udev: remove seqnum API and all assumptions about seqnums

The way the kernel namespaces have been implemented breaks assumptions
udev made regarding uevent sequence numbers. Creating devices in a
namespace "steals" uevents and its sequence numbers from the host. It
confuses the "udevadmin settle" logic, which might block until util a
timeout is reached, even when no uevent is pending.

Remove any assumptions about sequence numbers and deprecate libudev's
API exposing these numbers; none of that can reliably be used anymore
when namespaces are involved.

1 files changed, 0 insertions, 406 deletions

diff --git a/src/libudev/libudev-queue-private.c b/src/libudev/libudev-queue-private.c
deleted file mode 100644
index d5a2b503dd..0000000000
--- a/src/libudev/libudev-queue-private.c
+++ /dev/null
@@ -1,406 +0,0 @@
-/***
-  This file is part of systemd.
-
-  Copyright 2008-2012 Kay Sievers <kay@vrfy.org>
-  Copyright 2009 Alan Jenkins <alan-jenkins@tuffmail.co.uk>
-
-  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/>.
-***/
-
-/*
- * DISCLAIMER - The file format mentioned here is private to udev/libudev,
- *              and may be changed without notice.
- *
- * The udev event queue is exported as a binary log file.
- * Each log record consists of a sequence number followed by the device path.
- *
- * When a new event is queued, its details are appended to the log.
- * When the event finishes, a second record is appended to the log
- * with the same sequence number but a devpath len of 0.
- *
- * Example:
- *        { 0x0000000000000001 }
- *        { 0x0000000000000001, 0x0019, "/devices/virtual/mem/null" },
- *        { 0x0000000000000002, 0x001b, "/devices/virtual/mem/random" },
- *        { 0x0000000000000001, 0x0000 },
- *        { 0x0000000000000003, 0x0019, "/devices/virtual/mem/zero" },
- *
- * Events 2 and 3 are still queued, but event 1 has finished.
- *
- * The queue does not grow indefinitely. It is periodically re-created
- * to remove finished events. Atomic rename() makes this transparent to readers.
- *
- * The queue file starts with a single sequence number which specifies the
- * minimum sequence number in the log that follows. Any events prior to this
- * sequence number have already finished.
- */
-
-#include <stdio.h>
-#include <stdlib.h>
-#include <string.h>
-#include <unistd.h>
-#include <fcntl.h>
-#include <dirent.h>
-#include <limits.h>
-#include <errno.h>
-#include <sys/stat.h>
-#include <sys/types.h>
-
-#include "libudev.h"
-#include "libudev-private.h"
-
-static int rebuild_queue_file(struct udev_queue_export *udev_queue_export);
-
-struct udev_queue_export {
-        struct udev *udev;
-        int queued_count;        /* number of unfinished events exported in queue file */
-        FILE *queue_file;
-        unsigned long long int seqnum_max;        /* earliest sequence number in queue file */
-        unsigned long long int seqnum_min;        /* latest sequence number in queue file */
-        int waste_bytes;                        /* queue file bytes wasted on finished events */
-};
-
-struct udev_queue_export *udev_queue_export_new(struct udev *udev)
-{
-        struct udev_queue_export *udev_queue_export;
-        unsigned long long int initial_seqnum;
-
-        if (udev == NULL)
-                return NULL;
-
-        udev_queue_export = new0(struct udev_queue_export, 1);
-        if (udev_queue_export == NULL)
-                return NULL;
-        udev_queue_export->udev = udev;
-
-        initial_seqnum = udev_get_kernel_seqnum(udev);
-        udev_queue_export->seqnum_min = initial_seqnum;
-        udev_queue_export->seqnum_max = initial_seqnum;
-
-        udev_queue_export_cleanup(udev_queue_export);
-        if (rebuild_queue_file(udev_queue_export) != 0) {
-                free(udev_queue_export);
-                return NULL;
-        }
-
-        return udev_queue_export;
-}
-
-struct udev_queue_export *udev_queue_export_unref(struct udev_queue_export *udev_queue_export)
-{
-        if (udev_queue_export == NULL)
-                return NULL;
-        if (udev_queue_export->queue_file != NULL)
-                fclose(udev_queue_export->queue_file);
-        free(udev_queue_export);
-        return NULL;
-}
-
-void udev_queue_export_cleanup(struct udev_queue_export *udev_queue_export)
-{
-        if (udev_queue_export == NULL)
-                return;
-        unlink("/run/udev/queue.tmp");
-        unlink("/run/udev/queue.bin");
-}
-
-static int skip_to(FILE *file, long offset)
-{
-        long old_offset;
-
-        /* fseek may drop buffered data, avoid it for small seeks */
-        old_offset = ftell(file);
-        if (offset > old_offset && offset - old_offset <= BUFSIZ) {
-                size_t skip_bytes = offset - old_offset;
-                char *buf = alloca(skip_bytes);
-
-                if (fread(buf, skip_bytes, 1, file) != skip_bytes)
-                        return -1;
-        }
-
-        return fseek(file, offset, SEEK_SET);
-}
-
-struct queue_devpaths {
-        unsigned int devpaths_first;        /* index of first queued event */
-        unsigned int devpaths_size;
-        long devpaths[];                /* seqnum -> offset of devpath in queue file (or 0) */
-};
-
-/*
- * Returns a table mapping seqnum to devpath file offset for currently queued events.
