[lttng-tools.git] / src / bin / lttng / commands / add_trigger.c

/*
 * Copyright (C) 2021 Simon Marchi <simon.marchi@efficios.com>
 *
 * SPDX-License-Identifier: GPL-2.0-only
 *
 */

#include <ctype.h>
#include <stdio.h>

#include "../command.h"
#include "../loglevel.h"
#include "../uprobe.h"

#include "common/argpar/argpar.h"
#include "common/dynamic-array.h"
#include "common/string-utils/string-utils.h"
#include "common/utils.h"
/* For lttng_event_rule_type_str(). */
#include <lttng/event-rule/event-rule-internal.h>
#include <lttng/lttng.h>
#include "common/filter/filter-ast.h"
#include "common/filter/filter-ir.h"
#include "common/dynamic-array.h"

#if (LTTNG_SYMBOL_NAME_LEN == 256)
#define LTTNG_SYMBOL_NAME_LEN_SCANF_IS_A_BROKEN_API "255"
#endif

#ifdef LTTNG_EMBED_HELP
static const char help_msg[] =
#include <lttng-add-trigger.1.h>
;
#endif

enum {
	OPT_HELP,
	OPT_LIST_OPTIONS,

	OPT_CONDITION,
	OPT_ACTION,
	OPT_ID,
	OPT_FIRE_ONCE_AFTER,
	OPT_FIRE_EVERY,
	OPT_USER_ID,

	OPT_ALL,
	OPT_FILTER,
	OPT_EXCLUDE,
	OPT_LOGLEVEL,
	OPT_LOGLEVEL_ONLY,

	OPT_USERSPACE,
	OPT_KERNEL,
	OPT_LOG4J,
	OPT_JUL,
	OPT_PYTHON,

	OPT_FUNCTION,
	OPT_PROBE,
	OPT_USERSPACE_PROBE,
	OPT_SYSCALL,
	OPT_TRACEPOINT,

	OPT_NAME,
	OPT_MAX_SIZE,
	OPT_DATA_URL,
	OPT_CTRL_URL,
	OPT_URL,
	OPT_PATH,

	OPT_CAPTURE,
};

static const struct argpar_opt_descr event_rule_opt_descrs[] = {
	{ OPT_ALL, 'a', "all", false },
	{ OPT_FILTER, 'f', "filter", true },
	{ OPT_EXCLUDE, 'x', "exclude", true },
	{ OPT_LOGLEVEL, '\0', "loglevel", true },
	{ OPT_LOGLEVEL_ONLY, '\0', "loglevel-only", true },

	/* Domains */
	{ OPT_USERSPACE, 'u', "userspace", false },
	{ OPT_KERNEL, 'k', "kernel", false },
	{ OPT_LOG4J, 'l', "log4j", false },
	{ OPT_JUL, 'j', "jul", false },
	{ OPT_PYTHON, 'p', "python", false },

	/* Event rule types */
	{ OPT_FUNCTION, '\0', "function", true },
	{ OPT_PROBE, '\0', "probe", true },
	{ OPT_USERSPACE_PROBE, '\0', "userspace-probe", true },
	{ OPT_SYSCALL, '\0', "syscall" },
	{ OPT_TRACEPOINT, '\0', "tracepoint" },

	/* Capture descriptor */
	{ OPT_CAPTURE, '\0', "capture", true },

	ARGPAR_OPT_DESCR_SENTINEL
};

static
bool assign_domain_type(enum lttng_domain_type *dest,
		enum lttng_domain_type src)
{
	bool ret;

	if (*dest == LTTNG_DOMAIN_NONE || *dest == src) {
		*dest = src;
		ret = true;
	} else {
		ERR("Multiple domains specified.");
		ret = false;
	}

	return ret;
}

static
bool assign_event_rule_type(enum lttng_event_rule_type *dest,
		enum lttng_event_rule_type src)
{
	bool ret;

	if (*dest == LTTNG_EVENT_RULE_TYPE_UNKNOWN || *dest == src) {
		*dest = src;
		ret = true;
	} else {
		ERR("Multiple event types specified.");
		ret = false;
	}

	return ret;
}

static
bool assign_string(char **dest, const char *src, const char *opt_name)
{
	bool ret;

	if (*dest) {
		ERR("Duplicate '%s' given.", opt_name);
		goto error;
	}

	*dest = strdup(src);
	if (!*dest) {
		PERROR("Failed to allocate string '%s'.", opt_name);
		goto error;
	}

	ret = true;
	goto end;

error:
	ret = false;

end:
	return ret;
}

/* This is defined in enable_events.c. */
LTTNG_HIDDEN
int create_exclusion_list_and_validate(const char *event_name,
		const char *exclusions_arg,
		char ***exclusion_list);

/*
 * Parse `str` as a log level in domain `domain_type`. Return -1 if the string
 * is not recognized as a valid log level.
 */
static
int parse_loglevel_string(const char *str, enum lttng_domain_type domain_type)
{
	switch (domain_type) {
	case LTTNG_DOMAIN_UST:
	{
		enum lttng_loglevel loglevel;
		const int ret = loglevel_name_to_value(str, &loglevel);

		return ret == -1 ? ret : (int) loglevel;
	}
	case LTTNG_DOMAIN_LOG4J:
	{
		enum lttng_loglevel_log4j loglevel;
		const int ret = loglevel_log4j_name_to_value(str, &loglevel);

		return ret == -1 ? ret : (int) loglevel;
	}
	case LTTNG_DOMAIN_JUL:
	{
		enum lttng_loglevel_jul loglevel;
		const int ret = loglevel_jul_name_to_value(str, &loglevel);

		return ret == -1 ? ret : (int) loglevel;
	}
	case LTTNG_DOMAIN_PYTHON:
	{
		enum lttng_loglevel_python loglevel;
		const int ret = loglevel_python_name_to_value(str, &loglevel);

		return ret == -1 ? ret : (int) loglevel;
	}
	default:
		/* Invalid domain type. */
		abort();
	}
}

static int parse_kernel_probe_opts(const char *source,
		struct lttng_kernel_probe_location **location)
{
	int ret = 0;
	int match;
	char s_hex[19];
	char name[LTTNG_SYMBOL_NAME_LEN];
	char *symbol_name = NULL;
	uint64_t offset;

	/* Check for symbol+offset. */
	match = sscanf(source,
			"%" LTTNG_SYMBOL_NAME_LEN_SCANF_IS_A_BROKEN_API
			"[^'+']+%18s",
			name, s_hex);
	if (match == 2) {
		if (*s_hex == '\0') {
			ERR("Kernel probe symbol offset is missing.");
			goto error;
		}

		symbol_name = strndup(name, LTTNG_SYMBOL_NAME_LEN);
		if (!symbol_name) {
			PERROR("Failed to copy kernel probe location symbol name.");
			goto error;
		}
		offset = strtoul(s_hex, NULL, 0);

		*location = lttng_kernel_probe_location_symbol_create(
				symbol_name, offset);
		if (!*location) {
			ERR("Failed to create symbol kernel probe location.");
			goto error;
		}

		goto end;
	}

	/* Check for symbol. */
	if (isalpha(name[0]) || name[0] == '_') {
		match = sscanf(source,
				"%" LTTNG_SYMBOL_NAME_LEN_SCANF_IS_A_BROKEN_API
				"s",
				name);
		if (match == 1) {
			symbol_name = strndup(name, LTTNG_SYMBOL_NAME_LEN);
			if (!symbol_name) {
				ERR("Failed to copy kernel probe location symbol name.");
				goto error;
			}

