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1110 commits

Author SHA1 Message Date
Junio C Hamano
98c57ea6f0 Merge branch 'sb/diff-color-move'
The output from "git diff --summary" was broken in a recent topic
that has been merged to 'master' and lost a LF after reporting of
mode change.  This has been fixed.

* sb/diff-color-move:
  diff: correct newline in summary for renamed files
2017-10-03 15:42:49 +09:00
Junio C Hamano
14a8168e2f Merge branch 'rj/no-sign-compare'
Many codepaths have been updated to squelch -Wsign-compare
warnings.

* rj/no-sign-compare:
  ALLOC_GROW: avoid -Wsign-compare warnings
  cache.h: hex2chr() - avoid -Wsign-compare warnings
  commit-slab.h: avoid -Wsign-compare warnings
  git-compat-util.h: xsize_t() - avoid -Wsign-compare warnings
2017-09-29 11:23:42 +09:00
Stefan Beller
58aaced444 diff: correct newline in summary for renamed files
In 146fdb0dfe (diff.c: emit_diff_symbol learns about DIFF_SYMBOL_SUMMARY,
2017-06-29), the conversion from direct printing to the symbol emission
dropped the new line character for renamed, copied and rewritten files.

Add the emission of a newline, add a test for this case.

Reported-by: Linus Torvalds <torvalds@linux-foundation.org>
Helped-by: Jeff King <peff@peff.net>
Signed-off-by: Stefan Beller <sbeller@google.com>
Reviewed-by: Jonathan Nieder <jrnieder@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-09-28 13:15:59 +09:00
Junio C Hamano
c50424a6f0 Merge branch 'jk/write-in-full-fix'
Many codepaths did not diagnose write failures correctly when disks
go full, due to their misuse of write_in_full() helper function,
which have been corrected.

* jk/write-in-full-fix:
  read_pack_header: handle signed/unsigned comparison in read result
  config: flip return value of store_write_*()
  notes-merge: use ssize_t for write_in_full() return value
  pkt-line: check write_in_full() errors against "< 0"
  convert less-trivial versions of "write_in_full() != len"
  avoid "write_in_full(fd, buf, len) != len" pattern
  get-tar-commit-id: check write_in_full() return against 0
  config: avoid "write_in_full(fd, buf, len) < len" pattern
2017-09-25 15:24:06 +09:00
Ramsay Jones
071bcaab64 ALLOC_GROW: avoid -Wsign-compare warnings
Signed-off-by: Ramsay Jones <ramsay@ramsayjones.plus.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-09-22 13:21:11 +09:00
Junio C Hamano
d811ba1897 Merge branch 'rs/strbuf-leakfix'
Many leaks of strbuf have been fixed.

* rs/strbuf-leakfix: (34 commits)
  wt-status: release strbuf after use in wt_longstatus_print_tracking()
  wt-status: release strbuf after use in read_rebase_todolist()
  vcs-svn: release strbuf after use in end_revision()
  utf8: release strbuf on error return in strbuf_utf8_replace()
  userdiff: release strbuf after use in userdiff_get_textconv()
  transport-helper: release strbuf after use in process_connect_service()
  sequencer: release strbuf after use in save_head()
  shortlog: release strbuf after use in insert_one_record()
  sha1_file: release strbuf on error return in index_path()
  send-pack: release strbuf on error return in send_pack()
  remote: release strbuf after use in set_url()
  remote: release strbuf after use in migrate_file()
  remote: release strbuf after use in read_remote_branches()
  refs: release strbuf on error return in write_pseudoref()
  notes: release strbuf after use in notes_copy_from_stdin()
  merge: release strbuf after use in write_merge_heads()
  merge: release strbuf after use in save_state()
  mailinfo: release strbuf on error return in handle_boundary()
  mailinfo: release strbuf after use in handle_from()
  help: release strbuf on error return in exec_woman_emacs()
  ...
2017-09-19 10:47:57 +09:00
Jeff King
06f46f237a avoid "write_in_full(fd, buf, len) != len" pattern
The return value of write_in_full() is either "-1", or the
requested number of bytes[1]. If we make a partial write
before seeing an error, we still return -1, not a partial
value. This goes back to f6aa66cb95 (write_in_full: really
write in full or return error on disk full., 2007-01-11).

So checking anything except "was the return value negative"
is pointless. And there are a couple of reasons not to do
so:

  1. It can do a funny signed/unsigned comparison. If your
     "len" is signed (e.g., a size_t) then the compiler will
     promote the "-1" to its unsigned variant.

