PostgreSQL Source Code  git master
fd.h
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1 /*-------------------------------------------------------------------------
2  *
3  * fd.h
4  * Virtual file descriptor definitions.
5  *
6  *
7  * Portions Copyright (c) 1996-2023, PostgreSQL Global Development Group
8  * Portions Copyright (c) 1994, Regents of the University of California
9  *
10  * src/include/storage/fd.h
11  *
12  *-------------------------------------------------------------------------
13  */
14 
15 /*
16  * calls:
17  *
18  * File {Close, Read, Write, Size, Sync}
19  * {Path 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 = PathNameOpenFile("foo", O_RDONLY);
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*), and OpenTransientFile/CloseTransientFile for an
37  * unbuffered file descriptor.
38  *
39  * If you really can't use any of the above, at least call AcquireExternalFD
40  * or ReserveExternalFD to report any file descriptors that are held for any
41  * length of time. Failure to do so risks unnecessary EMFILE errors.
42  */
43 #ifndef FD_H
44 #define FD_H
45 
46 #include <dirent.h>
47 #include <fcntl.h>
48 
50 {
54 
55 typedef int File;
56 
57 
58 #define IO_DIRECT_DATA 0x01
59 #define IO_DIRECT_WAL 0x02
60 #define IO_DIRECT_WAL_INIT 0x04
61 
62 
63 /* GUC parameter */
65 extern PGDLLIMPORT bool data_sync_retry;
67 extern PGDLLIMPORT int io_direct_flags;
68 
69 /*
70  * This is private to fd.c, but exported for save/restore_backend_variables()
71  */
72 extern PGDLLIMPORT int max_safe_fds;
73 
74 /*
75  * On Windows, we have to interpret EACCES as possibly meaning the same as
76  * ENOENT, because if a file is unlinked-but-not-yet-gone on that platform,
77  * that's what you get. Ugh. This code is designed so that we don't
78  * actually believe these cases are okay without further evidence (namely,
79  * a pending fsync request getting canceled ... see ProcessSyncRequests).
80  */
81 #ifndef WIN32
82 #define FILE_POSSIBLY_DELETED(err) ((err) == ENOENT)
83 #else
84 #define FILE_POSSIBLY_DELETED(err) ((err) == ENOENT || (err) == EACCES)
85 #endif
86 
87 /*
88  * O_DIRECT is not standard, but almost every Unix has it. We translate it
89  * to the appropriate Windows flag in src/port/open.c. We simulate it with
90  * fcntl(F_NOCACHE) on macOS inside fd.c's open() wrapper. We use the name
91  * PG_O_DIRECT rather than defining O_DIRECT in that case (probably not a good
92  * idea on a Unix). We can only use it if the compiler will correctly align
93  * PGIOAlignedBlock for us, though.
