file.c

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/*
 *  file.c
 *
 *  file system operations
 *
 *  Copyright (c) 2010-2026, PostgreSQL Global Development Group
 *  src/bin/pg_upgrade/file.c
 */
 
#include "postgres_fe.h"
 
#include <sys/stat.h>
#include <limits.h>
#include <fcntl.h>
#ifdef HAVE_COPYFILE_H
#include <copyfile.h>
#endif
#ifdef __linux__
#include <sys/ioctl.h>
#include <linux/fs.h>
#endif
 
#include "common/file_perm.h"
#include "pg_upgrade.h"
 
 
/*
 * cloneFile()
 *
 * Clones/reflinks a relation file from src to dst.
 *
 * schemaName/relName are relation's SQL name (used for error messages only).
 */
void
cloneFile(const char *src, const char *dst,
          const char *schemaName, const char *relName)
{
#if defined(HAVE_COPYFILE) && defined(COPYFILE_CLONE_FORCE)
    if (copyfile(src, dst, NULL, COPYFILE_CLONE_FORCE) < 0)
        pg_fatal("error while cloning relation \"%s.%s\" (\"%s\" to \"%s\"): %m",
                 schemaName, relName, src, dst);
#elif defined(__linux__) && defined(FICLONE)
    int         src_fd;
    int         dest_fd;
 
    if ((src_fd = open(src, O_RDONLY | PG_BINARY, 0)) < 0)
        pg_fatal("error while cloning relation \"%s.%s\": could not open file \"%s\": %m",
                 schemaName, relName, src);
 
    if ((dest_fd = open(dst, O_RDWR | O_CREAT | O_EXCL | PG_BINARY,
                        pg_file_create_mode)) < 0)
        pg_fatal("error while cloning relation \"%s.%s\": could not create file \"%s\": %m",
                 schemaName, relName, dst);
 
    if (ioctl(dest_fd, FICLONE, src_fd) < 0)
    {
        int         save_errno = errno;
 
        unlink(dst);
 
        pg_fatal("error while cloning relation \"%s.%s\" (\"%s\" to \"%s\"): %s",
                 schemaName, relName, src, dst, strerror(save_errno));
    }
 
    close(src_fd);
    close(dest_fd);
#endif
}
 
 
/*
 * copyFile()
 *
 * Copies a relation file from src to dst.
 * schemaName/relName are relation's SQL name (used for error messages only).
 */
void
copyFile(const char *src, const char *dst,
         const char *schemaName, const char *relName)
{
#ifndef WIN32
    int         src_fd;
    int         dest_fd;
    char       *buffer;
 
    if ((src_fd = open(src, O_RDONLY | PG_BINARY, 0)) < 0)
        pg_fatal("error while copying relation \"%s.%s\": could not open file \"%s\": %m",
                 schemaName, relName, src);
 
    if ((dest_fd = open(dst, O_RDWR | O_CREAT | O_EXCL | PG_BINARY,
                        pg_file_create_mode)) < 0)
        pg_fatal("error while copying relation \"%s.%s\": could not create file \"%s\": %m",
                 schemaName, relName, dst);
 
    /* copy in fairly large chunks for best efficiency */
#define COPY_BUF_SIZE (50 * BLCKSZ)
 
    buffer = (char *) pg_malloc(COPY_BUF_SIZE);
 
    /* perform data copying i.e read src source, write to destination */
    while (true)
    {
        ssize_t     nbytes = read(src_fd, buffer, COPY_BUF_SIZE);
 
        if (nbytes < 0)
            pg_fatal("error while copying relation \"%s.%s\": could not read file \"%s\": %m",
                     schemaName, relName, src);
 
        if (nbytes == 0)
            break;
 
        errno = 0;
        if (write(dest_fd, buffer, nbytes) != nbytes)
        {
            /* if write didn't set errno, assume problem is no disk space */
            if (errno == 0)
                errno = ENOSPC;
            pg_fatal("error while copying relation \"%s.%s\": could not write file \"%s\": %m",
                     schemaName, relName, dst);
        }
    }
 
    pg_free(buffer);
    close(src_fd);
    close(dest_fd);
 
#else                           /* WIN32 */
 
    if (CopyFile(src, dst, true) == 0)
    {
        _dosmaperr(GetLastError());
        pg_fatal("error while copying relation \"%s.%s\" (\"%s\" to \"%s\"): %m",
                 schemaName, relName, src, dst);
    }
 
