[babeltrace.git] / src / plugins / ctf / common / bfcr / bfcr.c

/*
 * SPDX-License-Identifier: MIT
 *
 * Copyright (c) 2015-2016 EfficiOS Inc. and Linux Foundation
 * Copyright (c) 2015-2016 Philippe Proulx <pproulx@efficios.com>
 *
 * Babeltrace - CTF binary field class reader (BFCR)
 */

#define BT_COMP_LOG_SELF_COMP (bfcr->self_comp)
#define BT_LOG_OUTPUT_LEVEL (bfcr->log_level)
#define BT_LOG_TAG "PLUGIN/CTF/BFCR"
#include "logging/comp-logging.h"

#include <stdlib.h>
#include <stdint.h>
#include <inttypes.h>
#include <stdio.h>
#include <stddef.h>
#include <stdbool.h>
#include "common/assert.h"
#include <string.h>
#include "compat/bitfield.h"
#include "common/common.h"
#include <babeltrace2/babeltrace.h>
#include "common/align.h"
#include <glib.h>

#include "bfcr.h"
#include "../metadata/ctf-meta.h"

#define DIV8(_x)			((_x) >> 3)
#define BYTES_TO_BITS(_x)		((_x) * 8)
#define BITS_TO_BYTES_FLOOR(_x)		DIV8(_x)
#define BITS_TO_BYTES_CEIL(_x)		DIV8((_x) + 7)
#define IN_BYTE_OFFSET(_at)		((_at) & 7)

/* A visit stack entry */
struct stack_entry {
	/*
	 * Current class of base field, one of:
	 *
	 *   * Structure
	 *   * Array
	 *   * Sequence
	 *   * Variant
	 */
	struct ctf_field_class *base_class;

	/* Length of base field (always 1 for a variant class) */
	int64_t base_len;

	/* Index of next field to read */
	int64_t index;
};

struct bt_bfcr;

/* Visit stack */
struct stack {
	struct bt_bfcr *bfcr;

	/* Entries (struct stack_entry) */
	GArray *entries;

	/* Number of active entries */
	size_t size;
};

/* Reading states */
enum bfcr_state {
	BFCR_STATE_NEXT_FIELD,
	BFCR_STATE_ALIGN_BASIC,
	BFCR_STATE_ALIGN_COMPOUND,
	BFCR_STATE_READ_BASIC_BEGIN,
	BFCR_STATE_READ_BASIC_CONTINUE,
	BFCR_STATE_DONE,
};

/* Binary class reader */
struct bt_bfcr {
	bt_logging_level log_level;

	/* Weak */
	bt_self_component *self_comp;

	/* BFCR stack */
	struct stack *stack;

	/* Current basic field class */
	struct ctf_field_class *cur_basic_field_class;

	/* Current state */
	enum bfcr_state state;

	/*
	 * Last basic field class's byte order.
	 *
	 * This is used to detect errors since two contiguous basic
	 * classes for which the common boundary is not the boundary of
	 * a byte cannot have different byte orders.
	 *
	 * This is set to CTF_BYTE_ORDER_UNKNOWN on reset and when the last
	 * basic field class was a string class.
	 */
	enum ctf_byte_order last_bo;

	/* Current byte order (copied to last_bo after a successful read) */
	enum ctf_byte_order cur_bo;

	/* Stitch buffer infos */
	struct {
		/* Stitch buffer */
		uint8_t buf[16];

		/* Offset, within stitch buffer, of first bit */
		size_t offset;

		/* Length (bits) of data in stitch buffer from offset */
		size_t at;
	} stitch;

	/* User buffer infos */
	struct {
		/* Address */
		const uint8_t *addr;

		/* Offset of data from address (bits) */
		size_t offset;

		/* Current position from offset (bits) */
		size_t at;

		/* Offset of offset within whole packet (bits) */
		size_t packet_offset;

		/* Data size in buffer (bits) */
		size_t sz;

		/* Buffer size (bytes) */
		size_t buf_sz;
	} buf;

	/* User stuff */
	struct {
		/* Callback functions */
		struct bt_bfcr_cbs cbs;

		/* Private data */
		void *data;
	} user;
};

static inline
const char *bfcr_state_string(enum bfcr_state state)
{
	switch (state) {
	case BFCR_STATE_NEXT_FIELD:
		return "NEXT_FIELD";
	case BFCR_STATE_ALIGN_BASIC:
		return "ALIGN_BASIC";
	case BFCR_STATE_ALIGN_COMPOUND:
		return "ALIGN_COMPOUND";
	case BFCR_STATE_READ_BASIC_BEGIN:
		return "READ_BASIC_BEGIN";
	case BFCR_STATE_READ_BASIC_CONTINUE:
		return "READ_BASIC_CONTINUE";
	case BFCR_STATE_DONE:
		return "DONE";
	default:
		return "(unknown)";
	}
}

static
struct stack *stack_new(struct bt_bfcr *bfcr)
{
	struct stack *stack = NULL;

	stack = g_new0(struct stack, 1);
	if (!stack) {
		BT_COMP_LOGE_STR("Failed to allocate one stack.");
		goto error;
	}

	stack->bfcr = bfcr;
	stack->entries = g_array_new(FALSE, TRUE, sizeof(struct stack_entry));
	if (!stack->entries) {
		BT_COMP_LOGE_STR("Failed to allocate a GArray.");
		goto error;
	}

