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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
51typedef 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 */
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
104/* Operations on virtual Files --- equivalent to Unix kernel file ops */
105extern File PathNameOpenFile(const char *fileName, int fileFlags);
106extern File PathNameOpenFilePerm(const char *fileName, int fileFlags, mode_t fileMode);
107extern File OpenTemporaryFile(bool interXact);
108extern void FileClose(File file);
109extern int FilePrefetch(File file, off_t offset, off_t amount, uint32 wait_event_info);
110extern ssize_t FileReadV(File file, const struct iovec *iov, int iovcnt, off_t offset, uint32 wait_event_info);
111extern ssize_t FileWriteV(File file, const struct iovec *iov, int iovcnt, off_t offset, uint32 wait_event_info);
112extern int FileSync(File file, uint32 wait_event_info);
113extern int FileZero(File file, off_t offset, off_t amount, uint32 wait_event_info);
114extern int FileFallocate(File file, off_t offset, off_t amount, uint32 wait_event_info);
115
116extern off_t FileSize(File file);
117extern int FileTruncate(File file, off_t offset, uint32 wait_event_info);
118extern void FileWriteback(File file, off_t offset, off_t nbytes, uint32 wait_event_info);
119extern char *FilePathName(File file);
120extern int FileGetRawDesc(File file);
121extern int FileGetRawFlags(File file);
122extern mode_t FileGetRawMode(File file);
123
124/* Operations used for sharing named temporary files */
125extern File PathNameCreateTemporaryFile(const char *path, bool error_on_failure);
126extern File PathNameOpenTemporaryFile(const char *path, int mode);
127extern bool PathNameDeleteTemporaryFile(const char *path, bool error_on_failure);
128extern void PathNameCreateTemporaryDir(const char *basedir, const char *directory);
129extern void PathNameDeleteTemporaryDir(const char *dirname);
130extern void TempTablespacePath(char *path, Oid tablespace);
131
132/* Operations that allow use of regular stdio --- USE WITH CAUTION */
133extern FILE *AllocateFile(const char *name, const char *mode);
134extern int FreeFile(FILE *file);
135
136/* Operations that allow use of pipe streams (popen/pclose) */
137extern FILE *OpenPipeStream(const char *command, const char *mode);
138extern int ClosePipeStream(FILE *file);
139
140/* Operations to allow use of the <dirent.h> library routines */
141extern DIR *AllocateDir(const char *dirname);
142extern struct dirent *ReadDir(DIR *dir, const char *dirname);
143extern struct dirent *ReadDirExtended(DIR *dir, const char *dirname,
144 int elevel);
145extern int FreeDir(DIR *dir);
146
147/* Operations to allow use of a plain kernel FD, with automatic cleanup */
148extern int OpenTransientFile(const char *fileName, int fileFlags);
149extern int OpenTransientFilePerm(const char *fileName, int fileFlags, mode_t fileMode);
150extern int CloseTransientFile(int fd);
151
152/* If you've really really gotta have a plain kernel FD, use this */
153extern int BasicOpenFile(const char *fileName, int fileFlags);
154extern int BasicOpenFilePerm(const char *fileName, int fileFlags, mode_t fileMode);
155
156/* Use these for other cases, and also for long-lived BasicOpenFile FDs */
157extern bool AcquireExternalFD(void);
158extern void ReserveExternalFD(void);
159extern void ReleaseExternalFD(void);
160
161/* Make a directory with default permissions */
162extern int MakePGDirectory(const char *directoryName);
163
164/* Miscellaneous support routines */
165extern void InitFileAccess(void);
166extern void InitTemporaryFileAccess(void);
167extern void set_max_safe_fds(void);
168extern void closeAllVfds(void);
169extern void SetTempTablespaces(Oid *tableSpaces, int numSpaces);
170extern bool TempTablespacesAreSet(void);
171extern int GetTempTablespaces(Oid *tableSpaces, int numSpaces);
172extern Oid GetNextTempTableSpace(void);
173extern void AtEOXact_Files(bool isCommit);
174extern void AtEOSubXact_Files(bool isCommit, SubTransactionId mySubid,
175 SubTransactionId parentSubid);
176extern void RemovePgTempFiles(void);
177extern void RemovePgTempFilesInDir(const char *tmpdirname, bool missing_ok,
178 bool unlink_all);
179extern bool looks_like_temp_rel_name(const char *name);
180
181extern int pg_fsync(int fd);
182extern int pg_fsync_no_writethrough(int fd);
183extern int pg_fsync_writethrough(int fd);
184extern int pg_fdatasync(int fd);
185extern bool pg_file_exists(const char *name);
186extern void pg_flush_data(int fd, off_t offset, off_t nbytes);
187extern int pg_truncate(const char *path, off_t length);
188extern void fsync_fname(const char *fname, bool isdir);
189extern int fsync_fname_ext(const char *fname, bool isdir, bool ignore_perm, int elevel);
190extern int durable_rename(const char *oldfile, const char *newfile, int elevel);
191extern int durable_unlink(const char *fname, int elevel);
192extern void SyncDataDirectory(void);
193extern int data_sync_elevel(int elevel);
194
195static inline ssize_t
196FileRead(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
207static inline ssize_t
208FileWrite(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:1202
#define PGDLLIMPORT
Definition: c.h:1277
uint32 SubTransactionId
Definition: c.h:613
uint32_t uint32
Definition: c.h:488
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 * OpenPipeStream(const char *command, const char *mode)
Definition: fd.c:2708
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
char * FilePathName(File file)
Definition: fd.c:2483
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
struct dirent * ReadDirExtended(DIR *dir, const char *dirname, int elevel)
Definition: fd.c:2946
int pg_fsync_writethrough(int fd)
Definition: fd.c:460
void FileClose(File file)
Definition: fd.c:1977
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
DIR * AllocateDir(const char *dirname)
Definition: fd.c:2865
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
struct dirent * ReadDir(DIR *dir, const char *dirname)
Definition: fd.c:2931
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
FILE * AllocateFile(const char *name, const char *mode)
Definition: fd.c:2605
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
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: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