Correct cp's handling of destination symlinks in some cases.

* NEWS: "cp" no longer considers a destination symlink to be the
same as the referenced file when copying links or making backups.
* src/copy.c (copy_reg): When following a symlink, use the
followed name in later chown etc. requests, so that the created
file is affected, rather than the symlink.  Use O_NOFOLLOW on
source when not dereferencing symlinks; this avoids a race.
Preserve errno correctly when doing multiple open attempts on the
destination.
(copy_internal): Follow destination symlinks only when copying a
regular file and only when we don't intend to remove or rename the
destination first, regardless of whether following source
symlinks; this is because since POSIX and tradition (e.g.,
FreeBSD) say we should ordinarily follow destination symlinks if
the system calls would ordinarily do so.
* src/copy.h (struct cp_options): Add comment that 'dereference'
is only for source files.
* src/cp.c (usage): Note that --derereference etc. are only for
source files.
(make_dir_parents_private): Follow symlinks, regardless of whether
--dereference is specified, because these are destination symlinks.
* tests/cp/same-file: Adjust tests to match revised behavior.
Filter out perror output since it might vary from host to host.
Use sed alone instead of also using echo.

* doc/coreutils.texi (cp invocation): Document the behavior better when
the destination is a symlink.  Clarify source versus destination
symlinks.  Describe the new behavior for destination symlinks.

2007-06-15  Jim Meyering  <jim@meyering.net>

* src/copy.c: Include "canonicalize.h".
(copy_reg): Use canonicalize_filename_mode to follow the symlink,
so that we can always open with O_EXCL and avoid a race.

1 files changed, 15 insertions, 9 deletions

diff --git a/tests/cp/same-file b/tests/cp/same-file
index 44d5dd74c..8e0593e40 100755
--- a/tests/cp/same-file
+++ b/tests/cp/same-file
@@ -89,9 +89,15 @@ for args in 'foo symlink' 'symlink foo' 'foo foo' 'sl1 sl2' 'foo hardlink'; do
 	cp $options $args 2>_err
 	echo $? $options
 
-	# Normalize the program name in the error output,
+	# Normalize the program name and diagnostics in the error output,
 	# and put brackets around the output.
-	test -s _err && echo "[`sed 's/^[^:][^:]*:/cp:/' _err`]"
+	if test -s _err; then
+	  sed '
+	    s/^[^:]*:\([^:]*\).*/cp:\1/
+	    1s/^/[/
+	    $s/$/]/
+	  ' _err
+        fi
 	# Strip off all but the file names.
 	ls="`ls -gG --ignore=_err . \
 	    | sed \
@@ -128,13 +134,13 @@ cat <<\EOF > $expected
 0 -bd (foo symlink symlink.~1~ -> foo)
 0 -bf (foo symlink symlink.~1~ -> foo)
 0 -bdf (foo symlink symlink.~1~ -> foo)
-0 -l (foo symlink -> foo)
+1 -l [cp: cannot create link `symlink'] (foo symlink -> foo)
 0 -dl (foo symlink -> foo)
-0 -fl (foo symlink -> foo)
+0 -fl (foo symlink)
 0 -dfl (foo symlink)
-0 -bl (foo symlink -> foo)
+0 -bl (foo symlink symlink.~1~ -> foo)
 0 -bdl (foo symlink symlink.~1~ -> foo)
-0 -bfl (foo symlink -> foo)
+0 -bfl (foo symlink symlink.~1~ -> foo)
 0 -bdfl (foo symlink symlink.~1~ -> foo)
 
 1 [cp: `symlink' and `foo' are the same file] (foo symlink -> foo)
@@ -179,10 +185,10 @@ cat <<\EOF > $expected
 0 -bd (foo sl1 -> foo sl2 -> foo sl2.~1~ -> foo)
 0 -bf (foo sl1 -> foo sl2 sl2.~1~ -> foo)
 0 -bdf (foo sl1 -> foo sl2 -> foo sl2.~1~ -> foo)
-0 -l (foo sl1 -> foo sl2 -> foo)
+1 -l [cp: cannot create link `sl2'] (foo sl1 -> foo sl2 -> foo)
 0 -fl (foo sl1 -> foo sl2 -> foo)
-0 -bl (foo sl1 -> foo sl2 -> foo)
-0 -bfl (foo sl1 -> foo sl2 -> foo)
+0 -bl (foo sl1 -> foo sl2 -> foo sl2.~1~ -> foo)
+0 -bfl (foo sl1 -> foo sl2 -> foo sl2.~1~ -> foo)
 
 1 [cp: `foo' and `hardlink' are the same file] (foo hardlink)
 1 -d [cp: `foo' and `hardlink' are the same file] (foo hardlink)