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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) 1996-2024, 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, ReadV, Write, WriteV, 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 "port/pg_iovec.h"
47 
48 #include <dirent.h>
49 #include <fcntl.h>
50 
51 typedef int File;
52 
53 
54 #define IO_DIRECT_DATA 0x01
55 #define IO_DIRECT_WAL 0x02
56 #define IO_DIRECT_WAL_INIT 0x04
57 
58 
59 /* GUC parameter */
61 extern PGDLLIMPORT bool data_sync_retry;
63 extern PGDLLIMPORT int io_direct_flags;
64 
65 /*
66  * This is private to fd.c, but exported for save/restore_backend_variables()
67  */
68 extern PGDLLIMPORT int max_safe_fds;
69 
70 /*
71  * On Windows, we have to interpret EACCES as possibly meaning the same as
72  * ENOENT, because if a file is unlinked-but-not-yet-gone on that platform,
73  * that's what you get. Ugh. This code is designed so that we don't
74  * actually believe these cases are okay without further evidence (namely,
75  * a pending fsync request getting canceled ... see ProcessSyncRequests).
76  */
77 #ifndef WIN32
78 #define FILE_POSSIBLY_DELETED(err) ((err) == ENOENT)
79 #else
80 #define FILE_POSSIBLY_DELETED(err) ((err) == ENOENT || (err) == EACCES)
81 #endif
82 
83 /*
84  * O_DIRECT is not standard, but almost every Unix has it. We translate it
85  * to the appropriate Windows flag in src/port/open.c. We simulate it with
86  * fcntl(F_NOCACHE) on macOS inside fd.c's open() wrapper. We use the name
87  * PG_O_DIRECT rather than defining O_DIRECT in that case (probably not a good
88  * idea on a Unix). We can only use it if the compiler will correctly align
89  * PGIOAlignedBlock for us, though.
90  */
91 #if defined(O_DIRECT) && defined(pg_attribute_aligned)
92 #define PG_O_DIRECT O_DIRECT
93 #elif defined(F_NOCACHE)
94 #define PG_O_DIRECT 0x80000000
95 #define PG_O_DIRECT_USE_F_NOCACHE
96 #else
97 #define PG_O_DIRECT 0
98 #endif
99 
100 /*
101  * prototypes for functions in fd.c
102  */
103 
104 /* Operations on virtual Files --- equivalent to Unix kernel file ops */
105 extern File PathNameOpenFile(const char *fileName, int fileFlags);
106 extern File PathNameOpenFilePerm(const char *fileName, int fileFlags, mode_t fileMode);
107 extern File OpenTemporaryFile(bool interXact);
108 extern void FileClose(File file);
109 extern int FilePrefetch(File file, off_t offset, off_t amount, uint32 wait_event_info);
110 extern ssize_t FileReadV(File file, const struct iovec *iov, int iovcnt, off_t offset, uint32 wait_event_info);
111 extern ssize_t FileWriteV(File file, const struct iovec *iov, int iovcnt, off_t offset, uint32 wait_event_info);
112 extern int FileSync(File file, uint32 wait_event_info);
113 extern int FileZero(File file, off_t offset, off_t amount, uint32 wait_event_info);
114 extern int FileFallocate(File file, off_t offset, off_t amount, uint32 wait_event_info);
115 
116 extern off_t FileSize(File file);
117 extern int FileTruncate(File file, off_t offset, uint32 wait_event_info);
118 extern void FileWriteback(File file, off_t offset, off_t nbytes, uint32 wait_event_info);
119 extern char *FilePathName(File file);
120 extern int FileGetRawDesc(File file);
121 extern int FileGetRawFlags(File file);
122 extern mode_t FileGetRawMode(File file);
123 
124 /* Operations used for sharing named temporary files */
125 extern File PathNameCreateTemporaryFile(const char *path, bool error_on_failure);
126 extern File PathNameOpenTemporaryFile(const char *path, int mode);
127 extern bool PathNameDeleteTemporaryFile(const char *path, bool error_on_failure);
128 extern void PathNameCreateTemporaryDir(const char *basedir, const char *directory);
129 extern void PathNameDeleteTemporaryDir(const char *dirname);
130 extern void TempTablespacePath(char *path, Oid tablespace);
131 
132 /* Operations that allow use of regular stdio --- USE WITH CAUTION */
133 extern FILE *AllocateFile(const char *name, const char *mode);
134 extern int FreeFile(FILE *file);
135 
136 /* Operations that allow use of pipe streams (popen/pclose) */
137 extern FILE *OpenPipeStream(const char *command, const char *mode);
138 extern int ClosePipeStream(FILE *file);
139 
140 /* Operations to allow use of the <dirent.h> library routines */
141 extern DIR *AllocateDir(const char *dirname);
142 extern struct dirent *ReadDir(DIR *dir, const char *dirname);
