X-Git-Url: https://git.lttng.org/?a=blobdiff_plain;f=ustd%2Fustd.c;h=aae4b0248ba0a9a689ecb9f4de8f969c64e6d5f3;hb=463011e4be98c30caf7be5185463c732563a860f;hp=19981191e2d9d17be606d9358570118a6e36cc11;hpb=688760ef257bee85e3841e0d27ecf4e2f921ef00;p=ust.git

diff --git a/ustd/ustd.c b/ustd/ustd.c
index 1998119..aae4b02 100644
--- a/ustd/ustd.c
+++ b/ustd/ustd.c
@@ -1,38 +1,231 @@
+/* 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
+ */
+
 #define _GNU_SOURCE
 
 #include <sys/types.h>
+#include <sys/stat.h>
 #include <sys/shm.h>
 #include <fcntl.h>
 #include <unistd.h>
+#include <pthread.h>
+#include <signal.h>
 
 #include <stdlib.h>
 #include <stdio.h>
 #include <string.h>
+#include <errno.h>
+#include <assert.h>
+#include <getopt.h>
 
-#include "localerr.h"
+#include "ustd.h"
+#include "usterr.h"
 #include "ustcomm.h"
 
-struct list_head buffers = LIST_HEAD_INIT(buffers);
+/* return value: 0 = subbuffer is finished, it won't produce data anymore
+ *               1 = got subbuffer successfully
+ *               <0 = error
+ */
 
-struct buffer_info {
-	char *name;
-	pid_t pid;
+#define GET_SUBBUF_OK 1
+#define GET_SUBBUF_DONE 0
+#define GET_SUBBUF_DIED 2
 
-	int shmid;
-	void *mem;
-	int memlen;
+#define PUT_SUBBUF_OK 1
+#define PUT_SUBBUF_DIED 0
+#define PUT_SUBBUF_PUSHED 2
+#define PUT_SUBBUF_DONE 3
 
-	int n_subbufs;
-	int subbuf_size;
+char *sock_path=NULL;
+char *trace_path=NULL;
+int daemon_mode = 0;
+char *pidfile = NULL;
 
-	int file_fd; /* output file */
+/* Number of active buffers and the mutex to protect it. */
+int active_buffers = 0;
+pthread_mutex_t active_buffers_mutex = PTHREAD_MUTEX_INITIALIZER;
+/* Whether a request to end the program was received. */
+volatile sig_atomic_t terminate_req = 0;
 
-	struct list_head list;
+int get_subbuffer(struct buffer_info *buf)
+{
+	char *send_msg=NULL;
+	char *received_msg=NULL;
+	char *rep_code=NULL;
+	int retval;
+	int result;
 
-	long consumed_old;
-};
+	asprintf(&send_msg, "get_subbuffer %s", buf->name);
+	result = ustcomm_send_request(&buf->conn, send_msg, &received_msg);
+	if((result == -1 && (errno == ECONNRESET || errno == EPIPE)) || result == 0) {
+		DBG("app died while being traced");
+		retval = GET_SUBBUF_DIED;
+		goto end;
+	}
+	else if(result < 0) {
+		ERR("get_subbuffer: ustcomm_send_request failed");
+		retval = -1;
+		goto end;
+	}
+
+	result = sscanf(received_msg, "%as %ld", &rep_code, &buf->consumed_old);
+	if(result != 2 && result != 1) {
+		ERR("unable to parse response to get_subbuffer");
+		retval = -1;
+		free(received_msg);
+		goto end_rep;
+	}
+
+	if(!strcmp(rep_code, "OK")) {
+		DBG("got subbuffer %s", buf->name);
+		retval = GET_SUBBUF_OK;
+	}
+	else if(nth_token_is(received_msg, "END", 0) == 1) {
+		retval = GET_SUBBUF_DONE;
+		goto end_rep;
+	}
+	else if(!strcmp(received_msg, "NOTFOUND")) {
+		DBG("For buffer %s, the trace was not found. This likely means it was destroyed by the user.", buf->name);
+		retval = GET_SUBBUF_DIED;
+		goto end_rep;
+	}
+	else {
+		DBG("error getting subbuffer %s", buf->name);
+		retval = -1;
+	}
+
+	/* FIMXE: free correctly the stuff */
+end_rep:
+	if(rep_code)
+		free(rep_code);
+end:
+	if(send_msg)
+		free(send_msg);
+	if(received_msg)
+		free(received_msg);
+
+	return retval;
+}
+
+int put_subbuffer(struct buffer_info *buf)
+{
+	char *send_msg=NULL;
+	char *received_msg=NULL;
+	char *rep_code=NULL;
+	int retval;
+	int result;
+
+	asprintf(&send_msg, "put_subbuffer %s %ld", buf->name, buf->consumed_old);
+	result = ustcomm_send_request(&buf->conn, send_msg, &received_msg);
+	if(result < 0 && (errno == ECONNRESET || errno == EPIPE)) {
+		retval = PUT_SUBBUF_DIED;
+		goto end;
+	}
+	else if(result < 0) {
+		ERR("put_subbuffer: send_message failed");
+		retval = -1;
+		goto end;
+	}
+	else if(result == 0) {
+		/* Program seems finished. However this might not be
+		 * the last subbuffer that has to be collected.
+		 */
+		retval = PUT_SUBBUF_DIED;
+		goto end;
+	}
+
+	result = sscanf(received_msg, "%as", &rep_code);
+	if(result != 1) {
+		ERR("unable to parse response to put_subbuffer");
+		retval = -1;
+		goto end_rep;
+	}
 
