library mass rename: add lttng- prefix

[ust.git] / liblttng-ust / lttng-context-procname.c

diff --git a/liblttng-ust/lttng-context-procname.c b/liblttng-ust/lttng-context-procname.c
new file mode 100644 (file)
index 0000000..b9bae82
--- /dev/null
+++ b/liblttng-ust/lttng-context-procname.c
@@ -0,0 +1,88 @@
+/*
+ * (C) Copyright       2009-2011 -
+ *             Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
+ *
+ * LTTng UST procname context.
+ *
+ * Dual LGPL v2.1/GPL v2 license.
+ */
+
+#include <sys/prctl.h>
+#include <lttng/ust-events.h>
+#include <lttng/ust-tracer.h>
+#include <lttng/ringbuffer-config.h>
+#include <assert.h>
+
+#define PROCNAME_LEN   17      /* includes \0 */
+
+/*
+ * We cache the result to ensure we don't trigger a system call for
+ * each event.
+ * Upon exec, procname changes, but exec takes care of throwing away
+ * this cached version.
+ */
+static char cached_procname[17];
+
+static inline
+char *wrapper_getprocname(void)
+{
+       int ret;
+
+       if (caa_unlikely(!cached_procname[0])) {
+               ret = prctl(PR_GET_NAME, (unsigned long) cached_procname,
+                       0, 0, 0);
+               assert(!ret);
+       }
+       return cached_procname;
+}
+
+void lttng_context_procname_reset(void)
+{
+       cached_procname[0] = '\0';
+}
+
+static
+size_t procname_get_size(size_t offset)
+{
+       size_t size = 0;
+
+       size += PROCNAME_LEN;
+       return size;
+}
+
+static
+void procname_record(struct lttng_ctx_field *field,
+                struct lttng_ust_lib_ring_buffer_ctx *ctx,
+                struct ltt_channel *chan)
+{
+       char *procname;
+
+       procname = wrapper_getprocname();
+       chan->ops->event_write(ctx, procname, PROCNAME_LEN);
+}
+
+int lttng_add_procname_to_ctx(struct lttng_ctx **ctx)
+{
+       struct lttng_ctx_field *field;
+
+       field = lttng_append_context(ctx);
+       if (!field)
+               return -ENOMEM;
+       if (lttng_find_context(*ctx, "procname")) {
+               lttng_remove_context_field(ctx, field);
+               return -EEXIST;
+       }
+       field->event_field.name = "procname";
+       field->event_field.type.atype = atype_array;
+       field->event_field.type.u.array.elem_type.atype = atype_integer;
+       field->event_field.type.u.array.elem_type.u.basic.integer.size = sizeof(char) * CHAR_BIT;
+       field->event_field.type.u.array.elem_type.u.basic.integer.alignment = lttng_alignof(char) * CHAR_BIT;
+       field->event_field.type.u.array.elem_type.u.basic.integer.signedness = lttng_is_signed_type(char);
+       field->event_field.type.u.array.elem_type.u.basic.integer.reverse_byte_order = 0;
+       field->event_field.type.u.array.elem_type.u.basic.integer.base = 10;
+       field->event_field.type.u.array.elem_type.u.basic.integer.encoding = lttng_encode_UTF8;
+       field->event_field.type.u.array.length = PROCNAME_LEN;
+       field->get_size = procname_get_size;
+       field->record = procname_record;
+       return 0;
+}