     This works out for "!= len" (unless you really were
     trying to write the maximum size_t bytes), but is a
     bug if you check "< len" (an example of which was fixed
     recently in config.c).

     We should avoid promoting the mental model that you
     need to check the length at all, so that new sites are
     not tempted to copy us.

  2. Checking for a negative value is shorter to type,
     especially when the length is an expression.

  3. Linus says so. In d34cf19b89 (Clean up write_in_full()
     users, 2007-01-11), right after the write_in_full()
     semantics were changed, he wrote:

       I really wish every "write_in_full()" user would just
       check against "<0" now, but this fixes the nasty and
       stupid ones.

     Appeals to authority aside, this makes it clear that
     writing it this way does not have an intentional
     benefit. It's a historical curiosity that we never
     bothered to clean up (and which was undoubtedly
     cargo-culted into new sites).

So let's convert these obviously-correct cases (this
includes write_str_in_full(), which is just a wrapper for
write_in_full()).

[1] A careful reader may notice there is one way that
    write_in_full() can return a different value. If we ask
    write() to write N bytes and get a return value that is
    _larger_ than N, we could return a larger total. But
    besides the fact that this would imply a totally broken
    version of write(), it would already invoke undefined
    behavior. Our internal remaining counter is an unsigned
    size_t, which means that subtracting too many byte will
    wrap it around to a very large number. So we'll instantly
    begin reading off the end of the buffer, trying to write
    gigabytes (or petabytes) of data.

Signed-off-by: Jeff King <peff@peff.net>
Reviewed-by: Jonathan Nieder <jrnieder@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-09-14 15:17:59 +09:00
Rene Scharfe
5a612017eb diff: release strbuf after use in show_stats()
Signed-off-by: Rene Scharfe <l.s.r@web.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-09-07 08:49:27 +09:00
Rene Scharfe
348eda249e diff: release strbuf after use in show_rename_copy()
Signed-off-by: Rene Scharfe <l.s.r@web.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-09-07 08:49:27 +09:00
Rene Scharfe
fa842d843d diff: release strbuf after use in diff_summary()
Signed-off-by: Rene Scharfe <l.s.r@web.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-09-07 08:49:27 +09:00
Jeff King
076aa2cbda tempfile: auto-allocate tempfiles on heap
The previous commit taught the tempfile code to give up
ownership over tempfiles that have been renamed or deleted.
That makes it possible to use a stack variable like this:

  struct tempfile t;

  create_tempfile(&t, ...);
  ...
  if (!err)
          rename_tempfile(&t, ...);
  else
          delete_tempfile(&t);

But doing it this way has a high potential for creating
memory errors. The tempfile we pass to create_tempfile()
ends up on a global linked list, and it's not safe for it to
go out of scope until we've called one of those two
deactivation functions.

Imagine that we add an early return from the function that
forgets to call delete_tempfile(). With a static or heap
tempfile variable, the worst case is that the tempfile hangs
around until the program exits (and some functions like
setup_shallow_temporary rely on this intentionally, creating
a tempfile and then leaving it for later cleanup).

But with a stack variable as above, this is a serious memory
error: the variable goes out of scope and may be filled with
garbage by the time the tempfile code looks at it.  Let's
see if we can make it harder to get this wrong.

Since many callers need to allocate arbitrary numbers of
tempfiles, we can't rely on static storage as a general
solution. So we need to turn to the heap. We could just ask
all callers to pass us a heap variable, but that puts the
burden on them to call free() at the right time.

Instead, let's have the tempfile code handle the heap
allocation _and_ the deallocation (when the tempfile is
deactivated and removed from the list).

This changes the return value of all of the creation
functions. For the cleanup functions (delete and rename),
we'll add one extra bit of safety: instead of taking a
tempfile pointer, we'll take a pointer-to-pointer and set it
to NULL after freeing the object. This makes it safe to
double-call functions like delete_tempfile(), as the second
call treats the NULL input as a noop. Several callsites
follow this pattern.

