create libustd from ustd

[lttng-ust.git] / libustd / libustd.c

/* Copyright (C) 2009  Pierre-Marc Fournier
 *               2010  Alexis Halle
 *
 * 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/shm.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 "libustd.h"
#include "usterr.h"
#include "ustcomm.h"

/* return value: 0 = subbuffer is finished, it won't produce data anymore
 *               1 = got subbuffer successfully
 *               <0 = error
 */

#define GET_SUBBUF_OK 1
#define GET_SUBBUF_DONE 0
#define GET_SUBBUF_DIED 2

#define PUT_SUBBUF_OK 1
#define PUT_SUBBUF_DIED 0
#define PUT_SUBBUF_PUSHED 2
#define PUT_SUBBUF_DONE 3

#define UNIX_PATH_MAX 108

int get_subbuffer(struct buffer_info *buf)
{
	char *send_msg=NULL;
	char *received_msg=NULL;
	char *rep_code=NULL;
	int retval;
	int result;

	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;
	}

	/* FIXME: 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;
	}

	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)
{
	struct libustd_instance *instance = arg;
	pthread_mutex_lock(&instance->mutex);
	instance->active_buffers--;
	pthread_mutex_unlock(&instance->mutex);
}

struct buffer_info *connect_buffer(struct libustd_instance *instance, pid_t pid, const char *bufname)
{
	struct buffer_info *buf;
	char *send_msg;
	char *received_msg;
	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 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);
	result = ustcomm_send_request(&buf->conn, send_msg, &received_msg);
	free(send_msg);
	if(result == -1) {
		ERR("problem in ustcomm_send_request(get_shmid)");
		return NULL;
	}
	if(result == 0) {
		goto error;
	}

	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 shmids %d %d", buf->shmid, buf->bufstruct_shmid);

	/* get n_subbufs */
	asprintf(&send_msg, "get_n_subbufs %s", buf->name);
	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 NULL;
	}
	free(received_msg);
	DBG("got n_subbufs %d", buf->n_subbufs);

	/* get subbuf size */
	asprintf(&send_msg, "get_subbuf_size %s", buf->name);
	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 NULL;
	}
	free(received_msg);
	DBG("got subbuf_size %d", buf->subbuf_size);

	/* attach memory */
	buf->mem = shmat(buf->shmid, NULL, 0);
	if(buf->mem == (void *) 0) {
		PERROR("shmat");
		return NULL;
	}
	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;

	if(instance->callbacks->on_open_buffer)
		instance->callbacks->on_open_buffer(instance->callbacks, buf);

	pthread_mutex_lock(&instance->mutex);
	instance->active_buffers++;
	pthread_mutex_unlock(&instance->mutex);

	return buf;

error:
	free(buf);
	return NULL;
}

static void destroy_buffer(struct libustd_callbacks *callbacks,
			struct buffer_info *buf)
{
	int result;

	result = ustcomm_close_app(&buf->conn);
	if(result == -1) {
		WARN("problem calling ustcomm_close_app");
	}

	result = shmdt(buf->mem);
	if(result == -1) {
		PERROR("shmdt");
	}

	result = shmdt(buf->bufstruct_mem);
	if(result == -1) {
		PERROR("shmdt");
	}

	if(callbacks->on_close_buffer)
		callbacks->on_close_buffer(callbacks, buf);

	free(buf);
}

int consumer_loop(struct libustd_instance *instance, struct buffer_info *buf)
{
	int result;

	pthread_cleanup_push(decrement_active_buffers, instance);

	for(;;) {
		/* 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(instance->callbacks, buf);
			break;
		}

		if(instance->callbacks->on_read_subbuffer)
			instance->callbacks->on_read_subbuffer(instance->callbacks, buf);

		/* 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.
			 */
			if(instance->callbacks->on_put_error)
				instance->callbacks->on_put_error(instance->callbacks, buf);

			finish_consuming_dead_subbuffer(instance->callbacks, 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) {
		}
	}

	DBG("thread for buffer %s is stopping", buf->name);

	/* FIXME: destroy, unalloc... */

	pthread_cleanup_pop(1);

	return 0;
}

struct consumer_thread_args {
	pid_t pid;
	const char *bufname;
	struct libustd_instance *instance;
};

void *consumer_thread(void *arg)
{
	struct buffer_info *buf;
	struct consumer_thread_args *args = (struct consumer_thread_args *) arg;
	int result;
	sigset_t sigset;

	DBG("GOT ARGS: pid %d bufname %s", args->pid, args->bufname);

	if(args->instance->callbacks->on_new_thread)
		args->instance->callbacks->on_new_thread(args->instance->callbacks);