-int add_buffer(pid_t pid, char *bufname)
+	if(!strcmp(rep_code, "OK")) {
+		DBG("subbuffer put %s", buf->name);
+		retval = PUT_SUBBUF_OK;
+	}
+	else if(!strcmp(received_msg, "NOTFOUND")) {
+		DBG("For buffer %s, the trace was not found. This likely means it was destroyed by the user.", buf->name);
+		/* However, maybe this was not the last subbuffer. So
+		 * we return the program died.
+		 */
+		retval = PUT_SUBBUF_DIED;
+		goto end_rep;
+	}
+	else {
+		DBG("put_subbuffer: received error, we were pushed");
+		retval = PUT_SUBBUF_PUSHED;
+		goto end_rep;
+	}
+
+end_rep:
+	if(rep_code)
+		free(rep_code);
+
+end:
+	if(send_msg)
+		free(send_msg);
+	if(received_msg)
+		free(received_msg);
+
+	return retval;
+}
+
+void decrement_active_buffers(void *arg)
+{
+	pthread_mutex_lock(&active_buffers_mutex);
+	active_buffers--;
+	pthread_mutex_unlock(&active_buffers_mutex);
+}
+
+int create_dir_if_needed(char *dir)
+{
+	int result;
+	result = mkdir(dir, 0777);
+	if(result == -1) {
+		if(errno != EEXIST) {
+			PERROR("mkdir");
+			return -1;
+		}
+	}
+
+	return 0;
+}
+
+int is_directory(const char *dir)
+{
+	int result;
+	struct stat st;
+
+	result = stat(dir, &st);
+	if(result == -1) {
+		PERROR("stat");
+		return 0;
+	}
+
+	if(!S_ISDIR(st.st_mode)) {
+		return 0;
+	}
+
+	return 1;
+}
+
+struct buffer_info *connect_buffer(pid_t pid, const char *bufname)
 {
 	struct buffer_info *buf;
 	char *send_msg;
@@ -40,52 +233,100 @@ int add_buffer(pid_t pid, char *bufname)
 	int result;
 	char *tmp;
 	int fd;
+	struct shmid_ds shmds;
 
 	buf = (struct buffer_info *) malloc(sizeof(struct buffer_info));
 	if(buf == NULL) {
 		ERR("add_buffer: insufficient memory");
-		return -1;
+		return NULL;
 	}
 
 	buf->name = bufname;
 	buf->pid = pid;
 
