FreeBSD/Linux Kernel Cross Reference
sys/xen/xenstore/xenstorevar.h

     /******************************************************************************
      * xenstorevar.h
      *
      * Method declarations and structures for accessing the XenStore.h
      *
      * Copyright (C) 2005 Rusty Russell, IBM Corporation
      * Copyright (C) 2005 XenSource Ltd.
      * Copyright (C) 2009,2010 Spectra Logic Corporation
      * 
     * This file may be distributed separately from the Linux kernel, or
     * incorporated into other software packages, subject to the following license:
     * 
     * Permission is hereby granted, free of charge, to any person obtaining a copy
     * of this source file (the "Software"), to deal in the Software without
     * restriction, including without limitation the rights to use, copy, modify,
     * merge, publish, distribute, sublicense, and/or sell copies of the Software,
     * and to permit persons to whom the Software is furnished to do so, subject to
     * the following conditions:
     * 
     * The above copyright notice and this permission notice shall be included in
     * all copies or substantial portions of the Software.
     * 
     * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
     * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
     * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
     * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
     * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
     * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
     * IN THE SOFTWARE.
     *
     * $FreeBSD: releng/11.2/sys/xen/xenstore/xenstorevar.h 315667 2017-03-21 08:36:25Z royger $
     */
    
    #ifndef _XEN_XENSTORE_XENSTOREVAR_H
    #define _XEN_XENSTORE_XENSTOREVAR_H
    
    #include <sys/queue.h>
    #include <sys/bus.h>
    #include <sys/eventhandler.h>
    #include <sys/malloc.h>
    #include <sys/sbuf.h>
    
    #include <machine/stdarg.h>
    
    #include <xen/xen-os.h>
    #include <xen/interface/grant_table.h>
    #include <xen/interface/io/xenbus.h>
    #include <xen/interface/io/xs_wire.h>
    
    #include "xenbus_if.h"
    
    /* XenStore allocations including XenStore data returned to clients. */
    MALLOC_DECLARE(M_XENSTORE);
    
    struct xenstore_domain_interface;
    struct xs_watch;
    extern struct xenstore_domain_interface *xen_store;
    
    typedef void (xs_watch_cb_t)(struct xs_watch *, const char **vec,
        unsigned int len);
    
    /* Register callback to watch subtree (node) in the XenStore. */
    struct xs_watch
    {
            LIST_ENTRY(xs_watch) list;
    
            /* Path being watched. */
            char *node;
    
            /* Callback (executed in a process context with no locks held). */
            xs_watch_cb_t *callback;
    
            /* Callback client data untouched by the XenStore watch mechanism. */
            uintptr_t callback_data;
    };
    LIST_HEAD(xs_watch_list, xs_watch);
    
    typedef int (*xs_event_handler_t)(void *);
    
    struct xs_transaction
    {
            uint32_t id;
    };
    
    #define XST_NIL ((struct xs_transaction) { 0 })
    
    /**
     * Fetch the contents of a directory in the XenStore.
     *
     * \param t       The XenStore transaction covering this request.
     * \param dir     The dirname of the path to read.
     * \param node    The basename of the path to read.
     * \param num     The returned number of directory entries.
     * \param result  An array of directory entry strings.
     *
     * \return  On success, 0. Otherwise an errno value indicating the
     *          type of failure.
     *
     * \note The results buffer is malloced and should be free'd by the
    *       caller with 'free(*result, M_XENSTORE)'.
    */
   int xs_directory(struct xs_transaction t, const char *dir,
       const char *node, unsigned int *num, const char ***result);
   
   /**
    * Determine if a path exists in the XenStore.
    *
    * \param t       The XenStore transaction covering this request.
    * \param dir     The dirname of the path to read.
    * \param node    The basename of the path to read.
    *
    * \retval 1  The path exists.
    * \retval 0  The path does not exist or an error occurred attempting
    *            to make that determination.
    */
   int xs_exists(struct xs_transaction t, const char *dir, const char *node);
   
