1 files changed, 326 insertions, 0 deletions
diff --git a/src/import/export-tar.c b/src/import/export-tar.c
new file mode 100644
index 0000000..9e92bad
--- /dev/null
+++ b/src/import/export-tar.c
@@ -0,0 +1,326 @@
+/* SPDX-License-Identifier: LGPL-2.1-or-later */
+
+#include "sd-daemon.h"
+
+#include "alloc-util.h"
+#include "btrfs-util.h"
+#include "export-tar.h"
+#include "fd-util.h"
+#include "import-common.h"
+#include "process-util.h"
+#include "ratelimit.h"
+#include "string-util.h"
+#include "tmpfile-util.h"
+
+#define COPY_BUFFER_SIZE (16*1024)
+
+struct TarExport {
+        sd_event *event;
+
+        TarExportFinished on_finished;
+        void *userdata;
+
+        char *path;
+        char *temp_path;
+
+        int output_fd;
+        int tar_fd;
+
+        ImportCompress compress;
+
+        sd_event_source *output_event_source;
+
+        void *buffer;
+        size_t buffer_size;
+        size_t buffer_allocated;
+
+        uint64_t written_compressed;
+        uint64_t written_uncompressed;
+
+        pid_t tar_pid;
+
+        struct stat st;
+        uint64_t quota_referenced;
+
+        unsigned last_percent;
+        RateLimit progress_ratelimit;
+
+        bool eof;
+        bool tried_splice;
+};
+
+TarExport *tar_export_unref(TarExport *e) {
+        if (!e)
+                return NULL;
+
+        sd_event_source_unref(e->output_event_source);
+
+        if (e->tar_pid > 1)
+                sigkill_wait(e->tar_pid);
+
+        if (e->temp_path) {
+                (void) btrfs_subvol_remove(e->temp_path, BTRFS_REMOVE_QUOTA);
+                free(e->temp_path);
+        }
+
+        import_compress_free(&e->compress);
+
+        sd_event_unref(e->event);
+
+        safe_close(e->tar_fd);
+
+        free(e->buffer);
+        free(e->path);
+        return mfree(e);
+}
+
+int tar_export_new(
+                TarExport **ret,
+                sd_event *event,
+                TarExportFinished on_finished,
+                void *userdata) {
+
+        _cleanup_(tar_export_unrefp) TarExport *e = NULL;
+        int r;
+
+        assert(ret);
+
+        e = new(TarExport, 1);
+        if (!e)
+                return -ENOMEM;
+
+        *e = (TarExport) {
+                .output_fd = -EBADF,
+                .tar_fd = -EBADF,
+                .on_finished = on_finished,
+                .userdata = userdata,
+                .quota_referenced = UINT64_MAX,
+                .last_percent = UINT_MAX,
+                .progress_ratelimit = { 100 * USEC_PER_MSEC, 1 },
+        };
+
+        if (event)
+                e->event = sd_event_ref(event);
+        else {
+                r = sd_event_default(&e->event);
+                if (r < 0)
+                        return r;
+        }
+
+        *ret = TAKE_PTR(e);
+
+        return 0;
+}
+
+static void tar_export_report_progress(TarExport *e) {
+        unsigned percent;
+        assert(e);
+
+        /* Do we have any quota info? If not, we don't know anything about the progress */
+        if (e->quota_referenced == UINT64_MAX)
+                return;
+
+        if (e->written_uncompressed >= e->quota_referenced)
+                percent = 100;
+        else
+                percent = (unsigned) ((e->written_uncompressed * UINT64_C(100)) / e->quota_referenced);
+
+        if (percent == e->last_percent)
+                return;
+
+        if (!ratelimit_below(&e->progress_ratelimit))
+                return;
+
+        sd_notifyf(false, "X_IMPORT_PROGRESS=%u%%", percent);
+        log_info("Exported %u%%.", percent);
+
+        e->last_percent = percent;
+}
+
+static int tar_export_finish(TarExport *e) {
+        int r;
+
+        assert(e);
+        assert(e->tar_fd >= 0);
+
+        if (e->tar_pid > 0) {
+                r = wait_for_terminate_and_check("tar", TAKE_PID(e->tar_pid), WAIT_LOG);
+                if (r < 0)
+                        return r;
+                if (r != EXIT_SUCCESS)
+                        return -EPROTO;
+        }
+
+        e->tar_fd = safe_close(e->tar_fd);
+
+        return 0;
+}
+
+static int tar_export_process(TarExport *e) {
+        ssize_t l;
+        int r;
+
+        assert(e);
+
+        if (!e->tried_splice && e->compress.type == IMPORT_COMPRESS_UNCOMPRESSED) {
+
+                l = splice(e->tar_fd, NULL, e->output_fd, NULL, COPY_BUFFER_SIZE, 0);
+                if (l < 0) {
+                        if (errno == EAGAIN)
+                                return 0;
+
+                        e->tried_splice = true;
+                } else if (l == 0) {
+                        r = tar_export_finish(e);
+                        goto finish;
+                } else {
+                        e->written_uncompressed += l;
+                        e->written_compressed += l;
+
