logd.c

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/*
 * Copyright (C) 2013 John Crispin <blogic@openwrt.org>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU Lesser General Public License version 2.1
 * as published by the Free Software Foundation
 *
 * This program 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 General Public License for more details.
 */
 
#include <sys/types.h>
#include <pwd.h>
#include <stdio.h>
#include <unistd.h>
#include <syslog.h>
#include <unistd.h>
 
#include <linux/types.h>
 
#include <libubox/uloop.h>
#include <libubox/blobmsg.h>
#include <libubox/list.h>
#include <libubox/ustream.h>
#include <libubox/utils.h>
#include <libubus.h>
 
#include "syslog.h"
 
int debug = 0;
static struct blob_buf b;
static struct ubus_auto_conn conn;
static struct udebug_ubus udebug;
static LIST_HEAD(clients);
 
enum {
        READ_LINES,
        READ_STREAM,
        READ_ONESHOT,
        __READ_MAX
};
 
static const struct blobmsg_policy read_policy[__READ_MAX] = {
        [READ_LINES] = { .name = "lines", .type = BLOBMSG_TYPE_INT32 },
        [READ_STREAM] = { .name = "stream", .type = BLOBMSG_TYPE_BOOL },
        [READ_ONESHOT] = { .name = "oneshot", .type = BLOBMSG_TYPE_BOOL },
};
 
static const struct blobmsg_policy write_policy =
        { .name = "event", .type = BLOBMSG_TYPE_STRING };
 
struct client {
        struct list_head list;
 
        struct ustream_fd s;
        int fd;
};
 
static void
client_close(struct ustream *s)
{
        struct client *cl = container_of(s, struct client, s.stream);
 
        list_del(&cl->list);
        ustream_free(s);
        close(cl->fd);
        free(cl);
}
 
static void client_notify_state(struct ustream *s)
{
        client_close(s);
}
 
static void client_notify_write(struct ustream *s, int bytes)
{
        if (ustream_pending_data(s, true))
                return;
 
        client_close(s);
}
 
static void
log_fill_msg(struct blob_buf *b, struct log_head *l)
{
        blobmsg_add_string(b, "msg", l->data);
        blobmsg_add_u32(b, "id", l->id);
        blobmsg_add_u32(b, "priority", l->priority);
        blobmsg_add_u32(b, "source", l->source);
        blobmsg_add_u64(b, "time", (((__u64) l->ts.tv_sec) * 1000) + (l->ts.tv_nsec / 1000000));
}
 
static int
read_log(struct ubus_context *ctx, struct ubus_object *obj,
                struct ubus_request_data *req, const char *method,
                struct blob_attr *msg)
{
        struct client *cl;
        struct blob_attr *tb[__READ_MAX] = {};
        struct log_head *l;
        int count = 0;
        int fds[2];
        int ret;
        bool stream = true;
        bool oneshot = false;
        void *c, *e;
 
        if (!stream)
                count = 100;
 
        if (msg) {
                blobmsg_parse(read_policy, __READ_MAX, tb, blob_data(msg), blob_len(msg));
                if (tb[READ_LINES])
                        count = blobmsg_get_u32(tb[READ_LINES]);
                if (tb[READ_STREAM])
                        stream = blobmsg_get_bool(tb[READ_STREAM]);
                if (tb[READ_ONESHOT])
                        oneshot = blobmsg_get_bool(tb[READ_ONESHOT]);
        }
 
        l = log_list(count, NULL);
        if (stream) {
                if (pipe(fds) == -1) {
                        fprintf(stderr, "logd: failed to create pipe: %m\n");
                        return -1;
                }
 
                ubus_request_set_fd(ctx, req, fds[0]);
                cl = calloc(1, sizeof(*cl));
                cl->s.stream.notify_state = client_notify_state;
                cl->fd = fds[1];
                ustream_fd_init(&cl->s, cl->fd);
                list_add(&cl->list, &clients);
                while ((!tb[READ_LINES] || count) && l) {
                        blob_buf_init(&b, 0);
                        log_fill_msg(&b, l);
                        l = log_list(count, l);
                        ret = ustream_write(&cl->s.stream, (void *) b.head, blob_len(b.head) + sizeof(struct blob_attr), false);
                        if (ret < 0)
                                break;
                }
 
