-/*
- * lttng-context-provider.c
- *
- * LTTng UST application context provider.
- *
- * Copyright (C) 2016 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
- *
- * This library is free software; you can redistribute it and/or
- * modify it under the terms of the GNU Lesser General Public
- * License as published by the Free Software Foundation; only
- * version 2.1 of the License.
- *
- * This library is distributed in the hope that it will be useful,
- * but WITHOUT ANY WARRANTY; without even the implied warranty of
- * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
- * Lesser General Public License for more details.
- *
- * You should have received a copy of the GNU Lesser General Public
- * License along with this library; if not, write to the Free Software
- * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
- */
-
-#include <sys/types.h>
-#include <unistd.h>
-#include <lttng/ust-context-provider.h>
-#include "lttng-tracer-core.h"
-#include "jhash.h"
-#include <helper.h>
-
-#define CONTEXT_PROVIDER_HT_BITS 12
-#define CONTEXT_PROVIDER_HT_SIZE (1U << CONTEXT_PROVIDER_HT_BITS)
-struct context_provider_ht {
- struct cds_hlist_head table[CONTEXT_PROVIDER_HT_SIZE];
-};
-
-static struct context_provider_ht context_provider_ht;
-
-static struct lttng_ust_context_provider *
- lookup_provider_by_name(const char *name)
-{
- struct cds_hlist_head *head;
- struct cds_hlist_node *node;
- struct lttng_ust_context_provider *provider;
- uint32_t hash;
- const char *end;
- size_t len;
-
- /* Lookup using everything before first ':' as key. */
- end = strchr(name, ':');
- if (end)
- len = end - name;
- else
- len = strlen(name);
- hash = jhash(name, len, 0);
- head = &context_provider_ht.table[hash & (CONTEXT_PROVIDER_HT_SIZE - 1)];
- cds_hlist_for_each_entry(provider, node, head, node) {
- if (!strncmp(provider->name, name, len))
- return provider;
- }
- return NULL;
-}
-
-int lttng_ust_context_provider_register(struct lttng_ust_context_provider *provider)
-{
- struct cds_hlist_head *head;
- size_t name_len = strlen(provider->name);
- uint32_t hash;
- int ret = 0;
-
- /* Provider name starts with "$app.". */
- if (strncmp("$app.", provider->name, strlen("$app.") != 0))
- return -EINVAL;
- /* Provider name cannot contain a column character. */
- if (strchr(provider->name, ':'))
- return -EINVAL;
- if (ust_lock()) {
- ret = -EBUSY;
- goto end;
- }
- if (lookup_provider_by_name(provider->name)) {
- ret = -EBUSY;
- goto end;
- }
- hash = jhash(provider->name, name_len, 0);
- head = &context_provider_ht.table[hash & (CONTEXT_PROVIDER_HT_SIZE - 1)];
- cds_hlist_add_head(&provider->node, head);
- lttng_ust_context_set_session_provider(provider->name,
- provider->get_size, provider->record,
- provider->get_value);
-end:
- ust_unlock();
- return ret;
-}
-
-static
-size_t dummy_get_size(struct lttng_ctx_field *field, size_t offset)
-{
- size_t size = 0;
-
- size += lib_ring_buffer_align(offset, lttng_alignof(char));
- size += sizeof(char); /* tag */
- return size;
-}
-
-static
-void dummy_record(struct lttng_ctx_field *field,
- struct lttng_ust_lib_ring_buffer_ctx *ctx,
- struct lttng_channel *chan)
-{
- char sel_char = (char) LTTNG_UST_DYNAMIC_TYPE_NONE;
-
- lib_ring_buffer_align_ctx(ctx, lttng_alignof(sel_char));
- chan->ops->event_write(ctx, &sel_char, sizeof(sel_char));
-}
-
-static
-void dummy_get_value(struct lttng_ctx_field *field,
- struct lttng_ctx_value *value)
-{
- value->sel = LTTNG_UST_DYNAMIC_TYPE_NONE;
-}
-
-void lttng_ust_context_provider_unregister(struct lttng_ust_context_provider *provider)
-{
- if (ust_lock())
- goto end;
- lttng_ust_context_set_session_provider(provider->name,
- dummy_get_size, dummy_record, dummy_get_value);
- cds_hlist_del(&provider->node);
-end:
- ust_unlock();
-}
-
-/*
- * Called with ust mutex held.
- * Add application context to array of context, even if the application
- * context is not currently loaded by application. It will then use the
- * dummy callbacks in that case.
- * Always performed before tracing is started, since it modifies
- * metadata describing the context.
- */
-int lttng_ust_add_app_context_to_ctx_rcu(const char *name,
- struct lttng_ctx **ctx)
-{
- struct lttng_ust_context_provider *provider;
- struct lttng_ctx_field new_field;
- int ret;
-
- if (*ctx && lttng_find_context(*ctx, name))
- return -EEXIST;
- /*
- * For application context, add it by expanding
- * ctx array.
- */
- memset(&new_field, 0, sizeof(new_field));
- new_field.field_name = strdup(name);
- if (!new_field.field_name)
- return -ENOMEM;
- new_field.event_field.name = new_field.field_name;
- new_field.event_field.type.atype = atype_dynamic;
- /*
- * If provider is not found, we add the context anyway, but
- * it will provide a dummy context.
- */
- provider = lookup_provider_by_name(name);
- if (provider) {
- new_field.get_size = provider->get_size;
- new_field.record = provider->record;
- new_field.get_value = provider->get_value;
- } else {
- new_field.get_size = dummy_get_size;
- new_field.record = dummy_record;
- new_field.get_value = dummy_get_value;
- }
- ret = lttng_context_add_rcu(ctx, &new_field);
- if (ret) {
- free(new_field.field_name);
- return ret;
- }
- return 0;
-}