X-Git-Url: http://git.liburcu.org/?a=blobdiff_plain;f=libustcomm%2Fustcomm.c;h=dce1e521c5b5c83714d439a00edf07ccb73253dc;hb=dbd75de7b2c05c98d6171bc531a1ecb23fb7e80d;hp=f2aeb61fc423d2d818e89190fae44312d92f3658;hpb=4e2a88089f60f56b118bbfcbac65f74e79166436;p=ust.git

diff --git a/libustcomm/ustcomm.c b/libustcomm/ustcomm.c
index f2aeb61..dce1e52 100644
--- a/libustcomm/ustcomm.c
+++ b/libustcomm/ustcomm.c
@@ -1,3 +1,22 @@
+/* Copyright (C) 2009  Pierre-Marc Fournier
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301 USA
+ */
+
+/* API used by UST components to communicate with each other via sockets. */
+
 #define _GNU_SOURCE
 #include <sys/types.h>
 #include <signal.h>
@@ -6,6 +25,8 @@
 #include <sys/un.h>
 #include <unistd.h>
 #include <poll.h>
+#include <sys/epoll.h>
+#include <sys/stat.h>
 
 #include <stdio.h>
 #include <stdlib.h>
@@ -13,608 +34,817 @@
 #include <execinfo.h>
 
 #include "ustcomm.h"
-#include "localerr.h"
+#include "usterr.h"
+#include "share.h"
 
-#define UNIX_PATH_MAX 108
-#define SOCK_DIR "/tmp/socks"
-#define UST_SIGNAL SIGIO
+static int mkdir_p(const char *path, mode_t mode)
+{
+	const char *path_p;
+	char *tmp;
 
-#define MSG_MAX 1000
+	int retval = 0;
+	int result;
+	mode_t old_umask;
 
-/* FIXME: ustcomm blocks on message sending, which might be problematic in
- * some cases. Fix the poll() usage so sends are buffered until they don't
- * block.
- */
+	tmp = zmalloc(strlen(path) + 1);
+	if (tmp == NULL)
+		return -1;
+
+	/* skip first / */
+	path_p = path+1;
+
+	old_umask = umask(0);
+	for(;;) {
+		while (*path_p != '/') {
+			if(*path_p == 0)
+				break;
+			++path_p;
+		}
+		if (*path_p == '/') {
+			strncpy(tmp, path, path_p - path);
+			tmp[path_p-path] = '\0';
+			if (tmp[path_p - path - 1] != '/') {
+				result = mkdir(tmp, mode);
+				if(result == -1) {
+					if (!(errno == EEXIST || errno == EACCES || errno == EROFS)) {
+						/* Then this is a real error */
+						retval = -1;
+						break;
+					}
+				}
+			}
+			/* pass / */
+			path_p++;
+		} else {
+			/* last component */
+			result = mkdir(path, mode);
+			if (result == -1)
+				retval = -1;
+			break;
+		}
+	}
 
-//static void bt(void)
-//{
-//	void *buffer[100];
-//	int result;
-//
-//	result = backtrace(&buffer, 100);
-//	backtrace_symbols_fd(buffer, result, STDERR_FILENO);
-//}
+	free(tmp);
+	umask(old_umask);
+	return retval;
+}
 
-char *strdup_malloc(const char *s)
+static struct sockaddr_un * create_sock_addr(const char *name,
+					     size_t *sock_addr_size)
 {
-	char *retval;
+	struct sockaddr_un * addr;
+	size_t alloc_size;
 
-	if(s == NULL)
+	alloc_size = (size_t) (((struct sockaddr_un *) 0)->sun_path) +
+		strlen(name) + 1;
+
+	addr = malloc(alloc_size);
+	if (addr < 0) {
+		ERR("allocating addr failed");
 		return NULL;
+	}
 
-	retval = (char *) malloc(strlen(s)+1);
+	addr->sun_family = AF_UNIX;
+	strcpy(addr->sun_path, name);
 
-	strcpy(retval, s);
+	*sock_addr_size = alloc_size;
 
-	return retval;
+	return addr;
 }
 
-static void signal_process(pid_t pid)
+struct ustcomm_sock * ustcomm_init_sock(int fd, int epoll_fd,
+					struct cds_list_head *list)
 {
-	int result;
+	struct epoll_event ev;
+	struct ustcomm_sock *sock;
 
-	result = kill(pid, UST_SIGNAL);
-	if(result == -1) {
-		PERROR("kill");
-		return;
+	sock = malloc(sizeof(struct ustcomm_sock));
+	if (!sock) {
+		perror("malloc: couldn't allocate ustcomm_sock");
+		return NULL;
 	}
 
-	sleep(1);
-}
-
-static int send_message_fd(int fd, const char *msg)
-{
-	int result;
+	ev.events = EPOLLIN;
+	ev.data.ptr = sock;
+	sock->fd = fd;
 
