term% cat index.txt VENTI-FCALL(2) System Calls Manual VENTI-FCALL(2)
NAME
VtEntry, VtFcall, VtRoot, vtentrypack, vtentryunpack, vtfcallclear, vt‐
fcallfmt, vtfcallpack, vtfcallunpack, vtfromdisktype, vttodisktype, vt‐
getstring, 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)
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(6)) 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(6)) into a packet. Vtfcallunpack does the reverse
conversion.
The fields in a VtFcall are named after the protocol fields described
in venti(6), except that the type field is renamed blocktype. The msg‐
type 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(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 VtDataType+n and VtDirType+n blocks. Vttodisktype
converts a <venti.h> enumeration value to the disk value; vtfromdisk‐
type 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 val‐
ues 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(2) formatters to print VtFcall
structures and scores. Vtfcallfmt assumes that vtscorefmt is installed
as %V.
SOURCE
/sys/src/libventi
SEE ALSO
venti(1), venti(2), venti(6)
DIAGNOSTICS
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 pre‐
sented with invalid input.
VENTI-FCALL(2)