The resulting patch does have a fair bit of noise, as each
caller needs to be converted to handle:

  1. Storing a pointer instead of the struct itself.

  2. Passing the pointer instead of taking the struct
     address.

  3. Handling a "struct tempfile *" return instead of a file
     descriptor.

We could play games to make this less noisy. For example, by
defining the tempfile like this:

  struct tempfile {
	struct heap_allocated_part_of_tempfile {
                int fd;
                ...etc
        } *actual_data;
  }

Callers would continue to have a "struct tempfile", and it
would be "active" only when the inner pointer was non-NULL.
But that just makes things more awkward in the long run.
There aren't that many callers, so we can simply bite
the bullet and adjust all of them. And the compiler makes it
easy for us to find them all.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-09-06 17:19:54 +09:00
Jeff King
49bd0fc222 tempfile: do not delete tempfile on failed close
When close_tempfile() fails, we delete the tempfile and
reset the fields of the tempfile struct. This makes it
easier for callers to return without cleaning up, but it
also makes this common pattern:

  if (close_tempfile(tempfile))
	return error_errno("error closing %s", tempfile->filename.buf);

wrong, because the "filename" field has been reset after the
failed close. And it's not easy to fix, as in many cases we
don't have another copy of the filename (e.g., if it was
created via one of the mks_tempfile functions, and we just
have the original template string).

Let's drop the feature that a failed close automatically
deletes the file. This puts the burden on the caller to do
the deletion themselves, but this isn't that big a deal.
Callers which do:

  if (write(...) || close_tempfile(...)) {
	delete_tempfile(...);
	return -1;
  }

already had to call delete when the write() failed, and so
aren't affected. Likewise, any caller which just calls die()
in the error path is OK; we'll delete the tempfile during
the atexit handler.

Because this patch changes the semantics of close_tempfile()
without changing its signature, all callers need to be
manually checked and converted to the new scheme. This patch
covers all in-tree callers, but there may be others for
not-yet-merged topics. To catch these, we rename the
function to close_tempfile_gently(), which will attract
compile-time attention to new callers. (Technically the
original could be considered "gentle" already in that it
didn't die() on errors, but this one is even more so).

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-09-06 17:19:53 +09:00
Jeff King
45c6b1ed24 always check return value of close_tempfile
If close_tempfile() encounters an error, then it deletes the
tempfile and resets the "struct tempfile". But many code
paths ignore the return value and continue to use the
tempfile. Instead, we should generally treat this the same
as a write() error.

Note that in the postimage of some of these cases our error
message will be bogus after a failed close because we look
at tempfile->filename (either directly or via get_tempfile_path).
But after the failed close resets the tempfile object, this
is guaranteed to be the empty string. That will be addressed
in a future patch (because there are many more cases of the
same problem than just these instances).

Note also in the hunk in gpg-interface.c that it's fine to
call delete_tempfile() in the error path, even if
close_tempfile() failed and already deleted the file. The
tempfile code is smart enough to know the second deletion is
a noop.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-09-06 17:19:53 +09:00
Junio C Hamano
eabdcd4ab4 Merge branch 'jt/packmigrate'
Code movement to make it easier to hack later.

* jt/packmigrate: (23 commits)
  pack: move for_each_packed_object()
  pack: move has_pack_index()
  pack: move has_sha1_pack()
  pack: move find_pack_entry() and make it global
  pack: move find_sha1_pack()
  pack: move find_pack_entry_one(), is_pack_valid()
  pack: move check_pack_index_ptr(), nth_packed_object_offset()
  pack: move nth_packed_object_{sha1,oid}
  pack: move clear_delta_base_cache(), packed_object_info(), unpack_entry()
  pack: move unpack_object_header()
  pack: move get_size_from_delta()
  pack: move unpack_object_header_buffer()
  pack: move {,re}prepare_packed_git and approximate_object_count
  pack: move install_packed_git()
  pack: move add_packed_git()
  pack: move unuse_pack()
  pack: move use_pack()
  pack: move pack-closing functions
  pack: move release_pack_memory()
  pack: move open_pack_index(), parse_pack_index()
  ...
2017-08-26 22:55:09 -07:00
Junio C Hamano
614ea03a71 Merge branch 'bw/submodule-config-cleanup'
Code clean-up to avoid mixing values read from the .gitmodules file
and values read from the .git/config file.

* bw/submodule-config-cleanup:
  submodule: remove gitmodules_config
  unpack-trees: improve loading of .gitmodules
  submodule-config: lazy-load a repository's .gitmodules file
  submodule-config: move submodule-config functions to submodule-config.c
  submodule-config: remove support for overlaying repository config
  diff: stop allowing diff to have submodules configured in .git/config
  submodule: remove submodule_config callback routine
  unpack-trees: don't respect submodule.update
  submodule: don't rely on overlayed config when setting diffopts
  fetch: don't overlay config with submodule-config
  submodule--helper: don't overlay config in update-clone
  submodule--helper: don't overlay config in remote_submodule_branch
  add, reset: ensure submodules can be added or reset
  submodule: don't use submodule_from_name
  t7411: check configuration parsing errors
2017-08-26 22:55:08 -07:00
Junio C Hamano
6b8aa3294e Merge branch 'po/object-id'
* po/object-id:
  sha1_file: convert index_stream to struct object_id
  sha1_file: convert hash_sha1_file_literally to struct object_id
  sha1_file: convert index_fd to struct object_id
  sha1_file: convert index_path to struct object_id
  read-cache: convert to struct object_id
  builtin/hash-object: convert to struct object_id
2017-08-26 22:55:07 -07:00
Junio C Hamano
0b96358479 Merge branch 'jt/diff-color-move-fix'
A handful of bugfixes and an improvement to "diff --color-moved".