-	result = send(fd, msg, strlen(msg), 0);
-	if(result == -1) {
-		PERROR("send");
-		return -1;
+	if (epoll_ctl(epoll_fd, EPOLL_CTL_ADD, sock->fd, &ev) == -1) {
+		perror("epoll_ctl: failed to add socket\n");
+		free(sock);
+		return NULL;
 	}
-	else if(result == 0) {
-		return 0;
+
+	sock->epoll_fd = epoll_fd;
+	if (list) {
+		cds_list_add(&sock->list, list);
+	} else {
+		CDS_INIT_LIST_HEAD(&sock->list);
 	}
 
-	return 1;
+	return sock;
+}
 
-//	*reply = (char *) malloc(MSG_MAX+1);
-//	result = recv(fd, *reply, MSG_MAX, 0);
-//	if(result == -1) {
-//		PERROR("recv");
-//		return -1;
-//	}
-//	else if(result == 0) {
-//		return 0;
-//	}
-//	
-//	(*reply)[result] = '\0';
-//
-//	return 1;
+void ustcomm_del_sock(struct ustcomm_sock *sock, int keep_in_epoll)
+{
+	cds_list_del(&sock->list);
+	if (!keep_in_epoll) {
+		if (epoll_ctl(sock->epoll_fd, EPOLL_CTL_DEL, sock->fd, NULL) == -1) {
+			PERROR("epoll_ctl: failed to delete socket");
+		}
+	}
+	close(sock->fd);
+	free(sock);
 }
 
-static int send_message_path(const char *path, const char *msg, int signalpid)
+struct ustcomm_sock * ustcomm_init_named_socket(const char *name,
+						int epoll_fd)
 {
-	int fd;
 	int result;
-	struct sockaddr_un addr;
+	int fd;
+	size_t sock_addr_size;
+	struct sockaddr_un * addr;
+	struct ustcomm_sock *sock;
 
-	result = fd = socket(PF_UNIX, SOCK_STREAM, 0);
-	if(result == -1) {
+	fd = socket(PF_UNIX, SOCK_STREAM, 0);
+	if(fd == -1) {
 		PERROR("socket");
-		return -1;
+		return NULL;
 	}
 
-	addr.sun_family = AF_UNIX;
+	addr = create_sock_addr(name, &sock_addr_size);
+	if (addr == NULL) {
+		ERR("allocating addr, UST thread bailing");
+		goto close_sock;
+	}
 
-	result = snprintf(addr.sun_path, UNIX_PATH_MAX, "%s", path);
-	if(result >= UNIX_PATH_MAX) {
-		ERR("string overflow allocating socket name");
-		return -1;
+	result = access(name, F_OK);
+	if(result == 0) {
+		/* file exists */
+		result = unlink(name);
+		if(result == -1) {
+			PERROR("unlink of socket file");
+			goto free_addr;
+		}
+		DBG("socket already exists; overwriting");
 	}
 
-	if(signalpid >= 0)
-		signal_process(signalpid);
+	result = bind(fd, (struct sockaddr *)addr, sock_addr_size);
+	if(result == -1) {
+		PERROR("bind");
+		goto free_addr;
+	}
 
-	result = connect(fd, (struct sockaddr *)&addr, sizeof(addr));
+	result = listen(fd, 1);
 	if(result == -1) {
-		PERROR("connect");
-		return -1;
+		PERROR("listen");
+		goto free_addr;
+	}
+
+	sock = ustcomm_init_sock(fd, epoll_fd,
+				 NULL);
+	if (!sock) {
+		ERR("failed to create ustcomm_sock");
+		goto free_addr;
 	}
 
-	return send_message_fd(fd, msg);
+	free(addr);
+
+	return sock;
+
+free_addr:
+	free(addr);
+close_sock:
+	close(fd);
+
+	return NULL;
 }
 
-///* pid: the pid of the trace process that must receive the msg
-//   msg: pointer to a null-terminated message to send
-//   reply: location where to put the null-terminated string of the reply;
-//	  it must be free'd after usage
-// */
-//
-//int send_message_pid(pid_t pid, const char *msg, char **reply)
-//{
-//	int result;
-//	char path[UNIX_PATH_MAX];
-//
-//	result = snprintf(path, UNIX_PATH_MAX, "%s/%d", SOCK_DIR, pid);
-//	if(result >= UNIX_PATH_MAX) {
-//		fprintf(stderr, "string overflow allocating socket name");
-//		return -1;
-//	}
-//
-//	send_message_path(path, msg, reply, pid);
-//
-//	return 0;
-//}
-
-/* Called by an app to ask the consumer daemon to connect to it. */
-
-int ustcomm_request_consumer(pid_t pid, const char *channel)
+void ustcomm_del_named_sock(struct ustcomm_sock *sock,
+			    int keep_socket_file)
 {
-	char path[UNIX_PATH_MAX];
-	int result;
-	char *msg;
+	int result, fd;
+	struct stat st;
+	struct sockaddr dummy;
+	struct sockaddr_un *sockaddr = NULL;
+	int alloc_size;
 
