[lttng-modules.git] / lttng-context-hostname.c

/* SPDX-License-Identifier: (GPL-2.0-only or LGPL-2.1-only)
 *
 * lttng-context-hostname.c
 *
 * LTTng hostname context.
 *
 * Copyright (C) 2009-2012 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
 */

#include <linux/module.h>
#include <linux/slab.h>
#include <linux/sched.h>
#include <linux/utsname.h>
#include <lttng/lttng-events.h>
#include <ringbuffer/frontend_types.h>
#include <lttng/lttng-tracer.h>

#define LTTNG_HOSTNAME_CTX_LEN	(__NEW_UTS_LEN + 1)

static
size_t hostname_get_size(size_t offset)
{
	size_t size = 0;

	size += LTTNG_HOSTNAME_CTX_LEN;
	return size;
}

static
void hostname_record(struct lttng_ctx_field *field,
		 struct lib_ring_buffer_ctx *ctx,
		 struct lttng_channel *chan)
{
	struct nsproxy *nsproxy;
	struct uts_namespace *ns;
	char *hostname;

	/*
	 * No need to take the RCU read-side lock to read current
	 * nsproxy. (documented in nsproxy.h)
	 */
	nsproxy = current->nsproxy;
	if (nsproxy) {
		ns = nsproxy->uts_ns;
		hostname = ns->name.nodename;
		chan->ops->event_write(ctx, hostname,
				LTTNG_HOSTNAME_CTX_LEN);
	} else {
		chan->ops->event_memset(ctx, 0,
				LTTNG_HOSTNAME_CTX_LEN);
	}
}

static
void hostname_get_value(struct lttng_ctx_field *field,
		struct lttng_probe_ctx *lttng_probe_ctx,
		union lttng_ctx_value *value)
{
	struct nsproxy *nsproxy;
	struct uts_namespace *ns;
	char *hostname;

	/*
	 * No need to take the RCU read-side lock to read current
	 * nsproxy. (documented in nsproxy.h)
	 */
	nsproxy = current->nsproxy;
	if (nsproxy) {
		ns = nsproxy->uts_ns;
		hostname = ns->name.nodename;
	} else {
		hostname = "";
	}
	value->str = hostname;
}

static const struct lttng_type hostname_array_elem_type =
	__type_integer(char, 0, 0, -1, __BYTE_ORDER, 10, UTF8);

int lttng_add_hostname_to_ctx(struct lttng_ctx **ctx)
{
	struct lttng_ctx_field *field;

	field = lttng_append_context(ctx);
	if (!field)
		return -ENOMEM;
	if (lttng_find_context(*ctx, "hostname")) {
		lttng_remove_context_field(ctx, field);
		return -EEXIST;
	}
	field->event_field.name = "hostname";
	field->event_field.type.atype = atype_array_nestable;
	field->event_field.type.u.array_nestable.elem_type =
		&hostname_array_elem_type;
	field->event_field.type.u.array_nestable.length = LTTNG_HOSTNAME_CTX_LEN;
	field->event_field.type.u.array_nestable.alignment = 0;

	field->get_size = hostname_get_size;
	field->record = hostname_record;
	field->get_value = hostname_get_value;
	lttng_context_update(*ctx);
	return 0;
}
EXPORT_SYMBOL_GPL(lttng_add_hostname_to_ctx);
Commit	Line	Data
b7cdc182	1	/* SPDX-License-Identifier: (GPL-2.0-only or LGPL-2.1-only)
9f36eaed	2	*
975da2c0 JD	3	* lttng-context-hostname.c
	4	*
	5	* LTTng hostname context.
	6	*
	7	* Copyright (C) 2009-2012 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
975da2c0 JD	8	*/
	9
	10	#include <linux/module.h>
	11	#include <linux/slab.h>
	12	#include <linux/sched.h>
	13	#include <linux/utsname.h>
b5304713 MD	14	#include <lttng/lttng-events.h>
	15	#include <ringbuffer/frontend_types.h>
	16	#include <lttng/lttng-tracer.h>
975da2c0 JD	17
	18	#define LTTNG_HOSTNAME_CTX_LEN (__NEW_UTS_LEN + 1)
	19
	20	static
	21	size_t hostname_get_size(size_t offset)
	22	{
	23	size_t size = 0;
	24
	25	size += LTTNG_HOSTNAME_CTX_LEN;
	26	return size;
	27	}
	28
	29	static
	30	void hostname_record(struct lttng_ctx_field *field,
	31	struct lib_ring_buffer_ctx *ctx,
	32	struct lttng_channel *chan)
	33	{
	34	struct nsproxy *nsproxy;
	35	struct uts_namespace *ns;
	36	char *hostname;
	37
3d0d43db MD	38	/*
	39	* No need to take the RCU read-side lock to read current
	40	* nsproxy. (documented in nsproxy.h)
	41	*/
	42	nsproxy = current->nsproxy;
975da2c0 JD	43	if (nsproxy) {
	44	ns = nsproxy->uts_ns;
	45	hostname = ns->name.nodename;
	46	chan->ops->event_write(ctx, hostname,
	47	LTTNG_HOSTNAME_CTX_LEN);
	48	} else {
	49	chan->ops->event_memset(ctx, 0,
	50	LTTNG_HOSTNAME_CTX_LEN);
	51	}
975da2c0 JD	52	}
975da2c0 JD	53
f127e61e MD	54	static
f127e61e MD	55	void hostname_get_value(struct lttng_ctx_field *field,
79150a49	56	struct lttng_probe_ctx *lttng_probe_ctx,
f127e61e MD	57	union lttng_ctx_value *value)
	58	{
	59	struct nsproxy *nsproxy;
	60	struct uts_namespace *ns;
	61	char *hostname;
	62
	63	/*
	64	* No need to take the RCU read-side lock to read current
	65	* nsproxy. (documented in nsproxy.h)
	66	*/
	67	nsproxy = current->nsproxy;
	68	if (nsproxy) {
	69	ns = nsproxy->uts_ns;
	70	hostname = ns->name.nodename;
	71	} else {
	72	hostname = "";
	73	}
	74	value->str = hostname;
	75	}
	76
ceabb767 MD	77	static const struct lttng_type hostname_array_elem_type =
	78	__type_integer(char, 0, 0, -1, __BYTE_ORDER, 10, UTF8);
	79
975da2c0 JD	80	int lttng_add_hostname_to_ctx(struct lttng_ctx **ctx)
	81	{
	82	struct lttng_ctx_field *field;
	83
	84	field = lttng_append_context(ctx);
	85	if (!field)
	86	return -ENOMEM;
	87	if (lttng_find_context(*ctx, "hostname")) {
	88	lttng_remove_context_field(ctx, field);
	89	return -EEXIST;
	90	}
	91	field->event_field.name = "hostname";
ceabb767 MD	92	field->event_field.type.atype = atype_array_nestable;
	93	field->event_field.type.u.array_nestable.elem_type =
	94	&hostname_array_elem_type;
	95	field->event_field.type.u.array_nestable.length = LTTNG_HOSTNAME_CTX_LEN;
	96	field->event_field.type.u.array_nestable.alignment = 0;
975da2c0 JD	97
	98	field->get_size = hostname_get_size;
	99	field->record = hostname_record;
f127e61e	100	field->get_value = hostname_get_value;
a9dd15da	101	lttng_context_update(*ctx);
975da2c0 JD	102	return 0;
	103	}
	104	EXPORT_SYMBOL_GPL(lttng_add_hostname_to_ctx);