TH VENTI-FCALL 2
SH NAME
VtEntry, VtFcall, VtRoot,
vtentrypack,
vtentryunpack,
vtfcallclear,
vtfcallfmt,
vtfcallpack,
vtfcallunpack,
vtfromdisktype,
vttodisktype,
vtgetstring,
vtputstring,
vtrootpack,
vtrootunpack,
vtparsescore,
vtscorefmt \- venti data formats
SH SYNOPSIS
PP
ft L
#include <u.h>
br
#include <libc.h>
br
#include <venti.h>
ta +\w'\fLxxxx'u
PP
ft L
nf
enum
{
VtEntrySize = 40,
VtRootSize = 300,
VtScoreSize = 20,
};
PP
ft L
nf
typedef struct VtEntry
{
ulong gen; /* generation number */
ushort psize; /* pointer block size */
ushort dsize; /* data block size */
uchar type;
uchar flags;
uvlong size;
uchar score[VtScoreSize];
} VtEntry;
PP
ft L
nf
typedef struct VtRoot
{
char name[128];
char type[128];
uchar score[VtScoreSize]; /* to a Dir block */
ushort blocksize; /* maximum block size */
uchar prev[VtScoreSize]; /* previous root block */
} VtRoot;
ta +\w'\fLPacket* 'u
PP
B
void vtentrypack(VtEntry *e, uchar *buf, int index)
br
B
int vtentryunpack(VtEntry *e, uchar *buf, int index)
PP
B
Packet* vtfcallpack(VtFcall *f)
br
B
int vtfcallunpack(VtFcall *f, Packet *p)
PP
B
void vtfcallclear(VtFcall *f)
PP
B
uint vttodisktype(uint type)
br
B
uint vtfromdisktype(uint type)
PP
B
int vtputstring(Packet *p, char *s)
br
B
int vtgetstring(Packet *p, char **s)
PP
B
void vtrootpack(VtRoot *r, uchar *buf)
br
B
int vtrootunpack(VtRoot *r, uchar *buf)
PP
B
int vtparsescore(char *s, char **prefix, uchar score[VtScoreSize])
PP
B
int vtfcallfmt(Fmt *fmt)
B
int vtscorefmt(Fmt *fmt)
SH DESCRIPTION
These routines convert between C representations of Venti
structures and serialized representations used on disk and
on the network.
PP
I Vtentrypack
converts a
B VtEntry
structure describing a Venti file
(see
IR venti (6))
into a 40-byte
RB ( VtEntrySize )
structure at
IB buf + index *40 \fR.
Vtentryunpack
does the reverse conversion.
PP
I Vtfcallpack
converts a
B VtFcall
structure describing a Venti protocol message
(see
IR venti (6))
into a packet.
I Vtfcallunpack
does the reverse conversion.
PP
The fields in a
B VtFcall
are named after the protocol fields described in
IR venti (6),
except that the
B type
field is renamed
BR blocktype .
The
B msgtype
field holds the one-byte message type:
BR VtThello ,
BR VtRhello ,
and so on.
PP
I Vtfcallclear
frees the strings
IB f ->error \fR,
IB f ->version \fR,
IB f ->uid \fR,
IB f ->sid \fR,
the buffers
IB f ->crypto
and
IB f ->codec \fR,
and the packet
IB f ->data \fR.
PP
The block type enumeration defined in
B <venti.h>
(presented in
IR venti (6))
differs from the one used on disk and in the network
protocol.
The disk and network representation uses different
constants and does not distinguish between
BI VtDataType+ n
and
BI VtDirType+ n
blocks.
I Vttodisktype
converts a
B <venti.h>
enumeration value to the disk value;
I vtfromdisktype
converts a disk value to the enumeration value,
always using the
B VtDirType
pointers.
The
B VtFcall
field
B blocktype
is an enumeration value
RI ( vtfcallpack
and
I vtfcallunpack
convert to and from the disk values used in packets
automatically),
so most programs will not need to call these functions.
PP
I Vtputstring
appends the Venti protocol representation of the string
I s
to the packet
IR p .
I Vtgetstring
reads a string from the packet, returning a pointer to a copy
of the string in
BI * s \fR.
The copy must be freed by the caller.
These functions are used by
I vtfcallpack
and
IR vtfcallunpack ;
most programs will not need to call them directly.
PP
I Vtrootpack
converts a
B VtRoot
structure describing a Venti file tree
into the 300-byte
RB ( VtRootSize )
buffer pointed to by
IR buf .
I Vtrootunpack does the reverse conversion.
PP
I Vtparsescore
parses the 40-digit hexadecimal string
IR s ,
writing its value
into
IR score .
If the hexadecimal string is prefixed with
a text label followed by a colon, a copy of that
label is returned in
BI * prefix \fR.
If
I prefix
is nil, the label is ignored.
PP
I Vtfcallfmt
and
I vtscorefmt
are
IR print (2)
formatters to print
B VtFcall
structures and scores.
I Vtfcallfmt
assumes that
I vtscorefmt
is installed as
BR %V .
SH SOURCE
B /sys/src/libventi
SH SEE ALSO
IR venti (1),
IR venti (2),
IR venti (6)
SH DIAGNOSTICS
IR Vtentrypack ,
IR vtfcallpack ,
IR vtrootpack ,
and
I vtfcallclear
cannot fail.
PP
IR Vtentryunpack ,
IR vtrootunpack ,
IR vtputstring ,
IR vtgetstring ,
and
I vtparsescore
return 0 on success, \-1 on error.
PP
I Vtfcallpack
returns a packet on success, nil on error.
PP
I Vttodisktype
and
I vtfromdisktype
return
B VtCorruptType
(255)
when presented with invalid input.
