X-Git-Url: http://git.liburcu.org/?a=blobdiff_plain;f=liblttng-ust%2Flttng-context-procname.c;fp=liblttng-ust%2Flttng-context-procname.c;h=b9bae82eba91be79fdd2ca1749fe2e5f2066b570;hb=69400ac4a4e6575f749c6326df7c2a2c8ac3bdc5;hp=0000000000000000000000000000000000000000;hpb=f3049ad9e7b72287888452b9ed542c0f36e6eefe;p=ust.git

diff --git a/liblttng-ust/lttng-context-procname.c b/liblttng-ust/lttng-context-procname.c
new file mode 100644
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;
+}