			*location = lttng_kernel_probe_location_symbol_create(
					symbol_name, 0);
			if (!*location) {
				ERR("Failed to create symbol kernel probe location.");
				goto error;
			}

			goto end;
		}
	}

	/* Check for address. */
	match = sscanf(source, "%18s", s_hex);
	if (match > 0) {
		uint64_t address;

		if (*s_hex == '\0') {
			ERR("Invalid kernel probe location address.");
			goto error;
		}

		address = strtoul(s_hex, NULL, 0);
		*location = lttng_kernel_probe_location_address_create(address);
		if (!*location) {
			ERR("Failed to create symbol kernel probe location.");
			goto error;
		}

		goto end;
	}

error:
	/* No match */
	ret = -1;
	*location = NULL;

end:
	free(symbol_name);
	return ret;
}

static
struct lttng_event_expr *ir_op_load_expr_to_event_expr(
		const struct ir_load_expression *load_expr,
		const char *capture_str)
{
	char *provider_name = NULL;
	struct lttng_event_expr *event_expr = NULL;
	const struct ir_load_expression_op *load_expr_op = load_expr->child;
	const enum ir_load_expression_type load_expr_child_type =
			load_expr_op->type;

	switch (load_expr_child_type) {
	case IR_LOAD_EXPRESSION_GET_PAYLOAD_ROOT:
	case IR_LOAD_EXPRESSION_GET_CONTEXT_ROOT:
	{
		const char *field_name;

		load_expr_op = load_expr_op->next;
		assert(load_expr_op);
		assert(load_expr_op->type == IR_LOAD_EXPRESSION_GET_SYMBOL);
		field_name = load_expr_op->u.symbol;
		assert(field_name);

		event_expr = load_expr_child_type == IR_LOAD_EXPRESSION_GET_PAYLOAD_ROOT ?
				lttng_event_expr_event_payload_field_create(field_name) :
				lttng_event_expr_channel_context_field_create(field_name);
		if (!event_expr) {
			ERR("Failed to create %s event expression: field name = `%s`.",
					load_expr_child_type == IR_LOAD_EXPRESSION_GET_PAYLOAD_ROOT ?
							"payload field" : "channel context",
							field_name);
			goto error;
		}

		break;
	}
	case IR_LOAD_EXPRESSION_GET_APP_CONTEXT_ROOT:
	{
		const char *colon;
		const char *type_name;
		const char *field_name;

		load_expr_op = load_expr_op->next;
		assert(load_expr_op);
		assert(load_expr_op->type == IR_LOAD_EXPRESSION_GET_SYMBOL);
		field_name = load_expr_op->u.symbol;
		assert(field_name);

		/*
		 * The field name needs to be of the form PROVIDER:TYPE. We
		 * split it here.
		 */
		colon = strchr(field_name, ':');
		if (!colon) {
			ERR("Invalid app-specific context field name: missing colon in `%s`.",
					field_name);
			goto error;
		}

		type_name = colon + 1;
		if (*type_name == '\0') {
			ERR("Invalid app-specific context field name: missing type name after colon in `%s`.",
					field_name);
			goto error;
		}

		provider_name = strndup(field_name, colon - field_name);
		if (!provider_name) {
			PERROR("Failed to allocate field name string");
			goto error;
		}

		event_expr = lttng_event_expr_app_specific_context_field_create(
				provider_name, type_name);
		if (!event_expr) {
			ERR("Failed to create app-specific context field event expression: provider name = `%s`, type name = `%s`",
					provider_name, type_name);
			goto error;
		}

		break;
	}
	default:
		ERR("%s: unexpected load expr type %d.", __func__,
				load_expr_op->type);
		abort();
	}

	load_expr_op = load_expr_op->next;

	/* There may be a single array index after that. */
	if (load_expr_op->type == IR_LOAD_EXPRESSION_GET_INDEX) {
		struct lttng_event_expr *index_event_expr;
		const uint64_t index = load_expr_op->u.index;

		index_event_expr = lttng_event_expr_array_field_element_create(event_expr, index);
		if (!index_event_expr) {
			ERR("Failed to create array field element event expression.");
			goto error;
		}

		event_expr = index_event_expr;
		load_expr_op = load_expr_op->next;
	}

	switch (load_expr_op->type) {
	case IR_LOAD_EXPRESSION_LOAD_FIELD:
		/*
		 * This is what we expect, IR_LOAD_EXPRESSION_LOAD_FIELD is
		 * always found at the end of the chain.
		 */
		break;
	case IR_LOAD_EXPRESSION_GET_SYMBOL:
		ERR("While parsing expression `%s`: Capturing subfields is not supported.",
				capture_str);
		goto error;

	default:
		ERR("%s: unexpected load expression operator %s.", __func__,
				ir_load_expression_type_str(load_expr_op->type));
		abort();
	}

	goto end;

error:
	lttng_event_expr_destroy(event_expr);
	event_expr = NULL;

end:
	free(provider_name);

	return event_expr;
}

static
struct lttng_event_expr *ir_op_load_to_event_expr(
		const struct ir_op *ir, const char *capture_str)
{
	struct lttng_event_expr *event_expr = NULL;

	assert(ir->op == IR_OP_LOAD);

	switch (ir->data_type) {
	case IR_DATA_EXPRESSION:
	{
		const struct ir_load_expression *ir_load_expr =
				ir->u.load.u.expression;

		event_expr = ir_op_load_expr_to_event_expr(
				ir_load_expr, capture_str);
		break;
	}
	default:
		ERR("%s: unexpected data type: %s.", __func__,
				ir_data_type_str(ir->data_type));
		abort();
	}

	return event_expr;
}

static
const char *ir_operator_type_human_str(enum ir_op_type op)
{
	const char *name;

	switch (op) {
	case IR_OP_BINARY:
		name = "Binary";
		break;
	case IR_OP_UNARY:
		name = "Unary";
		break;
	case IR_OP_LOGICAL:
		name = "Logical";
		break;
	default:
		abort();
	}

	return name;
}

static
struct lttng_event_expr *ir_op_root_to_event_expr(const struct ir_op *ir,
		const char *capture_str)
{
	struct lttng_event_expr *event_expr = NULL;

	assert(ir->op == IR_OP_ROOT);
	ir = ir->u.root.child;

	switch (ir->op) {
	case IR_OP_LOAD:
		event_expr = ir_op_load_to_event_expr(ir, capture_str);
		break;
	case IR_OP_BINARY:
	case IR_OP_UNARY:
	case IR_OP_LOGICAL:
		ERR("While parsing expression `%s`: %s operators are not allowed in capture expressions.",
				capture_str,
				ir_operator_type_human_str(ir->op));
		break;
	default:
		ERR("%s: unexpected IR op type: %s.", __func__,
				ir_op_type_str(ir->op));
		abort();
	}

	return event_expr;
}

static
void destroy_event_expr(void *ptr)
{
	lttng_event_expr_destroy(ptr);
}

struct parse_event_rule_res {
	/* Owned by this. */
	struct lttng_event_rule *er;

	/* Array of `struct lttng_event_expr *` */
	struct lttng_dynamic_pointer_array capture_descriptors;
};

static
struct parse_event_rule_res parse_event_rule(int *argc, const char ***argv)
{
	enum lttng_domain_type domain_type = LTTNG_DOMAIN_NONE;
	enum lttng_event_rule_type event_rule_type =
			LTTNG_EVENT_RULE_TYPE_UNKNOWN;
	struct argpar_state *state;
	struct argpar_item *item = NULL;
	char *error = NULL;
	int consumed_args = -1;
	struct lttng_kernel_probe_location *kernel_probe_location = NULL;
	struct lttng_userspace_probe_location *userspace_probe_location = NULL;
	struct parse_event_rule_res res = { 0 };
	struct lttng_event_expr *event_expr = NULL;
	struct filter_parser_ctx *parser_ctx = NULL;
	struct lttng_log_level_rule *log_level_rule = NULL;

	/* Was the -a/--all flag provided? */
	bool all_events = false;

	/* Tracepoint name (non-option argument). */
	const char *tracepoint_name = NULL;

	/* Holds the argument of --probe / --userspace-probe. */
	char *source = NULL;

	/* Filter. */
	char *filter = NULL;

	/* Exclude. */
	char *exclude = NULL;
	char **exclusion_list = NULL;

	/* Log level. */
	char *loglevel_str = NULL;
	bool loglevel_only = false;

	lttng_dynamic_pointer_array_init(&res.capture_descriptors,
				destroy_event_expr);
	state = argpar_state_create(*argc, *argv, event_rule_opt_descrs);
	if (!state) {
		ERR("Failed to allocate an argpar state.");
		goto error;
	}

	while (true) {
		enum argpar_state_parse_next_status status;