-	result = snprintf(path, UNIX_PATH_MAX, "%s/ustd", SOCK_DIR);
-	if(result >= UNIX_PATH_MAX) {
-		fprintf(stderr, "string overflow allocating socket name");
-		return -1;
-	}
+	fd = sock->fd;
 
-	asprintf(&msg, "collect %d %s", pid, channel); 
+	if(!keep_socket_file) {
 
-	send_message_path(path, msg, -1);
-	free(msg);
+		/* Get the socket name */
+		alloc_size = sizeof(dummy);
+		if (getsockname(fd, &dummy, (socklen_t *)&alloc_size) < 0) {
+			PERROR("getsockname failed");
+			goto del_sock;
+		}
 
-	return 0;
-}
+		sockaddr = zmalloc(alloc_size);
+		if (!sockaddr) {
+			ERR("failed to allocate sockaddr");
+			goto del_sock;
+		}
 
-/* returns 1 to indicate a message was received
- * returns 0 to indicate no message was received (cannot happen)
- * returns -1 to indicate an error
- */
+		if (getsockname(fd, sockaddr, (socklen_t *)&alloc_size) < 0) {
+			PERROR("getsockname failed");
+			goto free_sockaddr;
+		}
 
-static int recv_message_fd(int fd, char **msg, struct ustcomm_source *src)
-{
-	int result;
+		/* Destroy socket */
+		result = stat(sockaddr->sun_path, &st);
+		if(result < 0) {
+			PERROR("stat (%s)", sockaddr->sun_path);
+			goto free_sockaddr;
+		}
 
-	*msg = (char *) malloc(MSG_MAX+1);
+		/* Paranoid check before deleting. */
+		result = S_ISSOCK(st.st_mode);
+		if(!result) {
+			ERR("The socket we are about to delete is not a socket.");
+			goto free_sockaddr;
+		}
 
-	result = recv(fd, *msg, MSG_MAX, 0);
-	if(result == -1) {
-		PERROR("recv");
-		return -1;
+		result = unlink(sockaddr->sun_path);
+		if(result < 0) {
+			PERROR("unlink");
+		}
 	}
 
-	(*msg)[result] = '\0';
-	
-	DBG("ustcomm_app_recv_message: result is %d, message is %s", result, (*msg));
-
-	if(src)
-		src->fd = fd;
+free_sockaddr:
+	free(sockaddr);
 
-	return 1;
+del_sock:
+	ustcomm_del_sock(sock, keep_socket_file);
 }
 
-int ustcomm_send_reply(struct ustcomm_server *server, char *msg, struct ustcomm_source *src)
-{
+int ustcomm_recv_alloc(int sock,
+		       struct ustcomm_header *header,
+		       char **data) {
 	int result;
+	struct ustcomm_header peek_header;
+	struct iovec iov[2];
+	struct msghdr msg;
 
-	result = send_message_fd(src->fd, msg);
-	if(result < 0) {
-		ERR("error in send_message_fd");
-		return -1;
+	/* Just to make the caller fail hard */
+	*data = NULL;
+
+	result = recv(sock, &peek_header, sizeof(peek_header),
+		      MSG_PEEK | MSG_WAITALL);
+	if (result <= 0) {
+		if(errno == ECONNRESET) {
+			return 0;
+		} else if (errno == EINTR) {
+			return -1;
+		} else if (result < 0) {
+			PERROR("recv");
+			return -1;
+		}
+		return 0;
 	}
 
-	return 0;
-} 
+	memset(&msg, 0, sizeof(msg));
 
-/* @timeout: max blocking time in milliseconds, -1 means infinity
- *
- * returns 1 to indicate a message was received
- * returns 0 to indicate no message was received
- * returns -1 to indicate an error
- */
+	iov[0].iov_base = (char *)header;
+	iov[0].iov_len = sizeof(struct ustcomm_header);
 
-int ustcomm_recv_message(struct ustcomm_server *server, char **msg, struct ustcomm_source *src, int timeout)
-{
-	struct pollfd *fds;
-	struct ustcomm_connection *conn;
-	int result;
-	int retval;
-
-	for(;;) {
-		int idx = 0;
-		int n_fds = 1;
+	msg.msg_iov = iov;
+	msg.msg_iovlen = 1;
 
-		list_for_each_entry(conn, &server->connections, list) {
-			n_fds++;
+	if (peek_header.size) {
+		*data = zmalloc(peek_header.size);
+		if (!*data) {
+			return -ENOMEM;
 		}
 