	BT_COMP_LOGD("Created stack: addr=%p", stack);
	return stack;

error:
	g_free(stack);
	return NULL;
}

static
void stack_destroy(struct stack *stack)
{
	struct bt_bfcr *bfcr;

	if (!stack) {
		return;
	}

	bfcr = stack->bfcr;
	BT_COMP_LOGD("Destroying stack: addr=%p", stack);

	if (stack->entries) {
		g_array_free(stack->entries, TRUE);
	}

	g_free(stack);
}

static
int stack_push(struct stack *stack, struct ctf_field_class *base_class,
	size_t base_len)
{
	struct stack_entry *entry;
	struct bt_bfcr *bfcr;

	BT_ASSERT_DBG(stack);
	BT_ASSERT_DBG(base_class);
	bfcr = stack->bfcr;
	BT_COMP_LOGT("Pushing field class on stack: stack-addr=%p, "
		"fc-addr=%p, fc-type=%d, base-length=%zu, "
		"stack-size-before=%zu, stack-size-after=%zu",
		stack, base_class, base_class->type,
		base_len, stack->size, stack->size + 1);

	if (stack->entries->len == stack->size) {
		g_array_set_size(stack->entries, stack->size + 1);
	}

	entry = &g_array_index(stack->entries, struct stack_entry, stack->size);
	entry->base_class = base_class;
	entry->base_len = base_len;
	entry->index = 0;
	stack->size++;
	return 0;
}

static inline
int64_t get_compound_field_class_length(struct bt_bfcr *bfcr,
		struct ctf_field_class *fc)
{
	int64_t length;

	switch (fc->type) {
	case CTF_FIELD_CLASS_TYPE_STRUCT:
	{
		struct ctf_field_class_struct *struct_fc = (void *) fc;

		length = (int64_t) struct_fc->members->len;
		break;
	}
	case CTF_FIELD_CLASS_TYPE_VARIANT:
	{
		/* Variant field classes always "contain" a single class */
		length = 1;
		break;
	}
	case CTF_FIELD_CLASS_TYPE_ARRAY:
	{
		struct ctf_field_class_array *array_fc = (void *) fc;

		length = (int64_t) array_fc->length;
		break;
	}
	case CTF_FIELD_CLASS_TYPE_SEQUENCE:
		length = bfcr->user.cbs.query.get_sequence_length(fc,
			bfcr->user.data);
		break;
	default:
		bt_common_abort();
	}

	return length;
}

static
int stack_push_with_len(struct bt_bfcr *bfcr, struct ctf_field_class *base_class)
{
	int ret;
	int64_t length = get_compound_field_class_length(bfcr, base_class);

	if (length < 0) {
		BT_COMP_LOGW("Cannot get compound field class's field count: "
			"bfcr-addr=%p, fc-addr=%p, fc-type=%d",
			bfcr, base_class, base_class->type);
		ret = BT_BFCR_STATUS_ERROR;
		goto end;
	}

	ret = stack_push(bfcr->stack, base_class, (size_t) length);

end:
	return ret;
}

static inline
unsigned int stack_size(struct stack *stack)
{
	BT_ASSERT_DBG(stack);
	return stack->size;
}

static
void stack_pop(struct stack *stack)
{
	struct bt_bfcr *bfcr;

	BT_ASSERT_DBG(stack);
	BT_ASSERT_DBG(stack_size(stack));
	bfcr = stack->bfcr;
	BT_COMP_LOGT("Popping from stack: "
		"stack-addr=%p, stack-size-before=%u, stack-size-after=%u",
		stack, stack->entries->len, stack->entries->len - 1);
	stack->size--;
}

static inline
bool stack_empty(struct stack *stack)
{
	return stack_size(stack) == 0;
}

static
void stack_clear(struct stack *stack)
{
	BT_ASSERT_DBG(stack);
	stack->size = 0;
}

static inline
struct stack_entry *stack_top(struct stack *stack)
{
	BT_ASSERT_DBG(stack);
	BT_ASSERT_DBG(stack_size(stack));
	return &g_array_index(stack->entries, struct stack_entry,
		stack->size - 1);
}

static inline
size_t available_bits(struct bt_bfcr *bfcr)
{
	return bfcr->buf.sz - bfcr->buf.at;
}

static inline
void consume_bits(struct bt_bfcr *bfcr, size_t incr)
{
	BT_COMP_LOGT("Advancing cursor: bfcr-addr=%p, cur-before=%zu, cur-after=%zu",
		bfcr, bfcr->buf.at, bfcr->buf.at + incr);
	bfcr->buf.at += incr;
}

static inline
bool has_enough_bits(struct bt_bfcr *bfcr, size_t sz)
{
	return available_bits(bfcr) >= sz;
}

static inline
bool at_least_one_bit_left(struct bt_bfcr *bfcr)
{
	return has_enough_bits(bfcr, 1);
}

static inline
size_t packet_at(struct bt_bfcr *bfcr)
{
	return bfcr->buf.packet_offset + bfcr->buf.at;
}

static inline
size_t buf_at_from_addr(struct bt_bfcr *bfcr)
{
	/*
	 * Considering this:
	 *
	 *     ====== offset ===== (17)
	 *
	 *     xxxxxxxx xxxxxxxx xxxxxxxx xxxxxxxx xxxxxxxx
	 *     ^
	 *     addr (0)           ==== at ==== (12)
	 *
	 * We want this:
	 *
	 *     =============================== (29)
	 */
	return bfcr->buf.offset + bfcr->buf.at;
}

static
void stitch_reset(struct bt_bfcr *bfcr)
{
	bfcr->stitch.offset = 0;
	bfcr->stitch.at = 0;
}

static inline
size_t stitch_at_from_addr(struct bt_bfcr *bfcr)
{
	return bfcr->stitch.offset + bfcr->stitch.at;
}