+	/* connect to app */
+	result = ustcomm_connect_app(buf->pid, &buf->conn);
+	if(result) {
+		WARN("unable to connect to process, it probably died before we were able to connect");
+		return NULL;
+	}
+
+	/* get pidunique */
+	asprintf(&send_msg, "get_pidunique");
+	result = ustcomm_send_request(&buf->conn, send_msg, &received_msg);
+	free(send_msg);
+	if(result == -1) {
+		ERR("problem in ustcomm_send_request(get_pidunique)");
+		return NULL;
+	}
+	if(result == 0) {
+		goto error;
+	}
+
+	result = sscanf(received_msg, "%lld", &buf->pidunique);
+	if(result != 1) {
+		ERR("unable to parse response to get_pidunique");
+		return NULL;
+	}
+	free(received_msg);
+	DBG("got pidunique %lld", buf->pidunique);
+
 	/* get shmid */
 	asprintf(&send_msg, "get_shmid %s", buf->name);
-	send_message(pid, send_msg, &received_msg);
+	result = ustcomm_send_request(&buf->conn, send_msg, &received_msg);
 	free(send_msg);
-	DBG("got buffer name %s", buf->name);
+	if(result == -1) {
+		ERR("problem in ustcomm_send_request(get_shmid)");
+		return NULL;
+	}
+	if(result == 0) {
+		goto error;
+	}
 
-	result = sscanf(received_msg, "%d", &buf->shmid);
-	if(result != 1) {
-		ERR("unable to parse response to get_shmid");
-		return -1;
+	result = sscanf(received_msg, "%d %d", &buf->shmid, &buf->bufstruct_shmid);
+	if(result != 2) {
+		ERR("unable to parse response to get_shmid (\"%s\")", received_msg);
+		return NULL;
 	}
 	free(received_msg);
-	DBG("got shmid %d", buf->shmid);
+	DBG("got shmids %d %d", buf->shmid, buf->bufstruct_shmid);
 
 	/* get n_subbufs */
 	asprintf(&send_msg, "get_n_subbufs %s", buf->name);
-	send_message(pid, send_msg, &received_msg);
+	result = ustcomm_send_request(&buf->conn, send_msg, &received_msg);
 	free(send_msg);
+	if(result == -1) {
+		ERR("problem in ustcomm_send_request(g_n_subbufs)");
+		return NULL;
+	}
+	if(result == 0) {
+		goto error;
+	}
 
 	result = sscanf(received_msg, "%d", &buf->n_subbufs);
 	if(result != 1) {
 		ERR("unable to parse response to get_n_subbufs");
-		return -1;
+		return NULL;
 	}
 	free(received_msg);
 	DBG("got n_subbufs %d", buf->n_subbufs);
 
 	/* get subbuf size */
 	asprintf(&send_msg, "get_subbuf_size %s", buf->name);
-	send_message(pid, send_msg, &received_msg);
+	result = ustcomm_send_request(&buf->conn, send_msg, &received_msg);
 	free(send_msg);
+	if(result == -1) {
+		ERR("problem in ustcomm_send_request(get_subbuf_size)");
+		return NULL;
+	}
+	if(result == 0) {
+		goto error;
+	}
 
 	result = sscanf(received_msg, "%d", &buf->subbuf_size);
 	if(result != 1) {
 		ERR("unable to parse response to get_subbuf_size");
-		return -1;
+		return NULL;
 	}
 	free(received_msg);
 	DBG("got subbuf_size %d", buf->subbuf_size);
@@ -93,139 +334,443 @@ int add_buffer(pid_t pid, char *bufname)
 	/* attach memory */
 	buf->mem = shmat(buf->shmid, NULL, 0);
 	if(buf->mem == (void *) 0) {
-		perror("shmat");
-		return -1;
+		PERROR("shmat");
+		return NULL;
 	}
-	DBG("successfully attached memory");
+	DBG("successfully attached buffer memory");
+
+	buf->bufstruct_mem = shmat(buf->bufstruct_shmid, NULL, 0);
+	if(buf->bufstruct_mem == (void *) 0) {
+		PERROR("shmat");
+		return NULL;
+	}
+	DBG("successfully attached buffer bufstruct memory");
+
+	/* obtain info on the memory segment */
+	result = shmctl(buf->shmid, IPC_STAT, &shmds);
+	if(result == -1) {
+		PERROR("shmctl");
+		return NULL;
+	}
+	buf->memlen = shmds.shm_segsz;
 