* jt/diff-color-move-fix:
  diff: define block by number of alphanumeric chars
  diff: respect MIN_BLOCK_LENGTH for last block
  diff: avoid redundantly clearing a flag
2017-08-26 22:55:04 -07:00
Junio C Hamano
b6c4058f97 Merge branch 'sb/diff-color-move'
"git diff" has been taught to optionally paint new lines that are
the same as deleted lines elsewhere differently from genuinely new
lines.

* sb/diff-color-move: (25 commits)
  diff: document the new --color-moved setting
  diff.c: add dimming to moved line detection
  diff.c: color moved lines differently, plain mode
  diff.c: color moved lines differently
  diff.c: buffer all output if asked to
  diff.c: emit_diff_symbol learns about DIFF_SYMBOL_SUMMARY
  diff.c: emit_diff_symbol learns about DIFF_SYMBOL_STAT_SEP
  diff.c: convert word diffing to use emit_diff_symbol
  diff.c: convert show_stats to use emit_diff_symbol
  diff.c: convert emit_binary_diff_body to use emit_diff_symbol
  submodule.c: migrate diff output to use emit_diff_symbol
  diff.c: emit_diff_symbol learns DIFF_SYMBOL_REWRITE_DIFF
  diff.c: emit_diff_symbol learns about DIFF_SYMBOL_BINARY_FILES
  diff.c: emit_diff_symbol learns DIFF_SYMBOL_HEADER
  diff.c: emit_diff_symbol learns DIFF_SYMBOL_FILEPAIR_{PLUS, MINUS}
  diff.c: emit_diff_symbol learns DIFF_SYMBOL_CONTEXT_INCOMPLETE
  diff.c: emit_diff_symbol learns DIFF_SYMBOL_WORDS[_PORCELAIN]
  diff.c: migrate emit_line_checked to use emit_diff_symbol
  diff.c: emit_diff_symbol learns DIFF_SYMBOL_NO_LF_EOF
  diff.c: emit_diff_symbol learns DIFF_SYMBOL_CONTEXT_FRAGINFO
  ...
2017-08-26 22:55:03 -07:00
Jonathan Tan
150e3001d0 pack: move has_sha1_pack()
Signed-off-by: Jonathan Tan <jonathantanmy@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-08-23 15:12:07 -07:00
Patryk Obara
98e019b067 sha1_file: convert index_path to struct object_id
Convert all remaining callers as well.

Signed-off-by: Patryk Obara <patryk.obara@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-08-20 21:51:38 -07:00
Junio C Hamano
08a8509e50 diff: retire sane_truncate_fn
Long time ago, 23707811 ("diff: do not chomp hunk-header in the
middle of a character", 2008-01-02) introduced sane_truncate_line()
helper function to trim the "function header" line that is shown at
the end of the hunk header line, in order to avoid chomping it in
the middle of a single UTF-8 character.  It also added a facility to
define a custom callback function to make it possible to extend it
to non UTF-8 encodings.

During the following 8 1/2 years, nobody found need for this custom
callback facility.

A custom callback function is a wrong design to use here anyway---if
your contents need support for non UTF-8 encoding, you shouldn't
have to write a custom function and recompile Git to plumb it in.  A
better approach would be to extend sane_truncate_line() function and
have a new member in emit_callback to conditionally trigger it.

Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-08-17 14:38:22 -07:00
Jonathan Tan
f0b8fb6e59 diff: define block by number of alphanumeric chars
The existing behavior of diff --color-moved=zebra does not define the
minimum size of a block at all, instead relying on a heuristic applied
later to filter out sets of adjacent moved lines that are shorter than 3
lines long. This can be confusing, because a block could thus be colored
as moved at the source but not at the destination (or vice versa),
depending on its neighbors.