   /**
    * Get the contents of a single "file".  Returns the contents in
    * *result which should be freed with free(*result, M_XENSTORE) after
    * use.  The length of the value in bytes is returned in *len.
    *
    * \param t       The XenStore transaction covering this request.
    * \param dir     The dirname of the file to read.
    * \param node    The basename of the file to read.
    * \param len     The amount of data read.
    * \param result  The returned contents from this file.
    *
    * \return  On success, 0. Otherwise an errno value indicating the
    *          type of failure.
    *
    * \note The results buffer is malloced and should be free'd by the
    *       caller with 'free(*result, M_XENSTORE)'.
    */
   int xs_read(struct xs_transaction t, const char *dir,
       const char *node, unsigned int *len, void **result);
   
   /**
    * Write to a single file.
    *
    * \param t       The XenStore transaction covering this request.
    * \param dir     The dirname of the file to write.
    * \param node    The basename of the file to write.
    * \param string  The NUL terminated string of data to write.
    *
    * \return  On success, 0. Otherwise an errno value indicating the
    *          type of failure.
    */
   int xs_write(struct xs_transaction t, const char *dir,
       const char *node, const char *string);
   
   /**
    * Create a new directory.
    *
    * \param t       The XenStore transaction covering this request.
    * \param dir     The dirname of the directory to create.
    * \param node    The basename of the directory to create.
    *
    * \return  On success, 0. Otherwise an errno value indicating the
    *          type of failure.
    */
   int xs_mkdir(struct xs_transaction t, const char *dir,
       const char *node);
   
   /**
    * Remove a file or directory (directories must be empty).
    *
    * \param t       The XenStore transaction covering this request.
    * \param dir     The dirname of the directory to remove.
    * \param node    The basename of the directory to remove.
    *
    * \return  On success, 0. Otherwise an errno value indicating the
    *          type of failure.
    */
   int xs_rm(struct xs_transaction t, const char *dir, const char *node);
   
   /**
    * Destroy a tree of files rooted at dir/node.
    *
    * \param t       The XenStore transaction covering this request.
    * \param dir     The dirname of the directory to remove.
    * \param node    The basename of the directory to remove.
    *
    * \return  On success, 0. Otherwise an errno value indicating the
    *          type of failure.
    */
   int xs_rm_tree(struct xs_transaction t, const char *dir,
       const char *node);
   
   /**
    * Start a transaction.
    *
    * Changes by others will not be seen during the lifetime of this
    * transaction, and changes will not be visible to others until it
    * is committed (xs_transaction_end).
    *
    * \param t  The returned transaction.
    *
    * \return  On success, 0. Otherwise an errno value indicating the
    *          type of failure.
    */
   int xs_transaction_start(struct xs_transaction *t);
   
   /**
    * End a transaction.
    *
    * \param t      The transaction to end/commit.
    * \param abort  If non-zero, the transaction is discarded
    *               instead of committed.
    *
    * \return  On success, 0. Otherwise an errno value indicating the
    *          type of failure.
    */
   int xs_transaction_end(struct xs_transaction t, int abort);
   
   /*
    * Single file read and scanf parsing of the result.
    *
    * \param t           The XenStore transaction covering this request.
    * \param dir         The dirname of the path to read.
    * \param node        The basename of the path to read.
    * \param scancountp  The number of input values assigned (i.e. the result
    *                    of scanf).
    * \param fmt         Scanf format string followed by a variable number of
    *                    scanf input arguments.
    *
    * \return  On success, 0. Otherwise an errno value indicating the
    *          type of failure.
    */
   int xs_scanf(struct xs_transaction t,
       const char *dir, const char *node, int *scancountp, const char *fmt, ...)
       __attribute__((format(scanf, 5, 6)));
   