143 extern struct dirent *ReadDirExtended(DIR *dir, const char *dirname,
144  int elevel);
145 extern int FreeDir(DIR *dir);
146 
147 /* Operations to allow use of a plain kernel FD, with automatic cleanup */
148 extern int OpenTransientFile(const char *fileName, int fileFlags);
149 extern int OpenTransientFilePerm(const char *fileName, int fileFlags, mode_t fileMode);
150 extern int CloseTransientFile(int fd);
151 
152 /* If you've really really gotta have a plain kernel FD, use this */
153 extern int BasicOpenFile(const char *fileName, int fileFlags);
154 extern int BasicOpenFilePerm(const char *fileName, int fileFlags, mode_t fileMode);
155 
156 /* Use these for other cases, and also for long-lived BasicOpenFile FDs */
157 extern bool AcquireExternalFD(void);
158 extern void ReserveExternalFD(void);
159 extern void ReleaseExternalFD(void);
160 
161 /* Make a directory with default permissions */
162 extern int MakePGDirectory(const char *directoryName);
163 
164 /* Miscellaneous support routines */
165 extern void InitFileAccess(void);
166 extern void InitTemporaryFileAccess(void);
167 extern void set_max_safe_fds(void);
168 extern void closeAllVfds(void);
169 extern void SetTempTablespaces(Oid *tableSpaces, int numSpaces);
170 extern bool TempTablespacesAreSet(void);
171 extern int GetTempTablespaces(Oid *tableSpaces, int numSpaces);
172 extern Oid GetNextTempTableSpace(void);
173 extern void AtEOXact_Files(bool isCommit);
174 extern void AtEOSubXact_Files(bool isCommit, SubTransactionId mySubid,
175  SubTransactionId parentSubid);
176 extern void RemovePgTempFiles(void);
177 extern void RemovePgTempFilesInDir(const char *tmpdirname, bool missing_ok,
178  bool unlink_all);
179 extern bool looks_like_temp_rel_name(const char *name);
180 
181 extern int pg_fsync(int fd);
182 extern int pg_fsync_no_writethrough(int fd);
183 extern int pg_fsync_writethrough(int fd);
184 extern int pg_fdatasync(int fd);
185 extern bool pg_file_exists(const char *name);
186 extern void pg_flush_data(int fd, off_t offset, off_t nbytes);
187 extern int pg_truncate(const char *path, off_t length);
188 extern void fsync_fname(const char *fname, bool isdir);
189 extern int fsync_fname_ext(const char *fname, bool isdir, bool ignore_perm, int elevel);
190 extern int durable_rename(const char *oldfile, const char *newfile, int elevel);
191 extern int durable_unlink(const char *fname, int elevel);
192 extern void SyncDataDirectory(void);
193 extern int data_sync_elevel(int elevel);
194 
195 static inline ssize_t
196 FileRead(File file, void *buffer, size_t amount, off_t offset,
197  uint32 wait_event_info)
198 {
199  struct iovec iov = {
200  .iov_base = buffer,
201  .iov_len = amount
202  };
203 
204  return FileReadV(file, &iov, 1, offset, wait_event_info);
205 }
206 
207 static inline ssize_t
208 FileWrite(File file, const void *buffer, size_t amount, off_t offset,
209  uint32 wait_event_info)
210 {
211  struct iovec iov = {
212  .iov_base = unconstify(void *, buffer),
213  .iov_len = amount
214  };
215 
216  return FileWriteV(file, &iov, 1, offset, wait_event_info);
217 }
218 
219 #endif /* FD_H */
#define unconstify(underlying_type, expr)
Definition: c.h:1250
unsigned int uint32
Definition: c.h:518
#define PGDLLIMPORT
Definition: c.h:1321
uint32 SubTransactionId
Definition: c.h:661
struct dirent * ReadDir(DIR *dir, const char *dirname)
Definition: fd.c:2931
PGDLLIMPORT int max_safe_fds
Definition: fd.c:158
void pg_flush_data(int fd, off_t offset, off_t nbytes)
Definition: fd.c:524
int FileGetRawDesc(File file)
Definition: fd.c:2499
int MakePGDirectory(const char *directoryName)
Definition: fd.c:3936
int FreeDir(DIR *dir)
Definition: fd.c:2983
void FileWriteback(File file, off_t offset, off_t nbytes, uint32 wait_event_info)
Definition: fd.c:2132
int pg_fsync_no_writethrough(int fd)
Definition: fd.c:440
FILE * AllocateFile(const char *name, const char *mode)
Definition: fd.c:2605
int BasicOpenFilePerm(const char *fileName, int fileFlags, mode_t fileMode)
Definition: fd.c:1108
PGDLLIMPORT int io_direct_flags
Definition: fd.c:167
int durable_rename(const char *oldfile, const char *newfile, int elevel)
Definition: fd.c:781
int GetTempTablespaces(Oid *tableSpaces, int numSpaces)
Definition: fd.c:3115
File PathNameOpenTemporaryFile(const char *path, int mode)
Definition: fd.c:1900
int pg_fdatasync(int fd)
Definition: fd.c:479
int FileSync(File file, uint32 wait_event_info)