		ARGPAR_ITEM_DESTROY_AND_RESET(item);
		status = argpar_state_parse_next(state, &item, &error);
		if (status == ARGPAR_STATE_PARSE_NEXT_STATUS_ERROR) {
			ERR("%s", error);
			goto error;
		} else if (status == ARGPAR_STATE_PARSE_NEXT_STATUS_ERROR_UNKNOWN_OPT) {
			/* Just stop parsing here. */
			break;
		} else if (status == ARGPAR_STATE_PARSE_NEXT_STATUS_END) {
			break;
		}

		assert(status == ARGPAR_STATE_PARSE_NEXT_STATUS_OK);

		if (item->type == ARGPAR_ITEM_TYPE_OPT) {
			const struct argpar_item_opt *item_opt =
					(const struct argpar_item_opt *) item;

			switch (item_opt->descr->id) {
			/* Domains. */
			case OPT_USERSPACE:
				if (!assign_domain_type(&domain_type, LTTNG_DOMAIN_UST)) {
					goto error;
				}

				break;
			case OPT_KERNEL:
				if (!assign_domain_type(&domain_type, LTTNG_DOMAIN_KERNEL)) {
					goto error;
				}

				break;
			case OPT_LOG4J:
				if (!assign_domain_type(&domain_type, LTTNG_DOMAIN_LOG4J)) {
					goto error;
				}

				break;
			case OPT_JUL:
				if (!assign_domain_type(&domain_type, LTTNG_DOMAIN_JUL)) {
					goto error;
				}

				break;
			case OPT_PYTHON:
				if (!assign_domain_type(&domain_type, LTTNG_DOMAIN_PYTHON)) {
					goto error;
				}

				break;

			/* Event rule types */
			case OPT_FUNCTION:
				if (!assign_event_rule_type(&event_rule_type,
						LTTNG_EVENT_RULE_TYPE_KERNEL_FUNCTION)) {
					goto error;
				}

				break;
			case OPT_PROBE:
				if (!assign_event_rule_type(&event_rule_type,
						LTTNG_EVENT_RULE_TYPE_KERNEL_PROBE)) {
					goto error;
				}

				if (!assign_string(&source, item_opt->arg, "source")) {
					goto error;
				}

				break;
			case OPT_USERSPACE_PROBE:
				if (!assign_event_rule_type(&event_rule_type,
						LTTNG_EVENT_RULE_TYPE_USERSPACE_PROBE)) {
					goto error;
				}

				if (!assign_string(&source, item_opt->arg, "source")) {
						goto error;
				}

				break;
			case OPT_SYSCALL:
				if (!assign_event_rule_type(&event_rule_type,
						LTTNG_EVENT_RULE_TYPE_SYSCALL)) {
					goto error;
				}

				break;
			case OPT_TRACEPOINT:
				if (!assign_event_rule_type(&event_rule_type,
						LTTNG_EVENT_RULE_TYPE_TRACEPOINT)) {
					goto error;
				}

				break;
			case OPT_ALL:
				all_events = true;
				break;
			case OPT_FILTER:
				if (!assign_string(&filter, item_opt->arg,
						    "--filter/-f")) {
					goto error;
				}

				break;
			case OPT_EXCLUDE:
				if (!assign_string(&exclude, item_opt->arg,
						    "--exclude/-x")) {
					goto error;
				}

				break;
			case OPT_LOGLEVEL:
			case OPT_LOGLEVEL_ONLY:
				if (!assign_string(&loglevel_str, item_opt->arg,
						    "--loglevel/--loglevel-only")) {
					goto error;
				}

				loglevel_only = item_opt->descr->id ==
						OPT_LOGLEVEL_ONLY;
				break;
			case OPT_CAPTURE:
			{
				int ret;
				const char *capture_str = item_opt->arg;

				ret = filter_parser_ctx_create_from_filter_expression(
						capture_str, &parser_ctx);
				if (ret) {
					ERR("Failed to parse capture expression `%s`.",
							capture_str);
					goto error;
				}

				event_expr = ir_op_root_to_event_expr(
						parser_ctx->ir_root,
						capture_str);
				if (!event_expr) {
					/*
					 * ir_op_root_to_event_expr has printed
					 * an error message.
					 */
					goto error;
				}

				ret = lttng_dynamic_pointer_array_add_pointer(
						&res.capture_descriptors,
						event_expr);
				if (ret) {
					goto error;
				}

				/*
				 * The ownership of event expression was
				 * transferred to the dynamic array.
				 */
				event_expr = NULL;

				break;
			}
			default:
				abort();
			}
		} else {
			const struct argpar_item_non_opt *item_non_opt =
					(const struct argpar_item_non_opt *)
							item;

			/*
			 * Don't accept two non-option arguments/tracepoint
			 * names.
			 */
			if (tracepoint_name) {
				ERR("Unexpected argument '%s'",
						item_non_opt->arg);
				goto error;
			}

			tracepoint_name = item_non_opt->arg;
		}
	}

	if (event_rule_type == LTTNG_EVENT_RULE_TYPE_UNKNOWN) {
		event_rule_type = LTTNG_EVENT_RULE_TYPE_TRACEPOINT;
	}

	/*
	 * Option -a is applicable to event rules of type tracepoint and
	 * syscall, and it is equivalent to using "*" as the tracepoint name.
	 */
	if (all_events) {
		switch (event_rule_type) {
		case LTTNG_EVENT_RULE_TYPE_TRACEPOINT:
		case LTTNG_EVENT_RULE_TYPE_SYSCALL:
			break;
		default:
			ERR("Can't use -a/--all with %s event rules.",
					lttng_event_rule_type_str(event_rule_type));
			goto error;
		}

		if (tracepoint_name) {
			ERR("Can't provide a tracepoint name with -a/--all.");
			goto error;
		}

		/* In which case, it's equivalent to tracepoint name "*". */
		tracepoint_name = "*";
	}

	/*
	 * A tracepoint name (or -a, for the event rule types that accept it)
	 * is required.
	 */
	if (!tracepoint_name) {
		ERR("Need to provide either a tracepoint name or -a/--all.");
		goto error;
	}

	/*
	 * We don't support multiple tracepoint names for now.
	 */
	if (strchr(tracepoint_name, ',')) {
		ERR("Comma separated tracepoint names are not supported.");
		goto error;
	}

	/*
	 * Update *argc and *argv so our caller can keep parsing what follows.
	 */
	consumed_args = argpar_state_get_ingested_orig_args(state);
	assert(consumed_args >= 0);
	*argc -= consumed_args;
	*argv += consumed_args;

	/* Need to specify a domain. */
	if (domain_type == LTTNG_DOMAIN_NONE) {
		ERR("Please specify a domain (--kernel/--userspace/--jul/--log4j/--python).");
		goto error;
	}

	/* Validate event rule type against domain. */
	switch (event_rule_type) {
	case LTTNG_EVENT_RULE_TYPE_KERNEL_PROBE:
	case LTTNG_EVENT_RULE_TYPE_KERNEL_FUNCTION:
	case LTTNG_EVENT_RULE_TYPE_USERSPACE_PROBE:
	case LTTNG_EVENT_RULE_TYPE_SYSCALL:
		if (domain_type != LTTNG_DOMAIN_KERNEL) {
			ERR("Event type not available for user-space tracing.");
			goto error;
		}
		break;

	case LTTNG_EVENT_RULE_TYPE_TRACEPOINT:
		break;

	default:
		abort();
	}

	/*
	 * Adding a filter to a probe, function or userspace-probe would be
	 * denied by the kernel tracer as it's not supported at the moment. We
	 * do an early check here to warn the user.
	 */
	if (filter && domain_type == LTTNG_DOMAIN_KERNEL) {
		switch (event_rule_type) {
		case LTTNG_EVENT_RULE_TYPE_TRACEPOINT:
		case LTTNG_EVENT_RULE_TYPE_SYSCALL:
			break;
		default:
			ERR("Filter expressions are not supported for %s event rules.",
					lttng_event_rule_type_str(event_rule_type));
			goto error;
		}
	}

	/* If --exclude/-x was passed, split it into an exclusion list. */
	if (exclude) {
		if (domain_type != LTTNG_DOMAIN_UST) {
			ERR("Event name exclusions are not yet implemented for %s event rules.",
					get_domain_str(domain_type));
			goto error;
		}


		if (create_exclusion_list_and_validate(tracepoint_name, exclude,
				&exclusion_list) != 0) {
			ERR("Failed to create exclusion list.");
			goto error;
		}
	}

	if (loglevel_str && event_rule_type != LTTNG_EVENT_RULE_TYPE_TRACEPOINT) {
		ERR("Log levels are only applicable to tracepoint event rules.");
		goto error;
	}

	/* Finally, create the event rule object. */
	switch (event_rule_type) {
	case LTTNG_EVENT_RULE_TYPE_TRACEPOINT:
	{
		enum lttng_event_rule_status event_rule_status;

		res.er = lttng_event_rule_tracepoint_create(domain_type);
		if (!res.er) {
			ERR("Failed to create tracepoint event rule.");
			goto error;
		}

