PostgreSQL Source Code: src/include/storage/fd.h Source File

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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) 1996-2025, 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 */
60extern PGDLLIMPORT int max_files_per_process;
61extern PGDLLIMPORT bool data_sync_retry;
62extern PGDLLIMPORT int recovery_init_sync_method;
63extern PGDLLIMPORT int io_direct_flags;
64
65/*
66 * This is private to fd.c, but exported for save/restore_backend_variables()
67 */
68extern 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
104struct PgAioHandle;
105
106/* Operations on virtual Files --- equivalent to Unix kernel file ops */
107extern File PathNameOpenFile(const char *fileName, int fileFlags);
108extern File PathNameOpenFilePerm(const char *fileName, int fileFlags, mode_t fileMode);
109extern File OpenTemporaryFile(bool interXact);
110extern void FileClose(File file);
111extern int FilePrefetch(File file, off_t offset, off_t amount, uint32 wait_event_info);
112extern ssize_t FileReadV(File file, const struct iovec *iov, int iovcnt, off_t offset, uint32 wait_event_info);
113extern ssize_t FileWriteV(File file, const struct iovec *iov, int iovcnt, off_t offset, uint32 wait_event_info);
114extern int FileStartReadV(struct PgAioHandle *ioh, File file, int iovcnt, off_t offset, uint32 wait_event_info);
115extern int FileSync(File file, uint32 wait_event_info);
116extern int FileZero(File file, off_t offset, off_t amount, uint32 wait_event_info);
117extern int FileFallocate(File file, off_t offset, off_t amount, uint32 wait_event_info);
118
119extern off_t FileSize(File file);
120extern int FileTruncate(File file, off_t offset, uint32 wait_event_info);
121extern void FileWriteback(File file, off_t offset, off_t nbytes, uint32 wait_event_info);
122extern char *FilePathName(File file);
123extern int FileGetRawDesc(File file);
124extern int FileGetRawFlags(File file);
125extern mode_t FileGetRawMode(File file);
126
127/* Operations used for sharing named temporary files */
128extern File PathNameCreateTemporaryFile(const char *path, bool error_on_failure);
129extern File PathNameOpenTemporaryFile(const char *path, int mode);
130extern bool PathNameDeleteTemporaryFile(const char *path, bool error_on_failure);
131extern void PathNameCreateTemporaryDir(const char *basedir, const char *directory);
132extern void PathNameDeleteTemporaryDir(const char *dirname);
133extern void TempTablespacePath(char *path, Oid tablespace);
134
135/* Operations that allow use of regular stdio --- USE WITH CAUTION */
136extern FILE *AllocateFile(const char *name, const char *mode);
137extern int FreeFile(FILE *file);
138
139/* Operations that allow use of pipe streams (popen/pclose) */
140extern FILE *OpenPipeStream(const char *command, const char *mode);
141extern int ClosePipeStream(FILE *file);
142
143/* Operations to allow use of the <dirent.h> library routines */
144extern DIR *AllocateDir(const char *dirname);
145extern struct dirent *ReadDir(DIR *dir, const char *dirname);
146extern struct dirent *ReadDirExtended(DIR *dir, const char *dirname,
147 int elevel);
148extern int FreeDir(DIR *dir);
149
150/* Operations to allow use of a plain kernel FD, with automatic cleanup */
151extern int OpenTransientFile(const char *fileName, int fileFlags);
152extern int OpenTransientFilePerm(const char *fileName, int fileFlags, mode_t fileMode);
153extern int CloseTransientFile(int fd);
154
155/* If you've really really gotta have a plain kernel FD, use this */
156extern int BasicOpenFile(const char *fileName, int fileFlags);
157extern int BasicOpenFilePerm(const char *fileName, int fileFlags, mode_t fileMode);
158
159/* Use these for other cases, and also for long-lived BasicOpenFile FDs */
160extern bool AcquireExternalFD(void);
161extern void ReserveExternalFD(void);
162extern void ReleaseExternalFD(void);
163
164/* Make a directory with default permissions */
165extern int MakePGDirectory(const char *directoryName);
166
