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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 
49 typedef int File;
50 
51 
52 #define IO_DIRECT_DATA 0x01
53 #define IO_DIRECT_WAL 0x02
54 #define IO_DIRECT_WAL_INIT 0x04
55 
56 
57 /* GUC parameter */
59 extern PGDLLIMPORT bool data_sync_retry;
61 extern PGDLLIMPORT int io_direct_flags;
62 
63 /*
64  * This is private to fd.c, but exported for save/restore_backend_variables()
65  */
66 extern PGDLLIMPORT int max_safe_fds;
67 
68 /*
69  * On Windows, we have to interpret EACCES as possibly meaning the same as
70  * ENOENT, because if a file is unlinked-but-not-yet-gone on that platform,
71  * that's what you get. Ugh. This code is designed so that we don't
72  * actually believe these cases are okay without further evidence (namely,
73  * a pending fsync request getting canceled ... see ProcessSyncRequests).
74  */
75 #ifndef WIN32
76 #define FILE_POSSIBLY_DELETED(err) ((err) == ENOENT)
77 #else
78 #define FILE_POSSIBLY_DELETED(err) ((err) == ENOENT || (err) == EACCES)
79 #endif
80 
81 /*
82  * O_DIRECT is not standard, but almost every Unix has it. We translate it
83  * to the appropriate Windows flag in src/port/open.c. We simulate it with
84  * fcntl(F_NOCACHE) on macOS inside fd.c's open() wrapper. We use the name
85  * PG_O_DIRECT rather than defining O_DIRECT in that case (probably not a good
86  * idea on a Unix). We can only use it if the compiler will correctly align
87  * PGIOAlignedBlock for us, though.
88  */
89 #if defined(O_DIRECT) && defined(pg_attribute_aligned)
90 #define PG_O_DIRECT O_DIRECT
91 #elif defined(F_NOCACHE)
92 #define PG_O_DIRECT 0x80000000
93 #define PG_O_DIRECT_USE_F_NOCACHE
94 #else
95 #define PG_O_DIRECT 0
96 #endif
97 
98 /*
99  * prototypes for functions in fd.c
100  */
101 
102 /* Operations on virtual Files --- equivalent to Unix kernel file ops */
103 extern File PathNameOpenFile(const char *fileName, int fileFlags);
104 extern File PathNameOpenFilePerm(const char *fileName, int fileFlags, mode_t fileMode);
105 extern File OpenTemporaryFile(bool interXact);
106 extern void FileClose(File file);
107 extern int FilePrefetch(File file, off_t offset, off_t amount, uint32 wait_event_info);
108 extern int FileRead(File file, void *buffer, size_t amount, off_t offset, uint32 wait_event_info);
109 extern int FileWrite(File file, const void *buffer, size_t amount, off_t offset, uint32 wait_event_info);
110 extern int FileSync(File file, uint32 wait_event_info);
111 extern int FileZero(File file, off_t offset, off_t amount, uint32 wait_event_info);
112 extern int FileFallocate(File file, off_t offset, off_t amount, uint32 wait_event_info);
113 
114 extern off_t FileSize(File file);
115 extern int FileTruncate(File file, off_t offset, uint32 wait_event_info);
116 extern void FileWriteback(File file, off_t offset, off_t nbytes, uint32 wait_event_info);
117 extern char *FilePathName(File file);
118 extern int FileGetRawDesc(File file);
119 extern int FileGetRawFlags(File file);
120 extern mode_t FileGetRawMode(File file);
121 
122 /* Operations used for sharing named temporary files */
123 extern File PathNameCreateTemporaryFile(const char *path, bool error_on_failure);
124 extern File PathNameOpenTemporaryFile(const char *path, int mode);
125 extern bool PathNameDeleteTemporaryFile(const char *path, bool error_on_failure);
126 extern void PathNameCreateTemporaryDir(const char *basedir, const char *directory);
127 extern void PathNameDeleteTemporaryDir(const char *dirname);
128 extern void TempTablespacePath(char *path, Oid tablespace);
129 
130 /* Operations that allow use of regular stdio --- USE WITH CAUTION */
131 extern FILE *AllocateFile(const char *name, const char *mode);
132 extern int FreeFile(FILE *file);
133 
134 /* Operations that allow use of pipe streams (popen/pclose) */
135 extern FILE *OpenPipeStream(const char *command, const char *mode);
136 extern int ClosePipeStream(FILE *file);
137 
138 /* Operations to allow use of the <dirent.h> library routines */
