Create non-transferred files in a more atomic manner:

If a symlink, device, special-file, or hard-linked file is replacing
an existing non-directory, the new file is created using a temporary
filename and then renamed into place.  Also changed the handling of
a cluster of hard-linked symlinks/devices/special-files to always
ensure the first item in the cluster is correct, since it doesn't
really save any significant work to try to find an existing correct
item later in the cluster to link with.

1 files changed, 78 insertions, 32 deletions

diff --git a/generator.c b/generator.c
index 6f4fa4f0..df2434f5 100644
--- a/generator.c
+++ b/generator.c
@@ -95,6 +95,7 @@ extern struct stats stats;
 extern dev_t filesystem_dev;
 extern mode_t orig_umask;
 extern uid_t our_uid;
+extern char *tmpdir;
 extern char *basis_dir[MAX_BASIS_DIRS+1];
 extern struct file_list *cur_flist, *first_flist, *dir_flist;
 extern filter_rule_list filter_list, daemon_filter_list;
@@ -131,7 +132,7 @@ static int start_delete_delay_temp(void)
 	int save_dry_run = dry_run;
 
 	dry_run = 0;
-	if (!get_tmpname(fnametmp, "deldelay")
+	if (!get_tmpname(fnametmp, "deldelay", False)
 	 || (deldelay_fd = do_mkstemp(fnametmp, 0600)) < 0) {
 		rprintf(FINFO, "NOTE: Unable to create delete-delay temp file%s.\n",
 			inc_recurse ? "" : " -- switching to --delete-after");
@@ -1360,10 +1361,9 @@ static void recv_generator(char *fname, struct file_struct *file, int ndx,
 			char lnk[MAXPATHLEN];
 			int len;
 
-			if (!S_ISLNK(sx.st.st_mode))
-				statret = -1;
-			else if ((len = readlink(fname, lnk, MAXPATHLEN-1)) > 0
-			      && strncmp(lnk, sl, len) == 0 && sl[len] == '\0') {
+			if (S_ISLNK(sx.st.st_mode)
+			 && (len = readlink(fname, lnk, MAXPATHLEN-1)) > 0
+			 && strncmp(lnk, sl, len) == 0 && sl[len] == '\0') {
 				/* The link is pointing to the right place. */
 				set_file_attrs(fname, file, &sx, NULL, maybe_ATTRS_REPORT);
 				if (itemizing)
@@ -1376,10 +1376,6 @@ static void recv_generator(char *fname, struct file_struct *file, int ndx,
 					goto return_with_success;
 				goto cleanup;
 			}
-			/* Not the right symlink (or not a symlink), so
-			 * delete it. */
-			if (delete_item(fname, sx.st.st_mode, del_opts | DEL_FOR_SYMLINK) != 0)
-				goto cleanup;
 		} else if (basis_dir[0] != NULL) {
 			int j = try_dests_non(file, fname, ndx, fnamecmpbuf, &sx,
 					      itemizing, code);
@@ -1396,18 +1392,11 @@ static void recv_generator(char *fname, struct file_struct *file, int ndx,
 			} else if (j >= 0)
 				statret = 1;
 		}
-#ifdef SUPPORT_HARD_LINKS
-		if (preserve_hard_links && F_HLINK_NOT_LAST(file)) {
-			cur_flist->in_progress++;
-			goto cleanup;
-		}
-#endif
-		if (do_symlink(sl, fname) != 0) {
-			rsyserr(FERROR_XFER, errno, "symlink %s -> \"%s\" failed",
-				full_fname(fname), sl);
-		} else {
+		if (atomic_create(file, fname, sl, MAKEDEV(0, 0), &sx, statret == 0 ? DEL_FOR_SYMLINK : 0)) {
 			set_file_attrs(fname, file, NULL, NULL, 0);
 			if (itemizing) {
+				if (statret == 0 && !S_ISLNK(sx.st.st_mode))
+					statret = -1;
 				itemize(fname, file, ndx, statret, &sx,
 					ITEM_LOCAL_CHANGE|ITEM_REPORT_CHANGE, 0, NULL);
 			}
@@ -1430,13 +1419,13 @@ static void recv_generator(char *fname, struct file_struct *file, int ndx,
 	if ((am_root && preserve_devices && IS_DEVICE(file->mode))
 	 || (preserve_specials && IS_SPECIAL(file->mode))) {
 		dev_t rdev;
+		int del_for_flag = 0;
 		if (IS_DEVICE(file->mode)) {
 			uint32 *devp = F_RDEV_P(file);
 			rdev = MAKEDEV(DEV_MAJOR(devp), DEV_MINOR(devp));
 		} else
 			rdev = 0;
 		if (statret == 0) {
-			int del_for_flag;
 			if (IS_DEVICE(file->mode)) {
 				if (!IS_DEVICE(sx.st.st_mode))
 					statret = -1;
@@ -1461,8 +1450,6 @@ static void recv_generator(char *fname, struct file_struct *file, int ndx,
 					goto return_with_success;
 				goto cleanup;
 			}
-			if (delete_item(fname, sx.st.st_mode, del_opts | del_for_flag) != 0)
-				goto cleanup;
 		} else if (basis_dir[0] != NULL) {
 			int j = try_dests_non(file, fname, ndx, fnamecmpbuf, &sx,
 					      itemizing, code);
@@ -1479,21 +1466,12 @@ static void recv_generator(char *fname, struct file_struct *file, int ndx,
 			} else if (j >= 0)
 				statret = 1;
 		}
-#ifdef SUPPORT_HARD_LINKS
-		if (preserve_hard_links && F_HLINK_NOT_LAST(file)) {
-			cur_flist->in_progress++;
-			goto cleanup;
-		}
-#endif
 		if (DEBUG_GTE(GENR, 1)) {
 			rprintf(FINFO, "mknod(%s, 0%o, [%ld,%ld])\n",
 				fname, (int)file->mode,
 				(long)major(rdev), (long)minor(rdev));
 		}
-		if (do_mknod(fname, file->mode, rdev) < 0) {
-			rsyserr(FERROR_XFER, errno, "mknod %s failed",
-				full_fname(fname));
-		} else {
+		if (atomic_create(file, fname, NULL, rdev, &sx, del_for_flag)) {
 			set_file_attrs(fname, file, NULL, NULL, 0);
 			if (itemizing) {
 				itemize(fname, file, ndx, statret, &sx,
@@ -1813,6 +1791,74 @@ static void recv_generator(char *fname, struct file_struct *file, int ndx,
 	return;
 }
 
