The code that sets custom abbreviation length, in response to
command line argument, often does something like this:

	if (skip_prefix(arg, "--abbrev=", &arg))
		abbrev = atoi(arg);
	else if (!strcmp("--abbrev", &arg))
		abbrev = DEFAULT_ABBREV;
	/* make the value sane */
	if (abbrev < 0 || 40 < abbrev)
		abbrev = ... some sane value ...

However, it is pointless to sanity-check and tweak the value
obtained from DEFAULT_ABBREV.  We are going to allow it to be
initially set to -1 to signal that the default abbreviation length
must be auto sized upon the first request to abbreviate, based on
the number of objects in the repository, and when that happens,
rejecting or tweaking a negative value to a "saner" one will
negatively interfere with the auto sizing.  The codepaths for

    git rev-parse --short <object>
    git diff --raw --abbrev

do exactly that; allow them to pass possibly negative abbrevs
intact, that will come from DEFAULT_ABBREV in the future.
Signed-off-by: NJunio C Hamano <gitster@pobox.com>

When `len < 1`, len has to be 0 or negative, emit_line will then remove the
first character and by then `len` would be negative. As this doesn't
happen, it is safe to assume it is dead code.

This continues to simplify the code, which was started in b8d9c1a6
(2009-09-03,  diff.c: the builtin_diff() deals with only two-file
comparison).
Signed-off-by: NStefan Beller <sbeller@google.com>
Signed-off-by: NJunio C Hamano <gitster@pobox.com>

We keep the actual data in the diff options, which are just as accessible.
Remove the pointer stored in struct emit_callback for readability.
Signed-off-by: NStefan Beller <sbeller@google.com>
Signed-off-by: NJunio C Hamano <gitster@pobox.com>

The value of `ecbdata->opt` is accessible via the short variable `o`
already, so let's use that instead.
Signed-off-by: NStefan Beller <sbeller@google.com>
Signed-off-by: NJunio C Hamano <gitster@pobox.com>

Convert struct cache_entry to use struct object_id by applying the
following semantic patch and the object_id transforms from contrib, plus
the actual change to the struct:

@@
struct cache_entry E1;
@@
- E1.sha1
+ E1.oid.hash

@@
struct cache_entry *E1;
@@
- E1->sha1
+ E1->oid.hash
Signed-off-by: Nbrian m. carlson <sandals@crustytoothpaste.net>
Signed-off-by: NJunio C Hamano <gitster@pobox.com>

Teach git-diff and friends a new format for displaying the difference
of a submodule. The new format is an inline diff of the contents of the
submodule between the commit range of the update. This allows the user
to see the actual code change caused by a submodule update.

Add tests for the new format and option.
Signed-off-by: NJacob Keller <jacob.keller@gmail.com>
Signed-off-by: NJunio C Hamano <gitster@pobox.com>

Since we're going to be changing this function in a future patch, lets
go ahead and convert this to use object_id now.
Signed-off-by: NJacob Keller <jacob.keller@gmail.com>
Signed-off-by: NJunio C Hamano <gitster@pobox.com>

A future patch will add a new format for displaying the difference of
a submodule. Make it easier by changing how we store the current
selected format. Replace the DIFF_OPT flag with an enumeration, as each
format will be mutually exclusive.
Signed-off-by: NJacob Keller <jacob.keller@gmail.com>
Signed-off-by: NJunio C Hamano <gitster@pobox.com>

Add an extension to git-diff and git-log (and any other graph-aware
displayable output) such that "--line-prefix=<string>" will print the
additional line-prefix on every line of output.

To make this work, we have to fix a few bugs in the graph API that force
graph_show_commit_msg to be used only when you have a valid graph.
Additionally, we extend the default_diff_output_prefix handler to work
even when no graph is enabled.

This is somewhat of a hack on top of the graph API, but I think it
should be acceptable here.

This will be used by a future extension of submodule display which
displays the submodule diff as the actual diff between the pre and post
commit in the submodule project.

Add some tests for both git-log and git-diff to ensure that the prefix
is honored correctly.
Signed-off-by: NJacob Keller <jacob.keller@gmail.com>
Signed-off-by: NJunio C Hamano <gitster@pobox.com>

"diff/log --stat" has a logic that determines the display columns
available for the diffstat part of the output and apportions it for
pathnames and diffstat graph automatically.

