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 <helper.h>
  27 #include <string.h>
  28 #include <assert.h>
  29
  30 /*
  31  * The filter implementation requires that two consecutive "get" for the
  32  * same context performed by the same thread return the same result.
  33  */
  34
  35 int lttng_find_context(struct lttng_ctx *ctx, const char *name)
  36 {
  37         unsigned int i;
  38
  39         for (i = 0; i < ctx->nr_fields; i++) {
  40                 /* Skip allocated (but non-initialized) contexts */
  41                 if (!ctx->fields[i].event_field.name)
  42                         continue;
  43                 if (!strcmp(ctx->fields[i].event_field.name, name))
  44                         return 1;
  45         }
  46         return 0;
  47 }
  48
  49 int lttng_get_context_index(struct lttng_ctx *ctx, const char *name)
  50 {
  51         unsigned int i;
  52
  53         if (!ctx)
  54                 return -1;
  55         for (i = 0; i < ctx->nr_fields; i++) {
  56                 /* Skip allocated (but non-initialized) contexts */
  57                 if (!ctx->fields[i].event_field.name)
  58                         continue;
  59                 if (!strcmp(ctx->fields[i].event_field.name, name))
  60                         return i;
  61         }
  62         return -1;
  63 }
  64
  65 /*
  66  * Note: as we append context information, the pointer location may change.
  67  */
  68 struct lttng_ctx_field *lttng_append_context(struct lttng_ctx **ctx_p)
  69 {
  70         struct lttng_ctx_field *field;
  71         struct lttng_ctx *ctx;
  72
  73         if (!*ctx_p) {
  74                 *ctx_p = zmalloc(sizeof(struct lttng_ctx));
  75                 if (!*ctx_p)
  76                         return NULL;
  77         }
  78         ctx = *ctx_p;
  79         if (ctx->nr_fields + 1 > ctx->allocated_fields) {
  80                 struct lttng_ctx_field *new_fields;
  81
  82                 ctx->allocated_fields = max_t(size_t, 1, 2 * ctx->allocated_fields);
  83                 new_fields = zmalloc(ctx->allocated_fields * sizeof(struct lttng_ctx_field));
  84                 if (!new_fields)
  85                         return NULL;
  86                 if (ctx->fields)
  87                         memcpy(new_fields, ctx->fields, sizeof(*ctx->fields) * ctx->nr_fields);
  88                 free(ctx->fields);
  89                 ctx->fields = new_fields;
  90         }
  91         field = &ctx->fields[ctx->nr_fields];
  92         ctx->nr_fields++;
  93         return field;
  94 }
  95
  96 /*
  97  * Remove last context field.
  98  */
  99 void lttng_remove_context_field(struct lttng_ctx **ctx_p,
 100                                 struct lttng_ctx_field *field)
 101 {
 102         struct lttng_ctx *ctx;
 103
 104         ctx = *ctx_p;
 105         ctx->nr_fields--;
 106         assert(&ctx->fields[ctx->nr_fields] == field);
 107         memset(&ctx->fields[ctx->nr_fields], 0, sizeof(struct lttng_ctx_field));
 108 }
 109
 110 void lttng_destroy_context(struct lttng_ctx *ctx)
 111 {
 112         int i;
 113
 114         if (!ctx)
 115                 return;
 116         for (i = 0; i < ctx->nr_fields; i++) {
 117                 if (ctx->fields[i].destroy)
 118                         ctx->fields[i].destroy(&ctx->fields[i]);
 119         }
 120         free(ctx->fields);
 121         free(ctx);
 122 }