Re: FYI: bug-fix: cp would fail to write through a dangling symlink

[Paul Eggert]

In rereading my proposed patch
<http://lists.gnu.org/archive/html/bug-coreutils/2007-06/msg00145.html>
I discovered that I sent in the wrong ChangeLog entry.  I
inadvertently omitted the part of the ChangeLog that described Jim
Meyering's contribution.  My apologies!  Here's the corrected
ChangeLog entry for that patch:

2007-06-14  Paul Eggert  <address@hidden>

        * 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, used 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) says 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.

2007-06-14  Jim Meyering  <address@hidden>

        * 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.