Instead, teach diff that the minimum size of a block is 20 alphanumeric
characters, the same heuristic used by "git blame". This allows diff to
still exclude uninteresting lines appearing on their own (such as those
solely consisting of one or a few closing braces), as was the intention
of the adjacent-moved-line heuristic.

This requires a change in some tests in that some of their lines are no
longer considered to be part of a block, because they are too short.

Signed-off-by: Jonathan Tan <jonathantanmy@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-08-16 11:44:00 -07:00
Jonathan Tan
09153277f8 diff: respect MIN_BLOCK_LENGTH for last block
Currently, MIN_BLOCK_LENGTH is only checked when diff encounters a line
that does not belong to the current block. In particular, this means
that MIN_BLOCK_LENGTH is not checked after all lines are encountered.

Perform that check.

Signed-off-by: Jonathan Tan <jonathantanmy@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-08-16 11:44:00 -07:00
Jonathan Tan
23b65f9528 diff: avoid redundantly clearing a flag
No code in diff.c sets DIFF_SYMBOL_MOVED_LINE except in
mark_color_as_moved(), so it is redundant to clear it for the current
line. Therefore, clear it only for previous lines.

This makes a refactoring in a subsequent patch easier.

Signed-off-by: Jonathan Tan <jonathantanmy@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-08-14 12:28:36 -07:00
Brandon Williams
078b75e99b diff: stop allowing diff to have submodules configured in .git/config
Traditionally a submodule is comprised of a gitlink as well as a
corresponding entry in the .gitmodules file.  Diff doesn't follow this
paradigm as its config callback routine falls back to populating the
submodule-config if a config entry starts with 'submodule.'.

Remove this behavior in order to be consistent with how the
submodule-config is populated, via calling 'gitmodules_config()' or
'repo_read_gitmodules()'.

Signed-off-by: Brandon Williams <bmwill@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-08-03 13:11:01 -07:00
Jeff King
136c8c8b8f color: check color.ui in git_default_config()
Back in prehistoric times, our decision on whether or not to
show color by default relied on using a config callback that
either did or didn't load color config like color.diff.
When we introduced color.ui, we put it in the same boat:
commands had to manually respect it by using git_color_config()
or its git_color_default_config() convenience wrapper.

But in 4c7f1819b (make color.ui default to 'auto',
2013-06-10), that changed. Since then, we default color.ui
to auto in all programs, meaning that even plumbing commands
like "git diff-tree --pretty" might colorize the output.
Nobody seems to have complained in the intervening years,
presumably because the "is stdout a tty" check does a good
job of catching the right cases.

But that leaves an interesting curiosity: color.ui defaults
to auto even in plumbing, but you can't actually _disable_
the color via config. So if you really hate color and set
"color.ui" to false, diff-tree will still show color (but
porcelain like git-diff won't).  Nobody noticed that either,
probably because very few people disable color.

One could argue that the plumbing should _always_ disable
color unless an explicit --color option is given on the
command line. But in practice, this creates a lot of
complications for scripts which do want plumbing to show
user-visible output. They can't just pass "--color" blindly;
they need to check the user's config and decide what to
send.

Given that nobody has complained about the current behavior,
let's assume it's a good path, and follow it to its
conclusion: supporting color.ui everywhere.

Note that you can create havoc by setting color.ui=always in
your config, but that's more or less already the case. We
could disallow it entirely, but it is handy for one-offs
like:

  git -c color.ui=always foo >not-a-tty

when "foo" does not take a --color option itself.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-07-13 12:42:51 -07:00
Junio C Hamano
f056cde60e Merge branch 'rs/use-div-round-up'
Code cleanup.

* rs/use-div-round-up:
  use DIV_ROUND_UP
2017-07-12 15:18:23 -07:00
René Scharfe
42c78a216e use DIV_ROUND_UP
Convert code that divides and rounds up to use DIV_ROUND_UP to make the
intent clearer and reduce the number of magic constants.

Signed-off-by: Rene Scharfe <l.s.r@web.de>
Reviewed-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-07-10 14:24:36 -07:00
Stefan Beller
86b452e276 diff.c: add dimming to moved line detection
Any lines inside a moved block of code are not interesting. Boundaries
of blocks are only interesting if they are next to another block of moved
code.

Signed-off-by: Stefan Beller <sbeller@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-06-30 13:59:42 -07:00
Stefan Beller
176841f0c9 diff.c: color moved lines differently, plain mode
Add the 'plain' mode for move detection of code. This omits the checking
for adjacent blocks, so it is not as useful. If you have a lot of the
same blocks moved in the same patch, the 'Zebra' would end up slow as it
is O(n^2) (n is number of same blocks). So this may be useful there and
is generally easy to add. Instead be very literal at the move detection,
do not skip over short blocks here.