167/* Miscellaneous support routines */
168extern void InitFileAccess(void);
169extern void InitTemporaryFileAccess(void);
170extern void set_max_safe_fds(void);
171extern void closeAllVfds(void);
172extern void SetTempTablespaces(Oid *tableSpaces, int numSpaces);
173extern bool TempTablespacesAreSet(void);
174extern int GetTempTablespaces(Oid *tableSpaces, int numSpaces);
175extern Oid GetNextTempTableSpace(void);
176extern void AtEOXact_Files(bool isCommit);
177extern void AtEOSubXact_Files(bool isCommit, SubTransactionId mySubid,
178 SubTransactionId parentSubid);
179extern void RemovePgTempFiles(void);
180extern void RemovePgTempFilesInDir(const char *tmpdirname, bool missing_ok,
181 bool unlink_all);
182extern bool looks_like_temp_rel_name(const char *name);
183
184extern int pg_fsync(int fd);
185extern int pg_fsync_no_writethrough(int fd);
186extern int pg_fsync_writethrough(int fd);
187extern int pg_fdatasync(int fd);
188extern bool pg_file_exists(const char *name);
189extern void pg_flush_data(int fd, off_t offset, off_t nbytes);
190extern int pg_truncate(const char *path, off_t length);
191extern void fsync_fname(const char *fname, bool isdir);
192extern int fsync_fname_ext(const char *fname, bool isdir, bool ignore_perm, int elevel);
193extern int durable_rename(const char *oldfile, const char *newfile, int elevel);
194extern int durable_unlink(const char *fname, int elevel);
195extern void SyncDataDirectory(void);
196extern int data_sync_elevel(int elevel);
197
198static inline ssize_t
199 FileRead(File file, void *buffer, size_t amount, off_t offset,
200 uint32 wait_event_info)
201{
202 struct iovec iov = {
203 .iov_base = buffer,
204 .iov_len = amount
205 };
206
207 return FileReadV(file, &iov, 1, offset, wait_event_info);
208}
209
210static inline ssize_t
211 FileWrite(File file, const void *buffer, size_t amount, off_t offset,
212 uint32 wait_event_info)
213{
214 struct iovec iov = {
215 .iov_base = unconstify(void *, buffer),
216 .iov_len = amount
217 };
218
219 return FileWriteV(file, &iov, 1, offset, wait_event_info);
220}
221
222#endif /* FD_H */
#define unconstify(underlying_type, expr)
Definition: c.h:1244
#define PGDLLIMPORT
Definition: c.h:1319
uint32 SubTransactionId
Definition: c.h:661
uint32_t uint32
Definition: c.h:538
PGDLLIMPORT int max_safe_fds
Definition: fd.c:159
void pg_flush_data(int fd, off_t offset, off_t nbytes)
Definition: fd.c:522
int FileGetRawDesc(File file)
Definition: fd.c:2529
int MakePGDirectory(const char *directoryName)
Definition: fd.c:3975
int FreeDir(DIR *dir)
Definition: fd.c:3022
void FileWriteback(File file, off_t offset, off_t nbytes, uint32 wait_event_info)
Definition: fd.c:2136
int pg_fsync_no_writethrough(int fd)
Definition: fd.c:438
FILE * OpenPipeStream(const char *command, const char *mode)
Definition: fd.c:2744
int BasicOpenFilePerm(const char *fileName, int fileFlags, mode_t fileMode)
Definition: fd.c:1108
PGDLLIMPORT int io_direct_flags
Definition: fd.c:168
int durable_rename(const char *oldfile, const char *newfile, int elevel)
Definition: fd.c:779
char * FilePathName(File file)
Definition: fd.c:2513
int GetTempTablespaces(Oid *tableSpaces, int numSpaces)
Definition: fd.c:3154
File PathNameOpenTemporaryFile(const char *path, int mode)
Definition: fd.c:1902
int pg_fdatasync(int fd)
Definition: fd.c:477
int FileSync(File file, uint32 wait_event_info)
Definition: fd.c:2349
int CloseTransientFile(int fd)
Definition: fd.c:2868
int BasicOpenFile(const char *fileName, int fileFlags)
Definition: fd.c:1086
void closeAllVfds(void)
Definition: fd.c:3081
File PathNameCreateTemporaryFile(const char *path, bool error_on_failure)
Definition: fd.c:1862
void PathNameDeleteTemporaryDir(const char *dirname)
Definition: fd.c:1692
int ClosePipeStream(FILE *file)
Definition: fd.c:3052
PGDLLIMPORT bool data_sync_retry
Definition: fd.c:162
void AtEOXact_Files(bool isCommit)
Definition: fd.c:3226
int FileGetRawFlags(File file)
Definition: fd.c:2545
int fsync_fname_ext(const char *fname, bool isdir, bool ignore_perm, int elevel)
