liblttng-ust/ltt-context.c

   1 /*
   2  * ltt-context.c
   3  *
   4  * Copyright 2011 (c) - Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
   5  *
   6  * LTTng UST trace/channel/event context management.
   7  *
   8  * Dual LGPL v2.1/GPL v2 license.
   9  */
  10
  11 #include <lttng/ust-events.h>
  12 #include <lttng/ust-tracer.h>
  13 #include <helper.h>
  14 #include <string.h>
  15 #include <assert.h>
  16
  17 int lttng_find_context(struct lttng_ctx *ctx, const char *name)
  18 {
  19         unsigned int i;
  20
  21         for (i = 0; i < ctx->nr_fields; i++) {
  22                 /* Skip allocated (but non-initialized) contexts */
  23                 if (!ctx->fields[i].event_field.name)
  24                         continue;
  25                 if (!strcmp(ctx->fields[i].event_field.name, name))
  26                         return 1;
  27         }
  28         return 0;
  29 }
  30
  31 /*
  32  * Note: as we append context information, the pointer location may change.
  33  */
  34 struct lttng_ctx_field *lttng_append_context(struct lttng_ctx **ctx_p)
  35 {
  36         struct lttng_ctx_field *field;
  37         struct lttng_ctx *ctx;
  38
  39         if (!*ctx_p) {
  40                 *ctx_p = zmalloc(sizeof(struct lttng_ctx));
  41                 if (!*ctx_p)
  42                         return NULL;
  43         }
  44         ctx = *ctx_p;
  45         if (ctx->nr_fields + 1 > ctx->allocated_fields) {
  46                 struct lttng_ctx_field *new_fields;
  47
  48                 ctx->allocated_fields = max_t(size_t, 1, 2 * ctx->allocated_fields);
  49                 new_fields = zmalloc(ctx->allocated_fields * sizeof(struct lttng_ctx_field));
  50                 if (!new_fields)
  51                         return NULL;
  52                 if (ctx->fields)
  53                         memcpy(new_fields, ctx->fields, sizeof(*ctx->fields) * ctx->nr_fields);
  54                 free(ctx->fields);
  55                 ctx->fields = new_fields;
  56         }
  57         field = &ctx->fields[ctx->nr_fields];
  58         ctx->nr_fields++;
  59         return field;
  60 }
  61
  62 /*
  63  * Remove last context field.
  64  */
  65 void lttng_remove_context_field(struct lttng_ctx **ctx_p,
  66                                 struct lttng_ctx_field *field)
  67 {
  68         struct lttng_ctx *ctx;
  69
  70         ctx = *ctx_p;
  71         ctx->nr_fields--;
  72         assert(&ctx->fields[ctx->nr_fields] == field);
  73         memset(&ctx->fields[ctx->nr_fields], 0, sizeof(struct lttng_ctx_field));
  74 }
  75
  76 void lttng_destroy_context(struct lttng_ctx *ctx)
  77 {
  78         int i;
  79
  80         if (!ctx)
  81                 return;
  82         for (i = 0; i < ctx->nr_fields; i++) {
  83                 if (ctx->fields[i].destroy)
  84                         ctx->fields[i].destroy(&ctx->fields[i]);
  85         }
  86         free(ctx->fields);
  87         free(ctx);
  88 }