 	/* open file for output */
-	asprintf(&tmp, "/tmp/trace/%s_0", buf->name);
-	result = fd = open(tmp, O_WRONLY | O_CREAT | O_TRUNC, 00600);
+	if(!trace_path) {
+		/* Only create the directory if using the default path, because
+		 * of the risk of typo when using trace path override. We don't
+		 * want to risk creating plenty of useless directories in that case.
+		 */
+		result = create_dir_if_needed(USTD_DEFAULT_TRACE_PATH);
+		if(result == -1) {
+			ERR("could not create directory %s", USTD_DEFAULT_TRACE_PATH);
+			return NULL;
+		}
+
+		trace_path = USTD_DEFAULT_TRACE_PATH;
+	}
+
+	asprintf(&tmp, "%s/%u_%lld", trace_path, buf->pid, buf->pidunique);
+	result = create_dir_if_needed(tmp);
+	if(result == -1) {
+		ERR("could not create directory %s", tmp);
+		free(tmp);
+		return NULL;
+	}
+	free(tmp);
+
+	asprintf(&tmp, "%s/%u_%lld/%s", trace_path, buf->pid, buf->pidunique, buf->name);
+	result = fd = open(tmp, O_WRONLY | O_CREAT | O_TRUNC | O_EXCL, 00600);
 	if(result == -1) {
 		PERROR("open");
-		return -1;
+		ERR("failed opening trace file %s", tmp);
+		return NULL;
 	}
 	buf->file_fd = fd;
 	free(tmp);
 
-	list_add(&buf->list, &buffers);
+	pthread_mutex_lock(&active_buffers_mutex);
+	active_buffers++;
+	pthread_mutex_unlock(&active_buffers_mutex);
 
-	return 0;
+	return buf;
+
+error:
+	free(buf);
+	return NULL;
 }
 
-int get_subbuffer(struct buffer_info *buf)
+static void destroy_buffer(struct buffer_info *buf)
 {
-	char *send_msg;
-	char *received_msg;
-	char *rep_code;
-	int retval;
 	int result;
 
-	asprintf(&send_msg, "get_subbuffer %s", buf->name);
-	result = send_message(buf->pid, send_msg, &received_msg);
-	if(result < 0) {
-		ERR("get_subbuffer: send_message failed");
-		return -1;
+	result = ustcomm_close_app(&buf->conn);
+	if(result == -1) {
+		WARN("problem calling ustcomm_close_app");
 	}
-	free(send_msg);
 
-	result = sscanf(received_msg, "%as %ld", &rep_code, &buf->consumed_old);
-	if(result != 2) {
-		ERR("unable to parse response to get_subbuffer");
-		return -1;
+	result = shmdt(buf->mem);
+	if(result == -1) {
+		PERROR("shmdt");
 	}
-	free(received_msg);
 
-	if(!strcmp(rep_code, "OK")) {
-		DBG("got subbuffer %s", buf->name);
-		retval = 1;
+	result = shmdt(buf->bufstruct_mem);
+	if(result == -1) {
+		PERROR("shmdt");
 	}
-	else {
-		DBG("did not get subbuffer %s", buf->name);
-		retval = 0;
+
+	result = close(buf->file_fd);
+	if(result == -1) {
+		PERROR("close");
 	}
 
-	free(rep_code);
-	return retval;
+	free(buf);
 }
 
-int put_subbuffer(struct buffer_info *buf)
+int unwrite_last_subbuffer(struct buffer_info *buf)
 {
-	char *send_msg;
-	char *received_msg;
-	char *rep_code;
-	int retval;
 	int result;
 
-	asprintf(&send_msg, "put_subbuffer %s %ld", buf->name, buf->consumed_old);
-	result = send_message(buf->pid, send_msg, &received_msg);
-	if(result < 0) {
-		ERR("put_subbuffer: send_message failed");
+	result = ftruncate(buf->file_fd, buf->previous_offset);
+	if(result == -1) {
+		PERROR("ftruncate");
 		return -1;
 	}
-	free(send_msg);
 
-	result = sscanf(received_msg, "%as", &rep_code);
-	if(result != 1) {
-		ERR("unable to parse response to put_subbuffer");
+	result = lseek(buf->file_fd, buf->previous_offset, SEEK_SET);
+	if(result == (int)(off_t)-1) {
+		PERROR("lseek");
 		return -1;
 	}
-	free(received_msg);
 