94  */
95 #if defined(O_DIRECT) && defined(pg_attribute_aligned)
96 #define PG_O_DIRECT O_DIRECT
97 #elif defined(F_NOCACHE)
98 #define PG_O_DIRECT 0x80000000
99 #define PG_O_DIRECT_USE_F_NOCACHE
100 #else
101 #define PG_O_DIRECT 0
102 #endif
103 
104 /*
105  * prototypes for functions in fd.c
106  */
107 
108 /* Operations on virtual Files --- equivalent to Unix kernel file ops */
109 extern File PathNameOpenFile(const char *fileName, int fileFlags);
110 extern File PathNameOpenFilePerm(const char *fileName, int fileFlags, mode_t fileMode);
111 extern File OpenTemporaryFile(bool interXact);
112 extern void FileClose(File file);
113 extern int FilePrefetch(File file, off_t offset, off_t amount, uint32 wait_event_info);
114 extern int FileRead(File file, void *buffer, size_t amount, off_t offset, uint32 wait_event_info);
115 extern int FileWrite(File file, const void *buffer, size_t amount, off_t offset, uint32 wait_event_info);
116 extern int FileSync(File file, uint32 wait_event_info);
117 extern int FileZero(File file, off_t offset, off_t amount, uint32 wait_event_info);
118 extern int FileFallocate(File file, off_t offset, off_t amount, uint32 wait_event_info);
119 
120 extern off_t FileSize(File file);
121 extern int FileTruncate(File file, off_t offset, uint32 wait_event_info);
122 extern void FileWriteback(File file, off_t offset, off_t nbytes, uint32 wait_event_info);
123 extern char *FilePathName(File file);
124 extern int FileGetRawDesc(File file);
125 extern int FileGetRawFlags(File file);
126 extern mode_t FileGetRawMode(File file);
127 
128 /* Operations used for sharing named temporary files */
129 extern File PathNameCreateTemporaryFile(const char *path, bool error_on_failure);
130 extern File PathNameOpenTemporaryFile(const char *path, int mode);
131 extern bool PathNameDeleteTemporaryFile(const char *path, bool error_on_failure);
132 extern void PathNameCreateTemporaryDir(const char *basedir, const char *directory);
133 extern void PathNameDeleteTemporaryDir(const char *dirname);
134 extern void TempTablespacePath(char *path, Oid tablespace);
135 
136 /* Operations that allow use of regular stdio --- USE WITH CAUTION */
137 extern FILE *AllocateFile(const char *name, const char *mode);
138 extern int FreeFile(FILE *file);
139 
140 /* Operations that allow use of pipe streams (popen/pclose) */
141 extern FILE *OpenPipeStream(const char *command, const char *mode);
142 extern int ClosePipeStream(FILE *file);
143 
144 /* Operations to allow use of the <dirent.h> library routines */
145 extern DIR *AllocateDir(const char *dirname);
146 extern struct dirent *ReadDir(DIR *dir, const char *dirname);
147 extern struct dirent *ReadDirExtended(DIR *dir, const char *dirname,
148  int elevel);
149 extern int FreeDir(DIR *dir);
150 
151 /* Operations to allow use of a plain kernel FD, with automatic cleanup */
152 extern int OpenTransientFile(const char *fileName, int fileFlags);
153 extern int OpenTransientFilePerm(const char *fileName, int fileFlags, mode_t fileMode);
154 extern int CloseTransientFile(int fd);
155 
156 /* If you've really really gotta have a plain kernel FD, use this */
157 extern int BasicOpenFile(const char *fileName, int fileFlags);
158 extern int BasicOpenFilePerm(const char *fileName, int fileFlags, mode_t fileMode);
159 
160 /* Use these for other cases, and also for long-lived BasicOpenFile FDs */
161 extern bool AcquireExternalFD(void);
162 extern void ReserveExternalFD(void);
163 extern void ReleaseExternalFD(void);
164 
165 /* Make a directory with default permissions */
166 extern int MakePGDirectory(const char *directoryName);
167 
