Clean up the internal of the name-hash mechanism used to work
around case insensitivity on some filesystems to cleanly fix a
long-standing API glitch where the caller of cache_name_exists()
that ask about a directory with a counted string was required to
have '/' at one location past the end of the string.

* es/name-hash-no-trailing-slash-in-dirs:
  dir: revert work-around for retired dangerous behavior
  name-hash: stop storing trailing '/' on paths in index_state.dir_hash
  employ new explicit "exists in index?" API
  name-hash: refactor polymorphic index_name_exists()

Earlier we started rejecting an attempt to add 0{40} object name to
the index and to tree objects, but it sometimes is necessary to
allow so to be able to use tools like filter-branch to correct such
broken tree objects.

* jk/write-broken-index-with-nul-sha1:
  write_index: optionally allow broken null sha1s

When 5102c617 (Add case insensitivity support for directories when using
git status, 2010-10-03) added directories to the name-hash there was
only a single hash table in which both real cache entries and leading
directory prefixes were registered. To distinguish between the two types
of entries, directories were stored with a trailing '/'.

2092678c (name-hash.c: fix endless loop with core.ignorecase=true,
2013-02-28), however, moved directories to a separate hash table
(index_state.dir_hash) but retained the (now) redundant trailing '/',
thus callers continue to bear the burden of ensuring the slash's
presence before searching the index for a directory. Eliminate this
redundancy by storing paths in the dir-hash without the trailing '/'.

An important benefit of this change is that it eliminates undocumented
and dangerous behavior of dir.c:directory_exists_in_index_icase() in
which it assumes not only that it can validly access one character
beyond the end of its incoming directory argument, but also that that
character will unconditionally be a '/'. This perilous behavior was
"tolerated" because the string passed in by its lone caller always had a
'/' in that position, however, things broke [1] when 2eac2a4c (ls-files
-k: a directory only can be killed if the index has a non-directory,
2013-08-15) added a new caller which failed to respect the undocumented
assumption.

[1]: http://thread.gmane.org/gmane.comp.version-control.git/232727

Signed-off-by: Eric Sunshine <sunshine@sunshineco.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

Each caller of index_name_exists() knows whether it is looking for a
directory or a file, and can avoid the unnecessary indirection of
index_name_exists() by instead calling index_dir_exists() or
index_file_exists() directly.

Invoking the appropriate search function explicitly will allow a
subsequent patch to relieve callers of the artificial burden of having
to add a trailing '/' to the pathname given to index_dir_exists().

Signed-off-by: Eric Sunshine <sunshine@sunshineco.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

The code that reads from a region that mmaps an on-disk index
assumed that "int"/"short" are always 32/16 bits.

* tg/index-struct-sizes:
  read-cache: use fixed width integer types

"git mv A B" when moving a submodule A does "the right thing",
inclusing relocating its working tree and adjusting the paths in
the .gitmodules file.

* jl/submodule-mv: (53 commits)
  rm: delete .gitmodules entry of submodules removed from the work tree
  mv: update the path entry in .gitmodules for moved submodules
  submodule.c: add .gitmodules staging helper functions
  mv: move submodules using a gitfile
  mv: move submodules together with their work trees
  rm: do not set a variable twice without intermediate reading.
  t6131 - skip tests if on case-insensitive file system
  parse_pathspec: accept :(icase)path syntax
  pathspec: support :(glob) syntax
  pathspec: make --literal-pathspecs disable pathspec magic
  pathspec: support :(literal) syntax for noglob pathspec
  kill limit_pathspec_to_literal() as it's only used by parse_pathspec()
  parse_pathspec: preserve prefix length via PATHSPEC_PREFIX_ORIGIN
  parse_pathspec: make sure the prefix part is wildcard-free
  rename field "raw" to "_raw" in struct pathspec
  tree-diff: remove the use of pathspec's raw[] in follow-rename codepath
  remove match_pathspec() in favor of match_pathspec_depth()
  remove init_pathspec() in favor of parse_pathspec()
  remove diff_tree_{setup,release}_paths
  convert common_prefix() to use struct pathspec
  ...

Commit 4337b58 (do not write null sha1s to on-disk index,
2012-07-28) added a safety check preventing git from writing
null sha1s into the index. The intent was to catch errors in
other parts of the code that might let such an entry slip
into the index (or worse, a tree).

Some existing repositories may have invalid trees that
contain null sha1s already, though.  Until 4337b58, a common
way to clean this up would be to use git-filter-branch's
index-filter to repair such broken entries.  That now fails
when filter-branch tries to write out the index.

Introduce a GIT_ALLOW_NULL_SHA1 environment variable to
relax this check and make it easier to recover from such a
history.

It is tempting to not involve filter-branch in this commit
at all, and instead require the user to manually invoke

	GIT_ALLOW_NULL_SHA1=1 git filter-branch ...

to perform an index-filter on a history with trees with null
sha1s.  That would be slightly safer, but requires some
specialized knowledge from the user.  So let's set the
GIT_ALLOW_NULL_SHA1 variable automatically when checking out
the to-be-filtered trees.  Advice on using filter-branch to
remove such entries already exists on places like
stackoverflow, and this patch makes it Just Work again on
recent versions of git.

Further commands that touch the index will still notice and
fail, unless they actually remove the broken entries.  A
filter-branch whose filters do not touch the index at all
will not error out (since we complain of the null sha1 only
on writing, not when making a tree out of the index), but
this is acceptable, as we still print a loud warning, so the
problem is unlikely to go unnoticed.

Signed-off-by: Jeff King <peff@peff.net>
Reviewed-by: Jonathan Nieder <jrnieder@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

Use the fixed width integer types uint16_t and uint32_t for on-disk
structures; unsigned short and unsigned int do not have a guaranteed
size.

Signed-off-by: Thomas Gummerer <t.gummerer@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

Signed-off-by: Ondřej Bílka <neleai@seznam.cz>
Reviewed-by: Marc Branchaud <marcnarc@xiplink.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

* rs/discard-index-discard-array:
  read-cache: free cache in discard_index
  read-cache: add simple performance test