-	if(!strcmp(rep_code, "OK")) {
-		DBG("subbuffer put %s", buf->name);
-		retval = 1;
+	return 0;
+}
+
+int write_current_subbuffer(struct buffer_info *buf)
+{
+	int result;
+
+	void *subbuf_mem = buf->mem + (buf->consumed_old & (buf->n_subbufs * buf->subbuf_size-1));
+
+	size_t cur_sb_size = subbuffer_data_size(subbuf_mem);
+
+	off_t cur_offset = lseek(buf->file_fd, 0, SEEK_CUR);
+	if(cur_offset == (off_t)-1) {
+		PERROR("lseek");
+		return -1;
 	}
-	else {
-		ERR("invalid response to put_subbuffer");
+
+	buf->previous_offset = cur_offset;
+	DBG("previous_offset: %ld", cur_offset);
+
+	result = patient_write(buf->file_fd, subbuf_mem, cur_sb_size);
+	if(result == -1) {
+		PERROR("write");
+		/* FIXME: maybe drop this trace */
+		return -1;
 	}
 
-	free(rep_code);
-	return retval;
+	return 0;
 }
 
-ssize_t patient_write(int fd, const void *buf, size_t count)
+int consumer_loop(struct buffer_info *buf)
 {
-	const char *bufc = (const char *) buf;
 	int result;
 
+	pthread_cleanup_push(decrement_active_buffers, NULL);
+
 	for(;;) {
-		result = write(fd, bufc, count);
-		if(result <= 0) {
-			return result;
+		/* get the subbuffer */
+		result = get_subbuffer(buf);
+		if(result == -1) {
+			ERR("error getting subbuffer");
+			continue;
+		}
+		else if(result == GET_SUBBUF_DONE) {
+			/* this is done */
+			break;
+		}
+		else if(result == GET_SUBBUF_DIED) {
+			finish_consuming_dead_subbuffer(buf);
+			break;
 		}
-		count -= result;
-		bufc += result;
 
-		if(count == 0) {
+		/* write data to file */
+		write_current_subbuffer(buf);
+		/* FIXME: handle return value? */
+
+		/* put the subbuffer */
+		result = put_subbuffer(buf);
+		if(result == -1) {
+			ERR("unknown error putting subbuffer (channel=%s)", buf->name);
 			break;
 		}
+		else if(result == PUT_SUBBUF_PUSHED) {
+			ERR("Buffer overflow (channel=%s), reader pushed. This channel will not be usable passed this point.", buf->name);
+			break;
+		}
+		else if(result == PUT_SUBBUF_DIED) {
+			DBG("application died while putting subbuffer");
+			/* Skip the first subbuffer. We are not sure it is trustable
+			 * because the put_subbuffer() did not complete.
+			 */
+			unwrite_last_subbuffer(buf);
+			finish_consuming_dead_subbuffer(buf);
+			break;
+		}
+		else if(result == PUT_SUBBUF_DONE) {
+			/* Done with this subbuffer */
+			/* FIXME: add a case where this branch is used? Upon
+			 * normal trace termination, at put_subbuf time, a
+			 * special last-subbuffer code could be returned by
+			 * the listener.
+			 */
+			break;
+		}
+		else if(result == PUT_SUBBUF_OK) {
+		}
 	}
 
-	return bufc-(const char *)buf;
+	DBG("thread for buffer %s is stopping", buf->name);
+
+	/* FIXME: destroy, unalloc... */
+
+	pthread_cleanup_pop(1);
+
+	return 0;
 }
 
