copydir.c File Reference

#include "postgres.h"
#include <fcntl.h>
#include <unistd.h>
#include <sys/stat.h>
#include "storage/copydir.h"
#include "storage/fd.h"
#include "miscadmin.h"
#include "pgstat.h"

Include dependency graph for copydir.c:

Go to the source code of this file.

Macros
#define	COPY_BUF_SIZE   (8 * BLCKSZ)

Functions
void	copydir (char *fromdir, char *todir, bool recurse)
void	copy_file (char *fromfile, char *tofile)

Macro Definition Documentation

#define COPY_BUF_SIZE   (8 * BLCKSZ)

Referenced by copy_file().

Function Documentation

void copy_file	(	char *	fromfile,
		char *	tofile
	)

Definition at line 135 of file copydir.c.

References buffer, CHECK_FOR_INTERRUPTS, CloseTransientFile(), COPY_BUF_SIZE, dstfd, ereport, errcode_for_file_access(), errmsg(), ERROR, OpenTransientFile(), palloc(), pfree(), PG_BINARY, pg_flush_data(), pgstat_report_wait_end(), pgstat_report_wait_start(), read, WAIT_EVENT_COPY_FILE_READ, WAIT_EVENT_COPY_FILE_WRITE, and write.

Referenced by copydir(), and ResetUnloggedRelationsInDbspaceDir().

{
    char       *buffer;
    int         srcfd;
    int         dstfd;
    int         nbytes;
    off_t       offset;

    /* Use palloc to ensure we get a maxaligned buffer */
#define COPY_BUF_SIZE (8 * BLCKSZ)

    buffer = palloc(COPY_BUF_SIZE);

    /*
     * Open the files
     */
    srcfd = OpenTransientFile(fromfile, O_RDONLY | PG_BINARY, 0);
    if (srcfd < 0)
        ereport(ERROR,
                (errcode_for_file_access(),
                 errmsg("could not open file \"%s\": %m", fromfile)));

    dstfd = OpenTransientFile(tofile, O_RDWR | O_CREAT | O_EXCL | PG_BINARY,
                              S_IRUSR | S_IWUSR);
    if (dstfd < 0)
        ereport(ERROR,
                (errcode_for_file_access(),
                 errmsg("could not create file \"%s\": %m", tofile)));

    /*
     * Do the data copying.
     */
    for (offset = 0;; offset += nbytes)
    {
        /* If we got a cancel signal during the copy of the file, quit */
        CHECK_FOR_INTERRUPTS();

        pgstat_report_wait_start(WAIT_EVENT_COPY_FILE_READ);
        nbytes = read(srcfd, buffer, COPY_BUF_SIZE);
        pgstat_report_wait_end();
        if (nbytes < 0)
            ereport(ERROR,
                    (errcode_for_file_access(),
                     errmsg("could not read file \"%s\": %m", fromfile)));
        if (nbytes == 0)
            break;
        errno = 0;
        pgstat_report_wait_start(WAIT_EVENT_COPY_FILE_WRITE);
        if ((int) write(dstfd, buffer, nbytes) != nbytes)
        {
            pgstat_report_wait_end();
            /* if write didn't set errno, assume problem is no disk space */
            if (errno == 0)
                errno = ENOSPC;
            ereport(ERROR,
                    (errcode_for_file_access(),
                     errmsg("could not write to file \"%s\": %m", tofile)));
        }
        pgstat_report_wait_end();

        /*
         * We fsync the files later but first flush them to avoid spamming the
         * cache and hopefully get the kernel to start writing them out before
         * the fsync comes.
         */
        pg_flush_data(dstfd, offset, nbytes);
    }

    if (CloseTransientFile(dstfd))
        ereport(ERROR,
                (errcode_for_file_access(),
                 errmsg("could not close file \"%s\": %m", tofile)));

    CloseTransientFile(srcfd);

    pfree(buffer);
}

void copydir	(	char *	fromdir,
		char *	todir,
		bool	recurse
	)

Definition at line 37 of file copydir.c.

References AllocateDir(), CHECK_FOR_INTERRUPTS, copy_file(), copydir(), dirent::d_name, enableFsync, ereport, errcode_for_file_access(), errmsg(), ERROR, FreeDir(), fsync_fname(), lstat, MAXPGPATH, mkdir, NULL, ReadDir(), and snprintf().

Referenced by copydir(), createdb(), dbase_redo(), and movedb().

{
    DIR        *xldir;
    struct dirent *xlde;
    char        fromfile[MAXPGPATH * 2];
    char        tofile[MAXPGPATH * 2];

    if (mkdir(todir, S_IRWXU) != 0)
        ereport(ERROR,
                (errcode_for_file_access(),
                 errmsg("could not create directory \"%s\": %m", todir)));

    xldir = AllocateDir(fromdir);
    if (xldir == NULL)
        ereport(ERROR,
                (errcode_for_file_access(),
                 errmsg("could not open directory \"%s\": %m", fromdir)));

    while ((xlde = ReadDir(xldir, fromdir)) != NULL)
    {
        struct stat fst;

        /* If we got a cancel signal during the copy of the directory, quit */
        CHECK_FOR_INTERRUPTS();

        if (strcmp(xlde->d_name, ".") == 0 ||
            strcmp(xlde->d_name, "..") == 0)
            continue;

        snprintf(fromfile, sizeof(fromfile), "%s/%s", fromdir, xlde->d_name);
        snprintf(tofile, sizeof(tofile), "%s/%s", todir, xlde->d_name);

        if (lstat(fromfile, &fst) < 0)
            ereport(ERROR,
                    (errcode_for_file_access(),
                     errmsg("could not stat file \"%s\": %m", fromfile)));

        if (S_ISDIR(fst.st_mode))
        {
            /* recurse to handle subdirectories */
            if (recurse)
                copydir(fromfile, tofile, true);
        }
        else if (S_ISREG(fst.st_mode))
            copy_file(fromfile, tofile);
    }
    FreeDir(xldir);

    /*
     * Be paranoid here and fsync all files to ensure the copy is really done.
     * But if fsync is disabled, we're done.
     */
    if (!enableFsync)
        return;

    xldir = AllocateDir(todir);
    if (xldir == NULL)
        ereport(ERROR,
                (errcode_for_file_access(),
                 errmsg("could not open directory \"%s\": %m", todir)));

    while ((xlde = ReadDir(xldir, todir)) != NULL)
    {
        struct stat fst;

        if (strcmp(xlde->d_name, ".") == 0 ||
            strcmp(xlde->d_name, "..") == 0)
            continue;

        snprintf(tofile, sizeof(tofile), "%s/%s", todir, xlde->d_name);

        /*
         * We don't need to sync subdirectories here since the recursive
         * copydir will do it before it returns
         */
        if (lstat(tofile, &fst) < 0)
            ereport(ERROR,
                    (errcode_for_file_access(),
                     errmsg("could not stat file \"%s\": %m", tofile)));

        if (S_ISREG(fst.st_mode))
            fsync_fname(tofile, false);
    }
    FreeDir(xldir);

    /*
     * It's important to fsync the destination directory itself as individual
     * file fsyncs don't guarantee that the directory entry for the file is
     * synced. Recent versions of ext4 have made the window much wider but
     * it's been true for ext3 and other filesystems in the past.
     */
    fsync_fname(todir, true);
}