		/* Set pattern. */
		event_rule_status = lttng_event_rule_tracepoint_set_pattern(
				res.er, tracepoint_name);
		if (event_rule_status != LTTNG_EVENT_RULE_STATUS_OK) {
			ERR("Failed to set tracepoint event rule's pattern to '%s'.",
					tracepoint_name);
			goto error;
		}

		/* Set filter. */
		if (filter) {
			event_rule_status = lttng_event_rule_tracepoint_set_filter(
					res.er, filter);
			if (event_rule_status != LTTNG_EVENT_RULE_STATUS_OK) {
				ERR("Failed to set tracepoint event rule's filter to '%s'.",
						filter);
				goto error;
			}
		}

		/* Set exclusion list. */
		if (exclusion_list) {
			int n;

			for (n = 0; exclusion_list[n]; n++) {
				event_rule_status = lttng_event_rule_tracepoint_add_exclusion(
						res.er,
						exclusion_list[n]);
				if (event_rule_status !=
						LTTNG_EVENT_RULE_STATUS_OK) {
					ERR("Failed to set tracepoint exclusion list element '%s'",
							exclusion_list[n]);
					goto error;
				}
			}
		}

		if (loglevel_str) {
			int loglevel;

			if (domain_type == LTTNG_DOMAIN_KERNEL) {
				ERR("Log levels are not supported by the kernel tracer.");
				goto error;
			}

			loglevel = parse_loglevel_string(
					loglevel_str, domain_type);
			if (loglevel < 0) {
				ERR("Failed to parse `%s` as a log level.",
						loglevel_str);
				goto error;
			}

			if (loglevel_only) {
				log_level_rule = lttng_log_level_rule_exactly_create(loglevel);
			} else {
				log_level_rule = lttng_log_level_rule_at_least_as_severe_as_create(loglevel);
			}

			if (log_level_rule == NULL) {
				ERR("Failed to create log level rule object.");
				goto error;
			}

			event_rule_status =
					lttng_event_rule_tracepoint_set_log_level_rule(
							res.er, log_level_rule);

			if (event_rule_status != LTTNG_EVENT_RULE_STATUS_OK) {
				ERR("Failed to set log level on event fule.");
				goto error;
			}
		}

		break;
	}
	case LTTNG_EVENT_RULE_TYPE_KERNEL_PROBE:
	{
		int ret;
		enum lttng_event_rule_status event_rule_status;


		ret = parse_kernel_probe_opts(source, &kernel_probe_location);
		if (ret) {
			ERR("Failed to parse kernel probe location.");
			goto error;
		}

		assert(kernel_probe_location);
		res.er = lttng_event_rule_kernel_probe_create(kernel_probe_location);
		if (!res.er) {
			ERR("Failed to create kprobe event rule.");
			goto error;
		}

		event_rule_status = lttng_event_rule_kernel_probe_set_event_name(res.er, tracepoint_name);
		if (event_rule_status != LTTNG_EVENT_RULE_STATUS_OK) {
			ERR("Failed to set kprobe event rule's name to '%s'.", tracepoint_name);
			goto error;
		}

		break;
	}
	case LTTNG_EVENT_RULE_TYPE_USERSPACE_PROBE:
	{
		int ret;
		enum lttng_event_rule_status event_rule_status;

		ret = parse_userspace_probe_opts(
				source, &userspace_probe_location);
		if (ret) {
			ERR("Failed to parse user space probe location.");
			goto error;
		}

		res.er = lttng_event_rule_userspace_probe_create(userspace_probe_location);
		if (!res.er) {
			ERR("Failed to create userspace probe event rule.");
			goto error;
		}

		event_rule_status = lttng_event_rule_userspace_probe_set_event_name(
				res.er, tracepoint_name);
		if (event_rule_status != LTTNG_EVENT_RULE_STATUS_OK) {
			ERR("Failed to set user space probe event rule's name to '%s'.",
					tracepoint_name);
			goto error;
		}

		break;
	}
	case LTTNG_EVENT_RULE_TYPE_SYSCALL:
	{
		enum lttng_event_rule_status event_rule_status;

		res.er = lttng_event_rule_syscall_create();
		if (!res.er) {
			ERR("Failed to create syscall event rule.");
			goto error;
		}

		event_rule_status = lttng_event_rule_syscall_set_pattern(
				res.er, tracepoint_name);
		if (event_rule_status != LTTNG_EVENT_RULE_STATUS_OK) {
			ERR("Failed to set syscall event rule's pattern to '%s'.",
					tracepoint_name);
			goto error;
		}

		if (filter) {
			event_rule_status = lttng_event_rule_syscall_set_filter(
					res.er, filter);
			if (event_rule_status != LTTNG_EVENT_RULE_STATUS_OK) {
				ERR("Failed to set syscall event rule's filter to '%s'.",
						filter);
				goto error;
			}
		}

		break;
	}
	default:
		abort();
		goto error;
	}

	goto end;

error:
	lttng_event_rule_destroy(res.er);
	res.er = NULL;
	lttng_dynamic_pointer_array_reset(&res.capture_descriptors);

end:
	if (parser_ctx) {
		filter_parser_ctx_free(parser_ctx);
	}

	lttng_event_expr_destroy(event_expr);
	argpar_item_destroy(item);
	free(error);
	argpar_state_destroy(state);
	free(filter);
	free(exclude);
	free(loglevel_str);
	free(source);
	strutils_free_null_terminated_array_of_strings(exclusion_list);
	lttng_kernel_probe_location_destroy(kernel_probe_location);
	lttng_userspace_probe_location_destroy(userspace_probe_location);
	lttng_log_level_rule_destroy(log_level_rule);
	return res;
}

static
struct lttng_condition *handle_condition_event(int *argc, const char ***argv)
{
	struct parse_event_rule_res res;
	struct lttng_condition *c;
	size_t i;

	res = parse_event_rule(argc, argv);
	if (!res.er) {
		c = NULL;
		goto error;
	}

	c = lttng_condition_on_event_create(res.er);
	lttng_event_rule_destroy(res.er);
	res.er = NULL;
	if (!c) {
		goto error;
	}

	for (i = 0; i < lttng_dynamic_pointer_array_get_count(&res.capture_descriptors);
			i++) {
		enum lttng_condition_status status;
		struct lttng_event_expr **expr =
				lttng_dynamic_array_get_element(
					&res.capture_descriptors.array, i);

		assert(expr);
		assert(*expr);
		status = lttng_condition_on_event_append_capture_descriptor(
				c, *expr);
		if (status != LTTNG_CONDITION_STATUS_OK) {
			if (status == LTTNG_CONDITION_STATUS_UNSUPPORTED) {
				ERR("The capture feature is unsupported by the event-rule condition type");
			}

			goto error;
		}

		/* Ownership of event expression moved to `c` */
		*expr = NULL;
	}

	goto end;

error:
	lttng_condition_destroy(c);
	c = NULL;

end:
	lttng_dynamic_pointer_array_reset(&res.capture_descriptors);
	lttng_event_rule_destroy(res.er);
	return c;
}

static
struct lttng_condition *handle_condition_session_consumed_size(int *argc, const char ***argv)
{
	struct lttng_condition *cond = NULL;
	struct argpar_state *state = NULL;
	struct argpar_item *item = NULL;
	const char *threshold_arg = NULL;
	const char *session_name_arg = NULL;
	uint64_t threshold;
	char *error = NULL;
	enum lttng_condition_status condition_status;

	state = argpar_state_create(*argc, *argv, event_rule_opt_descrs);
	if (!state) {
		ERR("Failed to allocate an argpar state.");
		goto error;
	}

	while (true) {
		enum argpar_state_parse_next_status status;

		ARGPAR_ITEM_DESTROY_AND_RESET(item);
		status = argpar_state_parse_next(state, &item, &error);
		if (status == ARGPAR_STATE_PARSE_NEXT_STATUS_ERROR) {
			ERR("%s", error);
			goto error;
		} else if (status == ARGPAR_STATE_PARSE_NEXT_STATUS_ERROR_UNKNOWN_OPT) {
			/* Just stop parsing here. */
			break;
		} else if (status == ARGPAR_STATE_PARSE_NEXT_STATUS_END) {
			break;
		}

		assert(status == ARGPAR_STATE_PARSE_NEXT_STATUS_OK);

		if (item->type == ARGPAR_ITEM_TYPE_OPT) {
			const struct argpar_item_opt *item_opt =
					(const struct argpar_item_opt *) item;

			switch (item_opt->descr->id) {
			default:
				abort();
			}
		} else {
			const struct argpar_item_non_opt *item_non_opt;

			assert(item->type == ARGPAR_ITEM_TYPE_NON_OPT);

			item_non_opt = (const struct argpar_item_non_opt *) item;

			switch (item_non_opt->non_opt_index) {
			case 0:
				session_name_arg = item_non_opt->arg;
				break;
			case 1:
				threshold_arg = item_non_opt->arg;
				break;
			default:
				ERR("Unexpected argument `%s`.",
						item_non_opt->arg);
				goto error;
			}
		}
	}