static
void stitch_append_from_buf(struct bt_bfcr *bfcr, size_t sz)
{
	size_t stitch_byte_at;
	size_t buf_byte_at;
	size_t nb_bytes;

	if (sz == 0) {
		return;
	}

	stitch_byte_at =
		BITS_TO_BYTES_FLOOR(stitch_at_from_addr(bfcr));
	buf_byte_at = BITS_TO_BYTES_FLOOR(buf_at_from_addr(bfcr));
	nb_bytes = BITS_TO_BYTES_CEIL(sz);
	BT_ASSERT(nb_bytes > 0);
	BT_ASSERT(bfcr->buf.addr);
	memcpy(&bfcr->stitch.buf[stitch_byte_at], &bfcr->buf.addr[buf_byte_at],
		nb_bytes);
	bfcr->stitch.at += sz;
	consume_bits(bfcr, sz);
}

static
void stitch_append_from_remaining_buf(struct bt_bfcr *bfcr)
{
	stitch_append_from_buf(bfcr, available_bits(bfcr));
}

static
void stitch_set_from_remaining_buf(struct bt_bfcr *bfcr)
{
	stitch_reset(bfcr);
	bfcr->stitch.offset = IN_BYTE_OFFSET(buf_at_from_addr(bfcr));
	stitch_append_from_remaining_buf(bfcr);
}

static inline
void read_unsigned_bitfield(struct bt_bfcr *bfcr, const uint8_t *buf, size_t at,
		unsigned int field_size, enum ctf_byte_order bo,
		uint64_t *v)
{
	switch (bo) {
	case CTF_BYTE_ORDER_BIG:
		bt_bitfield_read_be(buf, uint8_t, at, field_size, v);
		break;
	case CTF_BYTE_ORDER_LITTLE:
		bt_bitfield_read_le(buf, uint8_t, at, field_size, v);
		break;
	default:
		bt_common_abort();
	}

	BT_COMP_LOGT("Read unsigned bit array: cur=%zu, size=%u, "
		"bo=%d, val=%" PRIu64, at, field_size, bo, *v);
}

static inline
void read_signed_bitfield(struct bt_bfcr *bfcr, const uint8_t *buf, size_t at,
		unsigned int field_size, enum ctf_byte_order bo, int64_t *v)
{
	switch (bo) {
	case CTF_BYTE_ORDER_BIG:
		bt_bitfield_read_be(buf, uint8_t, at, field_size, v);
		break;
	case CTF_BYTE_ORDER_LITTLE:
		bt_bitfield_read_le(buf, uint8_t, at, field_size, v);
		break;
	default:
		bt_common_abort();
	}

	BT_COMP_LOGT("Read signed bit array: cur=%zu, size=%u, "
		"bo=%d, val=%" PRId64, at, field_size, bo, *v);
}

typedef enum bt_bfcr_status (* read_basic_and_call_cb_t)(struct bt_bfcr *,
		const uint8_t *, size_t);

static inline
enum bt_bfcr_status validate_contiguous_bo(struct bt_bfcr *bfcr,
		enum ctf_byte_order next_bo)
{
	enum bt_bfcr_status status = BT_BFCR_STATUS_OK;

	/* Always valid when at a byte boundary */
	if (packet_at(bfcr) % 8 == 0) {
		goto end;
	}

	/* Always valid if last byte order is unknown */
	if (bfcr->last_bo == CTF_BYTE_ORDER_UNKNOWN) {
		goto end;
	}

	/* Always valid if next byte order is unknown */
	if (next_bo == CTF_BYTE_ORDER_UNKNOWN) {
		goto end;
	}

	/* Make sure last byte order is compatible with the next byte order */
	switch (bfcr->last_bo) {
	case CTF_BYTE_ORDER_BIG:
		if (next_bo != CTF_BYTE_ORDER_BIG) {
			status = BT_BFCR_STATUS_ERROR;
		}
		break;
	case CTF_BYTE_ORDER_LITTLE:
		if (next_bo != CTF_BYTE_ORDER_LITTLE) {
			status = BT_BFCR_STATUS_ERROR;
		}
		break;
	default:
		status = BT_BFCR_STATUS_ERROR;
	}

end:
	if (status < 0) {
		BT_COMP_LOGW("Cannot read bit array: two different byte orders not at a byte boundary: "
			"bfcr-addr=%p, last-bo=%d, next-bo=%d",
			bfcr, bfcr->last_bo, next_bo);
	}

	return status;
}

static
enum bt_bfcr_status read_basic_float_and_call_cb(struct bt_bfcr *bfcr,
		const uint8_t *buf, size_t at)
{
	double dblval;
	unsigned int field_size;
	enum ctf_byte_order bo;
	enum bt_bfcr_status status = BT_BFCR_STATUS_OK;
	struct ctf_field_class_float *fc = (void *) bfcr->cur_basic_field_class;

	BT_ASSERT_DBG(fc);
	field_size = fc->base.size;
	bo = fc->base.byte_order;
	bfcr->cur_bo = bo;

	switch (field_size) {
	case 32:
	{
		uint64_t v;
		union {
			uint32_t u;
			float f;
		} f32;

		read_unsigned_bitfield(bfcr, buf, at, field_size, bo, &v);
		f32.u = (uint32_t) v;
		dblval = (double) f32.f;
		break;
	}
	case 64:
	{
		union {
			uint64_t u;
			double d;
		} f64;

		read_unsigned_bitfield(bfcr, buf, at, field_size, bo, &f64.u);
		dblval = f64.d;
		break;
	}
	default:
		/* Only 32-bit and 64-bit fields are supported currently */
		bt_common_abort();
	}

