patch to avoid race condition in rsync CVS

[Wayne Davison]

OK, here's a patch that tries to deal with the case of the rename
resulting in a copy.  It also attempts to deal with the possibility
that the source of the copy might not have read permissions set, and
the destination of the copy might not have write permissions.  This
passes "make check", but no other tests have been performed.

Comments?

..wayne..
-------------- next part --------------
--- backup.c	23 Feb 2004 07:03:03 -0000	1.27
+++ backup.c	25 Feb 2004 21:42:44 -0000
@@ -130,8 +130,8 @@ failure:
 /* robustly move a file, creating new directory structures if necessary */
 static int robust_move(char *src, char *dst)
 {
-	if (robust_rename(src, dst, 0755) != 0 && (errno != ENOENT
-	    || make_bak_dir(dst) < 0 || robust_rename(src, dst, 0755) != 0))
+	if (robust_rename(src, dst, 0755) < 0 && (errno != ENOENT
+	    || make_bak_dir(dst) < 0 || robust_rename(src, dst, 0755) < 0))
 		return -1;
 	return 0;
 }
--- rsync.c	25 Feb 2004 21:20:59 -0000	1.133
+++ rsync.c	25 Feb 2004 21:42:44 -0000
@@ -235,15 +235,19 @@ void finish_transfer(char *fname, char *
 	if (make_backups && !make_backup(fname))
 		return;
 
+	/* Change permissions before putting the file into place. */
+	set_perms(fnametmp, file, NULL, 0);
+
 	/* move tmp file over real file */
 	ret = robust_rename(fnametmp, fname, file->mode & INITACCESSPERMS);
-	if (ret != 0) {
+	if (ret < 0) {
 		rprintf(FERROR, "%s %s -> \"%s\": %s\n",
 		    ret == -2 ? "copy" : "rename",
 		    full_fname(fnametmp), fname, strerror(errno));
 		do_unlink(fnametmp);
-	} else {
-		set_perms(fname,file,NULL,0);
+	} else if (ret == 1) {
+		/* The file got copied, so set the permissions again. */
+		set_perms(fname, file, NULL, 0);
 	}
 }
 
--- t_stub.c	11 Sep 2003 04:48:13 -0000	1.4
+++ t_stub.c	25 Feb 2004 21:42:44 -0000
@@ -26,6 +26,7 @@
  * functions, so that module test harnesses can run standalone.
  **/
 
+int am_root = 0;
 int modify_window = 0;
 int module_id = -1;
 struct exclude_struct **server_exclude_list;
--- util.c	17 Feb 2004 23:13:10 -0000	1.132
+++ util.c	25 Feb 2004 21:42:44 -0000
@@ -28,6 +28,7 @@
 #include "rsync.h"
 
 extern int verbose;
+extern int am_root;
 
 int sanitize_paths = 0;
 
@@ -262,6 +263,8 @@ int copy_file(char *source, char *dest, 
 		return -1;
 	}
 
+	if (!am_root && !(mode & 0400))
+		mode |= 0400;
 	ofd = do_open(dest, O_WRONLY | O_CREAT | O_TRUNC | O_EXCL, mode);
 	if (ofd == -1) {
 		rprintf(FERROR,"open %s: %s\n",
@@ -353,8 +356,8 @@ int robust_unlink(char *fname)
 #endif
 }
 
-/* Returns 0 on success, -1 on most errors, and -2 if we got an error
- * trying to copy the file across file systems. */
+/* Returns 0 on successful rename, 1 if we successfully copied the file
+ * across filesystems, -1 on most errors, and -2 if copy_file() failed. */
 int robust_rename(char *from, char *to, int mode)
 {
 	int tries = 4;
@@ -371,10 +374,12 @@ int robust_rename(char *from, char *to, 
 			break;
 #endif
 		case EXDEV:
+			if (!am_root && !(mode & 0200))
+				do_chmod(from, (mode & CHMOD_BITS) | 0200);
 			if (copy_file(from, to, mode) != 0)
 				return -2;
 			do_unlink(from);
-			return 0;
+			return 1;
 		default:
 			return -1;
 		}