	*argc -= argpar_state_get_ingested_orig_args(state);
	*argv += argpar_state_get_ingested_orig_args(state);

	if (!session_name_arg) {
		ERR("Missing session name argument.");
		goto error;
	}

	if (!threshold_arg) {
		ERR("Missing threshold argument.");
		goto error;
	}

	if (utils_parse_size_suffix(threshold_arg, &threshold) != 0) {
		ERR("Failed to parse `%s` as a size.", threshold_arg);
		goto error;
	}

	cond = lttng_condition_session_consumed_size_create();
	if (!cond) {
		ERR("Failed to allocate a session consumed size condition.");
		goto error;
	}

	condition_status = lttng_condition_session_consumed_size_set_session_name(
		cond, session_name_arg);
	if (condition_status != LTTNG_CONDITION_STATUS_OK) {
		ERR("Failed to set session consumed size condition's session name to '%s'.",
				session_name_arg);
		goto error;
	}

	condition_status = lttng_condition_session_consumed_size_set_threshold(
			cond, threshold);
	if (condition_status != LTTNG_CONDITION_STATUS_OK) {
		ERR("Failed to set session consumed size condition threshold.");
		goto error;
	}

	goto end;

error:
	lttng_condition_destroy(cond);
	cond = NULL;

end:
	argpar_state_destroy(state);
	argpar_item_destroy(item);
	free(error);
	return cond;
}

static
struct lttng_condition *handle_condition_buffer_usage_high(int *argc, const char ***argv)
{
	ERR("High buffer usage threshold conditions are unsupported for the moment.");
	return NULL;
}

static
struct lttng_condition *handle_condition_buffer_usage_low(int *argc, const char ***argv)
{
	ERR("Low buffer usage threshold conditions are unsupported for the moment.");
	return NULL;
}

static
struct lttng_condition *handle_condition_session_rotation_ongoing(int *argc, const char ***argv)
{
	ERR("Session rotation ongoing conditions are unsupported for the moment.");
	return NULL;
}

static
struct lttng_condition *handle_condition_session_rotation_completed(int *argc, const char ***argv)
{
	ERR("Session rotation completed conditions are unsupported for the moment.");
	return NULL;
}

struct condition_descr {
	const char *name;
	struct lttng_condition *(*handler) (int *argc, const char ***argv);
};

static const
struct condition_descr condition_descrs[] = {
	{ "on-event", handle_condition_event },
	{ "on-session-consumed-size", handle_condition_session_consumed_size },
	{ "on-buffer-usage-high", handle_condition_buffer_usage_high },
	{ "on-buffer-usage-low", handle_condition_buffer_usage_low },
	{ "on-session-rotation-ongoing", handle_condition_session_rotation_ongoing },
	{ "on-session-rotation-completed", handle_condition_session_rotation_completed },
};

static
struct lttng_condition *parse_condition(int *argc, const char ***argv)
{
	int i;
	struct lttng_condition *cond;
	const char *condition_name;
	const struct condition_descr *descr = NULL;

	if (*argc == 0) {
		ERR("Missing condition name.");
		goto error;
	}

	condition_name = (*argv)[0];

	(*argc)--;
	(*argv)++;

	for (i = 0; i < ARRAY_SIZE(condition_descrs); i++) {
		if (strcmp(condition_name, condition_descrs[i].name) == 0) {
			descr = &condition_descrs[i];
			break;
		}
	}

	if (!descr) {
		ERR("Unknown condition name '%s'", condition_name);
		goto error;
	}

	cond = descr->handler(argc, argv);
	if (!cond) {
		/* The handler has already printed an error message. */
		goto error;
	}

	goto end;
error:
	cond = NULL;
end:
	return cond;
}
static const struct argpar_opt_descr notify_action_opt_descrs[] = {
	{ OPT_FIRE_ONCE_AFTER, '\0', "fire-once-after", true },
	{ OPT_FIRE_EVERY, '\0', "fire-every", true },
	ARGPAR_OPT_DESCR_SENTINEL
};


static
struct lttng_action *handle_action_notify(int *argc, const char ***argv)
{
	struct lttng_action *action = NULL;
	struct argpar_state *state = NULL;
	struct argpar_item *item = NULL;
	char *error = NULL;
	char *fire_once_after_str = NULL;
	char *fire_every_str = NULL;
	struct lttng_firing_policy *policy = NULL;

	state = argpar_state_create(*argc, *argv, notify_action_opt_descrs);
	if (!state) {
		ERR("Failed to allocate an argpar state.");
		goto error;
	}

	while (true) {
		enum argpar_state_parse_next_status status;

		ARGPAR_ITEM_DESTROY_AND_RESET(item);
		status = argpar_state_parse_next(state, &item, &error);
		if (status == ARGPAR_STATE_PARSE_NEXT_STATUS_ERROR) {
			ERR("%s", error);
			goto error;
		} else if (status == ARGPAR_STATE_PARSE_NEXT_STATUS_ERROR_UNKNOWN_OPT) {
			/* Just stop parsing here. */
			break;
		} else if (status == ARGPAR_STATE_PARSE_NEXT_STATUS_END) {
			break;
		}

		assert(status == ARGPAR_STATE_PARSE_NEXT_STATUS_OK);

		if (item->type == ARGPAR_ITEM_TYPE_OPT) {
			const struct argpar_item_opt *item_opt =
					(const struct argpar_item_opt *) item;

			switch (item_opt->descr->id) {
			case OPT_FIRE_ONCE_AFTER:
			{
				if (!assign_string(&fire_once_after_str,
						    item_opt->arg,
						    "--fire-once-after")) {
					goto error;
				}

				break;
			}
			case OPT_FIRE_EVERY:
			{
				if (!assign_string(&fire_every_str,
						    item_opt->arg,
						    "--fire-every")) {
					goto error;
				}

				break;
			}

			default:
				abort();
			}
		} else {
			const struct argpar_item_non_opt *item_non_opt;

			assert(item->type == ARGPAR_ITEM_TYPE_NON_OPT);

			item_non_opt = (const struct argpar_item_non_opt *) item;

			switch (item_non_opt->non_opt_index) {
			default:
				ERR("Unexpected argument `%s`.",
						item_non_opt->arg);
				goto error;
			}
		}
	}

	*argc -= argpar_state_get_ingested_orig_args(state);
	*argv += argpar_state_get_ingested_orig_args(state);

	if (fire_once_after_str && fire_every_str) {
		ERR("--fire-once and --fire-every are mutually exclusive.");
		goto error;
	}

	if (fire_once_after_str) {
		unsigned long long threshold;

		if (utils_parse_unsigned_long_long(
				    fire_once_after_str, &threshold) != 0) {
			ERR("Failed to parse `%s` as an integer.",
					fire_once_after_str);
			goto error;
		}

		if (threshold == 0) {
			ERR("Once after N policy threshold cannot be `0`.");
			goto error;
		}

		policy = lttng_firing_policy_once_after_n_create(threshold);
		if (!policy) {
			ERR("Failed to create policy once after `%s`.",
					fire_once_after_str);
			goto error;
		}
	}

	if (fire_every_str) {
		unsigned long long interval;
		if (utils_parse_unsigned_long_long(fire_every_str, &interval) !=
				0) {
			ERR("Failed to parse `%s` as an integer.",
					fire_every_str);
			goto error;
		}
		if (interval == 0) {
			ERR("Every N policy interval cannot be `0`.");
			goto error;
		}

		policy = lttng_firing_policy_every_n_create(interval);
		if (!policy) {
			ERR("Failed to create policy every `%s`.",
					fire_every_str);
			goto error;
		}
	}

	action = lttng_action_notify_create();
	if (!action) {
		ERR("Failed to create notify action");
		goto error;
	}

	if (policy) {
		enum lttng_action_status status;
		status = lttng_action_notify_set_firing_policy(action, policy);
		if (status != LTTNG_ACTION_STATUS_OK) {
			ERR("Failed to set firing policy");
			goto error;
		}
	}

	goto end;

error:
	lttng_action_destroy(action);
	action = NULL;
	free(error);
end:
	free(fire_once_after_str);
	free(fire_every_str);
	lttng_firing_policy_destroy(policy);
	argpar_state_destroy(state);
	argpar_item_destroy(item);
	return action;
}