-int main(int argc, char **argv)
+struct consumer_thread_args {
+	pid_t pid;
+	const char *bufname;
+};
+
+void *consumer_thread(void *arg)
+{
+	struct buffer_info *buf = (struct buffer_info *) arg;
+	struct consumer_thread_args *args = (struct consumer_thread_args *) arg;
+
+	DBG("GOT ARGS: pid %d bufname %s", args->pid, args->bufname);
+
+	buf = connect_buffer(args->pid, args->bufname);
+	if(buf == NULL) {
+		ERR("failed to connect to buffer");
+		goto end;
+	}
+
+	consumer_loop(buf);
+
+	free((void *)args->bufname);
+	destroy_buffer(buf);
+
+	end:
+	free(args);
+	return NULL;
+}
+
+int start_consuming_buffer(pid_t pid, const char *bufname)
+{
+	pthread_t thr;
+	struct consumer_thread_args *args;
+	int result;
+
+	DBG("beginning of start_consuming_buffer: args: pid %d bufname %s", pid, bufname);
+
+	args = (struct consumer_thread_args *) malloc(sizeof(struct consumer_thread_args));
+
+	args->pid = pid;
+	args->bufname = strdup(bufname);
+	DBG("beginning2 of start_consuming_buffer: args: pid %d bufname %s", args->pid, args->bufname);
+
+	result = pthread_create(&thr, NULL, consumer_thread, args);
+	if(result == -1) {
+		ERR("pthread_create failed");
+		return -1;
+	}
+	result = pthread_detach(thr);
+	if(result == -1) {
+		ERR("pthread_detach failed");
+		return -1;
+	}
+	DBG("end of start_consuming_buffer: args: pid %d bufname %s", args->pid, args->bufname);
+
+	return 0;
+}
+
+void usage(void)
+{
+	fprintf(stderr, "Usage:\nustd OPTIONS\n\nOptions:\n"
+			"\t-h\t\tDisplay this usage.\n"
+			"\t-o DIR\t\tSpecify the directory where to output the traces.\n"
+			"\t-s PATH\t\tSpecify the path to use for the daemon socket.\n"
+			"\t-d\t\tStart as a daemon.\n"
+			"\t--pidfile FILE\tWrite the PID in this file (when using -d).\n");
+}
+
+int parse_args(int argc, char **argv)
+{
+	int c;
+
+	while (1) {
+		int option_index = 0;
+		static struct option long_options[] = {
+			{"pidfile", 1, 0, 'p'},
+			{"help", 0, 0, 'h'},
+			{"version", 0, 0, 'V'},
+			{0, 0, 0, 0}
+		};
+
+		c = getopt_long(argc, argv, "hs:o:d", long_options, &option_index);
+		if (c == -1)
+			break;
+
+		switch (c) {
+		case 0:
+			printf("option %s", long_options[option_index].name);
+			if (optarg)
+				printf(" with arg %s", optarg);
+			printf("\n");
+			break;
+		case 's':
+			sock_path = optarg;
+			break;
+		case 'o':
+			trace_path = optarg;
+			if(!is_directory(trace_path)) {
+				ERR("Not a valid directory. (%s)", trace_path);
+				return -1;
+			}
+			break;
+		case 'd':
+			daemon_mode = 1;
+			break;
+		case 'p':
+			pidfile = strdup(optarg);
+			break;
+		case 'h':
+			usage();
+			exit(0);
+		case 'V':
+			printf("Version 0.0\n");
+			break;
+
+		default:
+			/* unknown option or other error; error is
+			printed by getopt, just return */
+			return -1;
+		}
+	}
+
+	return 0;
+}
+
+void sigterm_handler(int sig)
+{
+	terminate_req = 1;
+}
+
+static int write_pidfile(const char *file_name, pid_t pid)
+{
+	FILE *pidfp;
+
+	pidfp = fopen(file_name, "w");
+	if(!pidfp) {
+		PERROR("fopen (%s)", pidfile);
+		WARN("killing child process");
+		return -1;
+	}
+
+	fprintf(pidfp, "%d\n", pid);
+
+	fclose(pidfp);
+
+	return 0;
+}
+
+int start_ustd(int fd)
 {
 	struct ustcomm_ustd ustd;
 	int result;
+	sigset_t sigset;
+	struct sigaction sa;
 
-	result = ustcomm_init_ustd(&ustd);
+	result = sigemptyset(&sigset);
+	if(result == -1) {
+		PERROR("sigemptyset");
+		return 1;
+	}
+	sa.sa_handler = sigterm_handler;
+	sa.sa_mask = sigset;
+	sa.sa_flags = SA_RESTART;
+	result = sigaction(SIGTERM, &sa, NULL);
+	if(result == -1) {
+		PERROR("sigaction");
+		return 1;
+	}
+	result = sigaction(SIGINT, &sa, NULL);
+	if(result == -1) {
+		PERROR("sigaction");
+		return 1;
+	}
+
+	result = ustcomm_init_ustd(&ustd, sock_path);
 	if(result == -1) {
 		ERR("failed to initialize socket");
 		return 1;
 	}
 
