| 1 | /* |
| 2 | * SPDX-License-Identifier: LGPL-2.1-only |
| 3 | * |
| 4 | * Copyright (C) 2016 Mathieu Desnoyers <mathieu.desnoyers@efficios.com> |
| 5 | * |
| 6 | * LTTng UST application context provider. |
| 7 | */ |
| 8 | |
| 9 | #define _LGPL_SOURCE |
| 10 | #include <stddef.h> |
| 11 | #include <stdint.h> |
| 12 | #include <sys/types.h> |
| 13 | #include <unistd.h> |
| 14 | |
| 15 | #include <common/ust-context-provider.h> |
| 16 | |
| 17 | #include "context-internal.h" |
| 18 | #include "lttng-tracer-core.h" |
| 19 | #include "jhash.h" |
| 20 | #include "context-provider-internal.h" |
| 21 | #include "common/macros.h" |
| 22 | |
| 23 | struct lttng_ust_registered_context_provider { |
| 24 | const struct lttng_ust_context_provider *provider; |
| 25 | |
| 26 | struct cds_hlist_node node; |
| 27 | }; |
| 28 | |
| 29 | struct lttng_ust_app_ctx { |
| 30 | char *name; |
| 31 | struct lttng_ust_event_field *event_field; |
| 32 | struct lttng_ust_type_common *type; |
| 33 | }; |
| 34 | |
| 35 | #define CONTEXT_PROVIDER_HT_BITS 12 |
| 36 | #define CONTEXT_PROVIDER_HT_SIZE (1U << CONTEXT_PROVIDER_HT_BITS) |
| 37 | struct context_provider_ht { |
| 38 | struct cds_hlist_head table[CONTEXT_PROVIDER_HT_SIZE]; |
| 39 | }; |
| 40 | |
| 41 | static struct context_provider_ht context_provider_ht; |
| 42 | |
| 43 | static const struct lttng_ust_context_provider * |
| 44 | lookup_provider_by_name(const char *name) |
| 45 | { |
| 46 | struct cds_hlist_head *head; |
| 47 | struct cds_hlist_node *node; |
| 48 | struct lttng_ust_registered_context_provider *reg_provider; |
| 49 | uint32_t hash; |
| 50 | const char *end; |
| 51 | size_t len; |
| 52 | |
| 53 | /* Lookup using everything before first ':' as key. */ |
| 54 | end = strchr(name, ':'); |
| 55 | if (end) |
| 56 | len = end - name; |
| 57 | else |
| 58 | len = strlen(name); |
| 59 | hash = jhash(name, len, 0); |
| 60 | head = &context_provider_ht.table[hash & (CONTEXT_PROVIDER_HT_SIZE - 1)]; |
| 61 | cds_hlist_for_each_entry(reg_provider, node, head, node) { |
| 62 | if (!strncmp(reg_provider->provider->name, name, len)) |
| 63 | return reg_provider->provider; |
| 64 | } |
| 65 | return NULL; |
| 66 | } |
| 67 | |
| 68 | struct lttng_ust_registered_context_provider *lttng_ust_context_provider_register(struct lttng_ust_context_provider *provider) |
| 69 | { |
| 70 | struct lttng_ust_registered_context_provider *reg_provider = NULL; |
| 71 | struct cds_hlist_head *head; |
| 72 | size_t name_len = strlen(provider->name); |
| 73 | uint32_t hash; |
| 74 | |
| 75 | lttng_ust_fixup_tls(); |
| 76 | |
| 77 | /* Provider name starts with "$app.". */ |
| 78 | if (strncmp("$app.", provider->name, strlen("$app.")) != 0) |
| 79 | return NULL; |
| 80 | /* Provider name cannot contain a colon character. */ |
| 81 | if (strchr(provider->name, ':')) |
| 82 | return NULL; |
| 83 | if (ust_lock()) |
| 84 | goto end; |
| 85 | if (lookup_provider_by_name(provider->name)) |
| 86 | goto end; |
| 87 | reg_provider = zmalloc(sizeof(struct lttng_ust_registered_context_provider)); |
| 88 | if (!reg_provider) |
| 89 | goto end; |
| 90 | reg_provider->provider = provider; |
| 91 | hash = jhash(provider->name, name_len, 0); |
| 92 | head = &context_provider_ht.table[hash & (CONTEXT_PROVIDER_HT_SIZE - 1)]; |
| 93 | cds_hlist_add_head(®_provider->node, head); |
| 94 | |
| 95 | lttng_ust_context_set_session_provider(provider->name, |
| 96 | provider->get_size, provider->record, |
| 97 | provider->get_value, provider->priv); |
| 98 | |
| 99 | lttng_ust_context_set_event_notifier_group_provider(provider->name, |
| 100 | provider->get_size, provider->record, |
| 101 | provider->get_value, provider->priv); |
| 102 | end: |
| 103 | ust_unlock(); |
| 104 | return reg_provider; |
| 105 | } |
| 106 | |
| 107 | void lttng_ust_context_provider_unregister(struct lttng_ust_registered_context_provider *reg_provider) |
