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1 : /*-------------------------------------------------------------------------
2 : *
3 : * fd.h
4 : * Virtual file descriptor definitions.
5 : *
6 : *
7 : * Portions Copyright (c) 1996-2026, 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 : enum FileExtendMethod
59 : {
60 : #ifdef HAVE_POSIX_FALLOCATE
61 : FILE_EXTEND_METHOD_POSIX_FALLOCATE,
62 : #endif
63 : FILE_EXTEND_METHOD_WRITE_ZEROS,
64 : };
65 :
66 : /* Default to the first available file_extend_method. */
67 : #define DEFAULT_FILE_EXTEND_METHOD 0
68 :
69 : /* GUC parameter */
70 : extern PGDLLIMPORT int max_files_per_process;
71 : extern PGDLLIMPORT bool data_sync_retry;
72 : extern PGDLLIMPORT int recovery_init_sync_method;
73 : extern PGDLLIMPORT int io_direct_flags;
74 : extern PGDLLIMPORT int file_extend_method;
75 :
76 : /*
77 : * This is private to fd.c, but exported for save/restore_backend_variables()
78 : */
79 : extern PGDLLIMPORT int max_safe_fds;
80 :
81 : /*
82 : * On Windows, we have to interpret EACCES as possibly meaning the same as
83 : * ENOENT, because if a file is unlinked-but-not-yet-gone on that platform,
84 : * that's what you get. Ugh. This code is designed so that we don't
85 : * actually believe these cases are okay without further evidence (namely,
86 : * a pending fsync request getting canceled ... see ProcessSyncRequests).
87 : */
88 : #ifndef WIN32
89 : #define FILE_POSSIBLY_DELETED(err) ((err) == ENOENT)
90 : #else
91 : #define FILE_POSSIBLY_DELETED(err) ((err) == ENOENT || (err) == EACCES)
92 : #endif
93 :
94 : /*
95 : * O_DIRECT is not standard, but almost every Unix has it. We translate it
96 : * to the appropriate Windows flag in src/port/open.c. We simulate it with
97 : * fcntl(F_NOCACHE) on macOS inside fd.c's open() wrapper. We use the name
98 : * PG_O_DIRECT rather than defining O_DIRECT in that case (probably not a good
99 : * idea on a Unix).
100 : */
101 : #if defined(O_DIRECT)
102 : #define PG_O_DIRECT O_DIRECT
103 : #elif defined(F_NOCACHE)
104 : #define PG_O_DIRECT 0x80000000
105 : #define PG_O_DIRECT_USE_F_NOCACHE
106 : /*
107 : * The value we defined to stand in for O_DIRECT when simulating it with
108 : * F_NOCACHE had better not collide with any of the standard flags.
109 : */
110 : StaticAssertDecl((PG_O_DIRECT &
111 : (O_APPEND |
112 : O_CLOEXEC |
113 : O_CREAT |
114 : O_DSYNC |
115 : O_EXCL |
116 : O_RDWR |
117 : O_RDONLY |
118 : O_SYNC |
119 : O_TRUNC |
120 : O_WRONLY)) == 0,
121 : "PG_O_DIRECT value collides with standard flag");
122 : #else
123 : #define PG_O_DIRECT 0
124 : #endif
125 :
126 : /*
127 : * prototypes for functions in fd.c
128 : */
129 :
130 : struct PgAioHandle;
131 :
132 : /* Operations on virtual Files --- equivalent to Unix kernel file ops */
133 : extern File PathNameOpenFile(const char *fileName, int fileFlags);
134 : extern File PathNameOpenFilePerm(const char *fileName, int fileFlags, mode_t fileMode);
135 : extern File OpenTemporaryFile(bool interXact);
136 : extern void FileClose(File file);
137 : extern int FilePrefetch(File file, pgoff_t offset, pgoff_t amount, uint32 wait_event_info);
138 : extern ssize_t FileReadV(File file, const struct iovec *iov, int iovcnt, pgoff_t offset, uint32 wait_event_info);
139 : extern ssize_t FileWriteV(File file, const struct iovec *iov, int iovcnt, pgoff_t offset, uint32 wait_event_info);
140 : extern int FileStartReadV(struct PgAioHandle *ioh, File file, int iovcnt, pgoff_t offset, uint32 wait_event_info);
141 : extern int FileSync(File file, uint32 wait_event_info);
142 : extern int FileZero(File file, pgoff_t offset, pgoff_t amount, uint32 wait_event_info);
143 : extern int FileFallocate(File file, pgoff_t offset, pgoff_t amount, uint32 wait_event_info);
144 :
145 : extern pgoff_t FileSize(File file);
146 : extern int FileTruncate(File file, pgoff_t offset, uint32 wait_event_info);
147 : extern void FileWriteback(File file, pgoff_t offset, pgoff_t nbytes, uint32 wait_event_info);
148 : extern char *FilePathName(File file);
149 : extern int FileGetRawDesc(File file);
150 : extern int FileGetRawFlags(File file);
151 : extern mode_t FileGetRawMode(File file);
152 :
153 : /* Operations used for sharing named temporary files */
154 : extern File PathNameCreateTemporaryFile(const char *path, bool error_on_failure);