/*
 * Generic handler for a kind of action that takes a session name and an
 * optional firing policy.
 */

static struct lttng_action *handle_action_simple_session_with_policy(int *argc,
		const char ***argv,
		struct lttng_action *(*create_action_cb)(void),
		enum lttng_action_status (*set_session_name_cb)(
				struct lttng_action *, const char *),
		enum lttng_action_status (*set_firing_policy_cb)(
				struct lttng_action *,
				const struct lttng_firing_policy *),
		const char *action_name)
{
	struct lttng_action *action = NULL;
	struct argpar_state *state = NULL;
	struct argpar_item *item = NULL;
	const char *session_name_arg = NULL;
	char *fire_once_after_str = NULL;
	char *fire_every_str = NULL;
	char *error = NULL;
	enum lttng_action_status action_status;
	struct lttng_firing_policy *policy = NULL;

	assert(set_session_name_cb);
	assert(set_firing_policy_cb);

	const struct argpar_opt_descr firing_policy_opt_descrs[] = {
		{ OPT_FIRE_ONCE_AFTER, '\0', "fire-once-after", true },
		{ OPT_FIRE_EVERY, '\0', "fire-every", true },
		ARGPAR_OPT_DESCR_SENTINEL
	};
	
	state = argpar_state_create(*argc, *argv, firing_policy_opt_descrs);
	if (!state) {
		ERR("Failed to allocate an argpar state.");
		goto error;
	}

	while (true) {
		enum argpar_state_parse_next_status status;

		ARGPAR_ITEM_DESTROY_AND_RESET(item);
		status = argpar_state_parse_next(state, &item, &error);
		if (status == ARGPAR_STATE_PARSE_NEXT_STATUS_ERROR) {
			ERR("%s", error);
			goto error;
		} else if (status ==
				ARGPAR_STATE_PARSE_NEXT_STATUS_ERROR_UNKNOWN_OPT) {
			/* Just stop parsing here. */
			break;
		} else if (status == ARGPAR_STATE_PARSE_NEXT_STATUS_END) {
			break;
		}

		assert(status == ARGPAR_STATE_PARSE_NEXT_STATUS_OK);
		if (item->type == ARGPAR_ITEM_TYPE_OPT) {
			const struct argpar_item_opt *item_opt =
					(const struct argpar_item_opt *) item;

			switch (item_opt->descr->id) {
			case OPT_FIRE_ONCE_AFTER:
			{
				if (!assign_string(&fire_once_after_str,
						    item_opt->arg,
						    "--fire-once-after")) {
					goto error;
				}

				break;
			}
			case OPT_FIRE_EVERY:
			{
				if (!assign_string(&fire_every_str,
						    item_opt->arg,
						    "--fire-every")) {
					goto error;
				}

				break;
			}

			default:
				abort();
			}
		} else {
			const struct argpar_item_non_opt *item_non_opt;
			item_non_opt = (const struct argpar_item_non_opt *) item;

			switch (item_non_opt->non_opt_index) {
			case 0:
				session_name_arg = item_non_opt->arg;
				break;
			default:
				ERR("Unexpected argument `%s`.",
						item_non_opt->arg);
				goto error;
			}
		}
	}

	*argc -= argpar_state_get_ingested_orig_args(state);
	*argv += argpar_state_get_ingested_orig_args(state);

	if (!session_name_arg) {
		ERR("Missing session name.");
		goto error;
	}

	if (fire_once_after_str && fire_every_str) {
		ERR("--fire-once and --fire-every are mutually exclusive.");
		goto error;
	}

	if (fire_once_after_str) {
		unsigned long long threshold;

		if (utils_parse_unsigned_long_long(
				    fire_once_after_str, &threshold) != 0) {
			ERR("Failed to parse `%s` as an integer.",
					fire_once_after_str);
			goto error;
		}

		if (threshold == 0) {
			ERR("Once after N policy threshold cannot be `0`.");
			goto error;
		}

		policy = lttng_firing_policy_once_after_n_create(threshold);
		if (!policy) {
			ERR("Failed to create policy once after `%s`.",
					fire_once_after_str);
			goto error;
		}
	}

	if (fire_every_str) {
		unsigned long long interval;
		if (utils_parse_unsigned_long_long(fire_every_str, &interval) !=
				0) {
			ERR("Failed to parse `%s` as an integer.",
					fire_every_str);
			goto error;
		}
		if (interval == 0) {
			ERR("Every N policy interval cannot be `0`.");
			goto error;
		}

		policy = lttng_firing_policy_every_n_create(interval);
		if (!policy) {
			ERR("Failed to create policy every `%s`.",
					fire_every_str);
			goto error;
		}
	}

	action = create_action_cb();
	if (!action) {
		ERR("Failed to allocate %s session action.", action_name);
		goto error;
	}

	action_status = set_session_name_cb(action, session_name_arg);
	if (action_status != LTTNG_ACTION_STATUS_OK) {
		ERR("Failed to set action %s session's session name to '%s'.",
				action_name, session_name_arg);
		goto error;
	}

	if (policy) {
		action_status = set_firing_policy_cb(action, policy);
		if (action_status != LTTNG_ACTION_STATUS_OK) {
			ERR("Failed to set firing policy");
			goto error;
		}
	}

	goto end;

error:
	lttng_action_destroy(action);
	action = NULL;
	argpar_item_destroy(item);
end:
	lttng_firing_policy_destroy(policy);
	free(error);
	argpar_state_destroy(state);
	return action;
}

static
struct lttng_action *handle_action_start_session(int *argc,
		const char ***argv)
{
	return handle_action_simple_session_with_policy(argc, argv,
			lttng_action_start_session_create,
			lttng_action_start_session_set_session_name,
			lttng_action_start_session_set_firing_policy, "start");
}

static
struct lttng_action *handle_action_stop_session(int *argc,
		const char ***argv)
{
	return handle_action_simple_session_with_policy(argc, argv,
			lttng_action_stop_session_create,
			lttng_action_stop_session_set_session_name,
			lttng_action_stop_session_set_firing_policy, "stop");
}

static
struct lttng_action *handle_action_rotate_session(int *argc,
		const char ***argv)
{
	return handle_action_simple_session_with_policy(argc, argv,
		lttng_action_rotate_session_create,
		lttng_action_rotate_session_set_session_name,
		lttng_action_rotate_session_set_firing_policy,
		"rotate");
}

static const struct argpar_opt_descr snapshot_action_opt_descrs[] = {
	{ OPT_NAME, 'n', "name", true },
	{ OPT_MAX_SIZE, 'm', "max-size", true },
	{ OPT_CTRL_URL, '\0', "ctrl-url", true },
	{ OPT_DATA_URL, '\0', "data-url", true },
	{ OPT_URL, '\0', "url", true },
	{ OPT_PATH, '\0', "path", true },
	{ OPT_FIRE_ONCE_AFTER, '\0', "fire-once-after", true },
	{ OPT_FIRE_EVERY, '\0', "fire-every", true },
	ARGPAR_OPT_DESCR_SENTINEL
};

static
struct lttng_action *handle_action_snapshot_session(int *argc,
		const char ***argv)
{
	struct lttng_action *action = NULL;
	struct argpar_state *state = NULL;
	struct argpar_item *item = NULL;
	const char *session_name_arg = NULL;
	char *snapshot_name_arg = NULL;
	char *ctrl_url_arg = NULL;
	char *data_url_arg = NULL;
	char *max_size_arg = NULL;
	char *url_arg = NULL;
	char *path_arg = NULL;
	char *error = NULL;
	char *fire_once_after_str = NULL;
	char *fire_every_str = NULL;
	enum lttng_action_status action_status;
	struct lttng_snapshot_output *snapshot_output = NULL;
	struct lttng_firing_policy *policy = NULL;
	int ret;
	unsigned int locations_specified = 0;

	state = argpar_state_create(*argc, *argv, snapshot_action_opt_descrs);
	if (!state) {
		ERR("Failed to allocate an argpar state.");
		goto error;
	}

	while (true) {
		enum argpar_state_parse_next_status status;