#endif                          /* WIN32 */
}
 
 
/*
 * copyFileByRange()
 *
 * Copies a relation file from src to dst.
 * schemaName/relName are relation's SQL name (used for error messages only).
 */
void
copyFileByRange(const char *src, const char *dst,
                const char *schemaName, const char *relName)
{
#ifdef HAVE_COPY_FILE_RANGE
    int         src_fd;
    int         dest_fd;
    ssize_t     nbytes;
 
    if ((src_fd = open(src, O_RDONLY | PG_BINARY, 0)) < 0)
        pg_fatal("error while copying relation \"%s.%s\": could not open file \"%s\": %m",
                 schemaName, relName, src);
 
    if ((dest_fd = open(dst, O_RDWR | O_CREAT | O_EXCL | PG_BINARY,
                        pg_file_create_mode)) < 0)
        pg_fatal("error while copying relation \"%s.%s\": could not create file \"%s\": %m",
                 schemaName, relName, dst);
 
    do
    {
        nbytes = copy_file_range(src_fd, NULL, dest_fd, NULL, SSIZE_MAX, 0);
        if (nbytes < 0)
            pg_fatal("error while copying relation \"%s.%s\": could not copy file range from \"%s\" to \"%s\": %m",
                     schemaName, relName, src, dst);
    }
    while (nbytes > 0);
 
    close(src_fd);
    close(dest_fd);
#endif
}
 
 
/*
 * linkFile()
 *
 * Hard-links a relation file from src to dst.
 * schemaName/relName are relation's SQL name (used for error messages only).
 */
void
linkFile(const char *src, const char *dst,
         const char *schemaName, const char *relName)
{
    if (link(src, dst) < 0)
        pg_fatal("error while creating link for relation \"%s.%s\" (\"%s\" to \"%s\"): %m",
                 schemaName, relName, src, dst);
}
 
 
void
check_file_clone(void)
{
    char        existing_file[MAXPGPATH];
    char        new_link_file[MAXPGPATH];
 
    snprintf(existing_file, sizeof(existing_file), "%s/PG_VERSION", old_cluster.pgdata);
    snprintf(new_link_file, sizeof(new_link_file), "%s/PG_VERSION.clonetest", new_cluster.pgdata);
    unlink(new_link_file);      /* might fail */
 
#if defined(HAVE_COPYFILE) && defined(COPYFILE_CLONE_FORCE)
    if (copyfile(existing_file, new_link_file, NULL, COPYFILE_CLONE_FORCE) < 0)
        pg_fatal("could not clone file between old and new data directories: %m");
#elif defined(__linux__) && defined(FICLONE)
    {
        int         src_fd;
        int         dest_fd;
 
        if ((src_fd = open(existing_file, O_RDONLY | PG_BINARY, 0)) < 0)
            pg_fatal("could not open file \"%s\": %m",
                     existing_file);
 
        if ((dest_fd = open(new_link_file, O_RDWR | O_CREAT | O_EXCL | PG_BINARY,
                            pg_file_create_mode)) < 0)
            pg_fatal("could not create file \"%s\": %m",
                     new_link_file);
 
        if (ioctl(dest_fd, FICLONE, src_fd) < 0)
            pg_fatal("could not clone file between old and new data directories: %m");
 
        close(src_fd);
        close(dest_fd);
    }
#else
    pg_fatal("file cloning not supported on this platform");
#endif
 
    unlink(new_link_file);
}
 
void
check_copy_file_range(void)
{
    char        existing_file[MAXPGPATH];
    char        new_link_file[MAXPGPATH];
 
    snprintf(existing_file, sizeof(existing_file), "%s/PG_VERSION", old_cluster.pgdata);
    snprintf(new_link_file, sizeof(new_link_file), "%s/PG_VERSION.copy_file_range_test", new_cluster.pgdata);
    unlink(new_link_file);      /* might fail */
 
#if defined(HAVE_COPY_FILE_RANGE)
    {
        int         src_fd;
        int         dest_fd;
 
        if ((src_fd = open(existing_file, O_RDONLY | PG_BINARY, 0)) < 0)
            pg_fatal("could not open file \"%s\": %m",
                     existing_file);
 
        if ((dest_fd = open(new_link_file, O_RDWR | O_CREAT | O_EXCL | PG_BINARY,
                            pg_file_create_mode)) < 0)
            pg_fatal("could not create file \"%s\": %m",
                     new_link_file);
 
        if (copy_file_range(src_fd, NULL, dest_fd, NULL, SSIZE_MAX, 0) < 0)
            pg_fatal("could not copy file range between old and new data directories: %m");
 
        close(src_fd);
        close(dest_fd);
    }
#else
    pg_fatal("copy_file_range not supported on this platform");
#endif
 
    unlink(new_link_file);
}
 
void
check_hard_link(transferMode transfer_mode)
{
    char        existing_file[MAXPGPATH];
    char        new_link_file[MAXPGPATH];
 
    snprintf(existing_file, sizeof(existing_file), "%s/PG_VERSION", old_cluster.pgdata);
    snprintf(new_link_file, sizeof(new_link_file), "%s/PG_VERSION.linktest", new_cluster.pgdata);
    unlink(new_link_file);      /* might fail */
 
    if (link(existing_file, new_link_file) < 0)
    {
        if (transfer_mode == TRANSFER_MODE_LINK)
            pg_fatal("could not create hard link between old and new data directories: %m\n"
                     "In link mode the old and new data directories must be on the same file system.");
        else if (transfer_mode == TRANSFER_MODE_SWAP)
            pg_fatal("could not create hard link between old and new data directories: %m\n"
                     "In swap mode the old and new data directories must be on the same file system.");
        else
            pg_fatal("unrecognized transfer mode");
    }
 
    unlink(new_link_file);
}