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VENTI-CLIENT(3)		   Library Functions Manual	       VENTI-CLIENT(3)

       vtconnect,  vthello,  vtread, vtwrite, vtreadpacket, vtwritepacket, vt-
       sync, vtping, vtrpc, ventidoublechecksha1 - Venti client

       #include	<u.h>
       #include	<libc.h>
       #include	<venti.h>

       Packet* vtrpc(VtConn *z,	Packet *p)

       int     vthello(VtConn *z)

       int     vtconnect(VtConn	*z)

       int     vtread(VtConn *z, uchar score[VtScoreSize],
		       uint type, uchar	*buf, int n)

       int     vtwrite(VtConn *z, uchar	score[VtScoreSize],
		       uint type, uchar	*buf, int n)

       Packet* vtreadpacket(VtConn *z, uchar score[VtScoreSize],
		       uint type, int n)

       int     vtwritepacket(VtConn *z,	uchar score[VtScoreSize],
		       uint type, Packet *p)

       int     vtsync(VtConn *z)

       int     vtping(VtConn *z)

       extern int ventidoublechecksha1;	 /* default 1 */

       These routines execute the client side of the venti(7) protocol.

       Vtrpc executes a	single Venti  RPC  transaction,	 sending  the  request
       packet p	and then waiting for and returning the response	packet.	 Vtrpc
       will set	the tag	in the packet.	Vtrpc frees p, even on	error.	 Vtrpc
       is typically called only	indirectly, via	the functions below.

       Vthello	executes  a hello transaction, setting z->sid to the name used
       by the server.  Vthello is typically called only	indirectly, via	vtcon-

       Vtconnect  calls	vtversion (see venti-conn(3)) and vthello, in that or-
       der, returning success only if both succeed.   This  sequence  (calling
       vtversion and then vthello) must	be done	before the functions below can
       be called.

       Vtread reads the	block with the given score and type from  the  server,
       stores  the  returned  data in memory at	buf, and returns the number of
       bytes read.  If the server's block has size larger than n, vtread  does
       not modify buf and returns an error.

       Vtwrite writes the n bytes in buf as a block of the given type, setting

       Vtreadpacket and	vtwritepacket are like vtread and vtwrite  but	return
       or  accept the block contents in	the form of a Packet.  They avoid mak-
       ing a copy of the data.

       Vtsync causes the server	to flush all pending write  requests  to  disk
       before returning.

       Vtping executes a ping transaction with the server.

       By default, vtread and vtreadpacket check that the SHA1 hash of the re-
       turned data matches the requested score,	and vtwrite and	 vtwritepacket
       check  that  the	 returned  score  matches the SHA1 hash	of the written
       data.   Setting	ventidoublechecksha1  to  zero	disables  these	 extra
       checks,	mainly for benchmarking	purposes.  Doing so in production code
       is not recommended.

       These functions can be called from multiple threads or procs simultane-
       ously to	issue requests in parallel.  Programs that issue requests from
       multiple	threads	in the same proc should	start separate	procs  running
       vtsendproc and vtrecvproc as described in venti-conn(3).


       venti(3), venti-conn(3),	venti-packet(3), venti(7)

       Vtrpc  and  vtpacket return nil on error.  The other routines return -1
       on error.

       Vtwrite returns 0 on success: there are no partial writes.



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