5e71a84a (Add output_prefix_length to diff_options, 2012-04-16)
added the output_prefix_length field to diff_options structure to
allow this logic to subtract the display columns used for the
history graph part from the total "terminal width"; this matters
when the "git log --graph -p" option is in use.

The field must be set to the number of display columns needed to
show the output from the output_prefix() callback, which is error
prone.  As there is only one user of the field, and the user has the
actual value of the prefix string, let's get rid of the field and
have the user count the display width itself.
Signed-off-by: NJunio C Hamano <gitster@pobox.com>

This will allow a diff patch id to be created using only the header data
so that the contents of the file will not have to be loaded.
Signed-off-by: NKevin Willford <kcwillford@gmail.com>
Signed-off-by: NJunio C Hamano <gitster@pobox.com>

When accessing a blob for a diff, we may try to reuse file
contents in the working tree, under the theory that it is
faster to mmap those file contents than it would be to
extract the content from the object database.

When we have to filter those contents, though, that
assumption does not hold. Even for our internal conversions
like CRLF, we have to allocate and fill a new buffer anyway.
But much worse, for external clean filters we have to exec
an arbitrary script, and we have no idea how expensive it
may be to run.

So let's skip this optimization when conversion into git's
"clean" form is required. This applies whenever the
"want_file" flag is false. When it's true, the caller
actually wants the smudged worktree contents, which the
reused file by definition already has (in fact, this is a
key optimization going the other direction, since reusing
the worktree file there lets us skip smudge filters).
Signed-off-by: NJeff King <peff@peff.net>
Signed-off-by: NJunio C Hamano <gitster@pobox.com>

All of the callers of this function use struct object_id, so convert it
to use struct object_id in its arguments and internally.
Signed-off-by: Nbrian m. carlson <sandals@crustytoothpaste.net>
Signed-off-by: NJunio C Hamano <gitster@pobox.com>

Now that this struct's sha1 member is called "oid", update the comment
and the sha1_valid member to be called "oid_valid" instead.  The
following Coccinelle semantic patch was used to implement this, followed
by the transformations in object_id.cocci:

@@
struct diff_filespec o;
@@
- o.sha1_valid
+ o.oid_valid

@@
struct diff_filespec *p;
@@
- p->sha1_valid
+ p->oid_valid
Signed-off-by: Nbrian m. carlson <sandals@crustytoothpaste.net>
Signed-off-by: NJunio C Hamano <gitster@pobox.com>

Convert struct diff_filespec's sha1 member to use a struct object_id
called "oid" instead.  The following Coccinelle semantic patch was used
to implement this, followed by the transformations in object_id.cocci:

@@
struct diff_filespec o;
@@
- o.sha1
+ o.oid.hash

@@
struct diff_filespec *p;
@@
- p->sha1
+ p->oid.hash
Signed-off-by: Nbrian m. carlson <sandals@crustytoothpaste.net>
Signed-off-by: NJunio C Hamano <gitster@pobox.com>

hashcpy with null_sha1 as the source is equivalent to hashclr.  In
addition to being simpler, using hashclr may give the compiler a chance
to optimize better.  Convert instances of hashcpy with the source
argument of null_sha1 to hashclr.

This transformation was implemented using the following semantic patch:

@@
expression E1;
@@
-hashcpy(E1, null_sha1);
+hashclr(E1);
Signed-off-by: Nbrian m. carlson <sandals@crustytoothpaste.net>
Signed-off-by: NJunio C Hamano <gitster@pobox.com>

"git diff --output=<file> --color=auto" used to show the ANSI color
sequence in the resulting file when the standard output is connected
to a terminal, because --color=auto check always checks the standard
output, not the actual file that receives the output.

We could correct this by using freopen(3) to redirect the standard
output to the specified file, which is in like with how format-patch
used to match the world order, but following the same reasoning as
the earlier "format-patch: explicitly switch off color when writing
to files", let's be more strict by bypassing the "auto" check when
the --output=<file> option is in use.

Strictly speaking, this is a backwards-incompatible change, but
it is highly unlikely that any user would want to see ANSI color
sequences in a file.

The reason this was not caught earlier is most likely that either
--output=<file> is not used, or only when stdout is redirected
anyway.