+                        tar_export_report_progress(e);
+
+                        return 0;
+                }
+        }
+
+        while (e->buffer_size <= 0) {
+                uint8_t input[COPY_BUFFER_SIZE];
+
+                if (e->eof) {
+                        r = tar_export_finish(e);
+                        goto finish;
+                }
+
+                l = read(e->tar_fd, input, sizeof(input));
+                if (l < 0) {
+                        r = log_error_errno(errno, "Failed to read tar file: %m");
+                        goto finish;
+                }
+
+                if (l == 0) {
+                        e->eof = true;
+                        r = import_compress_finish(&e->compress, &e->buffer, &e->buffer_size, &e->buffer_allocated);
+                } else {
+                        e->written_uncompressed += l;
+                        r = import_compress(&e->compress, input, l, &e->buffer, &e->buffer_size, &e->buffer_allocated);
+                }
+                if (r < 0) {
+                        r = log_error_errno(r, "Failed to encode: %m");
+                        goto finish;
+                }
+        }
+
+        l = write(e->output_fd, e->buffer, e->buffer_size);
+        if (l < 0) {
+                if (errno == EAGAIN)
+                        return 0;
+
+                r = log_error_errno(errno, "Failed to write output file: %m");
+                goto finish;
+        }
+
+        assert((size_t) l <= e->buffer_size);
+        memmove(e->buffer, (uint8_t*) e->buffer + l, e->buffer_size - l);
+        e->buffer_size -= l;
+        e->written_compressed += l;
+
+        tar_export_report_progress(e);
+
+        return 0;
+
+finish:
+        if (e->on_finished)
+                e->on_finished(e, r, e->userdata);
+        else
+                sd_event_exit(e->event, r);
+
+        return 0;
+}
+
+static int tar_export_on_output(sd_event_source *s, int fd, uint32_t revents, void *userdata) {
+        TarExport *i = userdata;
+
+        return tar_export_process(i);
+}
+
+static int tar_export_on_defer(sd_event_source *s, void *userdata) {
+        TarExport *i = userdata;
+
+        return tar_export_process(i);
+}
+
+int tar_export_start(TarExport *e, const char *path, int fd, ImportCompressType compress) {
+        _cleanup_close_ int sfd = -EBADF;
+        int r;
+
+        assert(e);
+        assert(path);
+        assert(fd >= 0);
+        assert(compress < _IMPORT_COMPRESS_TYPE_MAX);
+        assert(compress != IMPORT_COMPRESS_UNKNOWN);
+
+        if (e->output_fd >= 0)
+                return -EBUSY;
+
+        sfd = open(path, O_DIRECTORY|O_RDONLY|O_NOCTTY|O_CLOEXEC);
+        if (sfd < 0)
+                return -errno;
+
+        if (fstat(sfd, &e->st) < 0)
+                return -errno;
+
+        r = fd_nonblock(fd, true);
+        if (r < 0)
+                return r;
+
+        r = free_and_strdup(&e->path, path);
+        if (r < 0)
+                return r;
+
+        e->quota_referenced = UINT64_MAX;
+
+        if (btrfs_might_be_subvol(&e->st)) {
+                BtrfsQuotaInfo q;
+
+                r = btrfs_subvol_get_subtree_quota_fd(sfd, 0, &q);
+                if (r >= 0)
+                        e->quota_referenced = q.referenced;
+
+                e->temp_path = mfree(e->temp_path);
+
+                r = tempfn_random(path, NULL, &e->temp_path);
+                if (r < 0)
+                        return r;
+
+                /* Let's try to make a snapshot, if we can, so that the export is atomic */
+                r = btrfs_subvol_snapshot_at(sfd, NULL, AT_FDCWD, e->temp_path, BTRFS_SNAPSHOT_READ_ONLY|BTRFS_SNAPSHOT_RECURSIVE);
+                if (r < 0) {
+                        log_debug_errno(r, "Couldn't create snapshot %s of %s, not exporting atomically: %m", e->temp_path, path);
+                        e->temp_path = mfree(e->temp_path);
+                }
+        }
+
+        r = import_compress_init(&e->compress, compress);
+        if (r < 0)
+                return r;
+
+        r = sd_event_add_io(e->event, &e->output_event_source, fd, EPOLLOUT, tar_export_on_output, e);
+        if (r == -EPERM) {
+                r = sd_event_add_defer(e->event, &e->output_event_source, tar_export_on_defer, e);
+                if (r < 0)
+                        return r;
+
+                r = sd_event_source_set_enabled(e->output_event_source, SD_EVENT_ON);
+        }
+        if (r < 0)
+                return r;
+
+        e->tar_fd = import_fork_tar_c(e->temp_path ?: e->path, &e->tar_pid);
+        if (e->tar_fd < 0) {
+                e->output_event_source = sd_event_source_unref(e->output_event_source);
+                return e->tar_fd;
+        }
+
+        e->output_fd = fd;
+        return r;
+}