| 108 | { |
| 109 | lttng_ust_fixup_tls(); |
| 110 | |
| 111 | if (ust_lock()) |
| 112 | goto end; |
| 113 | lttng_ust_context_set_session_provider(reg_provider->provider->name, |
| 114 | lttng_ust_dummy_get_size, lttng_ust_dummy_record, |
| 115 | lttng_ust_dummy_get_value, NULL); |
| 116 | |
| 117 | lttng_ust_context_set_event_notifier_group_provider(reg_provider->provider->name, |
| 118 | lttng_ust_dummy_get_size, lttng_ust_dummy_record, |
| 119 | lttng_ust_dummy_get_value, NULL); |
| 120 | |
| 121 | cds_hlist_del(®_provider->node); |
| 122 | end: |
| 123 | ust_unlock(); |
| 124 | free(reg_provider); |
| 125 | } |
| 126 | |
| 127 | static void destroy_app_ctx(void *priv) |
| 128 | { |
| 129 | struct lttng_ust_app_ctx *app_ctx = (struct lttng_ust_app_ctx *) priv; |
| 130 | |
| 131 | free(app_ctx->name); |
| 132 | free(app_ctx->event_field); |
| 133 | free(app_ctx->type); |
| 134 | free(app_ctx); |
| 135 | } |
| 136 | |
| 137 | /* |
| 138 | * Called with ust mutex held. |
| 139 | * Add application context to array of context, even if the application |
| 140 | * context is not currently loaded by application. It will then use the |
| 141 | * dummy callbacks in that case. |
| 142 | * Always performed before tracing is started, since it modifies |
| 143 | * metadata describing the context. |
| 144 | */ |
| 145 | int lttng_ust_add_app_context_to_ctx_rcu(const char *name, |
| 146 | struct lttng_ust_ctx **ctx) |
| 147 | { |
| 148 | const struct lttng_ust_context_provider *provider; |
| 149 | struct lttng_ust_ctx_field new_field = { 0 }; |
| 150 | struct lttng_ust_event_field *event_field = NULL; |
| 151 | struct lttng_ust_type_common *type = NULL; |
| 152 | struct lttng_ust_app_ctx *app_ctx = NULL; |
| 153 | char *ctx_name; |
| 154 | int ret; |
| 155 | |
| 156 | if (*ctx && lttng_find_context(*ctx, name)) |
| 157 | return -EEXIST; |
| 158 | event_field = zmalloc(sizeof(struct lttng_ust_event_field)); |
| 159 | if (!event_field) { |
| 160 | ret = -ENOMEM; |
| 161 | goto error_event_field_alloc; |
| 162 | } |
| 163 | ctx_name = strdup(name); |
| 164 | if (!ctx_name) { |
| 165 | ret = -ENOMEM; |
| 166 | goto error_field_name_alloc; |
| 167 | } |
| 168 | type = zmalloc(sizeof(struct lttng_ust_type_common)); |
| 169 | if (!type) { |
| 170 | ret = -ENOMEM; |
| 171 | goto error_field_type_alloc; |
| 172 | } |
| 173 | app_ctx = zmalloc(sizeof(struct lttng_ust_app_ctx)); |
| 174 | if (!app_ctx) { |
| 175 | ret = -ENOMEM; |
| 176 | goto error_app_ctx_alloc; |
| 177 | } |
| 178 | event_field->name = ctx_name; |
| 179 | type->type = lttng_ust_type_dynamic; |
| 180 | event_field->type = type; |
| 181 | new_field.event_field = event_field; |
| 182 | /* |
| 183 | * If provider is not found, we add the context anyway, but |
| 184 | * it will provide a dummy context. |
| 185 | */ |
| 186 | provider = lookup_provider_by_name(name); |
| 187 | if (provider) { |
| 188 | new_field.get_size = provider->get_size; |
| 189 | new_field.record = provider->record; |
| 190 | new_field.get_value = provider->get_value; |
| 191 | } else { |
| 192 | new_field.get_size = lttng_ust_dummy_get_size; |
| 193 | new_field.record = lttng_ust_dummy_record; |
| 194 | new_field.get_value = lttng_ust_dummy_get_value; |
| 195 | } |
| 196 | new_field.destroy = destroy_app_ctx; |
| 197 | new_field.priv = app_ctx; |
| 198 | /* |
| 199 | * For application context, add it by expanding |
| 200 | * ctx array. |
| 201 | */ |
| 202 | ret = lttng_ust_context_append_rcu(ctx, &new_field); |
| 203 | if (ret) { |
| 204 | destroy_app_ctx(app_ctx); |
| 205 | return ret; |
| 206 | } |
| 207 | return 0; |
| 208 | |
| 209 | error_app_ctx_alloc: |
| 210 | free(type); |
| 211 | error_field_type_alloc: |
| 212 | free(ctx_name); |
| 213 | error_field_name_alloc: |
| 214 | free(event_field); |
| 215 | error_event_field_alloc: |
| 216 | return ret; |
| 217 | } |