+	/* setup handler for SIGPIPE */
+	result = sigemptyset(&sigset);
+	if(result == -1) {
+		PERROR("sigemptyset");
+		return 1;
+	}
+	result = sigaddset(&sigset, SIGPIPE);
+	if(result == -1) {
+		PERROR("sigaddset");
+		return 1;
+	}
+	result = sigprocmask(SIG_BLOCK, &sigset, NULL);
+	if(result == -1) {
+		PERROR("sigprocmask");
+		return 1;
+	}
+
+	/* Write pidfile */
+	if(pidfile) {
+		result = write_pidfile(pidfile, getpid());
+		if(result == -1) {
+			ERR("failed to write pidfile");
+			return 1;
+		}
+	}
+
+	/* Notify parent that we are successfully started. */
+	if(fd != -1) {
+		/* write any one character */
+		result = write(fd, "!", 1);
+		if(result == -1) {
+			PERROR("write");
+			return -1;
+		}
+		if(result != 1) {
+			ERR("Problem sending confirmation of daemon start to parent");
+			return -1;
+		}
+		result = close(fd);
+		if(result == -1) {
+			PERROR("close");
+		}
+	}
+
 	/* app loop */
 	for(;;) {
 		char *recvbuf;
-		struct buffer_info *buf;
 
-		/* 1. check for requests on our public socket */
+		/* check for requests on our public socket */
 		result = ustcomm_ustd_recv_message(&ustd, &recvbuf, NULL, 100);
 		if(result == -1) {
 			ERR("error in ustcomm_ustd_recv_message");
-			continue;
+			goto loop_end;
 		}
 		if(result > 0) {
 			if(!strncmp(recvbuf, "collect", 7)) {
@@ -235,43 +780,101 @@ int main(int argc, char **argv)
 
 				result = sscanf(recvbuf, "%*s %d %50as", &pid, &bufname);
 				if(result != 2) {
-					fprintf(stderr, "parsing error: %s\n", recvbuf);
+					ERR("parsing error: %s", recvbuf);
+					goto free_bufname;
 				}
 
-				result = add_buffer(pid, bufname);
+				result = start_consuming_buffer(pid, bufname);
 				if(result < 0) {
 					ERR("error in add_buffer");
-					continue;
+					goto free_bufname;
 				}
+
+				free_bufname:
+				free(bufname);
+			}
+			else {
+				WARN("unknown command: %s", recvbuf);
 			}
 
 			free(recvbuf);
 		}
 
-		/* 2. try to consume data from tracing apps */
-		list_for_each_entry(buf, &buffers, list) {
-			result = get_subbuffer(buf);
-			if(result == -1) {
-				ERR("error getting subbuffer");
-				continue;
-			}
-			if(result == 0)
-				continue;
-
-			/* write data to file */
-			//result = write(buf->file_fd, buf->, );
-			result = patient_write(buf->file_fd, buf->mem + (buf->consumed_old & (buf->n_subbufs * buf->subbuf_size-1)), buf->subbuf_size);
-			if(result == -1) {
-				PERROR("write");
-				/* FIXME: maybe drop this trace */
-			}
+		loop_end:
 
-			result = put_subbuffer(buf);
-			if(result == -1) {
-				ERR("error putting subbuffer");
+		if(terminate_req) {
+			pthread_mutex_lock(&active_buffers_mutex);
+			if(active_buffers == 0) {
+				pthread_mutex_unlock(&active_buffers_mutex);
+				break;
 			}
+			pthread_mutex_unlock(&active_buffers_mutex);
 		}
 	}
 
+	ustcomm_fini_ustd(&ustd);
+
 	return 0;
 }
+
+int start_ustd_daemon()
+{
+	int result;
+	int fd[2];
+	pid_t child_pid;
+
+	result = pipe(fd);
+
+	result = child_pid = fork();
+	if(result == -1) {
+		PERROR("fork");
+		return -1;
+	}
+	else if(result == 0) {
+		return start_ustd(fd[1]);
+	}
+	else {
+		char buf;
+
+		result = read(fd[0], &buf, 1);
+		if(result == -1) {
+			PERROR("read");
+			return -1;
+		}
+		if(result != 1) {
+			ERR("did not receive valid confirmation that the daemon is started");
+			return -1;
+		}
+
+		result = close(fd[0]);
+		if(result == -1) {
+			PERROR("close");
+		}
+
+		DBG("The daemon is now successfully started");
+	}
+
+	/* Wait for confirmation that the server is ready. */
+
+
+	return 0;
+}
+
+int main(int argc, char **argv)
+{
+	int result;
+
+	result = parse_args(argc, argv);
+	if(result == -1) {
+		exit(1);
+	}
+
+	if(daemon_mode) {
+		result = start_ustd_daemon();
+	}
+	else {
+		result = start_ustd(-1);
+	}
+
+	return result;
+}