	BT_COMP_LOGT("Read floating point number value: bfcr=%p, cur=%zu, val=%f",
		bfcr, at, dblval);

	if (bfcr->user.cbs.classes.floating_point) {
		BT_COMP_LOGT("Calling user function (floating point number).");
		status = bfcr->user.cbs.classes.floating_point(dblval,
			bfcr->cur_basic_field_class, bfcr->user.data);
		BT_COMP_LOGT("User function returned: status=%s",
			bt_bfcr_status_string(status));
		if (status != BT_BFCR_STATUS_OK) {
			BT_COMP_LOGW("User function failed: bfcr-addr=%p, status=%s",
				bfcr, bt_bfcr_status_string(status));
		}
	}

	return status;
}

static inline
enum bt_bfcr_status read_basic_int_and_call_cb(struct bt_bfcr *bfcr,
		const uint8_t *buf, size_t at)
{
	unsigned int field_size;
	enum ctf_byte_order bo;
	enum bt_bfcr_status status = BT_BFCR_STATUS_OK;
	struct ctf_field_class_int *fc = (void *) bfcr->cur_basic_field_class;

	field_size = fc->base.size;
	bo = fc->base.byte_order;

	/*
	 * Update current byte order now because we could be reading
	 * the integer value of an enumeration class, and thus we know
	 * here the actual supporting integer class's byte order.
	 */
	bfcr->cur_bo = bo;

	if (fc->is_signed) {
		int64_t v;

		read_signed_bitfield(bfcr, buf, at, field_size, bo, &v);

		if (bfcr->user.cbs.classes.signed_int) {
			BT_COMP_LOGT("Calling user function (signed integer).");
			status = bfcr->user.cbs.classes.signed_int(v,
				bfcr->cur_basic_field_class, bfcr->user.data);
			BT_COMP_LOGT("User function returned: status=%s",
				bt_bfcr_status_string(status));
			if (status != BT_BFCR_STATUS_OK) {
				BT_COMP_LOGW("User function failed: "
					"bfcr-addr=%p, status=%s",
					bfcr, bt_bfcr_status_string(status));
			}
		}
	} else {
		uint64_t v;

		read_unsigned_bitfield(bfcr, buf, at, field_size, bo, &v);

		if (bfcr->user.cbs.classes.unsigned_int) {
			BT_COMP_LOGT("Calling user function (unsigned integer).");
			status = bfcr->user.cbs.classes.unsigned_int(v,
				bfcr->cur_basic_field_class, bfcr->user.data);
			BT_COMP_LOGT("User function returned: status=%s",
				bt_bfcr_status_string(status));
			if (status != BT_BFCR_STATUS_OK) {
				BT_COMP_LOGW("User function failed: "
					"bfcr-addr=%p, status=%s",
					bfcr, bt_bfcr_status_string(status));
			}
		}
	}

	return status;
}

static inline
enum bt_bfcr_status read_bit_array_class_and_call_continue(struct bt_bfcr *bfcr,
		read_basic_and_call_cb_t read_basic_and_call_cb)
{
	size_t available;
	size_t needed_bits;
	enum bt_bfcr_status status = BT_BFCR_STATUS_OK;
	struct ctf_field_class_bit_array *fc =
		(void *) bfcr->cur_basic_field_class;

	if (!at_least_one_bit_left(bfcr)) {
		BT_COMP_LOGT("Reached end of data: bfcr-addr=%p", bfcr);
		status = BT_BFCR_STATUS_EOF;
		goto end;
	}

	available = available_bits(bfcr);
	needed_bits = fc->size - bfcr->stitch.at;
	BT_COMP_LOGT("Continuing basic field decoding: "
		"bfcr-addr=%p, field-size=%u, needed-size=%zu, "
		"available-size=%zu",
		bfcr, fc->size, needed_bits, available);
	if (needed_bits <= available) {
		/* We have all the bits; append to stitch, then decode */
		stitch_append_from_buf(bfcr, needed_bits);
		status = read_basic_and_call_cb(bfcr, bfcr->stitch.buf,
			bfcr->stitch.offset);
		if (status != BT_BFCR_STATUS_OK) {
			BT_COMP_LOGW("Cannot read basic field: "
				"bfcr-addr=%p, fc-addr=%p, status=%s",
				bfcr, bfcr->cur_basic_field_class,
				bt_bfcr_status_string(status));
			goto end;
		}

		if (stack_empty(bfcr->stack)) {
			/* Root is a basic class */
			bfcr->state = BFCR_STATE_DONE;
		} else {
			/* Go to next field */
			stack_top(bfcr->stack)->index++;
			bfcr->state = BFCR_STATE_NEXT_FIELD;
			bfcr->last_bo = bfcr->cur_bo;
		}
		goto end;
	}