- * devpaths[i] represents the event with seqnum = i + udev_queue_export->seqnum_min.
- */
-static struct queue_devpaths *build_index(struct udev_queue_export *udev_queue_export)
-{
-        struct queue_devpaths *devpaths;
-        unsigned long long int range;
-        long devpath_offset;
-        ssize_t devpath_len;
-        unsigned long long int seqnum;
-        unsigned long long int n;
-        unsigned int i;
-
-        /* seek to the first event in the file */
-        rewind(udev_queue_export->queue_file);
-        udev_queue_read_seqnum(udev_queue_export->queue_file, &seqnum);
-
-        /* allocate the table */
-        range = udev_queue_export->seqnum_min - udev_queue_export->seqnum_max;
-        if (range - 1 > INT_MAX) {
-                udev_err(udev_queue_export->udev, "queue file overflow\n");
-                return NULL;
-        }
-        devpaths = malloc0(sizeof(struct queue_devpaths) + (range + 1) * sizeof(long));
-        if (devpaths == NULL)
-                return NULL;
-        devpaths->devpaths_size = range + 1;
-
-        /* read all records and populate the table */
-        for (;;) {
-                if (udev_queue_read_seqnum(udev_queue_export->queue_file, &seqnum) < 0)
-                        break;
-                n = seqnum - udev_queue_export->seqnum_max;
-                if (n >= devpaths->devpaths_size)
-                        goto read_error;
-
-                devpath_offset = ftell(udev_queue_export->queue_file);
-                devpath_len = udev_queue_skip_devpath(udev_queue_export->queue_file);
-                if (devpath_len < 0)
-                        goto read_error;
-
-                if (devpath_len > 0)
-                        devpaths->devpaths[n] = devpath_offset;
-                else
-                        devpaths->devpaths[n] = 0;
-        }
-
-        /* find first queued event */
-        for (i = 0; i < devpaths->devpaths_size; i++) {
-                if (devpaths->devpaths[i] != 0)
-                        break;
-        }
-        devpaths->devpaths_first = i;
-
-        return devpaths;
-
-read_error:
-        udev_err(udev_queue_export->udev, "queue file corrupted\n");
-        free(devpaths);
-        return NULL;
-}
-
-static int rebuild_queue_file(struct udev_queue_export *udev_queue_export)
-{
-        unsigned long long int seqnum;
-        struct queue_devpaths *devpaths = NULL;
-        FILE *new_queue_file = NULL;
-        unsigned int i;
-
-        /* read old queue file */
-        if (udev_queue_export->queue_file != NULL) {
-                devpaths = build_index(udev_queue_export);
-                if (devpaths != NULL)
-                        udev_queue_export->seqnum_max += devpaths->devpaths_first;
-        }
-        if (devpaths == NULL) {
-                udev_queue_export->queued_count = 0;
-                udev_queue_export->seqnum_max = udev_queue_export->seqnum_min;
-        }
-
-        /* create new queue file */
-        new_queue_file = fopen("/run/udev/queue.tmp", "w+e");
-        if (new_queue_file == NULL)
-                goto error;
-        seqnum = udev_queue_export->seqnum_max;
-        fwrite(&seqnum, 1, sizeof(unsigned long long int), new_queue_file);
-
-        /* copy unfinished events only to the new file */
-        if (devpaths != NULL) {
-                for (i = devpaths->devpaths_first; i < devpaths->devpaths_size; i++) {
-                        char devpath[UTIL_PATH_SIZE];
-                        int err;
-                        unsigned short devpath_len;
-
-                        if (devpaths->devpaths[i] != 0)
-                        {
-                                skip_to(udev_queue_export->queue_file, devpaths->devpaths[i]);
-                                err = udev_queue_read_devpath(udev_queue_export->queue_file, devpath, sizeof(devpath));
-                                devpath_len = err;
-
-                                fwrite(&seqnum, sizeof(unsigned long long int), 1, new_queue_file);
-                                fwrite(&devpath_len, sizeof(unsigned short), 1, new_queue_file);
-                                fwrite(devpath, 1, devpath_len, new_queue_file);
-                        }
-                        seqnum++;
-                }
-                free(devpaths);
-                devpaths = NULL;
-        }
-        fflush(new_queue_file);
-        if (ferror(new_queue_file))
-                goto error;
-
-        /* rename the new file on top of the old one */
-        if (rename("/run/udev/queue.tmp", "/run/udev/queue.bin") != 0)
-                goto error;
-
-        if (udev_queue_export->queue_file != NULL)
-                fclose(udev_queue_export->queue_file);
-        udev_queue_export->queue_file = new_queue_file;
-        udev_queue_export->waste_bytes = 0;
-
-        return 0;
-
-error:
-        udev_err(udev_queue_export->udev, "failed to create queue file: %m\n");
-        udev_queue_export_cleanup(udev_queue_export);
-
-        if (udev_queue_export->queue_file != NULL) {
-                fclose(udev_queue_export->queue_file);
