xenbus.c

来自「xen虚拟机源代码安装包」· C语言 代码 · 共 762 行 · 第 1/2 页

static char *errmsg(struct xsd_sockmsg *rep)
{
    char *res;
    if (!rep) {
	char msg[] = "No reply";
	size_t len = strlen(msg) + 1;
	return memcpy(malloc(len), msg, len);
    }
    if (rep->type != XS_ERROR)
	return NULL;
    res = malloc(rep->len + 1);
    memcpy(res, rep + 1, rep->len);
    res[rep->len] = 0;
    free(rep);
    return res;
}	

/* Send a debug message to xenbus.  Can block. */
static void xenbus_debug_msg(const char *msg)
{
    int len = strlen(msg);
    struct write_req req[] = {
        { "print", sizeof("print") },
        { msg, len },
        { "", 1 }};
    struct xsd_sockmsg *reply;

    reply = xenbus_msg_reply(XS_DEBUG, 0, req, ARRAY_SIZE(req));
    DEBUG("Got a reply, type %d, id %d, len %d.\n",
            reply->type, reply->req_id, reply->len);
}

/* List the contents of a directory.  Returns a malloc()ed array of
   pointers to malloc()ed strings.  The array is NULL terminated.  May
   block. */
char *xenbus_ls(xenbus_transaction_t xbt, const char *pre, char ***contents)
{
    struct xsd_sockmsg *reply, *repmsg;
    struct write_req req[] = { { pre, strlen(pre)+1 } };
    int nr_elems, x, i;
    char **res, *msg;

    repmsg = xenbus_msg_reply(XS_DIRECTORY, xbt, req, ARRAY_SIZE(req));
    msg = errmsg(repmsg);
    if (msg) {
	*contents = NULL;
	return msg;
    }
    reply = repmsg + 1;
    for (x = nr_elems = 0; x < repmsg->len; x++)
        nr_elems += (((char *)reply)[x] == 0);
    res = malloc(sizeof(res[0]) * (nr_elems + 1));
    for (x = i = 0; i < nr_elems; i++) {
        int l = strlen((char *)reply + x);
        res[i] = malloc(l + 1);
        memcpy(res[i], (char *)reply + x, l + 1);
        x += l + 1;
    }
    res[i] = NULL;
    free(repmsg);
    *contents = res;
    return NULL;
}

char *xenbus_read(xenbus_transaction_t xbt, const char *path, char **value)
{
    struct write_req req[] = { {path, strlen(path) + 1} };
    struct xsd_sockmsg *rep;
    char *res, *msg;
    rep = xenbus_msg_reply(XS_READ, xbt, req, ARRAY_SIZE(req));
    msg = errmsg(rep);
    if (msg) {
	*value = NULL;
	return msg;
    }
    res = malloc(rep->len + 1);
    memcpy(res, rep + 1, rep->len);
    res[rep->len] = 0;
    free(rep);
    *value = res;
    return NULL;
}

char *xenbus_write(xenbus_transaction_t xbt, const char *path, const char *value)
{
    struct write_req req[] = { 
	{path, strlen(path) + 1},
	{value, strlen(value)},
    };
    struct xsd_sockmsg *rep;
    char *msg;
    rep = xenbus_msg_reply(XS_WRITE, xbt, req, ARRAY_SIZE(req));
    msg = errmsg(rep);
    if (msg) return msg;
    free(rep);
    return NULL;
}

char* xenbus_watch_path_token( xenbus_transaction_t xbt, const char *path, const char *token, xenbus_event_queue *events)
{
    struct xsd_sockmsg *rep;

    struct write_req req[] = { 
        {path, strlen(path) + 1},
	{token, strlen(token) + 1},
    };

    struct watch *watch = malloc(sizeof(*watch));

    char *msg;

    if (!events)
        events = &xenbus_events;

    watch->token = strdup(token);
    watch->events = events;
    watch->next = watches;
    watches = watch;

    rep = xenbus_msg_reply(XS_WATCH, xbt, req, ARRAY_SIZE(req));

    msg = errmsg(rep);
    if (msg) return msg;
    free(rep);

    return NULL;
}

char* xenbus_unwatch_path_token( xenbus_transaction_t xbt, const char *path, const char *token)
{
    struct xsd_sockmsg *rep;

    struct write_req req[] = { 
        {path, strlen(path) + 1},
	{token, strlen(token) + 1},
    };

    struct watch *watch, **prev;

    char *msg;

    rep = xenbus_msg_reply(XS_UNWATCH, xbt, req, ARRAY_SIZE(req));

    msg = errmsg(rep);
    if (msg) return msg;
    free(rep);

    for (prev = &watches, watch = *prev; watch; prev = &watch->next, watch = *prev)
        if (!strcmp(watch->token, token)) {
            free(watch->token);
            *prev = watch->next;
            free(watch);
            break;
        }

    return NULL;
}

char *xenbus_rm(xenbus_transaction_t xbt, const char *path)
{
    struct write_req req[] = { {path, strlen(path) + 1} };
    struct xsd_sockmsg *rep;
    char *msg;
    rep = xenbus_msg_reply(XS_RM, xbt, req, ARRAY_SIZE(req));
    msg = errmsg(rep);
    if (msg)
	return msg;
    free(rep);
    return NULL;
}

char *xenbus_get_perms(xenbus_transaction_t xbt, const char *path, char **value)
{
    struct write_req req[] = { {path, strlen(path) + 1} };
    struct xsd_sockmsg *rep;
    char *res, *msg;
    rep = xenbus_msg_reply(XS_GET_PERMS, xbt, req, ARRAY_SIZE(req));
    msg = errmsg(rep);
    if (msg) {
	*value = NULL;
	return msg;
    }
    res = malloc(rep->len + 1);
    memcpy(res, rep + 1, rep->len);
    res[rep->len] = 0;
    free(rep);
    *value = res;
    return NULL;
}