	/* We are here; it means we don't have enough data to decode this */
	BT_COMP_LOGT_STR("Not enough data to read the next basic field: appending to stitch buffer.");
	stitch_append_from_remaining_buf(bfcr);
	status = BT_BFCR_STATUS_EOF;

end:
	return status;
}

static inline
enum bt_bfcr_status read_bit_array_class_and_call_begin(struct bt_bfcr *bfcr,
		read_basic_and_call_cb_t read_basic_and_call_cb)
{
	size_t available;
	enum bt_bfcr_status status = BT_BFCR_STATUS_OK;
	struct ctf_field_class_bit_array *fc =
		(void *) bfcr->cur_basic_field_class;

	if (!at_least_one_bit_left(bfcr)) {
		BT_COMP_LOGT("Reached end of data: bfcr-addr=%p", bfcr);
		status = BT_BFCR_STATUS_EOF;
		goto end;
	}

	status = validate_contiguous_bo(bfcr, fc->byte_order);
	if (status != BT_BFCR_STATUS_OK) {
		/* validate_contiguous_bo() logs errors */
		goto end;
	}

	available = available_bits(bfcr);

	if (fc->size <= available) {
		/* We have all the bits; decode and set now */
		BT_ASSERT_DBG(bfcr->buf.addr);
		status = read_basic_and_call_cb(bfcr, bfcr->buf.addr,
			buf_at_from_addr(bfcr));
		if (status != BT_BFCR_STATUS_OK) {
			BT_COMP_LOGW("Cannot read basic field: "
				"bfcr-addr=%p, fc-addr=%p, status=%s",
				bfcr, bfcr->cur_basic_field_class,
				bt_bfcr_status_string(status));
			goto end;
		}

		consume_bits(bfcr, fc->size);

		if (stack_empty(bfcr->stack)) {
			/* Root is a basic class */
			bfcr->state = BFCR_STATE_DONE;
		} else {
			/* Go to next field */
			stack_top(bfcr->stack)->index++;
			bfcr->state = BFCR_STATE_NEXT_FIELD;
			bfcr->last_bo = bfcr->cur_bo;
		}

		goto end;
	}

	/* We are here; it means we don't have enough data to decode this */
	BT_COMP_LOGT_STR("Not enough data to read the next basic field: setting stitch buffer.");
	stitch_set_from_remaining_buf(bfcr);
	bfcr->state = BFCR_STATE_READ_BASIC_CONTINUE;
	status = BT_BFCR_STATUS_EOF;

end:
	return status;
}

static inline
enum bt_bfcr_status read_basic_int_class_and_call_begin(
		struct bt_bfcr *bfcr)
{
	return read_bit_array_class_and_call_begin(bfcr, read_basic_int_and_call_cb);
}

static inline
enum bt_bfcr_status read_basic_int_class_and_call_continue(
		struct bt_bfcr *bfcr)
{
	return read_bit_array_class_and_call_continue(bfcr,
		read_basic_int_and_call_cb);
}

static inline
enum bt_bfcr_status read_basic_float_class_and_call_begin(
		struct bt_bfcr *bfcr)
{
	return read_bit_array_class_and_call_begin(bfcr,
		read_basic_float_and_call_cb);
}

static inline
enum bt_bfcr_status read_basic_float_class_and_call_continue(
		struct bt_bfcr *bfcr)
{
	return read_bit_array_class_and_call_continue(bfcr,
		read_basic_float_and_call_cb);
}

static inline
enum bt_bfcr_status read_basic_string_class_and_call(
		struct bt_bfcr *bfcr, bool begin)
{
	size_t buf_at_bytes;
	const uint8_t *result;
	size_t available_bytes;
	const uint8_t *first_chr;
	enum bt_bfcr_status status = BT_BFCR_STATUS_OK;

	if (!at_least_one_bit_left(bfcr)) {
		BT_COMP_LOGT("Reached end of data: bfcr-addr=%p", bfcr);
		status = BT_BFCR_STATUS_EOF;
		goto end;
	}

	BT_ASSERT_DBG(buf_at_from_addr(bfcr) % 8 == 0);
	available_bytes = BITS_TO_BYTES_FLOOR(available_bits(bfcr));
	buf_at_bytes = BITS_TO_BYTES_FLOOR(buf_at_from_addr(bfcr));
	BT_ASSERT_DBG(bfcr->buf.addr);
	first_chr = &bfcr->buf.addr[buf_at_bytes];
	result = memchr(first_chr, '\0', available_bytes);

	if (begin && bfcr->user.cbs.classes.string_begin) {
		BT_COMP_LOGT("Calling user function (string, beginning).");
		status = bfcr->user.cbs.classes.string_begin(
			bfcr->cur_basic_field_class, bfcr->user.data);
		BT_COMP_LOGT("User function returned: status=%s",
			bt_bfcr_status_string(status));
		if (status != BT_BFCR_STATUS_OK) {
			BT_COMP_LOGW("User function failed: bfcr-addr=%p, status=%s",
				bfcr, bt_bfcr_status_string(status));
			goto end;
		}
	}

	if (!result) {
		/* No null character yet */
		if (bfcr->user.cbs.classes.string) {
			BT_COMP_LOGT("Calling user function (substring).");
			status = bfcr->user.cbs.classes.string(
				(const char *) first_chr,
				available_bytes, bfcr->cur_basic_field_class,
				bfcr->user.data);
			BT_COMP_LOGT("User function returned: status=%s",
				bt_bfcr_status_string(status));
			if (status != BT_BFCR_STATUS_OK) {
				BT_COMP_LOGW("User function failed: "
					"bfcr-addr=%p, status=%s",
					bfcr, bt_bfcr_status_string(status));
				goto end;
			}
		}

		consume_bits(bfcr, BYTES_TO_BITS(available_bytes));
		bfcr->state = BFCR_STATE_READ_BASIC_CONTINUE;
		status = BT_BFCR_STATUS_EOF;
	} else {
		/* Found the null character */
		size_t result_len = (size_t) (result - first_chr);