		ARGPAR_ITEM_DESTROY_AND_RESET(item);
		status = argpar_state_parse_next(state, &item, &error);
		if (status == ARGPAR_STATE_PARSE_NEXT_STATUS_ERROR) {
			ERR("%s", error);
			goto error;
		} else if (status == ARGPAR_STATE_PARSE_NEXT_STATUS_ERROR_UNKNOWN_OPT) {
			/* Just stop parsing here. */
			break;
		} else if (status == ARGPAR_STATE_PARSE_NEXT_STATUS_END) {
			break;
		}

		assert(status == ARGPAR_STATE_PARSE_NEXT_STATUS_OK);

		if (item->type == ARGPAR_ITEM_TYPE_OPT) {
			const struct argpar_item_opt *item_opt =
					(const struct argpar_item_opt *) item;

			switch (item_opt->descr->id) {
			case OPT_NAME:
				if (!assign_string(&snapshot_name_arg, item_opt->arg, "--name/-n")) {
					goto error;
				}

				break;
			case OPT_MAX_SIZE:
				if (!assign_string(&max_size_arg, item_opt->arg, "--max-size/-m")) {
					goto error;
				}

				break;
			case OPT_CTRL_URL:
				if (!assign_string(&ctrl_url_arg, item_opt->arg, "--ctrl-url")) {
					goto error;
				}

				break;
			case OPT_DATA_URL:
				if (!assign_string(&data_url_arg, item_opt->arg, "--data-url")) {
					goto error;
				}

				break;
			case OPT_URL:
				if (!assign_string(&url_arg, item_opt->arg, "--url")) {
					goto error;
				}

				break;
			case OPT_PATH:
				if (!assign_string(&path_arg, item_opt->arg, "--path")) {
					goto error;
				}

				break;
			case OPT_FIRE_ONCE_AFTER:
			{
				if (!assign_string(&fire_once_after_str,
						    item_opt->arg,
						    "--fire-once-after")) {
					goto error;
				}

				break;
			}
			case OPT_FIRE_EVERY:
			{
				if (!assign_string(&fire_every_str,
						    item_opt->arg,
						    "--fire-every")) {
					goto error;
				}

				break;
			}

			default:
				abort();
			}
		} else {
			const struct argpar_item_non_opt *item_non_opt;

			assert(item->type == ARGPAR_ITEM_TYPE_NON_OPT);

			item_non_opt = (const struct argpar_item_non_opt *) item;

			switch (item_non_opt->non_opt_index) {
			case 0:
				session_name_arg = item_non_opt->arg;
				break;
			default:
				ERR("Unexpected argument `%s`.",
						item_non_opt->arg);
				goto error;
			}
		}
	}

	*argc -= argpar_state_get_ingested_orig_args(state);
	*argv += argpar_state_get_ingested_orig_args(state);

	if (!session_name_arg) {
		ERR("Missing session name.");
		goto error;
	}

	/* --ctrl-url and --data-url must come in pair. */
	if (ctrl_url_arg && !data_url_arg) {
		ERR("--ctrl-url is specified, but --data-url is missing.");
		goto error;
	}

	if (!ctrl_url_arg && data_url_arg) {
		ERR("--data-url is specified, but --ctrl-url is missing.");
		goto error;
	}

	locations_specified += !!(ctrl_url_arg || data_url_arg);
	locations_specified += !!url_arg;
	locations_specified += !!path_arg;

	/* --ctrl-url/--data-url, --url and --path are mutually exclusive. */
	if (locations_specified > 1) {
		ERR("The --ctrl-url/--data-url, --url, and --path options can't be used together.");
		goto error;
	}

	/*
	 * Did the user specify an option that implies using a
	 * custom/unregistered output?
	 */
	if (url_arg || ctrl_url_arg || path_arg) {
		snapshot_output = lttng_snapshot_output_create();
		if (!snapshot_output) {
			ERR("Failed to allocate a snapshot output.");
			goto error;
		}
	}

	/* Any firing policy ? */
	if (fire_once_after_str && fire_every_str) {
		ERR("--fire-once and --fire-every are mutually exclusive.");
		goto error;
	}

	if (fire_once_after_str) {
		unsigned long long threshold;

		if (utils_parse_unsigned_long_long(
				    fire_once_after_str, &threshold) != 0) {
			ERR("Failed to parse `%s` as an integer.",
					fire_once_after_str);
			goto error;
		}

		if (threshold == 0) {
			ERR("Once after N policy threshold cannot be `0`.");
			goto error;
		}

		policy = lttng_firing_policy_once_after_n_create(threshold);
		if (!policy) {
			ERR("Failed to create policy once after `%s`.",
					fire_once_after_str);
			goto error;
		}
	}

	if (fire_every_str) {
		unsigned long long interval;
		if (utils_parse_unsigned_long_long(fire_every_str, &interval) !=
				0) {
			ERR("Failed to parse `%s` as an integer.",
					fire_every_str);
			goto error;
		}
		if (interval == 0) {
			ERR("Every N policy interval cannot be `0`.");
			goto error;
		}

		policy = lttng_firing_policy_every_n_create(interval);
		if (!policy) {
			ERR("Failed to create policy every `%s`.",
					fire_every_str);
			goto error;
		}
	}

	action = lttng_action_snapshot_session_create();
	if (!action) {
		ERR("Failed to allocate snapshot session action.");
		goto error;
	}

	action_status = lttng_action_snapshot_session_set_session_name(
			action, session_name_arg);
	if (action_status != LTTNG_ACTION_STATUS_OK) {
		ERR("Failed to set action snapshot session's session name to '%s'.",
				session_name_arg);
		goto error;
	}

	if (snapshot_name_arg) {
		if (!snapshot_output) {
			ERR("Can't provide a snapshot output name without a snapshot output destination.");
			goto error;
		}

		ret = lttng_snapshot_output_set_name(
				snapshot_name_arg, snapshot_output);
		if (ret != 0) {
			ERR("Failed to set name of snapshot output.");
			goto error;
		}
	}

	if (max_size_arg) {
		uint64_t max_size;

		if (!snapshot_output) {
			ERR("Can't provide a snapshot output max size without a snapshot output destination.");
			goto error;
		}

		ret = utils_parse_size_suffix(max_size_arg, &max_size);
		if (ret != 0) {
			ERR("Failed to parse `%s` as a size.", max_size_arg);
			goto error;
		}

		ret = lttng_snapshot_output_set_size(max_size, snapshot_output);
		if (ret != 0) {
			ERR("Failed to set snapshot output's max size to %" PRIu64 " bytes.",
					max_size);
			goto error;
		}
	}

	if (url_arg) {
		int num_uris;
		struct lttng_uri *uris;

		if (!strstr(url_arg, "://")) {
			ERR("Failed to parse '%s' as an URL.", url_arg);
			goto error;
		}

		num_uris = uri_parse_str_urls(url_arg, NULL, &uris);
		if (num_uris < 1) {
			ERR("Failed to parse '%s' as an URL.", url_arg);
			goto error;
		}

		if (uris[0].dtype == LTTNG_DST_PATH) {
			ret = lttng_snapshot_output_set_local_path(
					uris[0].dst.path, snapshot_output);
			free(uris);
			if (ret != 0) {
				ERR("Failed to assign '%s' as a local destination.",
						url_arg);
				goto error;
			}
		} else {
			ret = lttng_snapshot_output_set_network_url(
					url_arg, snapshot_output);
			free(uris);
			if (ret != 0) {
				ERR("Failed to assign '%s' as a network URL.",
						url_arg);
				goto error;
			}
		}
	}

	if (path_arg) {
		ret = lttng_snapshot_output_set_local_path(
				path_arg, snapshot_output);
		if (ret != 0) {
			ERR("Failed to parse '%s' as a local path.", path_arg);
			goto error;
		}
	}

	if (ctrl_url_arg) {
		/*
		 * Two argument form, network output with separate control and
		 * data URLs.
		 */
		ret = lttng_snapshot_output_set_network_urls(
				ctrl_url_arg, data_url_arg, snapshot_output);
		if (ret != 0) {
			ERR("Failed to parse `%s` and `%s` as control and data URLs.",
					ctrl_url_arg, data_url_arg);
			goto error;
		}
	}

	if (snapshot_output) {
		action_status = lttng_action_snapshot_session_set_output(
				action, snapshot_output);
		if (action_status != LTTNG_ACTION_STATUS_OK) {
			ERR("Failed to set snapshot session action's output.");
			goto error;
		}