   /**
    * Printf formatted write to a XenStore file.
    *
    * \param t     The XenStore transaction covering this request.
    * \param dir   The dirname of the path to read.
    * \param node  The basename of the path to read.
    * \param fmt   Printf format string followed by a variable number of
    *              printf arguments.
    *
    * \return  On success, 0. Otherwise an errno value indicating the
    *          type of write failure.
    */
   int xs_printf(struct xs_transaction t, const char *dir,
       const char *node, const char *fmt, ...)
       __attribute__((format(printf, 4, 5)));
   
   /**
    * va_list version of xenbus_printf().
    *
    * \param t     The XenStore transaction covering this request.
    * \param dir   The dirname of the path to read.
    * \param node  The basename of the path to read.
    * \param fmt   Printf format string.
    * \param ap    Va_list of printf arguments.
    *
    * \return  On success, 0. Otherwise an errno value indicating the
    *          type of write failure.
    */
   int xs_vprintf(struct xs_transaction t, const char *dir,
       const char *node, const char *fmt, va_list ap);
   
   /**
    * Multi-file read within a single directory and scanf parsing of
    * the results.
    *
    * \param t    The XenStore transaction covering this request.
    * \param dir  The dirname of the paths to read.
    * \param ...  A variable number of argument triples specifying
    *             the file name, scanf-style format string, and
    *             output variable (pointer to storage of the results).
    *             The last triple in the call must be terminated
    *             will a final NULL argument.  A NULL format string
    *             will cause the entire contents of the given file
    *             to be assigned as a NUL terminated, M_XENSTORE heap
    *             backed, string to the output parameter of that tuple.
    *
    * \return  On success, 0. Otherwise an errno value indicating the
    *          type of read failure.
    *
    * Example:
    *         char protocol_abi[64];
    *         uint32_t ring_ref;
    *         char *dev_type;
    *         int error;
    *
    *         error = xenbus_gather(XBT_NIL, xenbus_get_node(dev),
    *             "ring-ref", "%" PRIu32, &ring_ref,
    *             "protocol", "%63s", protocol_abi,
    *             "device-type", NULL, &dev_type,
    *             NULL);
    *
    *         ...
    *
    *         free(dev_type, M_XENSTORE);
    */
   int xs_gather(struct xs_transaction t, const char *dir, ...);
   
   /**
    * Register a XenStore watch.
    *
    * XenStore watches allow a client to be notified via a callback (embedded
    * within the watch object) of changes to an object in the XenStore.
    *
    * \param watch  An xs_watch struct with it's node and callback fields
    *               properly initialized.
    *
    * \return  On success, 0. Otherwise an errno value indicating the
    *          type of write failure.  EEXIST errors from the XenStore
    *          are supressed, allowing multiple, physically different,
    *          xenbus_watch objects, to watch the same path in the XenStore.
    */
   int xs_register_watch(struct xs_watch *watch);
    
   /**
    * Unregister a XenStore watch.
    *
    * \param watch  An xs_watch object previously used in a successful call
    *               to xs_register_watch().
    *
    * The xs_watch object's node field is not altered by this call.
    * It is the caller's responsibility to properly dispose of both the
    * watch object and the data pointed to by watch->node.
    */
   void xs_unregister_watch(struct xs_watch *watch);
   
   /**
    * Allocate and return an sbuf containing the XenStore path string
    * <dir>/<name>.  If name is the NUL string, the returned sbuf contains
    * the path string <dir>.
    *
    * \param dir   The NUL terminated directory prefix for new path.
    * \param name  The NUL terminated basename for the new path.
    *
    * \return  A buffer containing the joined path.
    */
   struct sbuf *xs_join(const char *, const char *);
   
   /**
    * Lock the xenstore request mutex.
    */
   void xs_lock(void);
   
   /**
    * Unlock the xenstore request mutex.
    */
   void xs_unlock(void);
   
   #endif /* _XEN_XENSTORE_XENSTOREVAR_H */
   

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