Users can still give --color=always if they want a colored diff in
the resulting file.
Signed-off-by: NJohannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: NJunio C Hamano <gitster@pobox.com>

http://lkml.kernel.org/g/20160610075043.GA13411@sigill.intra.peff.net
reports that a change to add a new "function" with common ending
with the existing one at the end of the file is shown like this:

    def foo
      do_foo_stuff()

   +  common_ending()
   +end
   +
   +def bar
   +  do_bar_stuff()
   +
      common_ending()
    end

when the new heuristic is in use.  In reality, the change is to add
the blank line before "def bar" and everything below, which is what
the code without the new heuristic shows.

Disable the heuristics by default, and resurrect the documentation
for the option and the configuration variables, while clearly
marking the feature as still experimental.
Signed-off-by: NJunio C Hamano <gitster@pobox.com>

In order to produce the smallest possible diff and combine several diff
hunks together, we implement a heuristic from GNU Diff which moves diff
hunks forward as far as possible when we find common context above and
below a diff hunk. This sometimes produces less readable diffs when
writing C, Shell, or other programming languages, ie:

...
 /*
+ *
+ *
+ */
+
+/*
...

instead of the more readable equivalent of

...
+/*
+ *
+ *
+ */
+
 /*
...

Implement the following heuristic to (optionally) produce the desired
output.

  If there are diff chunks which can be shifted around, shift each hunk
  such that the last common empty line is below the chunk with the rest
  of the context above.

This heuristic appears to resolve the above example and several other
common issues without producing significantly weird results. However, as
with any heuristic it is not really known whether this will always be
more optimal. Thus, it can be disabled via diff.compactionHeuristic.
Signed-off-by: NStefan Beller <sbeller@google.com>
Signed-off-by: NJacob Keller <jacob.e.keller@intel.com>
Signed-off-by: NStefan Beller <sbeller@google.com>
Signed-off-by: NJunio C Hamano <gitster@pobox.com>

Rename detection is a very convenient feature, and new users shouldn't
have to dig in the documentation to benefit from it.

Potential objections to activating rename detection are that it
sometimes fail, and it is sometimes slow. But rename detection is
already activated by default in several cases like "git status" and "git
merge", so activating diff.renames does not fundamentally change the
situation. When the rename detection fails, it now fails consistently
between "git diff" and "git status".

This setting does not affect plumbing commands, hence well-written
scripts will not be affected.
Signed-off-by: NMatthieu Moy <Matthieu.Moy@imag.fr>
Signed-off-by: NJunio C Hamano <gitster@pobox.com>

We allocate 100 bytes to hold the "Submodule commit ..."
text. This is enough, but it's not immediately obvious that
this is the case, and we have to repeat the magic 100 twice.

We could get away with xstrfmt here, but we want to know the
size, as well, so let's use a real strbuf. And while we're
here, we can clean up the logic around size_only. It
currently sets and clears the "data" field pointlessly, and
leaves the "should_free" flag on even after we have cleared
the data.
Signed-off-by: NJeff King <peff@peff.net>
Signed-off-by: NJunio C Hamano <gitster@pobox.com>

Using FLEX_ARRAY macros reduces the amount of manual
computation size we have to do. It also ensures we don't
overflow size_t, and it makes sure we write the same number
of bytes that we allocated.
Signed-off-by: NJeff King <peff@peff.net>
Signed-off-by: NJunio C Hamano <gitster@pobox.com>

The memory allocation scheme for the textconv interface is a
bit tricky, and not well documented. It was originally
designed as an internal part of diff.c (matching
fill_mmfile), but gradually was made public.

Refactoring it is difficult, but we can at least improve the
situation by documenting the intended flow and enforcing it
with an in-code assertion.
Signed-off-by: NJeff King <peff@peff.net>
Signed-off-by: NJunio C Hamano <gitster@pobox.com>

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

After switching to use the tempfile module in commit 284098f1
(diff: use tempfile module), no declarations from sigchain.h are used in
diff.c anymore. Thus, remove the #include.
Signed-off-by: NTobias Klauser <tklauser@distanz.ch>
Signed-off-by: NJunio C Hamano <gitster@pobox.com>

Before sha1_to_hex_r() existed, a simple way to get hex
sha1 into a buffer was with:

  strcpy(buf, sha1_to_hex(sha1));

This isn't wrong (assuming the buf is 41 characters), but it
makes auditing the code base for bad strcpy() calls harder,
as these become false positives.