-		fds = (struct pollfd *) malloc(n_fds * sizeof(struct pollfd));
-		if(fds == NULL) {
-			ERR("malloc returned NULL");
-			return -1;
-		}
+		iov[1].iov_base = *data;
+		iov[1].iov_len = peek_header.size;
 
-		/* special idx 0 is for listening socket */
-		fds[idx].fd = server->listen_fd;
-		fds[idx].events = POLLIN;
-		idx++;
+		msg.msg_iovlen++;
+	}
 
-		list_for_each_entry(conn, &server->connections, list) {
-			fds[idx].fd = conn->fd;
-			fds[idx].events = POLLIN;
-			idx++;
-		}
+	result = recvmsg(sock, &msg, MSG_WAITALL);
+	if (result < 0) {
+		free(*data);
+		PERROR("recvmsg failed");
+	}
 
-		result = poll(fds, n_fds, timeout);
-		if(result == -1) {
-			PERROR("poll");
+	return result;
+}
+
+/* returns 1 to indicate a message was received
+ * returns 0 to indicate no message was received (end of stream)
+ * returns -1 to indicate an error
+ */
+int ustcomm_recv_fd(int sock,
+		    struct ustcomm_header *header,
+		    char *data, int *fd)
+{
+	int result;
+	struct ustcomm_header peek_header;
+	struct iovec iov[2];
+	struct msghdr msg;
+	struct cmsghdr *cmsg;
+	char buf[CMSG_SPACE(sizeof(int))];
+
+	result = recv(sock, &peek_header, sizeof(peek_header),
+		      MSG_PEEK | MSG_WAITALL);
+	if (result <= 0) {
+		if(errno == ECONNRESET) {
+			return 0;
+		} else if (errno == EINTR) {
+			return -1;
+		} else if (result < 0) {
+			PERROR("recv");
 			return -1;
 		}
+		return 0;
+	}
 
-		if(result == 0)
-			return 0;
+	memset(&msg, 0, sizeof(msg));
 
-		if(fds[0].revents) {
-			struct ustcomm_connection *newconn;
-			int newfd;
+	iov[0].iov_base = (char *)header;
+	iov[0].iov_len = sizeof(struct ustcomm_header);
 
-			result = newfd = accept(server->listen_fd, NULL, NULL);
-			if(result == -1) {
-				PERROR("accept");
-				return -1;
-			}
+	msg.msg_iov = iov;
+	msg.msg_iovlen = 1;
 
-			newconn = (struct ustcomm_connection *) malloc(sizeof(struct ustcomm_connection));
-			if(newconn == NULL) {
-				ERR("malloc returned NULL");
-				return -1;
-			}
+	if (peek_header.size && data) {
+		if (peek_header.size < 0 ||
+		    peek_header.size > USTCOMM_DATA_SIZE) {
+			ERR("big peek header! %ld", peek_header.size);
+			return 0;
+		}
 
-			newconn->fd = newfd;
+		iov[1].iov_base = data;
+		iov[1].iov_len = peek_header.size;
 
-			list_add(&newconn->list, &server->connections);
-		}
+		msg.msg_iovlen++;
+	}
 
-		for(idx=1; idx<n_fds; idx++) {
-			if(fds[idx].revents) {
-				retval = recv_message_fd(fds[idx].fd, msg, src);
-				if(**msg == 0) {
-					/* connection finished */
-					close(fds[idx].fd);
-
-					list_for_each_entry(conn, &server->connections, list) {
-						if(conn->fd == fds[idx].fd) {
-							list_del(&conn->list);
-							break;
-						}
-					}
-				}
-				else {
-					goto free_fds_return;
-				}
+	if (fd && peek_header.fd_included) {
+		msg.msg_control = buf;
+		msg.msg_controllen = sizeof(buf);
+	}
+
+	result = recvmsg(sock, &msg, MSG_WAITALL);
+	if (result <= 0) {
+		if (result < 0) {
+			PERROR("recvmsg failed");
+		}
+		return result;
+	}
+
+	if (fd && peek_header.fd_included) {
+		cmsg = CMSG_FIRSTHDR(&msg);
+		result = 0;
+		while (cmsg != NULL) {
+			if (cmsg->cmsg_level == SOL_SOCKET
+			    && cmsg->cmsg_type  == SCM_RIGHTS) {
+				*fd = *(int *) CMSG_DATA(cmsg);
+				result = 1;
+				break;
 			}
+			cmsg = CMSG_NXTHDR(&msg, cmsg);
+		}
+		if (!result) {
+			ERR("Failed to receive file descriptor\n");
 		}
-
-		free(fds);
 	}
 
