file_utils.h File Reference

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Functions
int	fsync_fname (const char *fname, bool isdir, const char *progname)
void	fsync_pgdata (const char *pg_data, const char *progname, int serverVersion)
void	fsync_dir_recurse (const char *dir, const char *progname)
int	durable_rename (const char *oldfile, const char *newfile, const char *progname)
int	fsync_parent_path (const char *fname, const char *progname)

Function Documentation

int durable_rename	(	const char *	oldfile,
		const char *	newfile,
		const char *	progname
	)

Definition at line 348 of file file_utils.c.

References _, close, fd(), fsync, fsync_fname(), fsync_parent_path(), PG_BINARY, and strerror().

{
    int         fd;

    /*
     * First fsync the old and target path (if it exists), to ensure that they
     * are properly persistent on disk. Syncing the target file is not
     * strictly necessary, but it makes it easier to reason about crashes;
     * because it's then guaranteed that either source or target file exists
     * after a crash.
     */
    if (fsync_fname(oldfile, false, progname) != 0)
        return -1;

    fd = open(newfile, PG_BINARY | O_RDWR, 0);
    if (fd < 0)
    {
        if (errno != ENOENT)
        {
            fprintf(stderr, _("%s: could not open file \"%s\": %s\n"),
                    progname, newfile, strerror(errno));
            return -1;
        }
    }
    else
    {
        if (fsync(fd) != 0)
        {
            fprintf(stderr, _("%s: could not fsync file \"%s\": %s\n"),
                    progname, newfile, strerror(errno));
            close(fd);
            return -1;
        }
        close(fd);
    }

    /* Time to do the real deal... */
    if (rename(oldfile, newfile) != 0)
    {
        fprintf(stderr, _("%s: could not rename file \"%s\" to \"%s\": %s\n"),
                progname, oldfile, newfile, strerror(errno));
        return -1;
    }

    /*
     * To guarantee renaming the file is persistent, fsync the file with its
     * new name, and its containing directory.
     */
    if (fsync_fname(newfile, false, progname) != 0)
        return -1;

    if (fsync_parent_path(newfile, progname) != 0)
        return -1;

    return 0;
}

void fsync_dir_recurse	(	const char *	dir,
		const char *	progname
	)

Definition at line 124 of file file_utils.c.

References fsync_fname(), and walkdir().

Referenced by _CloseArchive().

{
    /*
     * If possible, hint to the kernel that we're soon going to fsync the data
     * directory and its contents.
     */
#ifdef PG_FLUSH_DATA_WORKS
    walkdir(dir, pre_sync_fname, false, progname);
#endif

    walkdir(dir, fsync_fname, false, progname);
}

int fsync_fname	(	const char *	fname,
		bool	isdir,
		const char *	progname
	)

Definition at line 263 of file file_utils.c.

References _, close, fd(), fsync, PG_BINARY, and strerror().

Referenced by durable_rename(), fsync_dir_recurse(), fsync_parent_path(), and fsync_pgdata().

{
    int         fd;
    int         flags;
    int         returncode;

    /*
     * Some OSs require directories to be opened read-only whereas other
     * systems don't allow us to fsync files opened read-only; so we need both
     * cases here.  Using O_RDWR will cause us to fail to fsync files that are
     * not writable by our userid, but we assume that's OK.
     */
    flags = PG_BINARY;
    if (!isdir)
        flags |= O_RDWR;
    else
        flags |= O_RDONLY;

    /*
     * Open the file, silently ignoring errors about unreadable files (or
     * unsupported operations, e.g. opening a directory under Windows), and
     * logging others.
     */
    fd = open(fname, flags);
    if (fd < 0)
    {
        if (errno == EACCES || (isdir && errno == EISDIR))
            return 0;
        fprintf(stderr, _("%s: could not open file \"%s\": %s\n"),
                progname, fname, strerror(errno));
        return -1;
    }

    returncode = fsync(fd);

    /*
     * Some OSes don't allow us to fsync directories at all, so we can ignore
     * those errors. Anything else needs to be reported.
     */
    if (returncode != 0 && !(isdir && errno == EBADF))
    {
        fprintf(stderr, _("%s: could not fsync file \"%s\": %s\n"),
                progname, fname, strerror(errno));
        (void) close(fd);
        return -1;
    }

    (void) close(fd);
    return 0;
}

int fsync_parent_path	(	const char *	fname,
		const char *	progname
	)

Definition at line 321 of file file_utils.c.

References fsync_fname(), get_parent_directory(), MAXPGPATH, and strlcpy().

Referenced by durable_rename().

{
    char        parentpath[MAXPGPATH];

    strlcpy(parentpath, fname, MAXPGPATH);
    get_parent_directory(parentpath);

    /*
     * get_parent_directory() returns an empty string if the input argument is
     * just a file name (see comments in path.c), so handle that as being the
     * current directory.
     */
    if (strlen(parentpath) == 0)
        strlcpy(parentpath, ".", MAXPGPATH);

    if (fsync_fname(parentpath, true, progname) != 0)
        return -1;

    return 0;
}

void fsync_pgdata	(	const char *	pg_data,
		const char *	progname,
		int	serverVersion
	)

Definition at line 58 of file file_utils.c.

References _, fsync_fname(), lstat, MAXPGPATH, MINIMUM_VERSION_FOR_PG_WAL, snprintf(), strerror(), and walkdir().

Referenced by BaseBackup(), and main().

{
    bool        xlog_is_symlink;
    char        pg_wal[MAXPGPATH];
    char        pg_tblspc[MAXPGPATH];

    /* handle renaming of pg_xlog to pg_wal in post-10 clusters */
    snprintf(pg_wal, MAXPGPATH, "%s/%s", pg_data,
             serverVersion < MINIMUM_VERSION_FOR_PG_WAL ? "pg_xlog" : "pg_wal");
    snprintf(pg_tblspc, MAXPGPATH, "%s/pg_tblspc", pg_data);

    /*
     * If pg_wal is a symlink, we'll need to recurse into it separately,
     * because the first walkdir below will ignore it.
     */
    xlog_is_symlink = false;

#ifndef WIN32
    {
        struct stat st;

        if (lstat(pg_wal, &st) < 0)
            fprintf(stderr, _("%s: could not stat file \"%s\": %s\n"),
                    progname, pg_wal, strerror(errno));
        else if (S_ISLNK(st.st_mode))
            xlog_is_symlink = true;
    }
#else
    if (pgwin32_is_junction(pg_wal))
        xlog_is_symlink = true;
#endif

    /*
     * If possible, hint to the kernel that we're soon going to fsync the data
     * directory and its contents.
     */
#ifdef PG_FLUSH_DATA_WORKS
    walkdir(pg_data, pre_sync_fname, false, progname);
    if (xlog_is_symlink)
        walkdir(pg_wal, pre_sync_fname, false, progname);
    walkdir(pg_tblspc, pre_sync_fname, true, progname);
#endif

    /*
     * Now we do the fsync()s in the same order.
     *
     * The main call ignores symlinks, so in addition to specially processing
     * pg_wal if it's a symlink, pg_tblspc has to be visited separately with
     * process_symlinks = true.  Note that if there are any plain directories
     * in pg_tblspc, they'll get fsync'd twice.  That's not an expected case
     * so we don't worry about optimizing it.
     */
    walkdir(pg_data, fsync_fname, false, progname);
    if (xlog_is_symlink)
        walkdir(pg_wal, fsync_fname, false, progname);
    walkdir(pg_tblspc, fsync_fname, true, progname);
}