		if (bfcr->user.cbs.classes.string && result_len) {
			BT_COMP_LOGT("Calling user function (substring).");
			status = bfcr->user.cbs.classes.string(
				(const char *) first_chr,
				result_len, bfcr->cur_basic_field_class,
				bfcr->user.data);
			BT_COMP_LOGT("User function returned: status=%s",
				bt_bfcr_status_string(status));
			if (status != BT_BFCR_STATUS_OK) {
				BT_COMP_LOGW("User function failed: "
					"bfcr-addr=%p, status=%s",
					bfcr, bt_bfcr_status_string(status));
				goto end;
			}
		}

		if (bfcr->user.cbs.classes.string_end) {
			BT_COMP_LOGT("Calling user function (string, end).");
			status = bfcr->user.cbs.classes.string_end(
				bfcr->cur_basic_field_class, bfcr->user.data);
			BT_COMP_LOGT("User function returned: status=%s",
				bt_bfcr_status_string(status));
			if (status != BT_BFCR_STATUS_OK) {
				BT_COMP_LOGW("User function failed: "
					"bfcr-addr=%p, status=%s",
					bfcr, bt_bfcr_status_string(status));
				goto end;
			}
		}

		consume_bits(bfcr, BYTES_TO_BITS(result_len + 1));

		if (stack_empty(bfcr->stack)) {
			/* Root is a basic class */
			bfcr->state = BFCR_STATE_DONE;
		} else {
			/* Go to next field */
			stack_top(bfcr->stack)->index++;
			bfcr->state = BFCR_STATE_NEXT_FIELD;
			bfcr->last_bo = bfcr->cur_bo;
		}
	}

end:
	return status;
}

static inline
enum bt_bfcr_status read_basic_begin_state(struct bt_bfcr *bfcr)
{
	enum bt_bfcr_status status;

	BT_ASSERT_DBG(bfcr->cur_basic_field_class);

	switch (bfcr->cur_basic_field_class->type) {
	case CTF_FIELD_CLASS_TYPE_INT:
	case CTF_FIELD_CLASS_TYPE_ENUM:
		status = read_basic_int_class_and_call_begin(bfcr);
		break;
	case CTF_FIELD_CLASS_TYPE_FLOAT:
		status = read_basic_float_class_and_call_begin(bfcr);
		break;
	case CTF_FIELD_CLASS_TYPE_STRING:
		status = read_basic_string_class_and_call(bfcr, true);
		break;
	default:
		bt_common_abort();
	}

	return status;
}

static inline
enum bt_bfcr_status read_basic_continue_state(struct bt_bfcr *bfcr)
{
	enum bt_bfcr_status status;

	BT_ASSERT_DBG(bfcr->cur_basic_field_class);

	switch (bfcr->cur_basic_field_class->type) {
	case CTF_FIELD_CLASS_TYPE_INT:
	case CTF_FIELD_CLASS_TYPE_ENUM:
		status = read_basic_int_class_and_call_continue(bfcr);
		break;
	case CTF_FIELD_CLASS_TYPE_FLOAT:
		status = read_basic_float_class_and_call_continue(bfcr);
		break;
	case CTF_FIELD_CLASS_TYPE_STRING:
		status = read_basic_string_class_and_call(bfcr, false);
		break;
	default:
		bt_common_abort();
	}

	return status;
}

static inline
size_t bits_to_skip_to_align_to(struct bt_bfcr *bfcr, size_t align)
{
	size_t aligned_packet_at;

	aligned_packet_at = ALIGN(packet_at(bfcr), align);
	return aligned_packet_at - packet_at(bfcr);
}

static inline
enum bt_bfcr_status align_class_state(struct bt_bfcr *bfcr,
		struct ctf_field_class *field_class, enum bfcr_state next_state)
{
	unsigned int field_alignment;
	size_t skip_bits;
	enum bt_bfcr_status status = BT_BFCR_STATUS_OK;

	/* Get field's alignment */
	field_alignment = field_class->alignment;

	/*
	 * 0 means "undefined" for variants; what we really want is 1
	 * (always aligned)
	 */
	BT_ASSERT_DBG(field_alignment >= 1);

	/* Compute how many bits we need to skip */
	skip_bits = bits_to_skip_to_align_to(bfcr, (size_t) field_alignment);

	/* Nothing to skip? aligned */
	if (skip_bits == 0) {
		bfcr->state = next_state;
		goto end;
	}

	/* Make sure there's at least one bit left */
	if (!at_least_one_bit_left(bfcr)) {
		status = BT_BFCR_STATUS_EOF;
		goto end;
	}

	/* Consume as many bits as possible in what's left */
	consume_bits(bfcr, MIN(available_bits(bfcr), skip_bits));

	/* Are we done now? */
	skip_bits = bits_to_skip_to_align_to(bfcr, field_alignment);
	if (skip_bits == 0) {
		/* Yes: go to next state */
		bfcr->state = next_state;
		goto end;
	} else {
		/* No: need more data */
		BT_COMP_LOGT("Reached end of data when aligning: bfcr-addr=%p", bfcr);
		status = BT_BFCR_STATUS_EOF;
	}

end:
	return status;
}

static inline
enum bt_bfcr_status next_field_state(struct bt_bfcr *bfcr)
{
	int ret;
	struct stack_entry *top;
	struct ctf_field_class *next_field_class = NULL;
	enum bt_bfcr_status status = BT_BFCR_STATUS_OK;

	if (stack_empty(bfcr->stack)) {
		goto end;
	}

	top = stack_top(bfcr->stack);

