From 3d53e7fe1c31aa440cc9708c7c51db6b78c07653 Mon Sep 17 00:00:00 2001 From: =?utf8?q?P=C3=A1draig=20Brady?= Date: Thu, 12 Apr 2012 12:47:30 +0100 Subject: [PATCH] cp: change --attributes-only to not truncate existing files * src/copy.c (copy_reg): Don't truncate an existing file, to support copying attributes between existing files. The original use case only considered creating new files, and it would be a very unusual use case to be relying on the truncating behavior. * doc/coreutils.texi (cp invocation): Mention the non truncating behavior. * tests/cp/attr-existing: A new test to ensure O_TRUNC skipped. * tests/Makefile.am: Reference the new test. * NEWS: Mention the change in behavior. --- NEWS | 5 +++++ doc/coreutils.texi | 6 +++--- src/copy.c | 4 +++- tests/Makefile.am | 1 + tests/cp/attr-existing | 29 +++++++++++++++++++++++++++++ 5 files changed, 41 insertions(+), 4 deletions(-) create mode 100755 tests/cp/attr-existing diff --git a/NEWS b/NEWS index c8d2bbc..42df465 100644 --- a/NEWS +++ b/NEWS @@ -2,6 +2,11 @@ GNU coreutils NEWS -*- outline -*- * Noteworthy changes in release ?.? (????-??-??) [?] +** Changes in behavior + + cp --attributes-only no longer truncates any existing destination file, + allowing for more general copying of attributes from one file to another. + * Noteworthy changes in release 8.16 (2012-03-26) [stable] diff --git a/doc/coreutils.texi b/doc/coreutils.texi index 510abb9..1fbf051 100644 --- a/doc/coreutils.texi +++ b/doc/coreutils.texi @@ -7649,9 +7649,9 @@ Equivalent to @option{-dR --preserve=all} with the reduced diagnostics. @itemx --attributes-only @opindex --attributes-only -Preserve the specified attributes of the original files in the copy, -but do not copy any data. See the @option{--preserve} option for -controlling which attributes to copy. +Copy only the specified attributes of the source file to the destination. +If the destination already exists, do not alter its contents. +See the @option{--preserve} option for controlling which attributes to copy. @item -b @itemx @w{@kbd{--backup}[=@var{method}]} diff --git a/src/copy.c b/src/copy.c index f63a726..414fbe0 100644 --- a/src/copy.c +++ b/src/copy.c @@ -826,7 +826,9 @@ copy_reg (char const *src_name, char const *dst_name, by the specs for both cp and mv. */ if (! *new_dst) { - dest_desc = open (dst_name, O_WRONLY | O_TRUNC | O_BINARY); + int open_flags = + O_WRONLY | O_BINARY | (x->data_copy_required ? O_TRUNC : 0); + dest_desc = open (dst_name, open_flags); dest_errno = errno; /* When using cp --preserve=context to copy to an existing destination, diff --git a/tests/Makefile.am b/tests/Makefile.am index 011051a..4d73a92 100644 --- a/tests/Makefile.am +++ b/tests/Makefile.am @@ -320,6 +320,7 @@ TESTS = \ chown/separator \ cp/abuse \ cp/acl \ + cp/attr-existing \ cp/backup-1 \ cp/backup-dir \ cp/backup-is-src \ diff --git a/tests/cp/attr-existing b/tests/cp/attr-existing new file mode 100755 index 0000000..9cf0ffc --- /dev/null +++ b/tests/cp/attr-existing @@ -0,0 +1,29 @@ +#!/bin/sh +# Make sure cp --attributes-only doesn't truncate existing data + +# Copyright 2012 Free Software Foundation, Inc. + +# 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 3 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, see . + +. "${srcdir=.}/init.sh"; path_prepend_ ../src +print_ver_ cp + +printf '1' > file1 +printf '2' > file2 +printf '2' > file2.exp + +cp --attributes-only file1 file2 || fail=1 +cmp file2 file2.exp || fail=1 + +Exit $fail -- 2.7.4