-free_fds_return:
-	free(fds);
-	return retval;
+	return 1;
 }
 
-int ustcomm_ustd_recv_message(struct ustcomm_ustd *ustd, char **msg, struct ustcomm_source *src, int timeout)
+int ustcomm_recv(int sock,
+		 struct ustcomm_header *header,
+		 char *data)
 {
-	return ustcomm_recv_message(&ustd->server, msg, src, timeout);
+	return ustcomm_recv_fd(sock, header, data, NULL);
 }
 
-int ustcomm_app_recv_message(struct ustcomm_app *app, char **msg, struct ustcomm_source *src, int timeout)
+
+int ustcomm_send_fd(int sock,
+		    const struct ustcomm_header *header,
+		    const char *data,
+		    int *fd)
 {
-	return ustcomm_recv_message(&app->server, msg, src, timeout);
-}
+	struct iovec iov[2];
+	struct msghdr msg;
+	int result;
+	struct cmsghdr *cmsg;
+	char buf[CMSG_SPACE(sizeof(int))];
 
-/* This removes src from the list of active connections of app.
- */
+	memset(&msg, 0, sizeof(msg));
 
-int ustcomm_app_detach_client(struct ustcomm_app *app, struct ustcomm_source *src)
-{
-	struct ustcomm_server *server = (struct ustcomm_server *)app;
-	struct ustcomm_connection *conn;
+	iov[0].iov_base = (char *)header;
+	iov[0].iov_len = sizeof(struct ustcomm_header);
+
+	msg.msg_iov = iov;
+	msg.msg_iovlen = 1;
+
+	if (header->size && data) {
+		iov[1].iov_base = (char *)data;
+		iov[1].iov_len = header->size;
+
+		msg.msg_iovlen++;
 
-	list_for_each_entry(conn, &server->connections, list) {
-		if(conn->fd == src->fd) {
-			list_del(&conn->list);
-			goto found;
-		}
 	}
 
-	return -1;
-found:
-	return src->fd;
+	if (fd && header->fd_included) {
+		msg.msg_control = buf;
+		msg.msg_controllen = sizeof(buf);
+		cmsg = CMSG_FIRSTHDR(&msg);
+		cmsg->cmsg_level = SOL_SOCKET;
+		cmsg->cmsg_type = SCM_RIGHTS;
+		cmsg->cmsg_len = CMSG_LEN(sizeof(int));
+		*(int *) CMSG_DATA(cmsg) = *fd;
+		msg.msg_controllen = cmsg->cmsg_len;
+	}
+
+	result = sendmsg(sock, &msg, MSG_NOSIGNAL);
+	if (result < 0 && errno != EPIPE) {
+		PERROR("sendmsg failed");
+	}
+	return result;
 }
 
-static int init_named_socket(char *name, char **path_out)
+int ustcomm_send(int sock,
+		 const struct ustcomm_header *header,
+		 const char *data)
+{
+	return ustcomm_send_fd(sock, header, data, NULL);
+}
+
+int ustcomm_req(int sock,
+		const struct ustcomm_header *req_header,
+		const char *req_data,
+		struct ustcomm_header *res_header,
+		char *res_data)
 {
 	int result;
-	int fd;
 
-	struct sockaddr_un addr;
-	
-	result = fd = socket(PF_UNIX, SOCK_STREAM, 0);
-	if(result == -1) {
-		PERROR("socket");
-		return -1;
+	result = ustcomm_send(sock, req_header, req_data);
+	if ( result <= 0) {
+		return result;
 	}
 
-	addr.sun_family = AF_UNIX;
+	return ustcomm_recv(sock, res_header, res_data);
+}
 
-	strncpy(addr.sun_path, name, UNIX_PATH_MAX);
-	addr.sun_path[UNIX_PATH_MAX-1] = '\0';
+/* Return value:
+ *  0: success
+ * -1: error
+ */
 
-	result = access(name, F_OK);
-	if(result == 0) {
-		/* file exists */
-		result = unlink(name);
-		if(result == -1) {
-			PERROR("unlink of socket file");
-			goto close_sock;
-		}
-		WARN("socket already exists; overwriting");
+int ustcomm_connect_path(const char *name, int *connection_fd)
+{
+	int result, fd;
+	size_t sock_addr_size;
+	struct sockaddr_un *addr;
+
+	fd = socket(PF_UNIX, SOCK_STREAM, 0);
+	if(fd == -1) {
+		PERROR("socket");
+		return -1;
 	}
 
-	result = bind(fd, (struct sockaddr *)&addr, sizeof(addr));
-	if(result == -1) {
-		PERROR("bind");
+	addr = create_sock_addr(name, &sock_addr_size);
+	if (addr == NULL) {
+		ERR("allocating addr failed");
 		goto close_sock;
 	}
 