Signed-off-by: Stefan Beller <sbeller@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-06-30 13:59:42 -07:00
Stefan Beller
2e2d5ac184 diff.c: color moved lines differently
When a patch consists mostly of moving blocks of code around, it can
be quite tedious to ensure that the blocks are moved verbatim, and not
undesirably modified in the move. To that end, color blocks that are
moved within the same patch differently. For example (OM, del, add,
and NM are different colors):

    [OM]  -void sensitive_stuff(void)
    [OM]  -{
    [OM]  -        if (!is_authorized_user())
    [OM]  -                die("unauthorized");
    [OM]  -        sensitive_stuff(spanning,
    [OM]  -                        multiple,
    [OM]  -                        lines);
    [OM]  -}

           void another_function()
           {
    [del] -        printf("foo");
    [add] +        printf("bar");
           }

    [NM]  +void sensitive_stuff(void)
    [NM]  +{
    [NM]  +        if (!is_authorized_user())
    [NM]  +                die("unauthorized");
    [NM]  +        sensitive_stuff(spanning,
    [NM]  +                        multiple,
    [NM]  +                        lines);
    [NM]  +}

However adjacent blocks may be problematic. For example, in this
potentially malicious patch, the swapping of blocks can be spotted:

    [OM]  -void sensitive_stuff(void)
    [OM]  -{
    [OMA] -        if (!is_authorized_user())
    [OMA] -                die("unauthorized");
    [OM]  -        sensitive_stuff(spanning,
    [OM]  -                        multiple,
    [OM]  -                        lines);
    [OMA] -}

           void another_function()
           {
    [del] -        printf("foo");
    [add] +        printf("bar");
           }

    [NM]  +void sensitive_stuff(void)
    [NM]  +{
    [NMA] +        sensitive_stuff(spanning,
    [NMA] +                        multiple,
    [NMA] +                        lines);
    [NM]  +        if (!is_authorized_user())
    [NM]  +                die("unauthorized");
    [NMA] +}

If the moved code is larger, it is easier to hide some permutation in the
code, which is why some alternative coloring is needed.

This patch implements the first mode:
* basic alternating 'Zebra' mode
  This conveys all information needed to the user.  Defer customization to
  later patches.

First I implemented an alternative design, which would try to fingerprint
a line by its neighbors to detect if we are in a block or at the boundary.
This idea iss error prone as it inspected each line and its neighboring
lines to determine if the line was (a) moved and (b) if was deep inside
a hunk by having matching neighboring lines. This is unreliable as the
we can construct hunks which have equal neighbors that just exceed the
number of lines inspected. (Think of 'AXYZBXYZCXYZD..' with each letter
as a line, that is permutated to AXYZCXYZBXYZD..').

Instead this provides a dynamic programming greedy algorithm that finds
the largest moved hunk and then has several modes on highlighting bounds.

A note on the options '--submodule=diff' and '--color-words/--word-diff':
In the conversion to use emit_line in the prior patches both submodules
as well as word diff output carefully chose to call emit_line with sign=0.
All output with sign=0 is ignored for move detection purposes in this
patch, such that no weird looking output will be generated for these
cases. This leads to another thought: We could pass on '--color-moved' to
submodules such that they color up moved lines for themselves. If we'd do
so only line moves within a repository boundary are marked up.

It is useful to have moved lines colored, but there are annoying corner
cases, such as a single line moved, that is very common. For example
in a typical patch of C code, we have closing braces that end statement
blocks or functions.

While it is technically true that these lines are moved as they show up
elsewhere, it is harmful for the review as the reviewers attention is
drawn to such a minor side annoyance.

For now let's have a simple solution of hardcoding the number of
moved lines to be at least 3 before coloring them. Note, that the
length is applied across all blocks to find the 'lonely' blocks
that pollute new code, but do not interfere with a permutated
block where each permutation has less lines than 3.

Helped-by: Jonathan Tan <jonathantanmy@google.com>
Signed-off-by: Stefan Beller <sbeller@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-06-30 13:59:42 -07:00
Stefan Beller
e6e045f803 diff.c: buffer all output if asked to
Introduce a new option 'emitted_symbols' in the struct diff_options which
controls whether all output is buffered up until all output is available.
It is set internally in diff.c when necessary.

