udev: move libudev, gudev to src/; move gudev/docs/, udev/docs/ to to docs/

1 files changed, 406 insertions, 0 deletions

diff --git a/src/libudev/libudev-queue-private.c b/src/libudev/libudev-queue-private.c
new file mode 100644
index 0000000000..ca6d229a2c
--- /dev/null
+++ b/src/libudev/libudev-queue-private.c
@@ -0,0 +1,406 @@
+/*
+ * 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 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 = 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;
+}
+
+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)
+{
+        char filename[UTIL_PATH_SIZE];
+
+        if (udev_queue_export == NULL)
+                return;
+        util_strscpyl(filename, sizeof(filename), udev_get_run_path(udev_queue_export->udev), "/queue.tmp", NULL);
+        unlink(filename);
+        util_strscpyl(filename, sizeof(filename), udev_get_run_path(udev_queue_export->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 = 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) {
+                err(udev_queue_export->udev, "queue file overflow\n");
+                return NULL;
+        }
+        devpaths = calloc(1, 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:
+        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) {
+                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 */
+        util_strscpyl(filename_tmp, sizeof(filename_tmp), udev_get_run_path(udev_queue_export->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_run_path(udev_queue_export->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)
+                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. */
+        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);
+}