* src/safe.c (traverse_another_path): Don't report errors here.
* src/patch.c (main): Instead, recognize and report them here. Detect when an
output file name is invalid; it doesn't make sense to try creating a
reject file based on the same outbut file name in that case.

* src/util.c (make_tempfile): Remove error reporting here.
* src/inp.c (plan_b): Readd error reporting here.
* src/patch.c (main): Likewise.
* src/pch.c (open_patch_file): Likewise.

When a file has already been renamed, make sure it is not renamed back to its
old name.  Reported by Guido Draheim.
* src/patch.c (main): Make sure we never rename a file back to its previous
name. Report when a file was renamed already.
* tests/copy-rename: Add "already renamed" test cases.

Signed-off-by: Quentin Casasnovas <quentin.casasnovas@oracle.com>

Use the symlink-safe replacements for system calls in many places throughout
the code: In some places this makes patch safe against path traversal attacks;
in other places, it saves the kernel from having to re-traverse the pathnames.
* src/inp.c (plan_b): Use safe_open() + fdopen() instead of fopen().
* src/util.c (copy_attr): Document why we are safe here.
(create_backup): Use safe_open() instead of creat().

* src/patch.c (main): Make sure we don't close() outfd after passing it on to
fdopen(): the file descriptor might have been reused in the meantime.

* src/patch.c (main): Allow there_is_another_patch() to set the
skip_rest_of_patch flag.
* src/pch.c (intuit_diff_type): For renames and copies, also check the "other"
file name.
(pch_copy, pch_rename): Now that both names are checked in intuit_diff_type(),
we know they are defined here.

* src/patch.c (locate_hunk): Start trying to apply the hunk at the minimum
offset which puts the hunk in the valid range of lines. This will often still
be offset 0.

* src/patch.c (get_some_switches): The function savebuf (and therefore savestr)
copies strings using malloc.  If malloc fails, NULL is returned.  This is
intentional behavior so that in case of failure during "plan a" patching, "plan
b" can step in.  The return value has to be properly checked for NULL.  If the
return value must not be NULL, use xstrdup instead.

* src/patch.c: Improve error message.
* tests/create-delete: Update the test case.