liblttng-ust/lttng-context.c

   1 /*
   2  * lttng-context.c
   3  *
   4  * LTTng UST trace/channel/event context management.
   5  *
   6  * Copyright (C) 2011 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
   7  *
   8  * This library is free software; you can redistribute it and/or
   9  * modify it under the terms of the GNU Lesser General Public
  10  * License as published by the Free Software Foundation; only
  11  * version 2.1 of the License.
  12  *
  13  * This library is distributed in the hope that it will be useful,
  14  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  15  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
  16  * Lesser General Public License for more details.
  17  *
  18  * You should have received a copy of the GNU Lesser General Public
  19  * License along with this library; if not, write to the Free Software
  20  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
  21  */
  22
  23
  24 #include <lttng/ust-events.h>
  25 #include <lttng/ust-tracer.h>
  26 #include <usterr-signal-safe.h>
  27 #include <helper.h>
  28 #include <string.h>
  29 #include <assert.h>
  30
  31 /*
  32  * The filter implementation requires that two consecutive "get" for the
  33  * same context performed by the same thread return the same result.
  34  */
  35
  36 /*
  37  * Static array of contexts, for $ctx filters.
  38  */
  39 struct lttng_ctx *lttng_static_ctx;
  40
  41 int lttng_find_context(struct lttng_ctx *ctx, const char *name)
  42 {
  43         unsigned int i;
  44
  45         for (i = 0; i < ctx->nr_fields; i++) {
  46                 /* Skip allocated (but non-initialized) contexts */
  47                 if (!ctx->fields[i].event_field.name)
  48                         continue;
  49                 if (!strcmp(ctx->fields[i].event_field.name, name))
  50                         return 1;
  51         }
  52         return 0;
  53 }
  54
  55 int lttng_get_context_index(struct lttng_ctx *ctx, const char *name)
  56 {
  57         unsigned int i;
  58
  59         if (!ctx)
  60                 return -1;
  61         for (i = 0; i < ctx->nr_fields; i++) {
  62                 /* Skip allocated (but non-initialized) contexts */
  63                 if (!ctx->fields[i].event_field.name)
  64                         continue;
  65                 if (!strcmp(ctx->fields[i].event_field.name, name))
  66                         return i;
  67         }
  68         return -1;
  69 }
  70
  71 /*
  72  * Note: as we append context information, the pointer location may change.
  73  */
  74 struct lttng_ctx_field *lttng_append_context(struct lttng_ctx **ctx_p)
  75 {
  76         struct lttng_ctx_field *field;
  77         struct lttng_ctx *ctx;
  78
  79         if (!*ctx_p) {
  80                 *ctx_p = zmalloc(sizeof(struct lttng_ctx));
  81                 if (!*ctx_p)
  82                         return NULL;
  83         }
  84         ctx = *ctx_p;
  85         if (ctx->nr_fields + 1 > ctx->allocated_fields) {
  86                 struct lttng_ctx_field *new_fields;
  87
  88                 ctx->allocated_fields = max_t(size_t, 1, 2 * ctx->allocated_fields);
  89                 new_fields = zmalloc(ctx->allocated_fields * sizeof(struct lttng_ctx_field));
  90                 if (!new_fields)
  91                         return NULL;
  92                 if (ctx->fields)
  93                         memcpy(new_fields, ctx->fields, sizeof(*ctx->fields) * ctx->nr_fields);
  94                 free(ctx->fields);
  95                 ctx->fields = new_fields;
  96         }
  97         field = &ctx->fields[ctx->nr_fields];
  98         ctx->nr_fields++;
  99         return field;
 100 }
 101
 102 /*
 103  * Remove last context field.
 104  */
 105 void lttng_remove_context_field(struct lttng_ctx **ctx_p,
 106                                 struct lttng_ctx_field *field)
 107 {
 108         struct lttng_ctx *ctx;
 109
 110         ctx = *ctx_p;
 111         ctx->nr_fields--;
 112         assert(&ctx->fields[ctx->nr_fields] == field);
 113         memset(&ctx->fields[ctx->nr_fields], 0, sizeof(struct lttng_ctx_field));
 114 }
 115
 116 void lttng_destroy_context(struct lttng_ctx *ctx)
 117 {
 118         int i;
 119
 120         if (!ctx)
 121                 return;
 122         for (i = 0; i < ctx->nr_fields; i++) {
 123                 if (ctx->fields[i].destroy)
 124                         ctx->fields[i].destroy(&ctx->fields[i]);
 125         }
 126         free(ctx->fields);
 127         free(ctx);
 128 }
 129
 130 void lttng_context_init(void)
 131 {
 132         int ret;
 133
 134         ret = lttng_add_pthread_id_to_ctx(&lttng_static_ctx);
 135         if (ret) {
 136                 WARN("Cannot add context lttng_add_pthread_id_to_ctx");
 137         }
 138         ret = lttng_add_vtid_to_ctx(&lttng_static_ctx);
 139         if (ret) {
 140                 WARN("Cannot add context lttng_add_vtid_to_ctx");
 141         }
 142         ret = lttng_add_vpid_to_ctx(&lttng_static_ctx);
 143         if (ret) {
 144                 WARN("Cannot add context lttng_add_vpid_to_ctx");
 145         }
 146         ret = lttng_add_procname_to_ctx(&lttng_static_ctx);
 147         if (ret) {
 148                 WARN("Cannot add context lttng_add_procname_to_ctx");
 149         }
 150 }
 151
 152 void lttng_context_exit(void)
 153 {
 154         lttng_destroy_context(lttng_static_ctx);
 155         lttng_static_ctx = NULL;
 156 }