liblttng-ust/ltt-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 <helper.h>
  27 #include <string.h>
  28 #include <assert.h>
  29
  30 int lttng_find_context(struct lttng_ctx *ctx, const char *name)
  31 {
  32         unsigned int i;
  33
  34         for (i = 0; i < ctx->nr_fields; i++) {
  35                 /* Skip allocated (but non-initialized) contexts */
  36                 if (!ctx->fields[i].event_field.name)
  37                         continue;
  38                 if (!strcmp(ctx->fields[i].event_field.name, name))
  39                         return 1;
  40         }
  41         return 0;
  42 }
  43
  44 /*
  45  * Note: as we append context information, the pointer location may change.
  46  */
  47 struct lttng_ctx_field *lttng_append_context(struct lttng_ctx **ctx_p)
  48 {
  49         struct lttng_ctx_field *field;
  50         struct lttng_ctx *ctx;
  51
  52         if (!*ctx_p) {
  53                 *ctx_p = zmalloc(sizeof(struct lttng_ctx));
  54                 if (!*ctx_p)
  55                         return NULL;
  56         }
  57         ctx = *ctx_p;
  58         if (ctx->nr_fields + 1 > ctx->allocated_fields) {
  59                 struct lttng_ctx_field *new_fields;
  60
  61                 ctx->allocated_fields = max_t(size_t, 1, 2 * ctx->allocated_fields);
  62                 new_fields = zmalloc(ctx->allocated_fields * sizeof(struct lttng_ctx_field));
  63                 if (!new_fields)
  64                         return NULL;
  65                 if (ctx->fields)
  66                         memcpy(new_fields, ctx->fields, sizeof(*ctx->fields) * ctx->nr_fields);
  67                 free(ctx->fields);
  68                 ctx->fields = new_fields;
  69         }
  70         field = &ctx->fields[ctx->nr_fields];
  71         ctx->nr_fields++;
  72         return field;
  73 }
  74
  75 /*
  76  * Remove last context field.
  77  */
  78 void lttng_remove_context_field(struct lttng_ctx **ctx_p,
  79                                 struct lttng_ctx_field *field)
  80 {
  81         struct lttng_ctx *ctx;
  82
  83         ctx = *ctx_p;
  84         ctx->nr_fields--;
  85         assert(&ctx->fields[ctx->nr_fields] == field);
  86         memset(&ctx->fields[ctx->nr_fields], 0, sizeof(struct lttng_ctx_field));
  87 }
  88
  89 void lttng_destroy_context(struct lttng_ctx *ctx)
  90 {
  91         int i;
  92
  93         if (!ctx)
  94                 return;
  95         for (i = 0; i < ctx->nr_fields; i++) {
  96                 if (ctx->fields[i].destroy)
  97                         ctx->fields[i].destroy(&ctx->fields[i]);
  98         }
  99         free(ctx->fields);
 100         free(ctx);
 101 }