+/* If we are replacing an existing hard link, symlink, device, or special file,
+ * create a temp-name item and rename it into place.  Only a symlink or hard
+ * link puts a non-NULL value into the lnk arg.  Only a device puts a non-0
+ * value into the rdev arg.  Specify 0 for the del_for_flag if there is not a
+ * file to replace.  This returns 1 on success and 0 on failure. */
+int atomic_create(struct file_struct *file, char *fname, const char *lnk,
+		  dev_t rdev, stat_x *sxp, int del_for_flag)
+{
+	char tmpname[MAXPATHLEN];
+	const char *create_name;
+	int skip_atomic, dir_in_the_way = del_for_flag && S_ISDIR(sxp->st.st_mode);
+
+	if (!del_for_flag || dir_in_the_way || tmpdir || !get_tmpname(tmpname, fname, True))
+		skip_atomic = 1;
+	else
+		skip_atomic = 0;
+
+	if (del_for_flag) {
+		if (make_backups > 0 && !dir_in_the_way) {
+			if (!make_backup(fname, skip_atomic))
+				return 0;
+		} else if (skip_atomic) {
+			int del_opts = delete_mode || force_delete ? DEL_RECURSE : 0;
+			if (delete_item(fname, sxp->st.st_mode, del_opts | del_for_flag) != 0)
+				return 0;
+		}
+	}
+
+	create_name = skip_atomic ? fname : tmpname;
+
+	if (lnk) {
+#ifdef SUPPORT_LINKS
+		if (S_ISLNK(file->mode)
+#ifdef SUPPORT_HARD_LINKS /* The first symlink in a hard-linked cluster is always created. */
+		 && (!F_IS_HLINKED(file) || file->flags & FLAG_HLINK_FIRST)
+#endif
+		 ) {
+			if (do_symlink(lnk, create_name) < 0) {
+				rsyserr(FERROR_XFER, errno, "symlink %s -> \"%s\" failed",
+					full_fname(create_name), lnk);
+				return 0;
+			}
+		} else
+#endif
+#ifdef SUPPORT_HARD_LINKS
+		if (!hard_link_one(file, create_name, lnk, 0))
+			return 0;
+#endif
+	} else {
+		if (do_mknod(create_name, file->mode, rdev) < 0) {
+			rsyserr(FERROR_XFER, errno, "mknod %s failed",
+				full_fname(create_name));
+			return 0;
+		}
+	}
+
+	if (!skip_atomic) {
+		if (do_rename(tmpname, fname) < 0) {
+			rsyserr(FERROR_XFER, errno, "rename %s -> \"%s\" failed",
+				full_fname(tmpname), full_fname(fname));
+			do_unlink(tmpname);
+			return 0;
+		}
+	}
+
+	return 1;
+}
+
 #ifdef SUPPORT_HARD_LINKS
 static void handle_skipped_hlink(struct file_struct *file, int itemizing,
 				 enum logcode code, int f_out)