-	result = listen(fd, 1);
+	result = connect(fd, (struct sockaddr *)addr, sock_addr_size);
 	if(result == -1) {
-		PERROR("listen");
-		goto close_sock;
+		PERROR("connect (path=%s)", name);
+		goto free_sock_addr;
 	}
 
-	if(path_out) {
-		*path_out = "";
-		*path_out = strdupa(addr.sun_path);
-	}
+	*connection_fd = fd;
 
-	return fd;
+	free(addr);
 
-	close_sock:
+	return 0;
+
+free_sock_addr:
+	free(addr);
+close_sock:
 	close(fd);
 
 	return -1;
 }
 
-int ustcomm_send_request(struct ustcomm_connection *conn, char *req, char **reply)
+/* Returns the current users socket directory, must be freed */
+char *ustcomm_user_sock_dir(void)
 {
 	int result;
+	char *sock_dir = NULL;
 
-	result = send(conn->fd, req, strlen(req), 0);
-	if(result == -1) {
-		PERROR("send");
-		return -1;
-	}
-	else if(result == 0) {
-		return 0;
+	result = asprintf(&sock_dir, "%s%s", USER_SOCK_DIR,
+			  cuserid(NULL));
+	if (result < 0) {
+		ERR("string overflow allocating directory name");
+		return NULL;
 	}
 
-	if(!reply)
-		return 1;
+	return sock_dir;
+}
 
-	*reply = (char *) malloc(MSG_MAX+1);
-	result = recv(conn->fd, *reply, MSG_MAX, 0);
-	if(result == -1) {
-		PERROR("recv");
-		return -1;
+/* Open a connection to a traceable app.
+ *
+ * Return value:
+ *  0: success
+ * -1: error
+ */
+
+int ustcomm_connect_app(pid_t pid, int *app_fd)
+{
+	int result;
+	int retval = 0;
+	char *dir_name, *sock_name;
+
+	dir_name = ustcomm_user_sock_dir();
+	if (!dir_name)
+		return -ENOMEM;
+
+	result = asprintf(&sock_name, "%s/%d", dir_name, pid);
+	if (result < 0) {
+		ERR("failed to allocate socket name");
+		retval = -1;
+		goto free_dir_name;
 	}
-	else if(result == 0) {
-		return 0;
+
+	result = ustcomm_connect_path(sock_name, app_fd);
+	if (result < 0) {
+		ERR("failed to connect to app");
+		retval = -1;
+		goto free_sock_name;
 	}
-	
-	(*reply)[result] = '\0';
 
-	return 1;
+free_sock_name:
+	free(sock_name);
+free_dir_name:
+	free(dir_name);
+
+	return retval;
 }
 
-int ustcomm_connect_path(char *path, struct ustcomm_connection *conn, pid_t signalpid)
+int ensure_dir_exists(const char *dir)
 {
-	int fd;
+	struct stat st;
 	int result;
-	struct sockaddr_un addr;
 
-	result = fd = socket(PF_UNIX, SOCK_STREAM, 0);
-	if(result == -1) {
-		PERROR("socket");
+	if(!strcmp(dir, ""))
 		return -1;
-	}
-
-	addr.sun_family = AF_UNIX;
 
-	result = snprintf(addr.sun_path, UNIX_PATH_MAX, "%s", path);
-	if(result >= UNIX_PATH_MAX) {
-		ERR("string overflow allocating socket name");
+	result = stat(dir, &st);
+	if(result == -1 && errno != ENOENT) {
 		return -1;
 	}
+	else if(result == -1) {
+		/* ENOENT */
+		int result;
 
-	if(signalpid >= 0)
-		signal_process(signalpid);
-
-	result = connect(fd, (struct sockaddr *)&addr, sizeof(addr));
-	if(result == -1) {
-		PERROR("connect");
-		return -1;
+		/* mkdir mode to 0777 */
+		result = mkdir_p(dir, S_IRWXU | S_IRWXG | S_IRWXO);
+		if(result != 0) {
+			ERR("executing in recursive creation of directory %s", dir);
+			return -1;
+		}
 	}
 
-	conn->fd = fd;
-
 	return 0;
 }
 
-int ustcomm_disconnect(struct ustcomm_connection *conn)
+char * ustcomm_print_data(char *data_field, int field_size,
+			  int *offset, const char *format, ...)
 {
-	return close(conn->fd);
-}
-
-int ustcomm_connect_app(pid_t pid, struct ustcomm_connection *conn)
-{
-	int result;
-	char path[UNIX_PATH_MAX];
+	va_list args;
+	int count, limit;
+	char *ptr = USTCOMM_POISON_PTR;
 
+	limit = field_size - *offset;
+	va_start(args, format);
+	count = vsnprintf(&data_field[*offset], limit, format, args);
+	va_end(args);
 