-                udev_queue_export->queue_file = NULL;
-        }
-        if (new_queue_file != NULL)
-                fclose(new_queue_file);
-
-        if (devpaths != NULL)
-                free(devpaths);
-        udev_queue_export->queued_count = 0;
-        udev_queue_export->waste_bytes = 0;
-        udev_queue_export->seqnum_max = udev_queue_export->seqnum_min;
-
-        return -1;
-}
-
-static int write_queue_record(struct udev_queue_export *udev_queue_export,
-                              unsigned long long int seqnum, const char *devpath, size_t devpath_len)
-{
-        unsigned short len;
-
-        if (udev_queue_export->queue_file == NULL)
-                return -1;
-
-        if (fwrite(&seqnum, sizeof(unsigned long long int), 1, udev_queue_export->queue_file) != 1)
-                goto write_error;
-
-        len = (devpath_len < USHRT_MAX) ? devpath_len : USHRT_MAX;
-        if (fwrite(&len, sizeof(unsigned short), 1, udev_queue_export->queue_file) != 1)
-                goto write_error;
-        if (len > 0) {
-                if (fwrite(devpath, 1, len, udev_queue_export->queue_file) != len)
-                        goto write_error;
-        }
-
-        /* *must* flush output; caller may fork */
-        if (fflush(udev_queue_export->queue_file) != 0)
-                goto write_error;
-
-        return 0;
-
-write_error:
-        /* if we failed half way through writing a record to a file,
-           we should not try to write any further records to it. */
-        udev_err(udev_queue_export->udev, "error writing to queue file: %m\n");
-        fclose(udev_queue_export->queue_file);
-        udev_queue_export->queue_file = NULL;
-
-        return -1;
-}
-
-enum device_state {
-        DEVICE_QUEUED,
-        DEVICE_FINISHED,
-};
-
-static inline size_t queue_record_size(size_t devpath_len)
-{
-        return sizeof(unsigned long long int) + sizeof(unsigned short int) + devpath_len;
-}
-
-static int update_queue(struct udev_queue_export *udev_queue_export,
-                         struct udev_device *udev_device, enum device_state state)
-{
-        unsigned long long int seqnum = udev_device_get_seqnum(udev_device);
-        const char *devpath = NULL;
-        size_t devpath_len = 0;
-        int bytes;
-        int err;
-
-        /* FINISHED records have a zero length devpath */
-        if (state == DEVICE_QUEUED) {
-                devpath = udev_device_get_devpath(udev_device);
-                devpath_len = strlen(devpath);
-        }
-
-        /* recover from an earlier failed rebuild */
-        if (udev_queue_export->queue_file == NULL) {
-                if (rebuild_queue_file(udev_queue_export) != 0)
-                        return -1;
-        }
-
-        /* if we're removing the last event from the queue, that's the best time to rebuild it */
-        if (state != DEVICE_QUEUED && udev_queue_export->queued_count == 1) {
-                /* we don't need to read the old queue file */
-                fclose(udev_queue_export->queue_file);
-                udev_queue_export->queue_file = NULL;
-                rebuild_queue_file(udev_queue_export);
-                return 0;
-        }
-
-        /* try to rebuild the queue files before they grow larger than one page. */
-        bytes = ftell(udev_queue_export->queue_file) + queue_record_size(devpath_len);
-        if ((udev_queue_export->waste_bytes > bytes / 2) && bytes > 4096)
-                rebuild_queue_file(udev_queue_export);
-
-        /* don't record a finished event, if we already dropped the event in a failed rebuild */
-        if (seqnum < udev_queue_export->seqnum_max)
-                return 0;
-
-        /* now write to the queue */
-        if (state == DEVICE_QUEUED) {
-                udev_queue_export->queued_count++;
-                udev_queue_export->seqnum_min = seqnum;
-        } else {
-                udev_queue_export->waste_bytes += queue_record_size(devpath_len) + queue_record_size(0);
-                udev_queue_export->queued_count--;
-        }
-        err = write_queue_record(udev_queue_export, seqnum, devpath, devpath_len);
-
-        /* try to handle ENOSPC */
-        if (err != 0 && udev_queue_export->queued_count == 0) {
-                udev_queue_export_cleanup(udev_queue_export);
-                err = rebuild_queue_file(udev_queue_export);
-        }
-
-        return err;
-}
-
-static int update(struct udev_queue_export *udev_queue_export,
-                  struct udev_device *udev_device, enum device_state state)
-{
-        if (update_queue(udev_queue_export, udev_device, state) != 0)
-                return -1;
-
-        return 0;
-}
-
-int udev_queue_export_device_queued(struct udev_queue_export *udev_queue_export, struct udev_device *udev_device)
-{
-        return update(udev_queue_export, udev_device, DEVICE_QUEUED);
-}
-
-int udev_queue_export_device_finished(struct udev_queue_export *udev_queue_export, struct udev_device *udev_device)
-{
-        return update(udev_queue_export, udev_device, DEVICE_FINISHED);
-}