src/include/storage/fd.h

   1 /*-------------------------------------------------------------------------
   2  *
   3  * fd.h
   4  *        Virtual file descriptor definitions.
   5  *
   6  *
   7  * Portions Copyright (c) 1996-2021, 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
  48 typedef enum RecoveryInitSyncMethod
  49 {
  50         RECOVERY_INIT_SYNC_METHOD_FSYNC,
  51         RECOVERY_INIT_SYNC_METHOD_SYNCFS
  52 }                       RecoveryInitSyncMethod;
  53
  54 struct iovec;                                   /* avoid including port/pg_iovec.h here */
  55
  56 typedef int File;
  57
  58
  59 /* GUC parameter */
  60 extern PGDLLIMPORT int max_files_per_process;
  61 extern PGDLLIMPORT bool data_sync_retry;
  62 extern int      recovery_init_sync_method;
  63
  64 /*
  65  * This is private to fd.c, but exported for save/restore_backend_variables()
  66  */
  67 extern int      max_safe_fds;
  68
  69 /*
  70  * On Windows, we have to interpret EACCES as possibly meaning the same as
  71  * ENOENT, because if a file is unlinked-but-not-yet-gone on that platform,
  72  * that's what you get.  Ugh.  This code is designed so that we don't
  73  * actually believe these cases are okay without further evidence (namely,
  74  * a pending fsync request getting canceled ... see ProcessSyncRequests).
  75  */
  76 #ifndef WIN32
  77 #define FILE_POSSIBLY_DELETED(err)      ((err) == ENOENT)
  78 #else
  79 #define FILE_POSSIBLY_DELETED(err)      ((err) == ENOENT || (err) == EACCES)
  80 #endif
  81
  82 /*
  83  * O_DIRECT is not standard, but almost every Unix has it.  We translate it
  84  * to the appropriate Windows flag in src/port/open.c.  We simulate it with
  85  * fcntl(F_NOCACHE) on macOS inside fd.c's open() wrapper.  We use the name
  86  * PG_O_DIRECT rather than defining O_DIRECT in that case (probably not a good
  87  * idea on a Unix).
  88  */
  89 #if defined(O_DIRECT)
  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, int amount, uint32 wait_event_info);
 108 extern int      FileRead(File file, char *buffer, int amount, off_t offset, uint32 wait_event_info);
 109 extern int      FileWrite(File file, char *buffer, int amount, off_t offset, uint32 wait_event_info);
 110 extern int      FileSync(File file, uint32 wait_event_info);
 111 extern off_t FileSize(File file);
 112 extern int      FileTruncate(File file, off_t offset, uint32 wait_event_info);
 113 extern void FileWriteback(File file, off_t offset, off_t nbytes, uint32 wait_event_info);
 114 extern char *FilePathName(File file);
 115 extern int      FileGetRawDesc(File file);
 116 extern int      FileGetRawFlags(File file);
 117 extern mode_t FileGetRawMode(File file);
 118
 119 /* Operations used for sharing named temporary files */
 120 extern File PathNameCreateTemporaryFile(const char *name, bool error_on_failure);
 121 extern File PathNameOpenTemporaryFile(const char *path, int mode);
 122 extern bool PathNameDeleteTemporaryFile(const char *name, bool error_on_failure);
 123 extern void PathNameCreateTemporaryDir(const char *base, const char *name);
 124 extern void PathNameDeleteTemporaryDir(const char *name);
 125 extern void TempTablespacePath(char *path, Oid tablespace);
 126
 127 /* Operations that allow use of regular stdio --- USE WITH CAUTION */
 128 extern FILE *AllocateFile(const char *name, const char *mode);
 129 extern int      FreeFile(FILE *file);
 130
 131 /* Operations that allow use of pipe streams (popen/pclose) */
 132 extern FILE *OpenPipeStream(const char *command, const char *mode);
 133 extern int      ClosePipeStream(FILE *file);
 134
 135 /* Operations to allow use of the <dirent.h> library routines */
 136 extern DIR *AllocateDir(const char *dirname);
 137 extern struct dirent *ReadDir(DIR *dir, const char *dirname);
 138 extern struct dirent *ReadDirExtended(DIR *dir, const char *dirname,
 139                                                                           int elevel);
 140 extern int      FreeDir(DIR *dir);
 141
 142 /* Operations to allow use of a plain kernel FD, with automatic cleanup */
 143 extern int      OpenTransientFile(const char *fileName, int fileFlags);
 144 extern int      OpenTransientFilePerm(const char *fileName, int fileFlags, mode_t fileMode);
 145 extern int      CloseTransientFile(int fd);
 146
 147 /* If you've really really gotta have a plain kernel FD, use this */
 148 extern int      BasicOpenFile(const char *fileName, int fileFlags);
 149 extern int      BasicOpenFilePerm(const char *fileName, int fileFlags, mode_t fileMode);
 150
 151 /* Use these for other cases, and also for long-lived BasicOpenFile FDs */
 152 extern bool AcquireExternalFD(void);
 153 extern void ReserveExternalFD(void);
 154 extern void ReleaseExternalFD(void);
 155
 156 /* Make a directory with default permissions */
 157 extern int      MakePGDirectory(const char *directoryName);
 158
 159 /* Miscellaneous support routines */
 160 extern void InitFileAccess(void);
 161 extern void InitTemporaryFileAccess(void);
 162 extern void set_max_safe_fds(void);
 163 extern void closeAllVfds(void);
 164 extern void SetTempTablespaces(Oid *tableSpaces, int numSpaces);
 165 extern bool TempTablespacesAreSet(void);
 166 extern int      GetTempTablespaces(Oid *tableSpaces, int numSpaces);
 167 extern Oid      GetNextTempTableSpace(void);
 168 extern void AtEOXact_Files(bool isCommit);
 169 extern void AtEOSubXact_Files(bool isCommit, SubTransactionId mySubid,
 170                                                           SubTransactionId parentSubid);
 171 extern void RemovePgTempFiles(void);
 172 extern void RemovePgTempFilesInDir(const char *tmpdirname, bool missing_ok,
 173                                                                    bool unlink_all);
 174 extern bool looks_like_temp_rel_name(const char *name);
 175
 176 extern int      pg_fsync(int fd);
 177 extern int      pg_fsync_no_writethrough(int fd);
 178 extern int      pg_fsync_writethrough(int fd);
 179 extern int      pg_fdatasync(int fd);
 180 extern void pg_flush_data(int fd, off_t offset, off_t amount);
 181 extern ssize_t pg_pwritev_with_retry(int fd,
 182                                                                          const struct iovec *iov,
 183                                                                          int iovcnt,
 184                                                                          off_t offset);
 185 extern int      pg_truncate(const char *path, off_t length);
 186 extern void fsync_fname(const char *fname, bool isdir);
 187 extern int      fsync_fname_ext(const char *fname, bool isdir, bool ignore_perm, int elevel);
 188 extern int      durable_rename(const char *oldfile, const char *newfile, int loglevel);
 189 extern int      durable_unlink(const char *fname, int loglevel);
 190 extern int      durable_rename_excl(const char *oldfile, const char *newfile, int loglevel);
 191 extern void SyncDataDirectory(void);
 192 extern int      data_sync_elevel(int elevel);
 193
 194 /* Filename components */
 195 #define PG_TEMP_FILES_DIR "pgsql_tmp"
 196 #define PG_TEMP_FILE_PREFIX "pgsql_tmp"
 197
 198 #endif                                                  /* FD_H */