-	result = snprintf(path, UNIX_PATH_MAX, "%s/%d", SOCK_DIR, pid);
-	if(result >= UNIX_PATH_MAX) {
-		fprintf(stderr, "string overflow allocating socket name");
-		return -1;
+	if (count < limit && count > -1) {
+		ptr = NULL + *offset;
+		*offset = *offset + count + 1;
 	}
 
-	return ustcomm_connect_path(path, conn, pid);
+	return ptr;
 }
 
-int ustcomm_disconnect_app(struct ustcomm_connection *conn)
+char * ustcomm_restore_ptr(char *ptr, char *data_field, int data_field_size)
 {
-	close(conn->fd);
-	return 0;
+	if ((unsigned long)ptr > data_field_size ||
+	    ptr == USTCOMM_POISON_PTR) {
+		return NULL;
+	}
+
+	return data_field + (long)ptr;
 }
 
-int ustcomm_init_app(pid_t pid, struct ustcomm_app *handle)
+int ustcomm_pack_single_field(struct ustcomm_header *header,
+			      struct ustcomm_single_field *single_field,
+			      const char *string)
 {
-	int result;
-	char *name;
+	int offset = 0;
 
-	result = asprintf(&name, "%s/%d", SOCK_DIR, (int)pid);
-	if(result >= UNIX_PATH_MAX) {
-		ERR("string overflow allocating socket name");
-		return -1;
-	}
+	single_field->field = ustcomm_print_data(single_field->data,
+						 sizeof(single_field->data),
+						 &offset,
+						 string);
 
-	handle->server.listen_fd = init_named_socket(name, &(handle->server.socketpath));
-	if(handle->server.listen_fd < 0) {
-		ERR("error initializing named socket");
-		goto free_name;
+	if (single_field->field == USTCOMM_POISON_PTR) {
+		return -ENOMEM;
 	}
-	free(name);
 
-	INIT_LIST_HEAD(&handle->server.connections);
+	header->size = COMPUTE_MSG_SIZE(single_field, offset);
 
 	return 0;
+}
 
-free_name:
-	free(name);
-	return -1;
+int ustcomm_unpack_single_field(struct ustcomm_single_field *single_field)
+{
+	single_field->field = ustcomm_restore_ptr(single_field->field,
+						  single_field->data,
+						  sizeof(single_field->data));
+	if (!single_field->field) {
+		return -EINVAL;
+	}
+
+	return 0;
 }
 
-int ustcomm_init_ustd(struct ustcomm_ustd *handle)
+int ustcomm_pack_channel_info(struct ustcomm_header *header,
+			      struct ustcomm_channel_info *ch_inf,
+			      const char *trace,
+			      const char *channel)
 {
-	int result;
-	char *name;
+	int offset = 0;
 
-	result = asprintf(&name, "%s/%s", SOCK_DIR, "ustd");
-	if(result >= UNIX_PATH_MAX) {
-		ERR("string overflow allocating socket name");
-		return -1;
+	ch_inf->trace = ustcomm_print_data(ch_inf->data,
+					   sizeof(ch_inf->data),
+					   &offset,
+					   trace);
+
+	if (ch_inf->trace == USTCOMM_POISON_PTR) {
+		return -ENOMEM;
 	}
 
-	handle->server.listen_fd = init_named_socket(name, &handle->server.socketpath);
-	if(handle->server.listen_fd < 0) {
-		ERR("error initializing named socket");
-		goto free_name;
+	ch_inf->channel = ustcomm_print_data(ch_inf->data,
+					     sizeof(ch_inf->data),
+					     &offset,
+					     channel);
+
+	if (ch_inf->channel == USTCOMM_POISON_PTR) {
+		return -ENOMEM;
 	}
-	free(name);
 
-	INIT_LIST_HEAD(&handle->server.connections);
+	header->size = COMPUTE_MSG_SIZE(ch_inf, offset);
 
 	return 0;
-
-free_name:
-	free(name);
-	return -1;
 }
 
-static char *find_tok(char *str)
+
+int ustcomm_unpack_channel_info(struct ustcomm_channel_info *ch_inf)
 {
-	while(*str == ' ') {
-		str++;
+	ch_inf->trace = ustcomm_restore_ptr(ch_inf->trace,
+					    ch_inf->data,
+					    sizeof(ch_inf->data));
+	if (!ch_inf->trace) {
+		return -EINVAL;
+	}
 
-		if(*str == 0)
-			return NULL;
+	ch_inf->channel = ustcomm_restore_ptr(ch_inf->channel,
+					      ch_inf->data,
+					      sizeof(ch_inf->data));
+	if (!ch_inf->channel) {
+		return -EINVAL;
 	}
 
