libudev: move to top-level directory

1 files changed, 473 insertions, 0 deletions

diff --git a/libudev/libudev-queue-export.c b/libudev/libudev-queue-export.c
new file mode 100644
index 0000000000..a36ff5150a
--- /dev/null
+++ b/libudev/libudev-queue-export.c
@@ -0,0 +1,473 @@
+/*
+ * libudev - interface to udev device information
+ *
+ * Copyright (C) 2008 Kay Sievers <kay.sievers@vrfy.org>
+ * Copyright (C) 2009 Alan Jenkins <alan-jenkins@tuffmail.co.uk>
+ *
+ * This library 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.
+ */
+
+/*
+ * 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 null devpath.
+ *
+ * Example:
+ *	{1, "/devices/virtual/mem/null" },
+ *	{2, "/devices/virtual/mem/zero" },
+ *	{1, "" },
+ * Event 2 is still queued, but event 1 has been 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 <sys/stat.h>
+#include <sys/types.h>
+#include <assert.h>
+
+#include "udev.h"
+
+static int rebuild_queue_file(struct udev_queue_export *udev_queue_export);
+
+struct udev_queue_export {
+	struct udev *udev;
+	int failed_count;	/* number of failed events exported */
+	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 = calloc(1, sizeof(struct udev_queue_export));
+	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;
+}
+
+void udev_queue_export_unref(struct udev_queue_export *udev_queue_export)
+{
+	if (udev_queue_export == NULL)
+		return;
+	if (udev_queue_export->queue_file != NULL)
+		fclose(udev_queue_export->queue_file);
+	free(udev_queue_export);
+}
+
+void udev_queue_export_cleanup(struct udev_queue_export *udev_queue_export)
+{
+	char filename[UTIL_PATH_SIZE];
+
+	util_strscpyl(filename, sizeof(filename), udev_get_dev_path(udev_queue_export->udev), "/.udev/queue.tmp", NULL);
+	unlink(filename);
+
+	util_strscpyl(filename, sizeof(filename), udev_get_dev_path(udev_queue_export->udev), "/.udev/queue.bin", NULL);
+	unlink(filename);
+}
+
+
+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[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) {
+		err(udev_queue_export->udev, "queue file overflow\n");
+		return NULL;
+	}
+	devpaths = calloc(1, sizeof(struct queue_devpaths) + (range + 1) * sizeof(long));
+	if (index == NULL)
+		return NULL;
+	devpaths->devpaths_size = range + 1;
+
+	/* read all records and populate the table */
+	while(1) {
+		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:
+	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;
+	char filename[UTIL_PATH_SIZE];
+	char filename_tmp[UTIL_PATH_SIZE];
+	FILE *new_queue_file = NULL;
+	unsigned int i;
+
+	/* read old queue file */
+	if (udev_queue_export->queue_file != NULL) {
+		dbg(udev_queue_export->udev, "compacting queue file, freeing %d bytes\n",
+						udev_queue_export->waste_bytes);
+
+		devpaths = build_index(udev_queue_export);
+		if (devpaths != NULL)
+			udev_queue_export->seqnum_max += devpaths->devpaths_first;
+	}
+	if (devpaths == NULL) {
+		dbg(udev_queue_export->udev, "creating empty queue file\n");
+		udev_queue_export->queued_count = 0;
+		udev_queue_export->seqnum_max = udev_queue_export->seqnum_min;
+	}
+
+	/* create new queue file */
+	util_strscpyl(filename_tmp, sizeof(filename_tmp), udev_get_dev_path(udev_queue_export->udev), "/.udev/queue.tmp", NULL);
+	new_queue_file = fopen(filename_tmp, "w+");
+	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 */
+	util_strscpyl(filename, sizeof(filename), udev_get_dev_path(udev_queue_export->udev), "/.udev/queue.bin", NULL);
+	if (rename(filename_tmp, filename) != 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:
+	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) {
+		dbg(udev_queue_export->udev, "can't record event: queue file not available\n");
+		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 (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. */
+	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,
+	DEVICE_FAILED,
+};
+
+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;
+
+	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;
+	}
+
+	/* when the queue files grow too large, they must be garbage collected and rebuilt */
+	bytes = ftell(udev_queue_export->queue_file) + queue_record_size(devpath_len);
+
+	/* 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 && bytes > 2048) {
+		/* because 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. */
+	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 void update_failed(struct udev_queue_export *udev_queue_export,
+			  struct udev_device *udev_device, enum device_state state)
+{
+	struct udev *udev = udev_device_get_udev(udev_device);
+	char filename[UTIL_PATH_SIZE];
+	char *s;
+	size_t l;
+
+	if (state != DEVICE_FAILED && udev_queue_export->failed_count == 0)
+		return;
+
+	/* location of failed file */
+	s = filename;
+	l = util_strpcpyl(&s, sizeof(filename), udev_get_dev_path(udev_queue_export->udev), "/.udev/failed/", NULL);
+	util_path_encode(udev_device_get_devpath(udev_device), s, l);
+
+	switch (state) {
+	case DEVICE_FAILED:
+		/* record event in the failed directory */
+		if (udev_queue_export->failed_count == 0)
+			util_create_path(udev, filename);
+		udev_queue_export->failed_count++;
+
+		udev_selinux_setfscreatecon(udev, filename, S_IFLNK);
+		symlink(udev_device_get_devpath(udev_device), filename);
+		udev_selinux_resetfscreatecon(udev);
+		break;
+
+	case DEVICE_QUEUED:
+		/* delete failed file */
+		if (unlink(filename) == 0) {
+			util_delete_path(udev, filename);
+			udev_queue_export->failed_count--;
+		}
+		break;
+
+	case DEVICE_FINISHED:
+		if (udev_device_get_devpath_old(udev_device) != NULL) {
+			/* "move" event - rename failed file to current name, do not delete failed */
+			char filename_old[UTIL_PATH_SIZE];
+
+			s = filename_old;
+			l = util_strpcpyl(&s, sizeof(filename_old), udev_get_dev_path(udev_queue_export->udev), "/.udev/failed/", NULL);
+			util_path_encode(udev_device_get_devpath_old(udev_device), s, l);
+
+			if (rename(filename_old, filename) == 0)
+				info(udev, "renamed devpath, moved failed state of '%s' to %s'\n",
+				     udev_device_get_devpath_old(udev_device), udev_device_get_devpath(udev_device));
+		}
+		break;
+	}
+
+	return;
+}
+
+static int update(struct udev_queue_export *udev_queue_export,
+		  struct udev_device *udev_device, enum device_state state)
+{
+	update_failed(udev_queue_export, udev_device, 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);
+}
+
+int udev_queue_export_device_failed(struct udev_queue_export *udev_queue_export, struct udev_device *udev_device)
+{
+	return update(udev_queue_export, udev_device, DEVICE_FAILED);
+}