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/*-------------------------------------------------------------------------
*
* relpath.h
* Declarations for GetRelationPath() and friends
*
* Portions Copyright (c) 1996-2025, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
* src/include/common/relpath.h
*
*-------------------------------------------------------------------------
*/
#ifndef RELPATH_H
#define RELPATH_H
/*
* Required here; note that CppAsString2() does not throw an error if the
* symbol is not defined.
*/
#include "catalog/catversion.h"
/*
* RelFileNumber data type identifies the specific relation file name.
*/
typedef Oid RelFileNumber;
#define InvalidRelFileNumber ((RelFileNumber) InvalidOid)
#define RelFileNumberIsValid(relnumber) \
((bool) ((relnumber) != InvalidRelFileNumber))
/*
* Name of major-version-specific tablespace subdirectories
*/
#define TABLESPACE_VERSION_DIRECTORY "PG_" PG_MAJORVERSION "_" \
CppAsString2(CATALOG_VERSION_NO)
/*
* Tablespace path (relative to installation's $PGDATA).
*
* These values should not be changed as many tools rely on it.
*/
#define PG_TBLSPC_DIR "pg_tblspc"
#define PG_TBLSPC_DIR_SLASH "pg_tblspc/" /* required for strings
* comparisons */
/* Characters to allow for an OID in a relation path */
#define OIDCHARS 10 /* max chars printed by %u */
/*
* Stuff for fork names.
*
* The physical storage of a relation consists of one or more forks.
* The main fork is always created, but in addition to that there can be
* additional forks for storing various metadata. ForkNumber is used when
* we need to refer to a specific fork in a relation.
*/
typedef enum ForkNumber
{
InvalidForkNumber = -1,
MAIN_FORKNUM = 0,
FSM_FORKNUM,
VISIBILITYMAP_FORKNUM,
INIT_FORKNUM,
/*
* NOTE: if you add a new fork, change MAX_FORKNUM and possibly
* FORKNAMECHARS below, and update the forkNames array in
* src/common/relpath.c
*/
} ForkNumber;
#define MAX_FORKNUM INIT_FORKNUM
#define FORKNAMECHARS 4 /* max chars for a fork name */
extern PGDLLIMPORT const char *const forkNames[];
extern ForkNumber forkname_to_number(const char *forkName);
extern int forkname_chars(const char *str, ForkNumber *fork);
/*
* Unfortunately, there's no easy way to derive PROCNUMBER_CHARS from
* MAX_BACKENDS. MAX_BACKENDS is 2^18-1. Crosschecked in test_relpath().
*/
#define PROCNUMBER_CHARS 6
/*
* The longest possible relation path lengths is from the following format:
* sprintf(rp.path, "%s/%u/%s/%u/t%d_%u",
* PG_TBLSPC_DIR, spcOid,
* TABLESPACE_VERSION_DIRECTORY,
* dbOid, procNumber, relNumber);
*
* Note this does *not* include the trailing null-byte, to make it easier to
* combine it with other lengths.
*/
#define REL_PATH_STR_MAXLEN \
( \
sizeof(PG_TBLSPC_DIR) - 1 \
+ sizeof((char)'/') \
+ OIDCHARS /* spcOid */ \
+ sizeof((char)'/') \
+ sizeof(TABLESPACE_VERSION_DIRECTORY) - 1 \
+ sizeof((char)'/') \
+ OIDCHARS /* dbOid */ \
+ sizeof((char)'/') \
+ sizeof((char)'t') /* temporary table indicator */ \
+ PROCNUMBER_CHARS /* procNumber */ \
+ sizeof((char)'_') \
+ OIDCHARS /* relNumber */ \
+ sizeof((char)'_') \
+ FORKNAMECHARS /* forkNames[forkNumber] */ \
)
/*
* String of the exact length required to represent a relation path. We return
* this struct, instead of char[REL_PATH_STR_MAXLEN + 1], as the pointer would
* decay to a plain char * too easily, possibly preventing the compiler from
* detecting invalid references to the on-stack return value of
* GetRelationPath().
*/
typedef struct RelPathStr
{
char str[REL_PATH_STR_MAXLEN + 1];
} RelPathStr;
/*
* Stuff for computing filesystem pathnames for relations.
*/
extern char *GetDatabasePath(Oid dbOid, Oid spcOid);
extern RelPathStr GetRelationPath(Oid dbOid, Oid spcOid, RelFileNumber relNumber,
int procNumber, ForkNumber forkNumber);
/*
* Wrapper macros for GetRelationPath. Beware of multiple
* evaluation of the RelFileLocator or RelFileLocatorBackend argument!
*/
/* First argument is a RelFileLocator */
#define relpathbackend(rlocator, backend, forknum) \
GetRelationPath((rlocator).dbOid, (rlocator).spcOid, (rlocator).relNumber, \
backend, forknum)
/* First argument is a RelFileLocator */
#define relpathperm(rlocator, forknum) \
relpathbackend(rlocator, INVALID_PROC_NUMBER, forknum)
/* First argument is a RelFileLocatorBackend */
#define relpath(rlocator, forknum) \
relpathbackend((rlocator).locator, (rlocator).backend, forknum)
#endif /* RELPATH_H */
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