rsync/hlink.c

/*
   Copyright (C) Andrew Tridgell 1996
   Copyright (C) Paul Mackerras 1996
   Copyright (C) 2002 by Martin Pool <mbp@samba.org>

   This program is free software; you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation; either version 2 of the License, or
   (at your option) any later version.

   This program is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU General Public License for more details.

   You should have received a copy of the GNU General Public License
   along with this program; if not, write to the Free Software
   Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
*/

#include "rsync.h"

extern int dry_run;
extern int verbose;

#if SUPPORT_HARD_LINKS
static int hlink_compare(struct file_struct **file1, struct file_struct **file2)
{
	struct file_struct *f1 = *file1;
	struct file_struct *f2 = *file2;

	if (f1->F_DEV != f2->F_DEV)
		return (int) (f1->F_DEV > f2->F_DEV ? 1 : -1);

	if (f1->F_INODE != f2->F_INODE)
		return (int) (f1->F_INODE > f2->F_INODE ? 1 : -1);

	return file_compare(file1, file2);
}

static struct file_struct **hlink_list;
static int hlink_count;
#endif

void init_hard_links(struct file_list *flist)
{
#if SUPPORT_HARD_LINKS
	int i;

	if (flist->count < 2)
		return;

	if (hlink_list)
		free(hlink_list);

	if (!(hlink_list = new_array(struct file_struct *, flist->count)))
		out_of_memory("init_hard_links");

/*	we'll want to restore the memcpy when we purge the
 *	hlink list after the sort.
 *	memcpy(hlink_list, flist->files, sizeof(hlink_list[0]) * flist->count);	
 */
	hlink_count = 0;
	for (i = 0; i < flist->count; i++) {
		if (flist->files[i]->link_u.idev)
			hlink_list[hlink_count++] = flist->files[i];
	}

	qsort(hlink_list, hlink_count,
	      sizeof(hlink_list[0]), (int (*)()) hlink_compare);

	if (!hlink_count) {
		free(hlink_list);
		hlink_list = NULL;
	} else if (!(hlink_list = realloc_array(hlink_list,
					struct file_struct *, hlink_count)))
		out_of_memory("init_hard_links");
#endif
}

/* check if a file should be skipped because it is the same as an
   earlier hard link */
int check_hard_link(struct file_struct *file)
{
#if SUPPORT_HARD_LINKS
	int low = 0, high = hlink_count - 1;
	int ret = 0;

	if (!hlink_list || !file->link_u.idev)
		return 0;

	while (low != high) {
		int mid = (low + high) / 2;
		ret = hlink_compare(&hlink_list[mid], &file);
		if (ret == 0) {
			low = mid;
			break;
		}
		if (ret > 0)
			high = mid;
		else
			low = mid + 1;
	}

	/* XXX: To me this looks kind of dodgy -- why do we use [low]
	 * here and [low-1] below? -- mbp */
	if (hlink_compare(&hlink_list[low], &file) != 0)
		return 0;

	if (low > 0 &&
	    file->F_DEV == hlink_list[low - 1]->F_DEV &&
	    file->F_INODE == hlink_list[low - 1]->F_INODE) {
		if (verbose >= 2) {
			rprintf(FINFO, "check_hard_link: \"%s\" is a hard link to file %d, \"%s\"\n",
				f_name(file), low-1, f_name(hlink_list[low-1]));
		}
		return 1;
	}
#endif

	return 0;
}


#if SUPPORT_HARD_LINKS
static void hard_link_one(int i)
{
	STRUCT_STAT st1, st2;
	char *hlink2, *hlink1 = f_name(hlink_list[i - 1]);

	if (link_stat(hlink1, &st1) != 0)
		return;

	hlink2 = f_name(hlink_list[i]);
	if (link_stat(hlink2, &st2) != 0) {
		if (do_link(hlink1, hlink2)) {
			if (verbose > 0) {
				rprintf(FINFO, "link %s => %s : %s\n",
					hlink2, hlink1, strerror(errno));
			}
			return;
		}
	} else {
		if (st2.st_dev == st1.st_dev && st2.st_ino == st1.st_ino)
			return;

		if (robust_unlink(hlink2) || do_link(hlink1, hlink2)) {
			if (verbose > 0) {
				rprintf(FINFO, "link %s => %s : %s\n",
					hlink2, hlink1, strerror(errno));
			}
			return;
		}
	}
	if (verbose > 0)
		rprintf(FINFO, "%s => %s\n", hlink2, hlink1);
}
#endif



/**
 * Create any hard links in the global hlink_list.  They were put
 * there by running init_hard_links on the filelist.
 **/
void do_hard_links(void)
{
#if SUPPORT_HARD_LINKS
	int i;

	if (!hlink_list)
		return;

	for (i = 1; i < hlink_count; i++) {
		if (hlink_list[i]->basename && hlink_list[i - 1]->basename &&
		    hlink_list[i]->F_DEV == hlink_list[i - 1]->F_DEV &&
		    hlink_list[i]->F_INODE == hlink_list[i - 1]->F_INODE) {
			hard_link_one(i);
		}
	}
#endif
}