                if (oneshot) {
                        cl->s.stream.notify_write = client_notify_write;
                        client_notify_write(&cl->s.stream, 0);
                }
        } else {
                blob_buf_init(&b, 0);
                c = blobmsg_open_array(&b, "log");
                while ((!tb[READ_LINES] || count) && l) {
                        e = blobmsg_open_table(&b, NULL);
                        log_fill_msg(&b, l);
                        blobmsg_close_table(&b, e);
                        l = log_list(count, l);
                }
                blobmsg_close_array(&b, c);
                ubus_send_reply(ctx, req, b.head);
        }
        blob_buf_free(&b);
        return 0;
}
 
static int
write_log(struct ubus_context *ctx, struct ubus_object *obj,
                struct ubus_request_data *req, const char *method,
                struct blob_attr *msg)
{
        struct blob_attr *tb;
        char *event;
 
        if (msg) {
                int len;
 
                blobmsg_parse(&write_policy, 1, &tb, blob_data(msg), blob_len(msg));
                if (tb) {
                        event = blobmsg_get_string(tb);
                        len = strlen(event) + 1;
                        if (len > LOG_LINE_SIZE) {
                                len = LOG_LINE_SIZE;
                                event[len - 1] = 0;
                        }
 
                        log_add(event, len, SOURCE_SYSLOG);
                }
        }
 
        return 0;
}
 
static const struct ubus_method log_methods[] = {
        UBUS_METHOD("read", read_log, read_policy),
        { .name = "write", .handler = write_log, .policy = &write_policy, .n_policy = 1 },
};
 
static struct ubus_object_type log_object_type =
        UBUS_OBJECT_TYPE("log", log_methods);
 
static struct ubus_object log_object = {
        .name = "log",
        .type = &log_object_type,
        .methods = log_methods,
        .n_methods = ARRAY_SIZE(log_methods),
};
 
void
ubus_notify_log(struct log_head *l)
{
        struct client *c;
 
        if (list_empty(&clients) && !log_object.has_subscribers)
                return;
 
        blob_buf_init(&b, 0);
        blobmsg_add_string(&b, "msg", l->data);
        blobmsg_add_u32(&b, "id", l->id);
        blobmsg_add_u32(&b, "priority", l->priority);
        blobmsg_add_u32(&b, "source", l->source);
        blobmsg_add_u64(&b, "time", (((__u64) l->ts.tv_sec) * 1000) + (l->ts.tv_nsec / 1000000));
 
        if (log_object.has_subscribers)
                ubus_notify(&conn.ctx, &log_object, "message", b.head, -1);
 
        list_for_each_entry(c, &clients, list)
                ustream_write(&c->s.stream, (void *) b.head, blob_len(b.head) + sizeof(struct blob_attr), false);
 
        blob_buf_free(&b);
}
 
static void
ubus_connect_handler(struct ubus_context *ctx)
{
        int ret;
 
        ret = ubus_add_object(ctx, &log_object);
        if (ret) {
                fprintf(stderr, "Failed to add object: %s\n", ubus_strerror(ret));
                exit(1);
        }
        fprintf(stderr, "log: connected to ubus\n");
}
 
int
main(int argc, char **argv)
{
        int ch, log_size = 16;
        struct passwd *p = NULL;
 
        signal(SIGPIPE, SIG_IGN);
        while ((ch = getopt(argc, argv, "S:")) != -1) {
                switch (ch) {
                case 'S':
                        log_size = atoi(optarg);
                        if (log_size < 1)
                                log_size = 16;
                        break;
                }
        }
        log_size *= 1024;
 
        uloop_init();
        log_init(log_size);
        conn.cb = ubus_connect_handler;
        ubus_auto_connect(&conn);
        udebug_ubus_init(&udebug, &conn.ctx, "log", log_udebug_config);
        p = getpwnam("logd");
        if (p) {
                if (setgid(p->pw_gid) < 0) {
                        fprintf(stderr, "setgid() failed: %s\n", strerror(errno));
                        exit(1);
                }
 
                if (setuid(p->pw_uid) < 0) {
                        fprintf(stderr, "setuid() failed: %s\n", strerror(errno));
                        exit(1);
                }
        }
        uloop_run();
        udebug_ubus_free(&udebug);
        log_shutdown();
        uloop_done();
        ubus_auto_shutdown(&conn);
 
        return 0;
}