Definition: fd.c:3859
int FreeFile(FILE *file)
Definition: fd.c:2840
PGDLLIMPORT int recovery_init_sync_method
Definition: fd.c:165
mode_t FileGetRawMode(File file)
Definition: fd.c:2555
struct dirent * ReadDirExtended(DIR *dir, const char *dirname, int elevel)
Definition: fd.c:2985
int pg_fsync_writethrough(int fd)
Definition: fd.c:458
void FileClose(File file)
Definition: fd.c:1979
void ReleaseExternalFD(void)
Definition: fd.c:1238
void RemovePgTempFilesInDir(const char *tmpdirname, bool missing_ok, bool unlink_all)
Definition: fd.c:3395
bool pg_file_exists(const char *name)
Definition: fd.c:500
void RemovePgTempFiles(void)
Definition: fd.c:3335
bool TempTablespacesAreSet(void)
Definition: fd.c:3139
void fsync_fname(const char *fname, bool isdir)
Definition: fd.c:753
int FileFallocate(File file, off_t offset, off_t amount, uint32 wait_event_info)
Definition: fd.c:2421
int FilePrefetch(File file, off_t offset, off_t amount, uint32 wait_event_info)
Definition: fd.c:2080
int data_sync_elevel(int elevel)
Definition: fd.c:3998
File PathNameOpenFile(const char *fileName, int fileFlags)
Definition: fd.c:1576
Oid GetNextTempTableSpace(void)
Definition: fd.c:3172
File PathNameOpenFilePerm(const char *fileName, int fileFlags, mode_t fileMode)
Definition: fd.c:1589
int FileStartReadV(struct PgAioHandle *ioh, File file, int iovcnt, off_t offset, uint32 wait_event_info)
Definition: fd.c:2218
bool AcquireExternalFD(void)
Definition: fd.c:1185
DIR * AllocateDir(const char *dirname)
Definition: fd.c:2904
void InitFileAccess(void)
Definition: fd.c:900
File OpenTemporaryFile(bool interXact)
Definition: fd.c:1725
int durable_unlink(const char *fname, int elevel)
Definition: fd.c:869
PGDLLIMPORT int max_files_per_process
Definition: fd.c:146
void ReserveExternalFD(void)
Definition: fd.c:1220
struct dirent * ReadDir(DIR *dir, const char *dirname)
Definition: fd.c:2970
bool looks_like_temp_rel_name(const char *name)
Definition: fd.c:3511
bool PathNameDeleteTemporaryFile(const char *path, bool error_on_failure)
Definition: fd.c:1933
void set_max_safe_fds(void)
Definition: fd.c:1041
int pg_fsync(int fd)
Definition: fd.c:386
static ssize_t FileRead(File file, void *buffer, size_t amount, off_t offset, uint32 wait_event_info)
Definition: fd.h:199
int File
Definition: fd.h:51
void PathNameCreateTemporaryDir(const char *basedir, const char *directory)
Definition: fd.c:1661
FILE * AllocateFile(const char *name, const char *mode)
Definition: fd.c:2641
static ssize_t FileWrite(File file, const void *buffer, size_t amount, off_t offset, uint32 wait_event_info)
Definition: fd.h:211
void AtEOSubXact_Files(bool isCommit, SubTransactionId mySubid, SubTransactionId parentSubid)
Definition: fd.c:3193
int OpenTransientFile(const char *fileName, int fileFlags)
Definition: fd.c:2691
void InitTemporaryFileAccess(void)
Definition: fd.c:930
int OpenTransientFilePerm(const char *fileName, int fileFlags, mode_t fileMode)
Definition: fd.c:2700
ssize_t FileWriteV(File file, const struct iovec *iov, int iovcnt, off_t offset, uint32 wait_event_info)
Definition: fd.c:2244
void SyncDataDirectory(void)
Definition: fd.c:3606
int FileZero(File file, off_t offset, off_t amount, uint32 wait_event_info)
Definition: fd.c:2376
off_t FileSize(File file)
Definition: fd.c:2461
ssize_t FileReadV(File file, const struct iovec *iov, int iovcnt, off_t offset, uint32 wait_event_info)
Definition: fd.c:2162
int FileTruncate(File file, off_t offset, uint32 wait_event_info)
Definition: fd.c:2478
int pg_truncate(const char *path, off_t length)
Definition: fd.c:717
void SetTempTablespaces(Oid *tableSpaces, int numSpaces)
Definition: fd.c:3110
void TempTablespacePath(char *path, Oid tablespace)
Definition: fd.c:1780
static char * basedir
Definition: pg_basebackup.c:131
static PgChecksumMode mode
Definition: pg_checksums.c:55
static char * tablespace
Definition: pgbench.c:217
unsigned int Oid
Definition: postgres_ext.h:32
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

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