We'll have a new struct 'emitted_string' in diff.c which will be used to
buffer each line.  The emitted_string will duplicate the memory of the
line to buffer as that is easiest to reason about for now. In a future
patch we may want to decrease the memory usage by not duplicating all
output for buffering but rather we may want to store offsets into the
file or in case of hunk descriptions such as the similarity score, we
could just store the relevant number and reproduce the text later on.

This approach was chosen as a first step because it is quite simple
compared to the alternative with less memory footprint.

emit_diff_symbol factors out the emission part and depending on the
diff_options->emitted_symbols the emission will be performed directly
when calling emit_diff_symbol or after the whole process is done, i.e.
by buffering we have add the possibility for a second pass over the
whole output before doing the actual output.

In 6440d34 (2012-03-14, diff: tweak a _copy_ of diff_options with
word-diff) we introduced a duplicate diff options struct for word
emissions as we may have different regex settings in there.
When buffering the output, we need to operate on just one buffer,
so we have to copy back the emissions of the word buffer into the
main buffer.

Unconditionally enable output via buffer in this patch as it yields
a great opportunity for testing, i.e. all the diff tests from the
test suite pass without having reordering issues (i.e. only parts
of the output got buffered, and we forgot to buffer other parts).
The test suite passes, which gives confidence that we converted all
functions to use emit_string for output.

Signed-off-by: Stefan Beller <sbeller@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-06-30 13:13:02 -07:00
Stefan Beller
146fdb0dfe diff.c: emit_diff_symbol learns about DIFF_SYMBOL_SUMMARY
Signed-off-by: Stefan Beller <sbeller@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-06-30 13:13:02 -07:00
Stefan Beller
30b7e1e7ef diff.c: emit_diff_symbol learns about DIFF_SYMBOL_STAT_SEP
Signed-off-by: Stefan Beller <sbeller@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-06-30 13:13:02 -07:00
Stefan Beller
bd033291d5 diff.c: convert word diffing to use emit_diff_symbol
The word diffing is not line oriented and would need some serious
effort to be transformed into a line oriented approach, so
just go with a symbol DIFF_SYMBOL_WORD_DIFF that is a partial line.

Signed-off-by: Stefan Beller <sbeller@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-06-30 13:13:02 -07:00
Stefan Beller
0911c475c8 diff.c: convert show_stats to use emit_diff_symbol
We call print_stat_summary from builtin/apply, so we still
need the version with a file pointer, so introduce
print_stat_summary_0 that uses emit_string machinery and
keep print_stat_summary with the same arguments around.

Signed-off-by: Stefan Beller <sbeller@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-06-30 13:13:02 -07:00
Stefan Beller
4eed0ebd4d diff.c: convert emit_binary_diff_body to use emit_diff_symbol
Signed-off-by: Stefan Beller <sbeller@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-06-30 13:13:02 -07:00
Stefan Beller
f3597138df submodule.c: migrate diff output to use emit_diff_symbol
As the submodule process is no longer attached to the same file pointer
'o->file' as the superprojects process, there is a different result in
color.c::check_auto_color. That is why we need to pass coloring explicitly,
such that the submodule coloring decision will be made by the child process
processing the submodule. Only DIFF_SYMBOL_SUBMODULE_PIPETHROUGH contains
color, the other symbols are for embedding the submodule output into the
superprojects output.

Remove the colors from the function signatures, as all the coloring
decisions will be made either inside the child process or the final
emit_diff_symbol, but not in the functions driving the submodule diff.

Signed-off-by: Stefan Beller <sbeller@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-06-30 13:13:02 -07:00
Stefan Beller
5af6ea957c diff.c: emit_diff_symbol learns DIFF_SYMBOL_REWRITE_DIFF
Signed-off-by: Stefan Beller <sbeller@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-06-30 13:13:02 -07:00
Stefan Beller
4acaaa7af6 diff.c: emit_diff_symbol learns about DIFF_SYMBOL_BINARY_FILES
we could save a little bit of memory when buffering in a later mode
by just passing the inner part ("%s and %s", file1, file 2), but
those a just a few bytes, so instead let's reuse the implementation from
DIFF_SYMBOL_HEADER and keep the whole line around.

Signed-off-by: Stefan Beller <sbeller@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-06-30 13:13:01 -07:00
Stefan Beller
a29b0a13bd diff.c: emit_diff_symbol learns DIFF_SYMBOL_HEADER
The header is constructed lazily including line breaks, so just emit
the raw string as is.