	/* Are we done with this base class? */
	while (top->index == top->base_len) {
		if (bfcr->user.cbs.classes.compound_end) {
			BT_COMP_LOGT("Calling user function (compound, end).");
			status = bfcr->user.cbs.classes.compound_end(
				top->base_class, bfcr->user.data);
			BT_COMP_LOGT("User function returned: status=%s",
				bt_bfcr_status_string(status));
			if (status != BT_BFCR_STATUS_OK) {
				BT_COMP_LOGW("User function failed: bfcr-addr=%p, status=%s",
					bfcr, bt_bfcr_status_string(status));
				goto end;
			}
		}

		stack_pop(bfcr->stack);

		/* Are we done with the root class? */
		if (stack_empty(bfcr->stack)) {
			bfcr->state = BFCR_STATE_DONE;
			goto end;
		}

		top = stack_top(bfcr->stack);
		top->index++;
	}

	/* Get next field's class */
	switch (top->base_class->type) {
	case CTF_FIELD_CLASS_TYPE_STRUCT:
		next_field_class = ctf_field_class_struct_borrow_member_by_index(
			(void *) top->base_class, (uint64_t) top->index)->fc;
		break;
	case CTF_FIELD_CLASS_TYPE_ARRAY:
	case CTF_FIELD_CLASS_TYPE_SEQUENCE:
	{
		struct ctf_field_class_array_base *array_fc =
			(void *) top->base_class;

		next_field_class = array_fc->elem_fc;
		break;
	}
	case CTF_FIELD_CLASS_TYPE_VARIANT:
		/* Variant classes are dynamic: the user should know! */
		next_field_class =
			bfcr->user.cbs.query.borrow_variant_selected_field_class(
				top->base_class, bfcr->user.data);
		break;
	default:
		break;
	}

	if (!next_field_class) {
		BT_COMP_LOGW("Cannot get the field class of the next field: "
			"bfcr-addr=%p, base-fc-addr=%p, base-fc-type=%d, "
			"index=%" PRId64,
			bfcr, top->base_class, top->base_class->type,
			top->index);
		status = BT_BFCR_STATUS_ERROR;
		goto end;
	}

	if (next_field_class->is_compound) {
		if (bfcr->user.cbs.classes.compound_begin) {
			BT_COMP_LOGT("Calling user function (compound, begin).");
			status = bfcr->user.cbs.classes.compound_begin(
				next_field_class, bfcr->user.data);
			BT_COMP_LOGT("User function returned: status=%s",
				bt_bfcr_status_string(status));
			if (status != BT_BFCR_STATUS_OK) {
				BT_COMP_LOGW("User function failed: bfcr-addr=%p, status=%s",
					bfcr, bt_bfcr_status_string(status));
				goto end;
			}
		}

		ret = stack_push_with_len(bfcr, next_field_class);
		if (ret) {
			/* stack_push_with_len() logs errors */
			status = BT_BFCR_STATUS_ERROR;
			goto end;
		}

		/* Next state: align a compound class */
		bfcr->state = BFCR_STATE_ALIGN_COMPOUND;
	} else {
		/* Replace current basic field class */
		BT_COMP_LOGT("Replacing current basic field class: "
			"bfcr-addr=%p, cur-basic-fc-addr=%p, "
			"next-basic-fc-addr=%p",
			bfcr, bfcr->cur_basic_field_class, next_field_class);
		bfcr->cur_basic_field_class = next_field_class;

		/* Next state: align a basic class */
		bfcr->state = BFCR_STATE_ALIGN_BASIC;
	}

end:
	return status;
}

static inline
enum bt_bfcr_status handle_state(struct bt_bfcr *bfcr)
{
	enum bt_bfcr_status status = BT_BFCR_STATUS_OK;

	BT_COMP_LOGT("Handling state: bfcr-addr=%p, state=%s",
		bfcr, bfcr_state_string(bfcr->state));

	switch (bfcr->state) {
	case BFCR_STATE_NEXT_FIELD:
		status = next_field_state(bfcr);
		break;
	case BFCR_STATE_ALIGN_BASIC:
		status = align_class_state(bfcr, bfcr->cur_basic_field_class,
			BFCR_STATE_READ_BASIC_BEGIN);
		break;
	case BFCR_STATE_ALIGN_COMPOUND:
		status = align_class_state(bfcr, stack_top(bfcr->stack)->base_class,
			BFCR_STATE_NEXT_FIELD);
		break;
	case BFCR_STATE_READ_BASIC_BEGIN:
		status = read_basic_begin_state(bfcr);
		break;
	case BFCR_STATE_READ_BASIC_CONTINUE:
		status = read_basic_continue_state(bfcr);
		break;
	case BFCR_STATE_DONE:
		break;
	}

	BT_COMP_LOGT("Handled state: bfcr-addr=%p, status=%s",
		bfcr, bt_bfcr_status_string(status));
	return status;
}

BT_HIDDEN
struct bt_bfcr *bt_bfcr_create(struct bt_bfcr_cbs cbs, void *data,
		bt_logging_level log_level, bt_self_component *self_comp)
{
	struct bt_bfcr *bfcr;

	BT_COMP_LOG_CUR_LVL(BT_LOG_DEBUG, log_level, self_comp,
		"Creating binary field class reader (BFCR).");
	bfcr = g_new0(struct bt_bfcr, 1);
	if (!bfcr) {
		BT_COMP_LOG_CUR_LVL(BT_LOG_ERROR, log_level, self_comp,
			"Failed to allocate one binary class reader.");
		goto end;
	}

	bfcr->log_level = log_level;
	bfcr->self_comp = self_comp;
	bfcr->stack = stack_new(bfcr);
	if (!bfcr->stack) {
		BT_COMP_LOGE_STR("Cannot create BFCR's stack.");
		bt_bfcr_destroy(bfcr);
		bfcr = NULL;
		goto end;
	}

	bfcr->state = BFCR_STATE_NEXT_FIELD;
	bfcr->user.cbs = cbs;
	bfcr->user.data = data;
	BT_COMP_LOGD("Created BFCR: addr=%p", bfcr);

end:
	return bfcr;
}

BT_HIDDEN
void bt_bfcr_destroy(struct bt_bfcr *bfcr)
{
	if (bfcr->stack) {
		stack_destroy(bfcr->stack);
	}

