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NAME
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VtEntry, VtFcall, VtRoot, vtentrypack, vtentryunpack, vtfcallclear,
vtfcallfmt, vtfcallpack, vtfcallunpack, vtfromdisktype, vttodisktype,
vtgetstring, vtputstring, vtrootpack, vtrootunpack, vtparsescore,
vtscorefmt – venti data formats
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SYNOPSIS
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#include <u.h>
#include <libc.h>
#include <venti.h>
enum
{
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VtEntrySize = 40,
VtRootSize = 300,
VtScoreSize = 20,
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};
typedef struct VtEntry
{
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ulong gen; /* generation number */
ushort psize; /* pointer block size */
ushort dsize; /* data block size */
uchar type;
uchar flags;
uvlong size;
uchar score[VtScoreSize];
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} VtEntry;
typedef struct VtRoot
{
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char name[128];
char type[128];
uchar score[VtScoreSize]; /* to a Dir block */
ushort blocksize; /* maximum block size */
uchar prev[VtScoreSize]; /* previous root block */
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} 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)
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)
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DESCRIPTION
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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.
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, writing
its value into score. If the hexadecimal string is prefixed 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.
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SOURCE
SEE ALSO
DIAGNOSTICS
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Vtentrypack, vtfcallpack, vtrootpack, and vtfcallclear cannot
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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