]) { st.st_atim, st.st_mtim }) < 0)
+                return -errno;
+
+        if (FLAGS_SET(flags, COPY_CRTIME)) {
+                usec_t crtime;
+
+                if (fd_getcrtime(fdf, &crtime) >= 0)
+                        (void) fd_setcrtime(fdt, crtime);
+        }
+
+        return 0;
+}
+
+int copy_access(int fdf, int fdt) {
+        struct stat st;
+
+        assert(fdf >= 0);
+        assert(fdt >= 0);
+
+        /* Copies just the access mode (and not the ownership) from fdf to fdt */
+
+        if (fstat(fdf, &st) < 0)
+                return -errno;
+
+        return RET_NERRNO(fchmod(fdt, st.st_mode & 07777));
+}
+
+int copy_rights_with_fallback(int fdf, int fdt, const char *patht) {
+        struct stat st;
+
+        assert(fdf >= 0);
+        assert(fdt >= 0);
+
+        /* Copies both access mode and ownership from fdf to fdt */
+
+        if (fstat(fdf, &st) < 0)
+                return -errno;
+
+        return fchmod_and_chown_with_fallback(fdt, patht, st.st_mode & 07777, st.st_uid, st.st_gid);
+}
+
+int copy_xattr(int df, const char *from, int dt, const char *to, CopyFlags copy_flags) {
+        _cleanup_free_ char *names = NULL;
+        int ret = 0, r;
+
+        r = listxattr_at_malloc(df, from, 0, &names);
+        if (r < 0)
+                return r;
+
+        NULSTR_FOREACH(p, names) {
+                _cleanup_free_ char *value = NULL;
+
+                if (!FLAGS_SET(copy_flags, COPY_ALL_XATTRS) && !startswith(p, "user."))
+                        continue;
+
+                r = getxattr_at_malloc(df, from, p, 0, &value);
+                if (r == -ENODATA)
+                        continue; /* gone by now */
+                if (r < 0)
+                        return r;
+
+                if (xsetxattr(dt, to, p, value, r, 0) < 0)
+                        ret = -errno;
+        }
+
+        return ret;
+}
+
+int reflink(int infd, int outfd) {
+        int r;
+
+        assert(infd >= 0);
+        assert(outfd >= 0);
+
+        /* Make sure we invoke the ioctl on a regular file, so that no device driver accidentally gets it. */
+
+        r = fd_verify_regular(outfd);
+        if (r < 0)
+                return r;
+
+        /* FICLONE was introduced in Linux 4.5 but it uses the same number as BTRFS_IOC_CLONE introduced earlier */
+
+        assert_cc(FICLONE == BTRFS_IOC_CLONE);
+
+        return RET_NERRNO(ioctl(outfd, FICLONE, infd));
+}
+
+assert_cc(sizeof(struct file_clone_range) == sizeof(struct btrfs_ioctl_clone_range_args));
+
+int reflink_range(int infd, uint64_t in_offset, int outfd, uint64_t out_offset, uint64_t sz) {
+        struct file_clone_range args = {
+                .src_fd = infd,
+                .src_offset = in_offset,
+                .src_length = sz,
+                .dest_offset = out_offset,
+        };
+        int r;
+
+        assert(infd >= 0);
+        assert(outfd >= 0);
+
+        /* Inside the kernel, FICLONE is identical to FICLONERANGE with offsets and size set to zero, let's
+         * simplify things and use the simple ioctl in that case. Also, do the same if the size is
+         * UINT64_MAX, which is how we usually encode "everything". */
+        if (in_offset == 0 && out_offset == 0 && IN_SET(sz, 0, UINT64_MAX))
+                return reflink(infd, outfd);
+
+        r = fd_verify_regular(outfd);
+        if (r < 0)
+                return r;
+
+        assert_cc(FICLONERANGE == BTRFS_IOC_CLONE_RANGE);
+
+        return RET_NERRNO(ioctl(outfd, FICLONERANGE, &args));
+}