+++ /dev/null
-/***
- 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);
-}
~ianmdlvl / elogind.git / blobdiff