168 /* Miscellaneous support routines */
169 extern void InitFileAccess(void);
170 extern void InitTemporaryFileAccess(void);
171 extern void set_max_safe_fds(void);
172 extern void closeAllVfds(void);
173 extern void SetTempTablespaces(Oid *tableSpaces, int numSpaces);
174 extern bool TempTablespacesAreSet(void);
175 extern int GetTempTablespaces(Oid *tableSpaces, int numSpaces);
176 extern Oid GetNextTempTableSpace(void);
177 extern void AtEOXact_Files(bool isCommit);
178 extern void AtEOSubXact_Files(bool isCommit, SubTransactionId mySubid,
179  SubTransactionId parentSubid);
180 extern void RemovePgTempFiles(void);
181 extern void RemovePgTempFilesInDir(const char *tmpdirname, bool missing_ok,
182  bool unlink_all);
183 extern bool looks_like_temp_rel_name(const char *name);
184 
185 extern int pg_fsync(int fd);
186 extern int pg_fsync_no_writethrough(int fd);
187 extern int pg_fsync_writethrough(int fd);
188 extern int pg_fdatasync(int fd);
189 extern void pg_flush_data(int fd, off_t offset, off_t nbytes);
190 extern int pg_truncate(const char *path, off_t length);
191 extern void fsync_fname(const char *fname, bool isdir);
192 extern int fsync_fname_ext(const char *fname, bool isdir, bool ignore_perm, int elevel);
193 extern int durable_rename(const char *oldfile, const char *newfile, int elevel);
194 extern int durable_unlink(const char *fname, int elevel);
195 extern void SyncDataDirectory(void);
196 extern int data_sync_elevel(int elevel);
197 
198 /* Filename components */
199 #define PG_TEMP_FILES_DIR "pgsql_tmp"
200 #define PG_TEMP_FILE_PREFIX "pgsql_tmp"
201 
202 #endif /* FD_H */
unsigned int uint32
Definition: c.h:490
#define PGDLLIMPORT
Definition: c.h:1321
uint32 SubTransactionId
Definition: c.h:640
const char * name
Definition: encode.c:571
struct dirent * ReadDir(DIR *dir, const char *dirname)
Definition: fd.c:2806
PGDLLIMPORT int max_safe_fds
Definition: fd.c:159
void pg_flush_data(int fd, off_t offset, off_t nbytes)
Definition: fd.c:463
int FileGetRawDesc(File file)
Definition: fd.c:2374
int MakePGDirectory(const char *directoryName)
Definition: fd.c:3810
int FreeDir(DIR *dir)
Definition: fd.c:2858
void FileWriteback(File file, off_t offset, off_t nbytes, uint32 wait_event_info)
Definition: fd.c:2017
int pg_fsync_no_writethrough(int fd)
Definition: fd.c:416
FILE * AllocateFile(const char *name, const char *mode)
Definition: fd.c:2480
int BasicOpenFilePerm(const char *fileName, int fileFlags, mode_t fileMode)
Definition: fd.c:1020
PGDLLIMPORT int io_direct_flags
Definition: fd.c:168
int durable_rename(const char *oldfile, const char *newfile, int elevel)
Definition: fd.c:693
int GetTempTablespaces(Oid *tableSpaces, int numSpaces)
Definition: fd.c:2990
File PathNameOpenTemporaryFile(const char *path, int mode)
Definition: fd.c:1812
int pg_fdatasync(int fd)
Definition: fd.c:449
int FileSync(File file, uint32 wait_event_info)
Definition: fd.c:2197
int CloseTransientFile(int fd)
Definition: fd.c:2706
int BasicOpenFile(const char *fileName, int fileFlags)
Definition: fd.c:998
void closeAllVfds(void)
Definition: fd.c:2917
File PathNameCreateTemporaryFile(const char *path, bool error_on_failure)
Definition: fd.c:1772
void PathNameDeleteTemporaryDir(const char *dirname)
Definition: fd.c:1602
int ClosePipeStream(FILE *file)
Definition: fd.c:2888
PGDLLIMPORT bool data_sync_retry
Definition: fd.c:162
void AtEOXact_Files(bool isCommit)
Definition: fd.c:3062
int FileGetRawFlags(File file)
Definition: fd.c:2384
int fsync_fname_ext(const char *fname, bool isdir, bool ignore_perm, int elevel)
Definition: fd.c:3694
int FreeFile(FILE *file)
Definition: fd.c:2678