		/* Ownership of `snapshot_output` has been transferred to the action. */
		snapshot_output = NULL;
	}

	if (policy) {
		enum lttng_action_status status;
		status = lttng_action_snapshot_session_set_firing_policy(
				action, policy);
		if (status != LTTNG_ACTION_STATUS_OK) {
			ERR("Failed to set firing policy");
			goto error;
		}
	}

	goto end;

error:
	lttng_action_destroy(action);
	action = NULL;
	free(error);
end:
	free(snapshot_name_arg);
	free(path_arg);
	free(url_arg);
	free(ctrl_url_arg);
	free(data_url_arg);
	free(snapshot_output);
	free(max_size_arg);
	lttng_firing_policy_destroy(policy);
	argpar_state_destroy(state);
	argpar_item_destroy(item);
	return action;
}

struct action_descr {
	const char *name;
	struct lttng_action *(*handler) (int *argc, const char ***argv);
};

static const
struct action_descr action_descrs[] = {
	{ "notify", handle_action_notify },
	{ "start-session", handle_action_start_session },
	{ "stop-session", handle_action_stop_session },
	{ "rotate-session", handle_action_rotate_session },
	{ "snapshot-session", handle_action_snapshot_session },
};

static
struct lttng_action *parse_action(int *argc, const char ***argv)
{
	int i;
	struct lttng_action *action;
	const char *action_name;
	const struct action_descr *descr = NULL;

	if (*argc == 0) {
		ERR("Missing action name.");
		goto error;
	}

	action_name = (*argv)[0];

	(*argc)--;
	(*argv)++;

	for (i = 0; i < ARRAY_SIZE(action_descrs); i++) {
		if (strcmp(action_name, action_descrs[i].name) == 0) {
			descr = &action_descrs[i];
			break;
		}
	}

	if (!descr) {
		ERR("Unknown action name: %s", action_name);
		goto error;
	}

	action = descr->handler(argc, argv);
	if (!action) {
		/* The handler has already printed an error message. */
		goto error;
	}

	goto end;
error:
	action = NULL;
end:
	return action;
}

static const
struct argpar_opt_descr add_trigger_options[] = {
	{ OPT_HELP, 'h', "help", false },
	{ OPT_LIST_OPTIONS, '\0', "list-options", false },
	{ OPT_CONDITION, '\0', "condition", false },
	{ OPT_ACTION, '\0', "action", false },
	{ OPT_ID, '\0', "id", true },
	{ OPT_USER_ID, '\0', "user-id", true },
	ARGPAR_OPT_DESCR_SENTINEL,
};

static
void lttng_actions_destructor(void *p)
{
	struct lttng_action *action = p;

	lttng_action_destroy(action);
}

int cmd_add_trigger(int argc, const char **argv)
{
	int ret;
	int my_argc = argc - 1;
	const char **my_argv = argv + 1;
	struct lttng_condition *condition = NULL;
	struct lttng_dynamic_pointer_array actions;
	struct argpar_state *argpar_state = NULL;
	struct argpar_item *argpar_item = NULL;
	struct lttng_action *action_group = NULL;
	struct lttng_action *action = NULL;
	struct lttng_trigger *trigger = NULL;
	char *error = NULL;
	char *id = NULL;
	int i;
	char *user_id = NULL;

	lttng_dynamic_pointer_array_init(&actions, lttng_actions_destructor);

	while (true) {
		enum argpar_state_parse_next_status status;
		const struct argpar_item_opt *item_opt;
		int ingested_args;

		argpar_state_destroy(argpar_state);
		argpar_state = argpar_state_create(my_argc, my_argv,
			add_trigger_options);
		if (!argpar_state) {
			ERR("Failed to create argpar state.");
			goto error;
		}

		ARGPAR_ITEM_DESTROY_AND_RESET(argpar_item);
		status = argpar_state_parse_next(argpar_state, &argpar_item, &error);
		if (status == ARGPAR_STATE_PARSE_NEXT_STATUS_ERROR) {
			ERR("%s", error);
			goto error;
		} else if (status == ARGPAR_STATE_PARSE_NEXT_STATUS_ERROR_UNKNOWN_OPT) {
			ERR("%s", error);
			goto error;
		} else if (status == ARGPAR_STATE_PARSE_NEXT_STATUS_END) {
			break;
		}

		assert(status == ARGPAR_STATE_PARSE_NEXT_STATUS_OK);

		if (argpar_item->type == ARGPAR_ITEM_TYPE_NON_OPT) {
			const struct argpar_item_non_opt *item_non_opt =
					(const struct argpar_item_non_opt *)
							argpar_item;

			ERR("Unexpected argument `%s`.", item_non_opt->arg);
			goto error;
		}

		item_opt = (const struct argpar_item_opt *) argpar_item;

		ingested_args = argpar_state_get_ingested_orig_args(
				argpar_state);

		my_argc -= ingested_args;
		my_argv += ingested_args;

		switch (item_opt->descr->id) {
		case OPT_HELP:
			SHOW_HELP();
			ret = 0;
			goto end;
		case OPT_LIST_OPTIONS:
			list_cmd_options_argpar(stdout, add_trigger_options);
			ret = 0;
			goto end;
		case OPT_CONDITION:
		{
			if (condition) {
				ERR("A --condition was already given.");
				goto error;
			}

			condition = parse_condition(&my_argc, &my_argv);
			if (!condition) {
				/*
				 * An error message was already printed by
				 * parse_condition.
				 */
				goto error;
			}

			break;
		}
		case OPT_ACTION:
		{
			action = parse_action(&my_argc, &my_argv);
			if (!action) {
				/*
				 * An error message was already printed by
				 * parse_condition.
				 */
				goto error;
			}

			ret = lttng_dynamic_pointer_array_add_pointer(
					&actions, action);
			if (ret) {
				ERR("Failed to add pointer to pointer array.");
				goto error;
			}

			/* Ownership of the action was transferred to the group. */
			action = NULL;

			break;
		}
		case OPT_ID:
		{
			if (!assign_string(&id, item_opt->arg, "--id")) {
				goto error;
			}

			break;
		}
		case OPT_USER_ID:
		{
			if (!assign_string(&user_id, item_opt->arg,
					"--user-id")) {
				goto error;
			}

			break;
		}
		default:
			abort();
		}
	}

	if (!condition) {
		ERR("Missing --condition.");
		goto error;
	}

	if (lttng_dynamic_pointer_array_get_count(&actions) == 0) {
		ERR("Need at least one --action.");
		goto error;
	}

	action_group = lttng_action_group_create();
	if (!action_group) {
		goto error;
	}

	for (i = 0; i < lttng_dynamic_pointer_array_get_count(&actions); i++) {
		enum lttng_action_status status;

		action = lttng_dynamic_pointer_array_steal_pointer(&actions, i);

		status = lttng_action_group_add_action(action_group, action);
		if (status != LTTNG_ACTION_STATUS_OK) {
			goto error;
		}

		/*
		 * The `lttng_action_group_add_action()` takes a reference to
		 * the action. We can destroy ours.
		 */
		lttng_action_destroy(action);
		action = NULL;
	}

	trigger = lttng_trigger_create(condition, action_group);
	if (!trigger) {
		goto error;
	}

	if (id) {
		enum lttng_trigger_status trigger_status =
				lttng_trigger_set_name(trigger, id);

		if (trigger_status != LTTNG_TRIGGER_STATUS_OK) {
			ERR("Failed to set trigger id.");
			goto error;
		}
	}

	if (user_id) {
		enum lttng_trigger_status trigger_status;
		char *end;
		long long uid;

		errno = 0;
		uid = strtol(user_id, &end, 10);
		if (end == user_id || *end != '\0' || errno != 0) {
			ERR("Failed to parse `%s` as a user id.", user_id);
		}

		trigger_status = lttng_trigger_set_owner_uid(trigger, uid);
		if (trigger_status != LTTNG_TRIGGER_STATUS_OK) {
			ERR("Failed to set trigger's user identity.");
			goto error;
		}
	}

	ret = lttng_register_trigger(trigger);
	if (ret) {
		ERR("Failed to register trigger: %s.", lttng_strerror(ret));
		goto error;
	}

	MSG("Trigger registered successfully.");

	goto end;

error:
	ret = 1;

end:
	argpar_state_destroy(argpar_state);
	argpar_item_destroy(argpar_item);
	lttng_dynamic_pointer_array_reset(&actions);
	lttng_condition_destroy(condition);
	lttng_action_destroy(action_group);
	lttng_action_destroy(action);
	lttng_trigger_destroy(trigger);
	free(error);
	free(id);
	free(user_id);
	return ret;
}