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/*-------------------------------------------------------------------------
* relpath.c
* Shared frontend/backend code to compute pathnames of relation files
*
* This module also contains some logic associated with fork names.
*
* Portions Copyright (c) 1996-2023, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
* IDENTIFICATION
* src/common/relpath.c
*
*-------------------------------------------------------------------------
*/
#ifndef FRONTEND
#include "postgres.h"
#else
#include "postgres_fe.h"
#endif
#include "catalog/pg_tablespace_d.h"
#include "common/relpath.h"
#include "storage/backendid.h"
/*
* Lookup table of fork name by fork number.
*
* If you add a new entry, remember to update the errhint in
* forkname_to_number() below, and update the SGML documentation for
* pg_relation_size().
*/
const char *const forkNames[] = {
"main", /* MAIN_FORKNUM */
"fsm", /* FSM_FORKNUM */
"vm", /* VISIBILITYMAP_FORKNUM */
"init" /* INIT_FORKNUM */
};
StaticAssertDecl(lengthof(forkNames) == (MAX_FORKNUM + 1),
"array length mismatch");
/*
* forkname_to_number - look up fork number by name
*
* In backend, we throw an error for no match; in frontend, we just
* return InvalidForkNumber.
*/
ForkNumber
forkname_to_number(const char *forkName)
{
ForkNumber forkNum;
for (forkNum = 0; forkNum <= MAX_FORKNUM; forkNum++)
if (strcmp(forkNames[forkNum], forkName) == 0)
return forkNum;
#ifndef FRONTEND
ereport(ERROR,
(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
errmsg("invalid fork name"),
errhint("Valid fork names are \"main\", \"fsm\", "
"\"vm\", and \"init\".")));
#endif
return InvalidForkNumber;
}
/*
* forkname_chars
* We use this to figure out whether a filename could be a relation
* fork (as opposed to an oddly named stray file that somehow ended
* up in the database directory). If the passed string begins with
* a fork name (other than the main fork name), we return its length,
* and set *fork (if not NULL) to the fork number. If not, we return 0.
*
* Note that the present coding assumes that there are no fork names which
* are prefixes of other fork names.
*/
int
forkname_chars(const char *str, ForkNumber *fork)
{
ForkNumber forkNum;
for (forkNum = 1; forkNum <= MAX_FORKNUM; forkNum++)
{
int len = strlen(forkNames[forkNum]);
if (strncmp(forkNames[forkNum], str, len) == 0)
{
if (fork)
*fork = forkNum;
return len;
}
}
if (fork)
*fork = InvalidForkNumber;
return 0;
}
/*
* GetDatabasePath - construct path to a database directory
*
* Result is a palloc'd string.
*
* XXX this must agree with GetRelationPath()!
*/
char *
GetDatabasePath(Oid dbOid, Oid spcOid)
{
if (spcOid == GLOBALTABLESPACE_OID)
{
/* Shared system relations live in {datadir}/global */
Assert(dbOid == 0);
return pstrdup("global");
}
else if (spcOid == DEFAULTTABLESPACE_OID)
{
/* The default tablespace is {datadir}/base */
return psprintf("base/%u", dbOid);
}
else
{
/* All other tablespaces are accessed via symlinks */
return psprintf("pg_tblspc/%u/%s/%u",
spcOid, TABLESPACE_VERSION_DIRECTORY, dbOid);
}
}
/*
* GetRelationPath - construct path to a relation's file
*
* Result is a palloc'd string.
*
* Note: ideally, backendId would be declared as type BackendId, but relpath.h
* would have to include a backend-only header to do that; doesn't seem worth
* the trouble considering BackendId is just int anyway.
*/
char *
GetRelationPath(Oid dbOid, Oid spcOid, RelFileNumber relNumber,
int backendId, ForkNumber forkNumber)
{
char *path;
if (spcOid == GLOBALTABLESPACE_OID)
{
/* Shared system relations live in {datadir}/global */
Assert(dbOid == 0);
Assert(backendId == InvalidBackendId);
if (forkNumber != MAIN_FORKNUM)
path = psprintf("global/%u_%s",
relNumber, forkNames[forkNumber]);
else
path = psprintf("global/%u", relNumber);
}
else if (spcOid == DEFAULTTABLESPACE_OID)
{
/* The default tablespace is {datadir}/base */
if (backendId == InvalidBackendId)
{
if (forkNumber != MAIN_FORKNUM)
path = psprintf("base/%u/%u_%s",
dbOid, relNumber,
forkNames[forkNumber]);
else
path = psprintf("base/%u/%u",
dbOid, relNumber);
}
else
{
if (forkNumber != MAIN_FORKNUM)
path = psprintf("base/%u/t%d_%u_%s",
dbOid, backendId, relNumber,
forkNames[forkNumber]);
else
path = psprintf("base/%u/t%d_%u",
dbOid, backendId, relNumber);
}
}
else
{
/* All other tablespaces are accessed via symlinks */
if (backendId == InvalidBackendId)
{
if (forkNumber != MAIN_FORKNUM)
path = psprintf("pg_tblspc/%u/%s/%u/%u_%s",
spcOid, TABLESPACE_VERSION_DIRECTORY,
dbOid, relNumber,
forkNames[forkNumber]);
else
path = psprintf("pg_tblspc/%u/%s/%u/%u",
spcOid, TABLESPACE_VERSION_DIRECTORY,
dbOid, relNumber);
}
else
{
if (forkNumber != MAIN_FORKNUM)
path = psprintf("pg_tblspc/%u/%s/%u/t%d_%u_%s",
spcOid, TABLESPACE_VERSION_DIRECTORY,
dbOid, backendId, relNumber,
forkNames[forkNumber]);
else
path = psprintf("pg_tblspc/%u/%s/%u/t%d_%u",
spcOid, TABLESPACE_VERSION_DIRECTORY,
dbOid, backendId, relNumber);
}
}
return path;
}
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