155 : extern File PathNameOpenTemporaryFile(const char *path, int mode);
156 : extern bool PathNameDeleteTemporaryFile(const char *path, bool error_on_failure);
157 : extern void PathNameCreateTemporaryDir(const char *basedir, const char *directory);
158 : extern void PathNameDeleteTemporaryDir(const char *dirname);
159 : extern void TempTablespacePath(char *path, Oid tablespace);
160 :
161 : /* Operations that allow use of regular stdio --- USE WITH CAUTION */
162 : extern FILE *AllocateFile(const char *name, const char *mode);
163 : extern int FreeFile(FILE *file);
164 :
165 : /* Operations that allow use of pipe streams (popen/pclose) */
166 : extern FILE *OpenPipeStream(const char *command, const char *mode);
167 : extern int ClosePipeStream(FILE *file);
168 :
169 : /* Operations to allow use of the <dirent.h> library routines */
170 : extern DIR *AllocateDir(const char *dirname);
171 : extern struct dirent *ReadDir(DIR *dir, const char *dirname);
172 : extern struct dirent *ReadDirExtended(DIR *dir, const char *dirname,
173 : int elevel);
174 : extern int FreeDir(DIR *dir);
175 :
176 : /* Operations to allow use of a plain kernel FD, with automatic cleanup */
177 : extern int OpenTransientFile(const char *fileName, int fileFlags);
178 : extern int OpenTransientFilePerm(const char *fileName, int fileFlags, mode_t fileMode);
179 : extern int CloseTransientFile(int fd);
180 :
181 : /* If you've really really gotta have a plain kernel FD, use this */
182 : extern int BasicOpenFile(const char *fileName, int fileFlags);
183 : extern int BasicOpenFilePerm(const char *fileName, int fileFlags, mode_t fileMode);
184 :
185 : /* Use these for other cases, and also for long-lived BasicOpenFile FDs */
186 : extern bool AcquireExternalFD(void);
187 : extern void ReserveExternalFD(void);
188 : extern void ReleaseExternalFD(void);
189 :
190 : /* Make a directory with default permissions */
191 : extern int MakePGDirectory(const char *directoryName);
192 :
193 : /* Miscellaneous support routines */
194 : extern void InitFileAccess(void);
195 : extern void InitTemporaryFileAccess(void);
196 : extern void set_max_safe_fds(void);
197 : extern void closeAllVfds(void);
198 : extern void SetTempTablespaces(Oid *tableSpaces, int numSpaces);
199 : extern bool TempTablespacesAreSet(void);
200 : extern int GetTempTablespaces(Oid *tableSpaces, int numSpaces);
201 : extern Oid GetNextTempTableSpace(void);
202 : extern void AtEOXact_Files(bool isCommit);
203 : extern void AtEOSubXact_Files(bool isCommit, SubTransactionId mySubid,
204 : SubTransactionId parentSubid);
205 : extern void RemovePgTempFiles(void);
206 : extern void RemovePgTempFilesInDir(const char *tmpdirname, bool missing_ok,
207 : bool unlink_all);
208 : extern bool looks_like_temp_rel_name(const char *name);
209 :
210 : extern int pg_fsync(int fd);
211 : extern int pg_fsync_no_writethrough(int fd);
212 : extern int pg_fsync_writethrough(int fd);
213 : extern int pg_fdatasync(int fd);
214 : extern bool pg_file_exists(const char *name);
215 : extern void pg_flush_data(int fd, pgoff_t offset, pgoff_t nbytes);
216 : extern int pg_truncate(const char *path, pgoff_t length);
217 : extern void fsync_fname(const char *fname, bool isdir);
218 : extern int fsync_fname_ext(const char *fname, bool isdir, bool ignore_perm, int elevel);
219 : extern int durable_rename(const char *oldfile, const char *newfile, int elevel);
220 : extern int durable_unlink(const char *fname, int elevel);
221 : extern void SyncDataDirectory(void);
222 : extern int data_sync_elevel(int elevel);
223 :
224 : static inline ssize_t
225 406913 : FileRead(File file, void *buffer, size_t amount, pgoff_t offset,
226 : uint32 wait_event_info)
227 : {
228 406913 : struct iovec iov = {
229 : .iov_base = buffer,
230 : .iov_len = amount
231 : };
232 :
233 406913 : return FileReadV(file, &iov, 1, offset, wait_event_info);
234 : }
235 :
236 : static inline ssize_t
237 189877 : FileWrite(File file, const void *buffer, size_t amount, pgoff_t offset,
238 : uint32 wait_event_info)
239 : {
240 189877 : struct iovec iov = {
241 : .iov_base = unconstify(void *, buffer),
242 : .iov_len = amount
243 : };
244 :
245 189877 : return FileWriteV(file, &iov, 1, offset, wait_event_info);
246 : }
247 :
248 : #endif /* FD_H */
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