1 /*-------------------------------------------------------------------------
4 * Virtual file descriptor definitions.
7 * Portions Copyright (c) 1996-2019, PostgreSQL Global Development Group
8 * Portions Copyright (c) 1994, Regents of the University of California
10 * src/include/storage/fd.h
12 *-------------------------------------------------------------------------
18 * File {Close, Read, Write, Size, Sync}
19 * {Path Name Open, Allocate, Free} File
21 * These are NOT JUST RENAMINGS OF THE UNIX ROUTINES.
22 * Use them for all file activity...
25 * fd = PathNameOpenFile("foo", O_RDONLY);
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.
35 * Likewise, use AllocateDir/FreeDir, not opendir/closedir, to allocate
36 * open directories (DIR*), and OpenTransientFile/CloseTransientFile for an
37 * unbuffered file descriptor.
49 extern PGDLLIMPORT int max_files_per_process;
50 extern PGDLLIMPORT bool data_sync_retry;
53 * This is private to fd.c, but exported for save/restore_backend_variables()
55 extern int max_safe_fds;
58 * On Windows, we have to interpret EACCES as possibly meaning the same as
59 * ENOENT, because if a file is unlinked-but-not-yet-gone on that platform,
60 * that's what you get. Ugh. This code is designed so that we don't
61 * actually believe these cases are okay without further evidence (namely,
62 * a pending fsync request getting canceled ... see ProcessSyncRequests).
65 #define FILE_POSSIBLY_DELETED(err) ((err) == ENOENT)
67 #define FILE_POSSIBLY_DELETED(err) ((err) == ENOENT || (err) == EACCES)
71 * prototypes for functions in fd.c
74 /* Operations on virtual Files --- equivalent to Unix kernel file ops */
75 extern File PathNameOpenFile(const char *fileName, int fileFlags);
76 extern File PathNameOpenFilePerm(const char *fileName, int fileFlags, mode_t fileMode);
77 extern File OpenTemporaryFile(bool interXact);
78 extern void FileClose(File file);
79 extern int FilePrefetch(File file, off_t offset, int amount, uint32 wait_event_info);
80 extern int FileRead(File file, char *buffer, int amount, off_t offset, uint32 wait_event_info);
81 extern int FileWrite(File file, char *buffer, int amount, off_t offset, uint32 wait_event_info);
82 extern int FileSync(File file, uint32 wait_event_info);
83 extern off_t FileSize(File file);
84 extern int FileTruncate(File file, off_t offset, uint32 wait_event_info);
85 extern void FileWriteback(File file, off_t offset, off_t nbytes, uint32 wait_event_info);
86 extern char *FilePathName(File file);
87 extern int FileGetRawDesc(File file);
88 extern int FileGetRawFlags(File file);
89 extern mode_t FileGetRawMode(File file);
91 /* Operations used for sharing named temporary files */
92 extern File PathNameCreateTemporaryFile(const char *name, bool error_on_failure);
93 extern File PathNameOpenTemporaryFile(const char *name);
94 extern bool PathNameDeleteTemporaryFile(const char *name, bool error_on_failure);
95 extern void PathNameCreateTemporaryDir(const char *base, const char *name);
96 extern void PathNameDeleteTemporaryDir(const char *name);
97 extern void TempTablespacePath(char *path, Oid tablespace);
99 /* Operations that allow use of regular stdio --- USE WITH CAUTION */
100 extern FILE *AllocateFile(const char *name, const char *mode);
101 extern int FreeFile(FILE *file);
103 /* Operations that allow use of pipe streams (popen/pclose) */
104 extern FILE *OpenPipeStream(const char *command, const char *mode);
105 extern int ClosePipeStream(FILE *file);
107 /* Operations to allow use of the <dirent.h> library routines */
108 extern DIR *AllocateDir(const char *dirname);
109 extern struct dirent *ReadDir(DIR *dir, const char *dirname);
110 extern struct dirent *ReadDirExtended(DIR *dir, const char *dirname,
112 extern int FreeDir(DIR *dir);
114 /* Operations to allow use of a plain kernel FD, with automatic cleanup */
115 extern int OpenTransientFile(const char *fileName, int fileFlags);
116 extern int OpenTransientFilePerm(const char *fileName, int fileFlags, mode_t fileMode);
117 extern int CloseTransientFile(int fd);
119 /* If you've really really gotta have a plain kernel FD, use this */
120 extern int BasicOpenFile(const char *fileName, int fileFlags);
121 extern int BasicOpenFilePerm(const char *fileName, int fileFlags, mode_t fileMode);
123 /* Make a directory with default permissions */
124 extern int MakePGDirectory(const char *directoryName);
126 /* Miscellaneous support routines */
127 extern void InitFileAccess(void);
128 extern void set_max_safe_fds(void);
129 extern void closeAllVfds(void);
130 extern void SetTempTablespaces(Oid *tableSpaces, int numSpaces);
131 extern bool TempTablespacesAreSet(void);
132 extern int GetTempTablespaces(Oid *tableSpaces, int numSpaces);
133 extern Oid GetNextTempTableSpace(void);
134 extern void AtEOXact_Files(bool isCommit);
135 extern void AtEOSubXact_Files(bool isCommit, SubTransactionId mySubid,
136 SubTransactionId parentSubid);
137 extern void RemovePgTempFiles(void);
138 extern void RemovePgTempFilesInDir(const char *tmpdirname, bool missing_ok,
140 extern bool looks_like_temp_rel_name(const char *name);
142 extern int pg_fsync(int fd);
143 extern int pg_fsync_no_writethrough(int fd);
144 extern int pg_fsync_writethrough(int fd);
145 extern int pg_fdatasync(int fd);
146 extern void pg_flush_data(int fd, off_t offset, off_t amount);
147 extern void fsync_fname(const char *fname, bool isdir);
148 extern int durable_rename(const char *oldfile, const char *newfile, int loglevel);
149 extern int durable_unlink(const char *fname, int loglevel);
150 extern int durable_link_or_rename(const char *oldfile, const char *newfile, int loglevel);
151 extern void SyncDataDirectory(void);
152 extern int data_sync_elevel(int elevel);
154 /* Filename components */
155 #define PG_TEMP_FILES_DIR "pgsql_tmp"
156 #define PG_TEMP_FILE_PREFIX "pgsql_tmp"