Let's convert them to sha1_to_hex_r(), and likewise for
some calls to find_unique_abbrev(). While we're here, we'll
double-check that all of the buffers are correctly sized,
and use the more obvious GIT_SHA1_HEXSZ constant.
Signed-off-by: NJeff King <peff@peff.net>
Signed-off-by: NJunio C Hamano <gitster@pobox.com>

When we call into xdiff to perform a diff, we generally lose
the return code completely. Typically by ignoring the return
of our xdi_diff wrapper, but sometimes we even propagate
that return value up and then ignore it later.  This can
lead to us silently producing incorrect diffs (e.g., "git
log" might produce no output at all, not even a diff header,
for a content-level diff).

In practice this does not happen very often, because the
typical reason for xdiff to report failure is that it
malloc() failed (it uses straight malloc, and not our
xmalloc wrapper).  But it could also happen when xdiff
triggers one our callbacks, which returns an error (e.g.,
outf() in builtin/rerere.c tries to report a write failure
in this way). And the next patch also plans to add more
failure modes.

Let's notice an error return from xdiff and react
appropriately. In most of the diff.c code, we can simply
die(), which matches the surrounding code (e.g., that is
what we do if we fail to load a file for diffing in the
first place). This is not that elegant, but we are probably
better off dying to let the user know there was a problem,
rather than simply generating bogus output.

We could also just die() directly in xdi_diff, but the
callers typically have a bit more context, and can provide a
better message (and if we do later decide to pass errors up,
we're one step closer to doing so).

There is one interesting case, which is in diff_grep(). Here
if we cannot generate the diff, there is nothing to match,
and we silently return "no hits". This is actually what the
existing code does already, but we make it a little more
explicit.
Signed-off-by: NJeff King <peff@peff.net>
Signed-off-by: NJunio C Hamano <gitster@pobox.com>

We sometimes sprintf into fixed-size buffers when we know
that the buffer is large enough to fit the input (either
because it's a constant, or because it's numeric input that
is bounded in size). Likewise with strcpy of constant
strings.

However, these sites make it hard to audit sprintf and
strcpy calls for buffer overflows, as a reader has to
cross-reference the size of the array with the input. Let's
use xsnprintf instead, which communicates to a reader that
we don't expect this to overflow (and catches the mistake in
case we do).
Signed-off-by: NJeff King <peff@peff.net>
Signed-off-by: NJunio C Hamano <gitster@pobox.com>

We remove the extracted functions and directly parse into and read out
of the cache. This allows us to have one unified way of accessing
submodule configuration values specific to single submodules. Regardless
whether we need to access a configuration from history or from the
worktree.
Signed-off-by: NHeiko Voigt <hvoigt@hvoigt.net>
Signed-off-by: NJunio C Hamano <gitster@pobox.com>
Signed-off-by: NStefan Beller <sbeller@google.com>
Signed-off-by: NJunio C Hamano <gitster@pobox.com>

Also add some code comments explaining how the fields in "struct
diff_tempfile" are used.
Signed-off-by: NMichael Haggerty <mhagger@alum.mit.edu>
Signed-off-by: NJunio C Hamano <gitster@pobox.com>

Check if a matched token is followed by a delimiter before advancing the
pointer arg.  This avoids accepting composite words like "allnew" or
"defaultcontext" and misparsing them as "new" or "context".
Signed-off-by: NRene Scharfe <l.s.r@web.de>
Signed-off-by: NJunio C Hamano <gitster@pobox.com>

People who work on projects with mostly linear history with frequent
whole file renames may want to always use "git log --follow" when
inspecting the life of the content that live in a single path.

