From d174444dd0631c95a9bf943b0a4efc7bec61c511 Mon Sep 17 00:00:00 2001
From: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
Date: Wed, 3 Feb 2016 17:07:27 -0500
Subject: [PATCH] Handle application context cmd

Signed-off-by: Mathieu Desnoyers <mathieu.desnoyers@efficios.com>
---
 include/lttng/ust-abi.h       |  3 ++
 include/lttng/ust-events.h    |  1 +
 liblttng-ust/lttng-events.c   |  4 +++
 liblttng-ust/lttng-ust-abi.c  |  5 +--
 liblttng-ust/lttng-ust-comm.c | 59 +++++++++++++++++++++++++++++++++++
 5 files changed, 70 insertions(+), 2 deletions(-)

diff --git a/include/lttng/ust-abi.h b/include/lttng/ust-abi.h
index 6ea64c87..126e6124 100644
--- a/include/lttng/ust-abi.h
+++ b/include/lttng/ust-abi.h
@@ -307,6 +307,9 @@ union ust_args {
 	struct {
 		struct lttng_ust_field_iter entry;
 	} field_list;
+	struct {
+		char *ctxname;
+	} app_context;
 };
 
 struct lttng_ust_objd_ops {
diff --git a/include/lttng/ust-events.h b/include/lttng/ust-events.h
index f3ade45c..9eed21ef 100644
--- a/include/lttng/ust-events.h
+++ b/include/lttng/ust-events.h
@@ -629,6 +629,7 @@ int lttng_enabler_attach_exclusion(struct lttng_enabler *enabler,
 		struct lttng_ust_excluder_node *excluder);
 
 int lttng_attach_context(struct lttng_ust_context *context_param,
+		union ust_args *uargs,
 		struct lttng_ctx **ctx, struct lttng_session *session);
 int lttng_session_context_init(struct lttng_ctx **ctx);
 
diff --git a/liblttng-ust/lttng-events.c b/liblttng-ust/lttng-events.c
index f6db6e8a..d09c97ca 100644
--- a/liblttng-ust/lttng-events.c
+++ b/liblttng-ust/lttng-events.c
@@ -962,6 +962,7 @@ int lttng_enabler_attach_exclusion(struct lttng_enabler *enabler,
 }
 
 int lttng_attach_context(struct lttng_ust_context *context_param,
+		union ust_args *uargs,
 		struct lttng_ctx **ctx, struct lttng_session *session)
 {
 	/*
@@ -996,6 +997,9 @@ int lttng_attach_context(struct lttng_ust_context *context_param,
 		return lttng_add_ip_to_ctx(ctx);
 	case LTTNG_UST_CONTEXT_CPU_ID:
 		return lttng_add_cpu_id_to_ctx(ctx);
+	case LTTNG_UST_CONTEXT_APP_CONTEXT:
+		return lttng_ust_add_app_context_to_ctx_rcu(uargs->app_context.ctxname,
+			ctx);
 	default:
 		return -EINVAL;
 	}
diff --git a/liblttng-ust/lttng-ust-abi.c b/liblttng-ust/lttng-ust-abi.c
index c5cc42b7..762c9017 100644
--- a/liblttng-ust/lttng-ust-abi.c
+++ b/liblttng-ust/lttng-ust-abi.c
@@ -335,9 +335,10 @@ long lttng_abi_tracer_version(int objd,
 static
 long lttng_abi_add_context(int objd,
 	struct lttng_ust_context *context_param,
+	union ust_args *uargs,
 	struct lttng_ctx **ctx, struct lttng_session *session)
 {
-	return lttng_attach_context(context_param, ctx, session);
+	return lttng_attach_context(context_param, uargs, ctx, session);
 }
 
 /**
@@ -885,7 +886,7 @@ long lttng_channel_cmd(int objd, unsigned int cmd, unsigned long arg,
 	}
 	case LTTNG_UST_CONTEXT:
 		return lttng_abi_add_context(objd,
-				(struct lttng_ust_context *) arg,
+				(struct lttng_ust_context *) arg, uargs,
 				&channel->ctx, channel->session);
 	case LTTNG_UST_ENABLE:
 		return lttng_channel_enable(channel);
diff --git a/liblttng-ust/lttng-ust-comm.c b/liblttng-ust/lttng-ust-comm.c
index 1387aa82..3108e382 100644
--- a/liblttng-ust/lttng-ust-comm.c
+++ b/liblttng-ust/lttng-ust-comm.c
@@ -588,6 +588,7 @@ int handle_message(struct sock_info *sock_info,
 	const struct lttng_ust_objd_ops *ops;
 	struct ustcomm_ust_reply lur;
 	union ust_args args;
+	char ctxstr[LTTNG_UST_SYM_NAME_LEN];	/* App context string. */
 	ssize_t len;
 
 	memset(&lur, 0, sizeof(lur));
@@ -807,6 +808,64 @@ int handle_message(struct sock_info *sock_info,
 			ret = -ENOSYS;
 		break;
 	}
+	case LTTNG_UST_CONTEXT:
+		switch (lum->u.context.ctx) {
+		case LTTNG_UST_CONTEXT_APP_CONTEXT:
+		{
+			char *p;
+			size_t ctxlen, recvlen;
+
+			ctxlen = strlen("$app.") + lum->u.context.u.app_ctx.provider_name_len - 1
+					+ strlen(":") + lum->u.context.u.app_ctx.ctx_name_len;
+			if (ctxlen >= LTTNG_UST_SYM_NAME_LEN) {
+				ERR("Application context string length size is too large: %zu bytes",
+					ctxlen);
+				ret = -EINVAL;
+				goto error;
+			}
+			strcpy(ctxstr, "$app.");
+			p = &ctxstr[strlen("$app.")];
+			recvlen = ctxlen - strlen("$app.");
+			len = ustcomm_recv_unix_sock(sock, p, recvlen);
+			switch (len) {
+			case 0:	/* orderly shutdown */
+				ret = 0;
+				goto error;
+			default:
+				if (len == recvlen) {
+					DBG("app context data received");
+					break;
+				} else if (len < 0) {
+					DBG("Receive failed from lttng-sessiond with errno %d", (int) -len);
+					if (len == -ECONNRESET) {
+						ERR("%s remote end closed connection", sock_info->name);
+						ret = len;
+						goto error;
+					}
+					ret = len;
+					goto error;
+				} else {
+					DBG("incorrect app context data message size: %zd", len);
+					ret = -EINVAL;
+					goto error;
+				}
+			}
+			/* Put : between provider and ctxname. */
+			p[lum->u.context.u.app_ctx.provider_name_len - 1] = ':';
+			args.app_context.ctxname = ctxstr;
+			break;
+		}
+		default:
+			break;
+		}
+		if (ops->cmd) {
+			ret = ops->cmd(lum->handle, lum->cmd,
+					(unsigned long) &lum->u,
+					&args, sock_info);
+		} else {
+			ret = -ENOSYS;
+		}
+		break;
 	default:
 		if (ops->cmd)
 			ret = ops->cmd(lum->handle, lum->cmd,
-- 
2.34.1