Definition: fd.c:2319
int CloseTransientFile(int fd)
Definition: fd.c:2831
int BasicOpenFile(const char *fileName, int fileFlags)
Definition: fd.c:1086
void closeAllVfds(void)
Definition: fd.c:3042
File PathNameCreateTemporaryFile(const char *path, bool error_on_failure)
Definition: fd.c:1860
void PathNameDeleteTemporaryDir(const char *dirname)
Definition: fd.c:1690
int ClosePipeStream(FILE *file)
Definition: fd.c:3013
PGDLLIMPORT bool data_sync_retry
Definition: fd.c:161
void AtEOXact_Files(bool isCommit)
Definition: fd.c:3187
int FileGetRawFlags(File file)
Definition: fd.c:2509
int fsync_fname_ext(const char *fname, bool isdir, bool ignore_perm, int elevel)
Definition: fd.c:3820
int FreeFile(FILE *file)
Definition: fd.c:2803
PGDLLIMPORT int recovery_init_sync_method
Definition: fd.c:164
mode_t FileGetRawMode(File file)
Definition: fd.c:2519
int pg_fsync_writethrough(int fd)
Definition: fd.c:460
void FileClose(File file)
Definition: fd.c:1977
FILE * OpenPipeStream(const char *command, const char *mode)
Definition: fd.c:2708
void ReleaseExternalFD(void)
Definition: fd.c:1238
void RemovePgTempFilesInDir(const char *tmpdirname, bool missing_ok, bool unlink_all)
Definition: fd.c:3356
bool pg_file_exists(const char *name)
Definition: fd.c:502
void RemovePgTempFiles(void)
Definition: fd.c:3296
bool TempTablespacesAreSet(void)
Definition: fd.c:3100
void fsync_fname(const char *fname, bool isdir)
Definition: fd.c:755
int FileFallocate(File file, off_t offset, off_t amount, uint32 wait_event_info)
Definition: fd.c:2391
int FilePrefetch(File file, off_t offset, off_t amount, uint32 wait_event_info)
Definition: fd.c:2076
int data_sync_elevel(int elevel)
Definition: fd.c:3959
File PathNameOpenFile(const char *fileName, int fileFlags)
Definition: fd.c:1574
Oid GetNextTempTableSpace(void)
Definition: fd.c:3133
File PathNameOpenFilePerm(const char *fileName, int fileFlags, mode_t fileMode)
Definition: fd.c:1587
bool AcquireExternalFD(void)
Definition: fd.c:1185
struct dirent * ReadDirExtended(DIR *dir, const char *dirname, int elevel)
Definition: fd.c:2946
void InitFileAccess(void)
Definition: fd.c:902
File OpenTemporaryFile(bool interXact)
Definition: fd.c:1723
int durable_unlink(const char *fname, int elevel)
Definition: fd.c:871
PGDLLIMPORT int max_files_per_process
Definition: fd.c:145
void ReserveExternalFD(void)
Definition: fd.c:1220
char * FilePathName(File file)
Definition: fd.c:2483
bool looks_like_temp_rel_name(const char *name)
Definition: fd.c:3472
bool PathNameDeleteTemporaryFile(const char *path, bool error_on_failure)
Definition: fd.c:1931
void set_max_safe_fds(void)
Definition: fd.c:1043
int pg_fsync(int fd)
Definition: fd.c:385
static ssize_t FileRead(File file, void *buffer, size_t amount, off_t offset, uint32 wait_event_info)
Definition: fd.h:196
int File
Definition: fd.h:51
void PathNameCreateTemporaryDir(const char *basedir, const char *directory)
Definition: fd.c:1659
static ssize_t FileWrite(File file, const void *buffer, size_t amount, off_t offset, uint32 wait_event_info)
Definition: fd.h:208
void AtEOSubXact_Files(bool isCommit, SubTransactionId mySubid, SubTransactionId parentSubid)
Definition: fd.c:3154
int OpenTransientFile(const char *fileName, int fileFlags)
Definition: fd.c:2655
void InitTemporaryFileAccess(void)
Definition: fd.c:932
int OpenTransientFilePerm(const char *fileName, int fileFlags, mode_t fileMode)
Definition: fd.c:2664
ssize_t FileWriteV(File file, const struct iovec *iov, int iovcnt, off_t offset, uint32 wait_event_info)
Definition: fd.c:2214
void SyncDataDirectory(void)
Definition: fd.c:3567
int FileZero(File file, off_t offset, off_t amount, uint32 wait_event_info)
Definition: fd.c:2346
off_t FileSize(File file)
Definition: fd.c:2431
ssize_t FileReadV(File file, const struct iovec *iov, int iovcnt, off_t offset, uint32 wait_event_info)
Definition: fd.c:2158
int FileTruncate(File file, off_t offset, uint32 wait_event_info)
Definition: fd.c:2448
int pg_truncate(const char *path, off_t length)
Definition: fd.c:719
void SetTempTablespaces(Oid *tableSpaces, int numSpaces)
Definition: fd.c:3071
DIR * AllocateDir(const char *dirname)
Definition: fd.c:2865
void TempTablespacePath(char *path, Oid tablespace)
Definition: fd.c:1778
static char * basedir
static PgChecksumMode mode
Definition: pg_checksums.c:55
static 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