X-Git-Url: http://git.liburcu.org/?a=blobdiff_plain;f=src%2Flttng-context-hostname.c;fp=src%2Flttng-context-hostname.c;h=86c5d021dd9c42f4cfedbfc250d889a691e5a7f9;hb=cfa6cc1d0f01c2cfcc1a679abf3a6572d411c309;hp=0000000000000000000000000000000000000000;hpb=cd4486798c2b046ea93b89439cd705e93c40b349;p=lttng-modules.git

diff --git a/src/lttng-context-hostname.c b/src/lttng-context-hostname.c
new file mode 100644
index 00000000..86c5d021
--- /dev/null
+++ b/src/lttng-context-hostname.c
@@ -0,0 +1,106 @@
+/* SPDX-License-Identifier: (GPL-2.0-only or LGPL-2.1-only)
+ *
+ * lttng-context-hostname.c
+ *
+ * LTTng hostname context.
+ *
+ * Copyright (C) 2009-2012 Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
+ */
+
+#include <linux/module.h>
+#include <linux/slab.h>
+#include <linux/sched.h>
+#include <linux/utsname.h>
+#include <lttng/events.h>
+#include <ringbuffer/frontend_types.h>
+#include <wrapper/vmalloc.h>
+#include <lttng/tracer.h>
+
+#define LTTNG_HOSTNAME_CTX_LEN	(__NEW_UTS_LEN + 1)
+
+static
+size_t hostname_get_size(size_t offset)
+{
+	size_t size = 0;
+
+	size += LTTNG_HOSTNAME_CTX_LEN;
+	return size;
+}
+
+static
+void hostname_record(struct lttng_ctx_field *field,
+		 struct lib_ring_buffer_ctx *ctx,
+		 struct lttng_channel *chan)
+{
+	struct nsproxy *nsproxy;
+	struct uts_namespace *ns;
+	char *hostname;
+
+	/*
+	 * No need to take the RCU read-side lock to read current
+	 * nsproxy. (documented in nsproxy.h)
+	 */
+	nsproxy = current->nsproxy;
+	if (nsproxy) {
+		ns = nsproxy->uts_ns;
+		hostname = ns->name.nodename;
+		chan->ops->event_write(ctx, hostname,
+				LTTNG_HOSTNAME_CTX_LEN);
+	} else {
+		chan->ops->event_memset(ctx, 0,
+				LTTNG_HOSTNAME_CTX_LEN);
+	}
+}
+
+static
+void hostname_get_value(struct lttng_ctx_field *field,
+		struct lttng_probe_ctx *lttng_probe_ctx,
+		union lttng_ctx_value *value)
+{
+	struct nsproxy *nsproxy;
+	struct uts_namespace *ns;
+	char *hostname;
+
+	/*
+	 * No need to take the RCU read-side lock to read current
+	 * nsproxy. (documented in nsproxy.h)
+	 */
+	nsproxy = current->nsproxy;
+	if (nsproxy) {
+		ns = nsproxy->uts_ns;
+		hostname = ns->name.nodename;
+	} else {
+		hostname = "";
+	}
+	value->str = hostname;
+}
+
+static const struct lttng_type hostname_array_elem_type =
+	__type_integer(char, 0, 0, -1, __BYTE_ORDER, 10, UTF8);
+
+int lttng_add_hostname_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, "hostname")) {
+		lttng_remove_context_field(ctx, field);
+		return -EEXIST;
+	}
+	field->event_field.name = "hostname";
+	field->event_field.type.atype = atype_array_nestable;
+	field->event_field.type.u.array_nestable.elem_type =
+		&hostname_array_elem_type;
+	field->event_field.type.u.array_nestable.length = LTTNG_HOSTNAME_CTX_LEN;
+	field->event_field.type.u.array_nestable.alignment = 0;
+
+	field->get_size = hostname_get_size;
+	field->record = hostname_record;
+	field->get_value = hostname_get_value;
+	lttng_context_update(*ctx);
+	wrapper_vmalloc_sync_mappings();
+	return 0;
+}
+EXPORT_SYMBOL_GPL(lttng_add_hostname_to_ctx);