	BT_COMP_LOGD("Destroying BFCR: addr=%p", bfcr);
	g_free(bfcr);
}

static
void reset(struct bt_bfcr *bfcr)
{
	BT_COMP_LOGD("Resetting BFCR: addr=%p", bfcr);
	stack_clear(bfcr->stack);
	stitch_reset(bfcr);
	bfcr->buf.addr = NULL;
	bfcr->last_bo = CTF_BYTE_ORDER_UNKNOWN;
}

static
void update_packet_offset(struct bt_bfcr *bfcr)
{
	BT_COMP_LOGT("Updating packet offset for next call: "
		"bfcr-addr=%p, cur-packet-offset=%zu, next-packet-offset=%zu",
		bfcr, bfcr->buf.packet_offset,
		bfcr->buf.packet_offset + bfcr->buf.at);
	bfcr->buf.packet_offset += bfcr->buf.at;
}

BT_HIDDEN
size_t bt_bfcr_start(struct bt_bfcr *bfcr,
	struct ctf_field_class *cls, const uint8_t *buf,
	size_t offset, size_t packet_offset, size_t sz,
	enum bt_bfcr_status *status)
{
	BT_ASSERT_DBG(bfcr);
	BT_ASSERT_DBG(BYTES_TO_BITS(sz) >= offset);
	reset(bfcr);
	bfcr->buf.addr = buf;
	bfcr->buf.offset = offset;
	bfcr->buf.at = 0;
	bfcr->buf.packet_offset = packet_offset;
	bfcr->buf.buf_sz = sz;
	bfcr->buf.sz = BYTES_TO_BITS(sz) - offset;
	*status = BT_BFCR_STATUS_OK;

	BT_COMP_LOGT("Starting decoding: bfcr-addr=%p, fc-addr=%p, "
		"buf-addr=%p, buf-size=%zu, offset=%zu, "
		"packet-offset=%zu",
		bfcr, cls, buf, sz, offset, packet_offset);

	/* Set root class */
	if (cls->is_compound) {
		/* Compound class: push on visit stack */
		int stack_ret;

		if (bfcr->user.cbs.classes.compound_begin) {
			BT_COMP_LOGT("Calling user function (compound, begin).");
			*status = bfcr->user.cbs.classes.compound_begin(
				cls, bfcr->user.data);
			BT_COMP_LOGT("User function returned: status=%s",
				bt_bfcr_status_string(*status));
			if (*status != BT_BFCR_STATUS_OK) {
				BT_COMP_LOGW("User function failed: bfcr-addr=%p, status=%s",
					bfcr, bt_bfcr_status_string(*status));
				goto end;
			}
		}

		stack_ret = stack_push_with_len(bfcr, cls);
		if (stack_ret) {
			/* stack_push_with_len() logs errors */
			*status = BT_BFCR_STATUS_ERROR;
			goto end;
		}

		bfcr->state = BFCR_STATE_ALIGN_COMPOUND;
	} else {
		/* Basic class: set as current basic class */
		bfcr->cur_basic_field_class = cls;
		bfcr->state = BFCR_STATE_ALIGN_BASIC;
	}

	/* Run the machine! */
	BT_COMP_LOGT_STR("Running the state machine.");

	while (true) {
		*status = handle_state(bfcr);
		if (*status != BT_BFCR_STATUS_OK ||
				bfcr->state == BFCR_STATE_DONE) {
			break;
		}
	}

	/* Update packet offset for next time */
	update_packet_offset(bfcr);

end:
	return bfcr->buf.at;
}

BT_HIDDEN
size_t bt_bfcr_continue(struct bt_bfcr *bfcr, const uint8_t *buf, size_t sz,
		enum bt_bfcr_status *status)
{
	BT_ASSERT_DBG(bfcr);
	BT_ASSERT_DBG(buf);
	BT_ASSERT_DBG(sz > 0);
	bfcr->buf.addr = buf;
	bfcr->buf.offset = 0;
	bfcr->buf.at = 0;
	bfcr->buf.buf_sz = sz;
	bfcr->buf.sz = BYTES_TO_BITS(sz);
	*status = BT_BFCR_STATUS_OK;

	BT_COMP_LOGT("Continuing decoding: bfcr-addr=%p, buf-addr=%p, buf-size=%zu",
		bfcr, buf, sz);

	/* Continue running the machine */
	BT_COMP_LOGT_STR("Running the state machine.");

	while (true) {
		*status = handle_state(bfcr);
		if (*status != BT_BFCR_STATUS_OK ||
				bfcr->state == BFCR_STATE_DONE) {
			break;
		}
	}

	/* Update packet offset for next time */
	update_packet_offset(bfcr);
	return bfcr->buf.at;
}

BT_HIDDEN
void bt_bfcr_set_unsigned_int_cb(struct bt_bfcr *bfcr,
		bt_bfcr_unsigned_int_cb_func cb)
{
	BT_ASSERT_DBG(bfcr);
	BT_ASSERT_DBG(cb);
	bfcr->user.cbs.classes.unsigned_int = cb;
}