139 extern DIR *AllocateDir(const char *dirname);
140 extern struct dirent *ReadDir(DIR *dir, const char *dirname);
141 extern struct dirent *ReadDirExtended(DIR *dir, const char *dirname,
142  int elevel);
143 extern int FreeDir(DIR *dir);
144 
145 /* Operations to allow use of a plain kernel FD, with automatic cleanup */
146 extern int OpenTransientFile(const char *fileName, int fileFlags);
147 extern int OpenTransientFilePerm(const char *fileName, int fileFlags, mode_t fileMode);
148 extern int CloseTransientFile(int fd);
149 
150 /* If you've really really gotta have a plain kernel FD, use this */
151 extern int BasicOpenFile(const char *fileName, int fileFlags);
152 extern int BasicOpenFilePerm(const char *fileName, int fileFlags, mode_t fileMode);
153 
154 /* Use these for other cases, and also for long-lived BasicOpenFile FDs */
155 extern bool AcquireExternalFD(void);
156 extern void ReserveExternalFD(void);
157 extern void ReleaseExternalFD(void);
158 
159 /* Make a directory with default permissions */
160 extern int MakePGDirectory(const char *directoryName);
161 
162 /* Miscellaneous support routines */
163 extern void InitFileAccess(void);
164 extern void InitTemporaryFileAccess(void);
165 extern void set_max_safe_fds(void);
166 extern void closeAllVfds(void);
167 extern void SetTempTablespaces(Oid *tableSpaces, int numSpaces);
168 extern bool TempTablespacesAreSet(void);
169 extern int GetTempTablespaces(Oid *tableSpaces, int numSpaces);
170 extern Oid GetNextTempTableSpace(void);
171 extern void AtEOXact_Files(bool isCommit);
172 extern void AtEOSubXact_Files(bool isCommit, SubTransactionId mySubid,
173  SubTransactionId parentSubid);
174 extern void RemovePgTempFiles(void);
175 extern void RemovePgTempFilesInDir(const char *tmpdirname, bool missing_ok,
176  bool unlink_all);
177 extern bool looks_like_temp_rel_name(const char *name);
178 
179 extern int pg_fsync(int fd);
180 extern int pg_fsync_no_writethrough(int fd);
181 extern int pg_fsync_writethrough(int fd);
182 extern int pg_fdatasync(int fd);
183 extern void pg_flush_data(int fd, off_t offset, off_t nbytes);
184 extern int pg_truncate(const char *path, off_t length);
185 extern void fsync_fname(const char *fname, bool isdir);
186 extern int fsync_fname_ext(const char *fname, bool isdir, bool ignore_perm, int elevel);
187 extern int durable_rename(const char *oldfile, const char *newfile, int elevel);
188 extern int durable_unlink(const char *fname, int elevel);
189 extern void SyncDataDirectory(void);
190 extern int data_sync_elevel(int elevel);
191 
192 #endif /* FD_H */
unsigned int uint32
Definition: c.h:495
#define PGDLLIMPORT
Definition: c.h:1326
uint32 SubTransactionId
Definition: c.h:645
struct dirent * ReadDir(DIR *dir, const char *dirname)
Definition: fd.c:2879
PGDLLIMPORT int max_safe_fds
Definition: fd.c:159
void pg_flush_data(int fd, off_t offset, off_t nbytes)
Definition: fd.c:502
int FileGetRawDesc(File file)
Definition: fd.c:2447
int MakePGDirectory(const char *directoryName)
Definition: fd.c:3883
int FreeDir(DIR *dir)
Definition: fd.c:2931
void FileWriteback(File file, off_t offset, off_t nbytes, uint32 wait_event_info)
Definition: fd.c:2087
int pg_fsync_no_writethrough(int fd)
Definition: fd.c:441
FILE * AllocateFile(const char *name, const char *mode)
Definition: fd.c:2553
int BasicOpenFilePerm(const char *fileName, int fileFlags, mode_t fileMode)
Definition: fd.c:1086
PGDLLIMPORT int io_direct_flags
Definition: fd.c:168
int durable_rename(const char *oldfile, const char *newfile, int elevel)
Definition: fd.c:759
int GetTempTablespaces(Oid *tableSpaces, int numSpaces)
Definition: fd.c:3063
File PathNameOpenTemporaryFile(const char *path, int mode)
Definition: fd.c:1878
int pg_fdatasync(int fd)
Definition: fd.c:480
int FileSync(File file, uint32 wait_event_info)
Definition: fd.c:2267
int CloseTransientFile(int fd)
Definition: fd.c:2779
int BasicOpenFile(const char *fileName, int fileFlags)
Definition: fd.c:1064
