src/include/storage/fd.h

   1 /*-------------------------------------------------------------------------
   2  *
   3  * fd.h
   4  *        Virtual file descriptor definitions.
   5  *
   6  *
   7  * Portions Copyright (c) 1996-2009, PostgreSQL Global Development Group
   8  * Portions Copyright (c) 1994, Regents of the University of California
   9  *
  10  * $PostgreSQL$
  11  *
  12  *-------------------------------------------------------------------------
  13  */
  14
  15 /*
  16  * calls:
  17  *
  18  *      File {Close, Read, Write, Seek, Tell, Sync}
  19  *      {File Name Open, Allocate, Free} File
  20  *
  21  * These are NOT JUST RENAMINGS OF THE UNIX ROUTINES.
  22  * Use them for all file activity...
  23  *
  24  *      File fd;
  25  *      fd = FilePathOpenFile("foo", O_RDONLY, 0600);
  26  *
  27  *      AllocateFile();
  28  *      FreeFile();
  29  *
  30  * Use AllocateFile, not fopen, if you need a stdio file (FILE*); then
  31  * use FreeFile, not fclose, to close it.  AVOID using stdio for files
  32  * that you intend to hold open for any length of time, since there is
  33  * no way for them to share kernel file descriptors with other files.
  34  *
  35  * Likewise, use AllocateDir/FreeDir, not opendir/closedir, to allocate
  36  * open directories (DIR*).
  37  */
  38 #ifndef FD_H
  39 #define FD_H
  40
  41 #include <dirent.h>
  42
  43
  44 /*
  45  * FileSeek uses the standard UNIX lseek(2) flags.
  46  */
  47
  48 typedef char *FileName;
  49
  50 typedef int File;
  51
  52
  53 /* GUC parameter */
  54 extern int      max_files_per_process;
  55
  56
  57 /*
  58  * prototypes for functions in fd.c
  59  */
  60
  61 /* Operations on virtual Files --- equivalent to Unix kernel file ops */
  62 extern File PathNameOpenFile(FileName fileName, int fileFlags, int fileMode);
  63 extern File OpenTemporaryFile(bool interXact);
  64 extern void FileClose(File file);
  65 extern int      FilePrefetch(File file, off_t offset, int amount);
  66 extern int      FileRead(File file, char *buffer, int amount);
  67 extern int      FileWrite(File file, char *buffer, int amount);
  68 extern int      FileSync(File file);
  69 extern off_t FileSeek(File file, off_t offset, int whence);
  70 extern int      FileTruncate(File file, off_t offset);
  71
  72 /* Operations that allow use of regular stdio --- USE WITH CAUTION */
  73 extern FILE *AllocateFile(const char *name, const char *mode);
  74 extern int      FreeFile(FILE *file);
  75
  76 /* Operations to allow use of the <dirent.h> library routines */
  77 extern DIR *AllocateDir(const char *dirname);
  78 extern struct dirent *ReadDir(DIR *dir, const char *dirname);
  79 extern int      FreeDir(DIR *dir);
  80
  81 /* If you've really really gotta have a plain kernel FD, use this */
  82 extern int      BasicOpenFile(FileName fileName, int fileFlags, int fileMode);
  83
  84 /* Miscellaneous support routines */
  85 extern void InitFileAccess(void);
  86 extern void set_max_safe_fds(void);
  87 extern void closeAllVfds(void);
  88 extern void SetTempTablespaces(Oid *tableSpaces, int numSpaces);
  89 extern bool TempTablespacesAreSet(void);
  90 extern Oid      GetNextTempTableSpace(void);
  91 extern void AtEOXact_Files(void);
  92 extern void AtEOSubXact_Files(bool isCommit, SubTransactionId mySubid,
  93                                   SubTransactionId parentSubid);
  94 extern void RemovePgTempFiles(void);
  95
  96 extern int      pg_fsync(int fd);
  97 extern int      pg_fsync_no_writethrough(int fd);
  98 extern int      pg_fsync_writethrough(int fd);
  99 extern int      pg_fdatasync(int fd);
 100
 101 /* Filename components for OpenTemporaryFile */
 102 #define PG_TEMP_FILES_DIR "pgsql_tmp"
 103 #define PG_TEMP_FILE_PREFIX "pgsql_tmp"
 104
 105 #endif   /* FD_H */