PGDLLIMPORT int recovery_init_sync_method
Definition: fd.c:165
mode_t FileGetRawMode(File file)
Definition: fd.c:2394
int pg_fsync_writethrough(int fd)
Definition: fd.c:428
void FileClose(File file)
Definition: fd.c:1889
FILE * OpenPipeStream(const char *command, const char *mode)
Definition: fd.c:2583
void ReleaseExternalFD(void)
Definition: fd.c:1150
void RemovePgTempFilesInDir(const char *tmpdirname, bool missing_ok, bool unlink_all)
Definition: fd.c:3230
void RemovePgTempFiles(void)
Definition: fd.c:3171
bool TempTablespacesAreSet(void)
Definition: fd.c:2975
void fsync_fname(const char *fname, bool isdir)
Definition: fd.c:667
int FileFallocate(File file, off_t offset, off_t amount, uint32 wait_event_info)
Definition: fd.c:2269
int FilePrefetch(File file, off_t offset, off_t amount, uint32 wait_event_info)
Definition: fd.c:1989
int data_sync_elevel(int elevel)
Definition: fd.c:3833
File PathNameOpenFile(const char *fileName, int fileFlags)
Definition: fd.c:1486
int FileWrite(File file, const void *buffer, size_t amount, off_t offset, uint32 wait_event_info)
Definition: fd.c:2099
Oid GetNextTempTableSpace(void)
Definition: fd.c:3008
File PathNameOpenFilePerm(const char *fileName, int fileFlags, mode_t fileMode)
Definition: fd.c:1499
bool AcquireExternalFD(void)
Definition: fd.c:1097
int FileRead(File file, void *buffer, size_t amount, off_t offset, uint32 wait_event_info)
Definition: fd.c:2043
struct dirent * ReadDirExtended(DIR *dir, const char *dirname, int elevel)
Definition: fd.c:2821
void InitFileAccess(void)
Definition: fd.c:814
File OpenTemporaryFile(bool interXact)
Definition: fd.c:1635
int durable_unlink(const char *fname, int elevel)
Definition: fd.c:783
PGDLLIMPORT int max_files_per_process
Definition: fd.c:146
void ReserveExternalFD(void)
Definition: fd.c:1132
char * FilePathName(File file)
Definition: fd.c:2358
bool looks_like_temp_rel_name(const char *name)
Definition: fd.c:3346
bool PathNameDeleteTemporaryFile(const char *path, bool error_on_failure)
Definition: fd.c:1843
void set_max_safe_fds(void)
Definition: fd.c:955
int pg_fsync(int fd)
Definition: fd.c:361
int File
Definition: fd.h:55
void PathNameCreateTemporaryDir(const char *basedir, const char *directory)
Definition: fd.c:1571
void AtEOSubXact_Files(bool isCommit, SubTransactionId mySubid, SubTransactionId parentSubid)
Definition: fd.c:3029
int OpenTransientFile(const char *fileName, int fileFlags)
Definition: fd.c:2530
void InitTemporaryFileAccess(void)
Definition: fd.c:844
int OpenTransientFilePerm(const char *fileName, int fileFlags, mode_t fileMode)
Definition: fd.c:2539
RecoveryInitSyncMethod
Definition: fd.h:50
@ RECOVERY_INIT_SYNC_METHOD_SYNCFS
Definition: fd.h:52
@ RECOVERY_INIT_SYNC_METHOD_FSYNC
Definition: fd.h:51
void SyncDataDirectory(void)
Definition: fd.c:3441
int FileZero(File file, off_t offset, off_t amount, uint32 wait_event_info)
Definition: fd.c:2224
off_t FileSize(File file)
Definition: fd.c:2306
int FileTruncate(File file, off_t offset, uint32 wait_event_info)
Definition: fd.c:2323
int pg_truncate(const char *path, off_t length)
Definition: fd.c:636
void SetTempTablespaces(Oid *tableSpaces, int numSpaces)
Definition: fd.c:2946
DIR * AllocateDir(const char *dirname)
Definition: fd.c:2740
void TempTablespacePath(char *path, Oid tablespace)
Definition: fd.c:1690
static char * basedir
static PgChecksumMode mode
Definition: pg_checksums.c:65
char * tablespace
Definition: pgbench.c:226
unsigned int Oid
Definition: postgres_ext.h:31
static int fd(const char *x, int i)
Definition: preproc-init.c:105
Definition: dirent.c:26
Definition: dirent.h:10
static const char * directory
Definition: zic.c:634