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pg_include/storage/fd.h

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+/*-------------------------------------------------------------------------
+ *
+ * fd.h
+ *	  Virtual file descriptor definitions.
+ *
+ *
+ * Portions Copyright (c) 1996-2012, PostgreSQL Global Development Group
+ * Portions Copyright (c) 1994, Regents of the University of California
+ *
+ * src/include/storage/fd.h
+ *
+ *-------------------------------------------------------------------------
+ */
+
+/*
+ * calls:
+ *
+ *	File {Close, Read, Write, Seek, Tell, Sync}
+ *	{File Name Open, Allocate, Free} File
+ *
+ * These are NOT JUST RENAMINGS OF THE UNIX ROUTINES.
+ * Use them for all file activity...
+ *
+ *	File fd;
+ *	fd = FilePathOpenFile("foo", O_RDONLY, 0600);
+ *
+ *	AllocateFile();
+ *	FreeFile();
+ *
+ * Use AllocateFile, not fopen, if you need a stdio file (FILE*); then
+ * use FreeFile, not fclose, to close it.  AVOID using stdio for files
+ * that you intend to hold open for any length of time, since there is
+ * no way for them to share kernel file descriptors with other files.
+ *
+ * Likewise, use AllocateDir/FreeDir, not opendir/closedir, to allocate
+ * open directories (DIR*).
+ */
+#ifndef FD_H
+#define FD_H
+
+#include <dirent.h>
+
+
+/*
+ * FileSeek uses the standard UNIX lseek(2) flags.
+ */
+
+typedef char *FileName;
+
+typedef int File;
+
+
+/* GUC parameter */
+extern int	max_files_per_process;
+
+/*
+ * This is private to fd.c, but exported for save/restore_backend_variables()
+ */
+extern int	max_safe_fds;
+
+
+/*
+ * prototypes for functions in fd.c
+ */
+
+/* Operations on virtual Files --- equivalent to Unix kernel file ops */
+extern File PathNameOpenFile(FileName fileName, int fileFlags, int fileMode);
+extern File OpenTemporaryFile(bool interXact);
+extern void FileClose(File file);
+extern int	FilePrefetch(File file, off_t offset, int amount);
+extern int	FileRead(File file, char *buffer, int amount);
+extern int	FileWrite(File file, char *buffer, int amount);
+extern int	FileSync(File file);
+extern off_t FileSeek(File file, off_t offset, int whence);
+extern int	FileTruncate(File file, off_t offset);
+extern char *FilePathName(File file);
+
+/* Operations that allow use of regular stdio --- USE WITH CAUTION */
+extern FILE *AllocateFile(const char *name, const char *mode);
+extern int	FreeFile(FILE *file);
+
+/* Operations to allow use of the <dirent.h> library routines */
+extern DIR *AllocateDir(const char *dirname);
+extern struct dirent *ReadDir(DIR *dir, const char *dirname);
+extern int	FreeDir(DIR *dir);
+
+/* If you've really really gotta have a plain kernel FD, use this */
+extern int	BasicOpenFile(FileName fileName, int fileFlags, int fileMode);
+
+/* Miscellaneous support routines */
+extern void InitFileAccess(void);
+extern void set_max_safe_fds(void);
+extern void closeAllVfds(void);
+extern void SetTempTablespaces(Oid *tableSpaces, int numSpaces);
+extern bool TempTablespacesAreSet(void);
+extern Oid	GetNextTempTableSpace(void);
+extern void AtEOXact_Files(void);
+extern void AtEOSubXact_Files(bool isCommit, SubTransactionId mySubid,
+				  SubTransactionId parentSubid);
+extern void RemovePgTempFiles(void);
+
+extern int	pg_fsync(int fd);
+extern int	pg_fsync_no_writethrough(int fd);
+extern int	pg_fsync_writethrough(int fd);
+extern int	pg_fdatasync(int fd);
+extern int	pg_flush_data(int fd, off_t offset, off_t amount);
+
+/* Filename components for OpenTemporaryFile */
+#define PG_TEMP_FILES_DIR "pgsql_tmp"
+#define PG_TEMP_FILE_PREFIX "pgsql_tmp"
+
+#endif   /* FD_H */