void closeAllVfds(void)
Definition: fd.c:2990
File PathNameCreateTemporaryFile(const char *path, bool error_on_failure)
Definition: fd.c:1838
void PathNameDeleteTemporaryDir(const char *dirname)
Definition: fd.c:1668
int ClosePipeStream(FILE *file)
Definition: fd.c:2961
PGDLLIMPORT bool data_sync_retry
Definition: fd.c:162
void AtEOXact_Files(bool isCommit)
Definition: fd.c:3135
int FileGetRawFlags(File file)
Definition: fd.c:2457
int fsync_fname_ext(const char *fname, bool isdir, bool ignore_perm, int elevel)
Definition: fd.c:3767
int FreeFile(FILE *file)
Definition: fd.c:2751
PGDLLIMPORT int recovery_init_sync_method
Definition: fd.c:165
mode_t FileGetRawMode(File file)
Definition: fd.c:2467
int pg_fsync_writethrough(int fd)
Definition: fd.c:461
void FileClose(File file)
Definition: fd.c:1955
FILE * OpenPipeStream(const char *command, const char *mode)
Definition: fd.c:2656
void ReleaseExternalFD(void)
Definition: fd.c:1216
void RemovePgTempFilesInDir(const char *tmpdirname, bool missing_ok, bool unlink_all)
Definition: fd.c:3303
void RemovePgTempFiles(void)
Definition: fd.c:3244
bool TempTablespacesAreSet(void)
Definition: fd.c:3048
void fsync_fname(const char *fname, bool isdir)
Definition: fd.c:733
int FileFallocate(File file, off_t offset, off_t amount, uint32 wait_event_info)
Definition: fd.c:2339
int FilePrefetch(File file, off_t offset, off_t amount, uint32 wait_event_info)
Definition: fd.c:2055
int data_sync_elevel(int elevel)
Definition: fd.c:3906
File PathNameOpenFile(const char *fileName, int fileFlags)
Definition: fd.c:1552
int FileWrite(File file, const void *buffer, size_t amount, off_t offset, uint32 wait_event_info)
Definition: fd.c:2169
Oid GetNextTempTableSpace(void)
Definition: fd.c:3081
File PathNameOpenFilePerm(const char *fileName, int fileFlags, mode_t fileMode)
Definition: fd.c:1565
bool AcquireExternalFD(void)
Definition: fd.c:1163
int FileRead(File file, void *buffer, size_t amount, off_t offset, uint32 wait_event_info)
Definition: fd.c:2113
struct dirent * ReadDirExtended(DIR *dir, const char *dirname, int elevel)
Definition: fd.c:2894
void InitFileAccess(void)
Definition: fd.c:880
File OpenTemporaryFile(bool interXact)
Definition: fd.c:1701
int durable_unlink(const char *fname, int elevel)
Definition: fd.c:849
PGDLLIMPORT int max_files_per_process
Definition: fd.c:146
void ReserveExternalFD(void)
Definition: fd.c:1198
char * FilePathName(File file)
Definition: fd.c:2431
bool looks_like_temp_rel_name(const char *name)
Definition: fd.c:3419
bool PathNameDeleteTemporaryFile(const char *path, bool error_on_failure)
Definition: fd.c:1909
void set_max_safe_fds(void)
Definition: fd.c:1021
int pg_fsync(int fd)
Definition: fd.c:386
int File
Definition: fd.h:49
void PathNameCreateTemporaryDir(const char *basedir, const char *directory)
Definition: fd.c:1637
void AtEOSubXact_Files(bool isCommit, SubTransactionId mySubid, SubTransactionId parentSubid)
Definition: fd.c:3102
int OpenTransientFile(const char *fileName, int fileFlags)
Definition: fd.c:2603
void InitTemporaryFileAccess(void)
Definition: fd.c:910
int OpenTransientFilePerm(const char *fileName, int fileFlags, mode_t fileMode)
Definition: fd.c:2612
void SyncDataDirectory(void)
Definition: fd.c:3514
int FileZero(File file, off_t offset, off_t amount, uint32 wait_event_info)
Definition: fd.c:2294
off_t FileSize(File file)
Definition: fd.c:2379
int FileTruncate(File file, off_t offset, uint32 wait_event_info)
Definition: fd.c:2396
int pg_truncate(const char *path, off_t length)
Definition: fd.c:697
void SetTempTablespaces(Oid *tableSpaces, int numSpaces)
Definition: fd.c:3019
DIR * AllocateDir(const char *dirname)
Definition: fd.c:2813
void TempTablespacePath(char *path, Oid tablespace)
Definition: fd.c:1756
static char * basedir
static PgChecksumMode mode
Definition: pg_checksums.c:56
char * tablespace
Definition: pgbench.c:216
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
const char * name
static const char * directory
Definition: zic.c:634