buffile.h

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/*-------------------------------------------------------------------------
 *
 * buffile.h
 *    Management of large buffered temporary files.
 *
 * The BufFile routines provide a partial replacement for stdio atop
 * virtual file descriptors managed by fd.c.  Currently they only support
 * buffered access to a virtual file, without any of stdio's formatting
 * features.  That's enough for immediate needs, but the set of facilities
 * could be expanded if necessary.
 *
 * BufFile also supports working with temporary files that exceed the OS
 * file size limit and/or the largest offset representable in an int.
 * It might be better to split that out as a separately accessible module,
 * but currently we have no need for oversize temp files without buffered
 * access.
 *
 * Portions Copyright (c) 1996-2025, PostgreSQL Global Development Group
 * Portions Copyright (c) 1994, Regents of the University of California
 *
 * src/include/storage/buffile.h
 *
 *-------------------------------------------------------------------------
 */
 
#ifndef BUFFILE_H
#define BUFFILE_H
 
#include "storage/fileset.h"
 
/* BufFile is an opaque type whose details are not known outside buffile.c. */
 
typedef struct BufFile BufFile;
 
/*
 * prototypes for functions in buffile.c
 */
 
extern BufFile *BufFileCreateTemp(bool interXact);
extern void BufFileClose(BufFile *file);
pg_nodiscard extern size_t BufFileRead(BufFile *file, void *ptr, size_t size);
extern void BufFileReadExact(BufFile *file, void *ptr, size_t size);
extern size_t BufFileReadMaybeEOF(BufFile *file, void *ptr, size_t size, bool eofOK);
extern void BufFileWrite(BufFile *file, const void *ptr, size_t size);
extern int  BufFileSeek(BufFile *file, int fileno, off_t offset, int whence);
extern void BufFileTell(BufFile *file, int *fileno, off_t *offset);
extern int  BufFileSeekBlock(BufFile *file, int64 blknum);
extern int64 BufFileSize(BufFile *file);
extern int64 BufFileAppend(BufFile *target, BufFile *source);
 
extern BufFile *BufFileCreateFileSet(FileSet *fileset, const char *name);
extern void BufFileExportFileSet(BufFile *file);
extern BufFile *BufFileOpenFileSet(FileSet *fileset, const char *name,
                                   int mode, bool missing_ok);
extern void BufFileDeleteFileSet(FileSet *fileset, const char *name,
                                 bool missing_ok);
extern void BufFileTruncateFileSet(BufFile *file, int fileno, off_t offset);
 
#endif                          /* BUFFILE_H */