	/* Block signals that should be handled by the main thread. */
	result = sigemptyset(&sigset);
	if(result == -1) {
		PERROR("sigemptyset");
		goto end;
	}
	result = sigaddset(&sigset, SIGTERM);
	if(result == -1) {
		PERROR("sigaddset");
		goto end;
	}
	result = sigaddset(&sigset, SIGINT);
	if(result == -1) {
		PERROR("sigaddset");
		goto end;
	}
	result = sigprocmask(SIG_BLOCK, &sigset, NULL);
	if(result == -1) {
		PERROR("sigprocmask");
		goto end;
	}

	buf = connect_buffer(args->instance, args->pid, args->bufname);
	if(buf == NULL) {
		ERR("failed to connect to buffer");
		goto end;
	}

	consumer_loop(args->instance, buf);

	destroy_buffer(args->instance->callbacks, buf);

	end:

	if(args->instance->callbacks->on_close_thread)
		args->instance->callbacks->on_close_thread(args->instance->callbacks);

	free((void *)args->bufname);
	free(args);
	return NULL;
}

int start_consuming_buffer(
	struct libustd_instance *instance, 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);
	args->instance = instance;
	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;
}

int libustd_start_instance(struct libustd_instance *instance)
{
	int result;
	int timeout = -1;

	if(!instance->is_init) {
		ERR("libustd instance not initialized");
		return 1;
	}

	/* app loop */
	for(;;) {
		char *recvbuf;

		/* check for requests on our public socket */
		result = ustcomm_ustd_recv_message(&instance->comm, &recvbuf, NULL, timeout);
		if(result == -1 && errno == EINTR) {
			/* Caught signal */
		}
		else if(result == -1) {
			ERR("error in ustcomm_ustd_recv_message");
			goto loop_end;
		}
		else if(result > 0) {
			if(!strncmp(recvbuf, "collect", 7)) {
				pid_t pid;
				char *bufname;
				int result;

				result = sscanf(recvbuf, "%*s %d %50as", &pid, &bufname);
				if(result != 2) {
					ERR("parsing error: %s", recvbuf);
					goto free_bufname;
				}

				result = start_consuming_buffer(instance, pid, bufname);
				if(result < 0) {
					ERR("error in add_buffer");
					goto free_bufname;
				}

				free_bufname:
				free(bufname);
			}
			else if(!strncmp(recvbuf, "exit", 4)) {
				/* Only there to force poll to return */
			}
			else {
				WARN("unknown command: %s", recvbuf);
			}

			free(recvbuf);
		}

		loop_end:

		if(instance->quit_program) {
			pthread_mutex_lock(&instance->mutex);
			if(instance->active_buffers == 0) {
				pthread_mutex_unlock(&instance->mutex);
				break;
			}
			pthread_mutex_unlock(&instance->mutex);
			timeout = 100;
		}
	}

	if(instance->callbacks->on_trace_end)
		instance->callbacks->on_trace_end(instance);

	libustd_delete_instance(instance);

	return 0;
}

void libustd_delete_instance(struct libustd_instance *instance)
{
	if(instance->is_init)
		ustcomm_fini_ustd(&instance->comm);

	pthread_mutex_destroy(&instance->mutex);
	free(instance->sock_path);
	free(instance);
}

int libustd_stop_instance(struct libustd_instance *instance, int send_msg)
{
	int result;
	int fd;
	int bytes = 0;

	char msg[] = "exit";

	instance->quit_program = 1;

	if(!send_msg)
		return 0;

	/* Send a message through the socket to force poll to return */

	struct sockaddr_un addr;

	result = fd = socket(PF_UNIX, SOCK_STREAM, 0);
	if(result == -1) {
		PERROR("socket");
		return 1;
	}

	addr.sun_family = AF_UNIX;

	strncpy(addr.sun_path, instance->sock_path, UNIX_PATH_MAX);
	addr.sun_path[UNIX_PATH_MAX-1] = '\0';

	result = connect(fd, (struct sockaddr *)&addr, sizeof(addr));
	if(result == -1) {
		PERROR("connect");
	}

	while(bytes != sizeof(msg))
		bytes += send(fd, msg, sizeof(msg), 0);

	close(fd);

	return 0;
}

struct libustd_instance *libustd_new_instance(
	struct libustd_callbacks *callbacks, char *sock_path)
{
	struct libustd_instance *instance =
		malloc(sizeof(struct libustd_instance));
	if(!instance)
		return NULL;

	instance->callbacks = callbacks;
	instance->quit_program = 0;
	instance->is_init = 0;
	instance->active_buffers = 0;
	pthread_mutex_init(&instance->mutex, NULL);

	if(sock_path)
		instance->sock_path = strdup(sock_path);
	else
		instance->sock_path = NULL;

	return instance;
}

int libustd_init_instance(struct libustd_instance *instance)
{
	int result;
	result = ustcomm_init_ustd(&instance->comm, instance->sock_path);
	if(result == -1) {
		ERR("failed to initialize socket");
		return 1;
	}
	instance->is_init = 1;
	return 0;
}