default should proceed at the speed of the disk. Previously /dev/urandom
was used if available, which is relatively slow on GNU/Linux systems.
+** Improved robustness
+
+ cp would exit successfully after copying less than the full contents
+ of a file larger than ~4000 bytes from a linux-/proc file system to a
+ destination file system with a fundamental block size of 4KiB or greater.
+ Reading into a 4KiB-or-larger buffer, cp's "read" syscall would return
+ a value smaller than 4096, and cp would interpret that as EOF (POSIX
+ allows this). This optimization, now removed, saved 50% of cp's read
+ syscalls when copying small files. Affected linux kernels: at least
+ 2.6.9 through 2.6.29.
+ [the optimization was introduced in coreutils-6.0]
+
** Portability
`id -G $USER` now works correctly even on Darwin and NetBSD. Previously it
}
last_write_made_hole = false;
- /* A short read on a regular file means EOF. */
- if (n_read != buf_size && S_ISREG (src_open_sb.st_mode))
- break;
+ /* It is tempting to return early here upon a short read from a
+ regular file. That would save the final read syscall for each
+ file. Unfortunately that doesn't work for certain files in
+ /proc with linux kernels from at least 2.6.9 .. 2.6.29. */
}
}
--- /dev/null
+#!/bin/sh
+# exercise cp's short-read failure when operating on >4KB files in /proc
+
+# Copyright (C) 2009 Free Software Foundation, Inc.
+
+# This program is free software: you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+# GNU General Public License for more details.
+
+# You should have received a copy of the GNU General Public License
+# along with this program. If not, see <http://www.gnu.org/licenses/>.
+
+if test "$VERBOSE" = yes; then
+ set -x
+ cp --version
+fi
+
+. $srcdir/test-lib.sh
+
+fail=0
+kall=/proc/kallsyms
+
+test -r $kall || skip_test_ "your system lacks $kall"
+
+# Before coreutils-7.3, cp would copy less than 4KiB of this 1MB+ file.
+cp $kall 1 || fail=1
+cat $kall > 2 || fail=1
+compare 1 2 || fail=1
+
+# Also check md5sum, just for good measure.
+md5sum $kall > 3 || fail=1
+md5sum 2 > 4 || fail=1
+
+# Remove each file name before comparing checksums.
+sed 's/ .*//' 3 > sum.proc || fail=1
+sed 's/ .*//' 4 > sum.2 || fail=1
+compare sum.proc sum.2 || fail=1
+
+Exit $fail