src/include/storage/buffile.h

   1 /*-------------------------------------------------------------------------
   2  *
   3  * buffile.h
   4  *        Management of large buffered temporary files.
   5  *
   6  * The BufFile routines provide a partial replacement for stdio atop
   7  * virtual file descriptors managed by fd.c.  Currently they only support
   8  * buffered access to a virtual file, without any of stdio's formatting
   9  * features.  That's enough for immediate needs, but the set of facilities
  10  * could be expanded if necessary.
  11  *
  12  * BufFile also supports working with temporary files that exceed the OS
  13  * file size limit and/or the largest offset representable in an int.
  14  * It might be better to split that out as a separately accessible module,
  15  * but currently we have no need for oversize temp files without buffered
  16  * access.
  17  *
  18  * Portions Copyright (c) 1996-2024, PostgreSQL Global Development Group
  19  * Portions Copyright (c) 1994, Regents of the University of California
  20  *
  21  * src/include/storage/buffile.h
  22  *
  23  *-------------------------------------------------------------------------
  24  */
  25
  26 #ifndef BUFFILE_H
  27 #define BUFFILE_H
  28
  29 #include "storage/fileset.h"
  30
  31 /* BufFile is an opaque type whose details are not known outside buffile.c. */
  32
  33 typedef struct BufFile BufFile;
  34
  35 /*
  36  * prototypes for functions in buffile.c
  37  */
  38
  39 extern BufFile *BufFileCreateTemp(bool interXact);
  40 extern void BufFileClose(BufFile *file);
  41 extern pg_nodiscard size_t BufFileRead(BufFile *file, void *ptr, size_t size);
  42 extern void BufFileReadExact(BufFile *file, void *ptr, size_t size);
  43 extern size_t BufFileReadMaybeEOF(BufFile *file, void *ptr, size_t size, bool eofOK);
  44 extern void BufFileWrite(BufFile *file, const void *ptr, size_t size);
  45 extern int      BufFileSeek(BufFile *file, int fileno, off_t offset, int whence);
  46 extern void BufFileTell(BufFile *file, int *fileno, off_t *offset);
  47 extern int      BufFileSeekBlock(BufFile *file, int64 blknum);
  48 extern int64 BufFileSize(BufFile *file);
  49 extern int64 BufFileAppend(BufFile *target, BufFile *source);
  50
  51 extern BufFile *BufFileCreateFileSet(FileSet *fileset, const char *name);
  52 extern void BufFileExportFileSet(BufFile *file);
  53 extern BufFile *BufFileOpenFileSet(FileSet *fileset, const char *name,
  54                                                                    int mode, bool missing_ok);
  55 extern void BufFileDeleteFileSet(FileSet *fileset, const char *name,
  56                                                                  bool missing_ok);
  57 extern void BufFileTruncateFileSet(BufFile *file, int fileno, off_t offset);
  58
  59 #endif                                                  /* BUFFILE_H */