-	return str;
+	return 0;
 }
 
-static char *find_sep(char *str)
+int ustcomm_pack_buffer_info(struct ustcomm_header *header,
+			     struct ustcomm_buffer_info *buf_inf,
+			     const char *trace,
+			     const char *channel,
+			     int channel_cpu)
 {
-	while(*str != ' ') {
-		str++;
+	int offset = 0;
 
-		if(*str == 0)
-			break;
+	buf_inf->trace = ustcomm_print_data(buf_inf->data,
+					    sizeof(buf_inf->data),
+					    &offset,
+					    trace);
+
+	if (buf_inf->trace == USTCOMM_POISON_PTR) {
+		return -ENOMEM;
 	}
 
-	return str;
+	buf_inf->channel = ustcomm_print_data(buf_inf->data,
+					      sizeof(buf_inf->data),
+					      &offset,
+					      channel);
+
+	if (buf_inf->channel == USTCOMM_POISON_PTR) {
+		return -ENOMEM;
+	}
+
+	buf_inf->ch_cpu = channel_cpu;
+
+	header->size = COMPUTE_MSG_SIZE(buf_inf, offset);
+
+	return 0;
 }
 
-int nth_token_is(char *str, char *token, int tok_no)
+
+int ustcomm_unpack_buffer_info(struct ustcomm_buffer_info *buf_inf)
 {
-	int i;
-	char *start;
-	char *end;
+	buf_inf->trace = ustcomm_restore_ptr(buf_inf->trace,
+					     buf_inf->data,
+					     sizeof(buf_inf->data));
+	if (!buf_inf->trace) {
+		return -EINVAL;
+	}
 
-	for(i=0; i<=tok_no; i++) {
-		str = find_tok(str);
-		if(str == NULL)
-			return -1;
+	buf_inf->channel = ustcomm_restore_ptr(buf_inf->channel,
+					       buf_inf->data,
+					       sizeof(buf_inf->data));
+	if (!buf_inf->channel) {
+		return -EINVAL;
+	}
 
-		start = str;
+	return 0;
+}
 
-		str = find_sep(str);
-		if(str == NULL)
-			return -1;
+int ustcomm_pack_marker_info(struct ustcomm_header *header,
+			     struct ustcomm_marker_info *marker_inf,
+			     const char *trace,
+			     const char *channel,
+			     const char *marker)
+{
+	int offset = 0;
+
+	marker_inf->trace = ustcomm_print_data(marker_inf->data,
+					       sizeof(marker_inf->data),
+					       &offset,
+					       trace);
 
-		end = str;
+	if (marker_inf->trace == USTCOMM_POISON_PTR) {
+		return -ENOMEM;
 	}
 
-	if(end-start != strlen(token))
-		return 0;
 
-	if(strncmp(start, token, end-start))
-		return 0;
+	marker_inf->channel = ustcomm_print_data(marker_inf->data,
+						 sizeof(marker_inf->data),
+						 &offset,
+						 channel);
 
-	return 1;
-}
+	if (marker_inf->channel == USTCOMM_POISON_PTR) {
+		return -ENOMEM;
+	}
 
-char *nth_token(char *str, int tok_no)
-{
-	static char *retval = NULL;
-	int i;
-	char *start;
-	char *end;
 
-	for(i=0; i<=tok_no; i++) {
-		str = find_tok(str);
-		if(str == NULL)
-			return NULL;
+	marker_inf->marker = ustcomm_print_data(marker_inf->data,
+						 sizeof(marker_inf->data),
+						 &offset,
+						 marker);
 
-		start = str;
+	if (marker_inf->marker == USTCOMM_POISON_PTR) {
+		return -ENOMEM;
+	}
+
+	header->size = COMPUTE_MSG_SIZE(marker_inf, offset);
 
-		str = find_sep(str);
-		if(str == NULL)
-			return NULL;
+	return 0;
+}
 
-		end = str;
+int ustcomm_unpack_marker_info(struct ustcomm_marker_info *marker_inf)
+{
+	marker_inf->trace = ustcomm_restore_ptr(marker_inf->trace,
+						marker_inf->data,
+						sizeof(marker_inf->data));
+	if (!marker_inf->trace) {
+		return -EINVAL;
 	}
 
-	if(retval) {
-		free(retval);
-		retval = NULL;
+	marker_inf->channel = ustcomm_restore_ptr(marker_inf->channel,
+						  marker_inf->data,
+						  sizeof(marker_inf->data));
+	if (!marker_inf->channel) {
+		return -EINVAL;
 	}
 
-	asprintf(&retval, "%.*s", (int)(end-start), start);
+	marker_inf->marker = ustcomm_restore_ptr(marker_inf->marker,
+						 marker_inf->data,
+						 sizeof(marker_inf->data));
+	if (!marker_inf->marker) {
+		return -EINVAL;
+	}
 
-	return retval;
+	return 0;
 }