#define PERM_MAX_SIZE 32
char *xenbus_set_perms(xenbus_transaction_t xbt, const char *path, domid_t dom, char perm)
{
    char value[PERM_MAX_SIZE];
    struct write_req req[] = { 
	{path, strlen(path) + 1},
	{value, 0},
    };
    struct xsd_sockmsg *rep;
    char *msg;
    snprintf(value, PERM_MAX_SIZE, "%c%hu", perm, dom);
    req[1].len = strlen(value) + 1;
    rep = xenbus_msg_reply(XS_SET_PERMS, xbt, req, ARRAY_SIZE(req));
    msg = errmsg(rep);
    if (msg)
	return msg;
    free(rep);
    return NULL;
}

char *xenbus_transaction_start(xenbus_transaction_t *xbt)
{
    /* xenstored becomes angry if you send a length 0 message, so just
       shove a nul terminator on the end */
    struct write_req req = { "", 1};
    struct xsd_sockmsg *rep;
    char *err;

    rep = xenbus_msg_reply(XS_TRANSACTION_START, 0, &req, 1);
    err = errmsg(rep);
    if (err)
	return err;
    sscanf((char *)(rep + 1), "%u", xbt);
    free(rep);
    return NULL;
}

char *
xenbus_transaction_end(xenbus_transaction_t t, int abort, int *retry)
{
    struct xsd_sockmsg *rep;
    struct write_req req;
    char *err;

    *retry = 0;

    req.data = abort ? "F" : "T";
    req.len = 2;
    rep = xenbus_msg_reply(XS_TRANSACTION_END, t, &req, 1);
    err = errmsg(rep);
    if (err) {
	if (!strcmp(err, "EAGAIN")) {
	    *retry = 1;
	    free(err);
	    return NULL;
	} else {
	    return err;
	}
    }
    free(rep);
    return NULL;
}

int xenbus_read_integer(char *path)
{
    char *res, *buf;
    int t;

    res = xenbus_read(XBT_NIL, path, &buf);
    if (res) {
	printk("Failed to read %s.\n", path);
	free(res);
	return -1;
    }
    sscanf(buf, "%d", &t);
    free(buf);
    return t;
}

char* xenbus_printf(xenbus_transaction_t xbt,
                                  char* node, char* path,
                                  char* fmt, ...)
{
#define BUFFER_SIZE 256
    char fullpath[BUFFER_SIZE];
    char val[BUFFER_SIZE];
    va_list args;

    BUG_ON(strlen(node) + strlen(path) + 1 >= BUFFER_SIZE);
    sprintf(fullpath,"%s/%s", node, path);
    va_start(args, fmt);
    vsprintf(val, fmt, args);
    va_end(args);
    return xenbus_write(xbt,fullpath,val);
}

static void do_ls_test(const char *pre)
{
    char **dirs, *msg;
    int x;

    DEBUG("ls %s...\n", pre);
    msg = xenbus_ls(XBT_NIL, pre, &dirs);
    if (msg) {
	DEBUG("Error in xenbus ls: %s\n", msg);
	free(msg);
	return;
    }
    for (x = 0; dirs[x]; x++) 
    {
        DEBUG("ls %s[%d] -> %s\n", pre, x, dirs[x]);
        free(dirs[x]);
    }
    free(dirs);
}

static void do_read_test(const char *path)
{
    char *res, *msg;
    DEBUG("Read %s...\n", path);
    msg = xenbus_read(XBT_NIL, path, &res);
    if (msg) {
	DEBUG("Error in xenbus read: %s\n", msg);
	free(msg);
	return;
    }
    DEBUG("Read %s -> %s.\n", path, res);
    free(res);
}

static void do_write_test(const char *path, const char *val)
{
    char *msg;
    DEBUG("Write %s to %s...\n", val, path);
    msg = xenbus_write(XBT_NIL, path, val);
    if (msg) {
	DEBUG("Result %s\n", msg);
	free(msg);
    } else {
	DEBUG("Success.\n");
    }
}

static void do_rm_test(const char *path)
{
    char *msg;
    DEBUG("rm %s...\n", path);
    msg = xenbus_rm(XBT_NIL, path);
    if (msg) {
	DEBUG("Result %s\n", msg);
	free(msg);
    } else {
	DEBUG("Success.\n");
    }
}

/* Simple testing thing */
void test_xenbus(void)
{
    DEBUG("Doing xenbus test.\n");
    xenbus_debug_msg("Testing xenbus...\n");

    DEBUG("Doing ls test.\n");
    do_ls_test("device");
    do_ls_test("device/vif");
    do_ls_test("device/vif/0");

    DEBUG("Doing read test.\n");
    do_read_test("device/vif/0/mac");
    do_read_test("device/vif/0/backend");

    DEBUG("Doing write test.\n");
    do_write_test("device/vif/0/flibble", "flobble");
    do_read_test("device/vif/0/flibble");
    do_write_test("device/vif/0/flibble", "widget");
    do_read_test("device/vif/0/flibble");

    DEBUG("Doing rm test.\n");
    do_rm_test("device/vif/0/flibble");
    do_read_test("device/vif/0/flibble");
    DEBUG("(Should have said ENOENT)\n");
}

/*
 * Local variables:
 * mode: C
 * c-basic-offset: 4
 * End:
 */