t9300: document fast-import empty path issues

When given an empty path, fast-import sometimes reports "missing"
instead of using the root tree object.  On top of this, for "ls" and
file copy (but not move) it dies with "Empty path component found in
input".

Document this behaviour with failing test cases.

Reported-by: Dave Abrahams <dave@boostpro.com>
Signed-off-by: John Keeping <john@keeping.me.uk>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
fast-import: set valid mode on root tree in "ls"

This prevents a failure later when we lift the restriction on ls with
the empty path.

Signed-off-by: John Keeping <john@keeping.me.uk>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
fast-import: allow ls or filecopy of the root tree

Commit 178e1de (fast-import: don't allow 'ls' of path with empty
components, 2012-03-09) restricted paths which:

    . contain an empty directory component (e.g. foo//bar is invalid),
    . end with a directory separator (e.g. foo/ is invalid),
    . start with a directory separator (e.g. /foo is invalid).

However, the implementation also caught the empty path, which should
represent the root tree.  Relax this restriction so that the empty path
is explicitly allowed and refers to the root tree.

Reported-by: Dave Abrahams <dave@boostpro.com>
Signed-off-by: John Keeping <john@keeping.me.uk>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
fast-import: allow moving the root tree

Because fast-import.c::tree_content_remove does not check for the empty
path, it is not possible to move the root tree to a subdirectory.
Instead the error "Path  not in branch" is produced (note the double
space where the empty path has been inserted).

Fix this by explicitly checking for the empty path and handling it.

Signed-off-by: John Keeping <john@keeping.me.uk>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
clean: remove unused variable "seen"

Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
move struct pathspec and related functions to pathspec.[ch]

Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
pathspec: i18n-ize error strings in pathspec parsing code

Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
pathspec: add copy_pathspec

Because free_pathspec wants to free "items" pointer in the pathspec
structure, a simple structure assignment is not enough if you want to
copy an existing pathspec into another.  Freeing the original will
damage the copy unless a deep copy is made.

Note that the strings in pathspec->items->match and the array
pathspec->raw[] are still shared between the original and the copy.

Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
add parse_pathspec() that converts cmdline args to struct pathspec

Currently to fill a struct pathspec, we do:

   const char **paths;
   paths = get_pathspec(prefix, argv);
   ...
   init_pathspec(&pathspec, paths);

"paths" can only carry bare strings, which loses information from
command line arguments such as pathspec magic or the prefix part's
length for each argument.

parse_pathspec() is introduced to combine the two calls into one. The
plan is gradually replace all get_pathspec() and init_pathspec() with
parse_pathspec(). get_pathspec() now becomes a thin wrapper of
parse_pathspec().

parse_pathspec() allows the caller to reject the pathspec magics that
it does not support. When a new pathspec magic is introduced, we can
enable it per command after making sure that all underlying code has no
problem with the new magic.

"flags" parameter is currently unused. But it would allow callers to
pass certain instructions to parse_pathspec, for example forcing
literal pathspec when no magic is used.

With the introduction of parse_pathspec, there are now two functions
that can initialize struct pathspec: init_pathspec and
parse_pathspec. Any semantic changes in struct pathspec must be
reflected in both functions. init_pathspec() will be phased out in
favor of parse_pathspec().

Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
parse_pathspec: save original pathspec for reporting

We usually use pathspec_item's match field for pathspec error
reporting. However "match" (or "raw") does not show the magic part,
which will play more important role later on. Preserve exact user
input for reporting.

Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
parse_pathspec: add PATHSPEC_PREFER_{CWD,FULL} flags

We have two ways of dealing with empty pathspec:

1. limit it to current prefix
2. match the entire working directory

Some commands go with #1, some #2. get_pathspec() and parse_pathspec()
only support #1. Make parse_pathspec() reject empty pathspec by
default. #1 and #2 can be specified via new flags. This makes it more
expressive about default behavior at command level.

Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
convert some get_pathspec() calls to parse_pathspec()

These call sites follow the pattern:

   paths = get_pathspec(prefix, argv);
   init_pathspec(&pathspec, paths);

which can be converted into a single parse_pathspec() call.

Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
parse_pathspec: add special flag for max_depth feature

match_pathspec_depth() and tree_entry_interesting() check max_depth
field in order to support "git grep --max-depth". The feature
activation is tied to "recursive" field, which led to some unwanted
activation, e.g. 5c8eeb8 (diff-index: enable recursive pathspec
matching in unpack_trees - 2012-01-15).

This patch decouples the activation from "recursive" field, puts it in
"magic" field instead. This makes sure that only "git grep" can
activate this feature. And because parse_pathspec knows when the
feature is not used, it does not need to sort pathspec (required for
max_depth to work correctly). A small win for non-grep cases.

Even though a new magic flag is introduced, no magic syntax is. The
magic can be only enabled by parse_pathspec() caller. We might someday
want to support ":(maxdepth:10)src." It all depends on actual use
cases.

max_depth feature cannot be enabled via init_pathspec() anymore. But
that's ok because init_pathspec() is on its way to /dev/null.

Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
parse_pathspec: support stripping submodule trailing slashes

This flag is equivalent to builtin/ls-files.c:strip_trailing_slashes()
and is intended to replace that function when ls-files is converted to
use parse_pathspec.

Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
parse_pathspec: support stripping/checking submodule paths

PATHSPEC_SYMLINK_LEADING_PATH and _STRIP_SUBMODULE_SLASH_EXPENSIVE are
respectively the alternate implementation of
pathspec.c:die_if_path_beyond_symlink() and
pathspec.c:check_path_for_gitlink(). They are intended to replace
those functions when builtin/add.c and builtin/check-ignore.c are
converted to use parse_pathspec.

Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
parse_pathspec: support prefixing original patterns

This makes 'original' suitable for passing to an external command
because all pathspec magic is left in place, provided that the
external command understands pathspec. The prefixing is needed because
we usually launch a subcommand at worktree's top directory and the
subcommand can no longer calculate the prefix itself.

This slightly affects the original purpose of 'original'
(i.e. reporting). We should report without prefixing. So only turn
this flag on when you know you are about to pass the result straight
away to an external command.

Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
guard against new pathspec magic in pathspec matching code

GUARD_PATHSPEC() marks pathspec-sensitive code, basically all those
that touch anything in 'struct pathspec' except fields "nr" and
"original". GUARD_PATHSPEC() is not supposed to fail. It's mainly to
help the designers catch unsupported codepaths.

Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
clean: convert to use parse_pathspec

Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
commit: convert to use parse_pathspec

Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
status: convert to use parse_pathspec

Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>