VENTI-FCALL(3) VENTI-FCALL(3)
NAME
VtEntry, VtFcall, VtRoot, vtentrypack, vtentryunpack,
vtfcallclear, vtfcallfmt, vtfcallpack, vtfcallunpack,
vtfromdisktype, vttodisktype, vtgetstring, vtputstring,
vtrootpack, vtrootunpack, vtparsescore, vtscorefmt - venti
data formats
SYNOPSIS
#include <u.h>
#include <libc.h>
#include <venti.h>
enum
{
VtEntrySize = 40,
VtRootSize = 300,
VtScoreSize = 20,
};
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;
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;
void vtentrypack(VtEntry *e, uchar *buf, int index)
int vtentryunpack(VtEntry *e, uchar *buf, int index)
Packet* vtfcallpack(VtFcall *f)
int vtfcallunpack(VtFcall *f, Packet *p)
void vtfcallclear(VtFcall *f)
uint vttodisktype(uint type)
uint vtfromdisktype(uint type)
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int vtputstring(Packet *p, char *s)
int vtgetstring(Packet *p, char **s)
void vtrootpack(VtRoot *r, uchar *buf)
int vtrootunpack(VtRoot *r, uchar *buf)
int vtparsescore(char *s, char **prefix, uchar score[VtScoreSize])
int vtfcallfmt(Fmt *fmt)
int vtscorefmt(Fmt *fmt)
DESCRIPTION
These routines convert between C representations of Venti
structures and serialized representations used on disk and
on the network.
Vtentrypack converts a VtEntry structure describing a Venti
file (see venti(7)) into a 40-byte (VtEntrySize) structure
at buf+index*40. Vtentryunpack does the reverse conversion.
Vtfcallpack converts a VtFcall structure describing a Venti
protocol message (see venti(7)) into a packet.
Vtfcallunpack does the reverse conversion.
The fields in a VtFcall are named after the protocol fields
described in venti(7), except that the type field is renamed
blocktype. The msgtype field holds the one-byte message
type: VtThello, VtRhello, and so on.
Vtfcallclear frees the strings f->error, f->version, f->uid,
f->sid, the buffers f->crypto and f->codec, and the packet
f->data.
The block type enumeration defined in <venti.h> (presented
in venti(7)) 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
VtDataType+n and VtDirType+n blocks. Vttodisktype converts
a <venti.h> enumeration value to the disk value;
vtfromdisktype converts a disk value to the enumeration
value, always using the VtDirType pointers. The VtFcall
field blocktype is an enumeration value (vtfcallpack and
vtfcallunpack convert to and from the disk values used in
packets automatically), so most programs will not need to
call these functions.
Vtputstring appends the Venti protocol representation of the
string s to the packet p. Vtgetstring reads a string from
the packet, returning a pointer to a copy of the string in
*s. The copy must be freed by the caller. These functions
are used by vtfcallpack and vtfcallunpack; most programs
will not need to call them directly.
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Vtrootpack converts a VtRoot structure describing a Venti
file tree into the 300-byte (VtRootSize) buffer pointed to
by buf. Vtrootunpack does the reverse conversion.
Vtparsescore parses the 40-digit hexadecimal string s, writ-
ing its value into score. If the hexadecimal string is pre-
fixed with a text label followed by a colon, a copy of that
label is returned in *prefix. If prefix is nil, the label
is ignored.
Vtfcallfmt and vtscorefmt are print(3) formatters to print
VtFcall structures and scores. Vtfcallfmt assumes that
vtscorefmt is installed as %V.
SOURCE
/usr/local/plan9/src/libventi
SEE ALSO
venti(1), venti(3), venti(7)
DIAGNOSTICS
Vtentrypack, vtfcallpack, vtrootpack, and vtfcallclear can-
not fail.
Vtentryunpack, vtrootunpack, vtputstring, vtgetstring, and
vtparsescore return 0 on success, -1 on error.
Vtfcallpack returns a packet on success, nil on error.
Vttodisktype and vtfromdisktype return VtCorruptType (255)
when presented with invalid input.
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