Teach the command to behave as if "--follow" was given from the
command line when log.follow configuration variable is set *and*
there is one (and only one) path on the command line.
Signed-off-by: NDavid Turner <dturner@twopensource.com>
Signed-off-by: NJunio C Hamano <gitster@pobox.com>

The latter is a much more descriptive name (and we support
"color.diff.context" now). This also updates the name of any
local variables which were used to store the color.
Signed-off-by: NJeff King <peff@peff.net>
Signed-off-by: NJunio C Hamano <gitster@pobox.com>

The term "plain" is a bit ambiguous; let's allow the more
specific "context", but keep "plain" around for
compatibility.
Signed-off-by: NJeff King <peff@peff.net>
Signed-off-by: NJunio C Hamano <gitster@pobox.com>

Traditionally, we only cared about whitespace breakages introduced
in new lines.  Some people want to paint whitespace breakages on old
lines, too.  When they see a whitespace breakage on a new line, they
can spot the same kind of whitespace breakage on the corresponding
old line and want to say "Ah, those breakages are there but they
were inherited from the original, so let's not touch them for now."

Introduce `--ws-error-highlight=<kind>` option, that lets them pass
a comma separated list of `old`, `new`, and `context` to specify
what lines to highlight whitespace errors on.
Signed-off-by: NJunio C Hamano <gitster@pobox.com>

Traditionally, we only had emit_add_line() helper, which knows how
to find and paint whitespace breakages on the given line, because we
only care about whitespace breakages introduced in new lines.  The
context lines and old (i.e. deleted) lines are emitted with a
simpler emit_line_0() that paints the entire line in plain or old
colors.

Identify callers of emit_line_0() that show deleted lines and
context lines, have them call new helpers, emit_del_line() and
emit_context_line(), so that we can later tweak what is done to
these two classes of lines.
Signed-off-by: NJunio C Hamano <gitster@pobox.com>

Clear the git_zstream variable at the start of git_deflate_init() etc.
so that callers don't have to do that.
Signed-off-by: NRene Scharfe <l.s.r@web.de>
Signed-off-by: NJunio C Hamano <gitster@pobox.com>

When --shortstat is used in conjunction with --dirstat=changes, git diff will
output the dirstat information twice: first as calculated by the 'lines'
algorithm, then as calculated by the 'changes' algorithm:

    $ git diff --dirstat=changes,10 --shortstat v2.2.0..v2.2.1
     23 files changed, 453 insertions(+), 54 deletions(-)
      33.5% Documentation/RelNotes/
      26.2% t/
      46.6% Documentation/RelNotes/
      16.6% t/

The same duplication happens for --shortstat together with --dirstat=files, but
not for --shortstat together with --dirstat=lines.

Limit output to only include one dirstat part, calculated as specified
by the --dirstat parameter. Also, add test for this.
Signed-off-by: NMårten Kongstad <marten.kongstad@gmail.com>
Signed-off-by: NJunio C Hamano <gitster@pobox.com>

Originally the color-parsing function was used only for
config variables. It made sense to pass the variable name so
that the die() message could be something like:

  $ git -c color.branch.plain=bogus branch
  fatal: bad color value 'bogus' for variable 'color.branch.plain'

These days we call it in other contexts, and the resulting
error messages are a little confusing:

  $ git log --pretty='%C(bogus)'
  fatal: bad color value 'bogus' for variable '--pretty format'

  $ git config --get-color foo.bar bogus
  fatal: bad color value 'bogus' for variable 'command line'

This patch teaches color_parse to complain only about the
value, and then return an error code. Config callers can
then propagate that up to the config parser, which mentions
the variable name. Other callers can provide a custom
message. After this patch these three cases now look like:

  $ git -c color.branch.plain=bogus branch
  error: invalid color value: bogus
  fatal: unable to parse 'color.branch.plain' from command-line config

  $ git log --pretty='%C(bogus)'
  error: invalid color value: bogus
  fatal: unable to parse --pretty format

  $ git config --get-color foo.bar bogus
  error: invalid color value: bogus
  fatal: unable to parse default color value
Signed-off-by: NJeff King <peff@peff.net>
Signed-off-by: NJunio C Hamano <gitster@pobox.com>

Most struct child_process variables are cleared using memset first after
declaration.  Provide a macro, CHILD_PROCESS_INIT, that can be used to
initialize them statically instead.  That's shorter, doesn't require a
function call and is slightly more readable (especially given that we
already have STRBUF_INIT, ARGV_ARRAY_INIT etc.).
Helped-by: NJohannes Sixt <j6t@kdbg.org>
Signed-off-by: NRene Scharfe <l.s.r@web.de>
Signed-off-by: NJunio C Hamano <gitster@pobox.com>