Signed-off-by: Stefan Beller <sbeller@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-06-30 13:13:01 -07:00
Stefan Beller
3ee8b7bfe4 diff.c: emit_diff_symbol learns DIFF_SYMBOL_FILEPAIR_{PLUS, MINUS}
We have to use fprintf instead of emit_line, because we want to emit the
tab after the color. This is important for ancient versions of gnu patch
AFAICT, although we probably do not want to feed colored output to the
patch utility, such that it would not matter if the trailing tab is
colored. Keep the corner case as-is though.

Signed-off-by: Stefan Beller <sbeller@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-06-30 13:13:01 -07:00
Stefan Beller
f2bb1218f1 diff.c: emit_diff_symbol learns DIFF_SYMBOL_CONTEXT_INCOMPLETE
The context marker use the exact same output pattern, so reuse it.

Signed-off-by: Stefan Beller <sbeller@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-06-30 13:13:01 -07:00
Stefan Beller
ff958679cd diff.c: emit_diff_symbol learns DIFF_SYMBOL_WORDS[_PORCELAIN]
Signed-off-by: Stefan Beller <sbeller@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-06-30 13:13:01 -07:00
Stefan Beller
091f8e28b4 diff.c: migrate emit_line_checked to use emit_diff_symbol
Add a new flags field to emit_diff_symbol, that will be used by
context lines for:
* white space rules that are applicable (The first 12 bits)
  Take a note in cahe.c as well, when this ws rules are extended we have
  to fix the bits in the flags field.
* how the rules are evaluated (actually this double encodes the sign
  of the line, but the code is easier to keep this way, bits 13,14,15)
* if the line a blank line at EOF (bit 16)

The check if new lines need to be marked up as extra lines at the end of
file, is now done unconditionally. That should be ok, as
'new_blank_line_at_eof' has a quick early return.

Signed-off-by: Stefan Beller <sbeller@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-06-30 13:13:01 -07:00
Stefan Beller
b9cbfde6b1 diff.c: emit_diff_symbol learns DIFF_SYMBOL_NO_LF_EOF
Signed-off-by: Stefan Beller <sbeller@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-06-30 13:13:01 -07:00
Stefan Beller
68abc6f1c7 diff.c: emit_diff_symbol learns DIFF_SYMBOL_CONTEXT_FRAGINFO
Signed-off-by: Stefan Beller <sbeller@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-06-30 13:13:01 -07:00
Stefan Beller
c64b420b4c diff.c: emit_diff_symbol learns DIFF_SYMBOL_CONTEXT_MARKER
Signed-off-by: Stefan Beller <sbeller@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-06-30 13:13:01 -07:00
Stefan Beller
36a4cefdf4 diff.c: introduce emit_diff_symbol
In a later patch we want to buffer all output before emitting it as a
new feature ("markup moved lines") conceptually cannot be implemented
in a single pass over the output.

There are different approaches to buffer all output such as:
* Buffering on the char level, i.e. we'd have a char[] which would
  grow at approximately 80 characters a line. This would keep the
  output completely unstructured, but might be very easy to implement,
  such as redirecting all output to a temporary file and working off
  that. The later passes over the buffer are quite complicated though,
  because we have to parse back any output and then decide if it should
  be modified.

* Buffer on a line level. As the output is mostly line oriented already,
  this would make sense, but it still is a bit awkward as we'd have to
  make sense of it again by looking at the first characters of a line
  to decide what part of a diff a line is.

* Buffer semantically. Imagine there is a formal grammar for the diff
  output and we'd keep the symbols of this grammar around. This keeps
  the highest level of structure in the buffered data, such that the
  actual memory requirements are less than say the first option. Instead
  of buffering the characters of the line, we'll buffer what we intend
  to do plus additional information for the specifics. An output of

    diff --git a/new.txt b/new.txt
    index fa69b07..412428c 100644
    Binary files a/new.txt and b/new.txt differ

  could be buffered as
     DIFF_SYMBOL_DIFF_START + new.txt
     DIFF_SYMBOL_INDEX_MODE + fa69b07 412428c "non-executable" flag
     DIFF_SYMBOL_BINARY_FILES + new.txt

This and the following patches introduce the third option of buffering
by first moving any output to emit_diff_symbol, and then introducing the
buffering in this function.

Signed-off-by: Stefan Beller <sbeller@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-06-30 13:13:01 -07:00
Stefan Beller
ec33150671 diff.c: factor out diff_flush_patch_all_file_pairs
In a later patch we want to do more things before and after all filepairs
are flushed. So factor flushing out all file pairs into its own function
that the new code can be plugged in easily.

Signed-off-by: Stefan Beller <sbeller@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-06-30 13:13:01 -07:00