sequencer.c: check for lock failure and bail early in fast_forward_to

Change fast_forward_to() to check if locking the ref failed, print a
nice error message and bail out early.

The old code did not check if ref_lock was NULL and relied on the
fact that the write_ref_sha1() would safely detect this condition
and set the return variable ret to indicate an error.

While that is safe, it makes the code harder to read for two reasons:

 * Inconsistency.  Almost all other places we do check the lock for
   NULL explicitly, so the naive reader is confused "why don't we
   check here?"

 * And relying on write_ref_sha1() to detect and return an error for
   when a previous lock_any_ref_for_update() failed feels obfuscated.

This change should not change any functionality or logic aside from
adding an extra error message when this condition is triggered
(write_ref_sha1() returns an error silently for this condition).

Signed-off-by: Ronnie Sahlberg <sahlberg@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
commit.c: check for lock error and return early

Move the check for the lock failure to happen immediately after
lock_any_ref_for_update().  Previously the lock and the
check-if-lock-failed was separated by a handful of string
manipulation statements.

Moving the check to occur immediately after the failed lock makes
the code slightly easier to read and makes it follow the pattern of

 try-to-take-a-lock();
 if (check-if-lock-failed) {
    error();
 }

Signed-off-by: Ronnie Sahlberg <sahlberg@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
run_external_diff: use an argv_array for the environment

We currently use static buffers and a static array for
formatting the environment passed to the external diff.
There's nothing wrong in the code, but it is much easier to
verify that it is correct if we use a dynamic argv_array.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
run_external_diff: clean up error handling

When the external diff reports an error, we try to clean up
and die. However, we can make this process a bit simpler:

  1. We do not need to bother freeing memory, since we are
     about to exit.  Nor do we need to clean up our
     tempfiles, since the atexit() handler will do it for
     us. So we can die as soon as we see the error.

  3. We can just call die() rather than fprintf/exit. This
     does technically change our exit code, but the exit
     code of "1" is not meaningful here. In fact, it is
     probably wrong, since "1" from diff usually means
     "completed successfully, but there were differences".

And while we're there, we can mark the error message for
translation, and drop the full stop at the end to make it
more like our other messages.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
run_external_diff: drop fflush(NULL)

This fflush was added in d5535ec (Use run_command() to spawn
external diff programs instead of fork/exec., 2007-10-19),
because flushing buffers before forking is a good habit.

But later, 7d0b18a (Add output flushing before fork(),
2008-08-04) added it to the generic run-command interface,
meaning that our flush here is redundant.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
run_external_diff: hoist common bits out of conditional

Whether we have diff_filespecs to give to the diff command
or not, we always are going to run the program and pass it
the pathname. Let's pull that duplicated part out of the
conditional to make it more obvious.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
run_external_diff: refactor cmdline setup logic

The current logic makes it hard to see what gets put onto
the command line in which cases. Pulling out a helper
function lets us see that we have two sets of file data, and
the second set either uses the original name, or the "other"
renamed/copy name.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
fast-export: improve argument parsing

We don't want to pass arguments specific to fast-export to
setup_revisions.

Signed-off-by: Felipe Contreras <felipe.contreras@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
fast-export: add new --refspec option

So that we can convert the exported ref names.

Signed-off-by: Felipe Contreras <felipe.contreras@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
transport-helper: add support for old:new refspec

By using fast-export's new --refspec option.

Signed-off-by: Felipe Contreras <felipe.contreras@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
transport-helper: add support to push symbolic refs

For example 'HEAD'.

Signed-off-by: Felipe Contreras <felipe.contreras@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
fast-import: add support to delete refs

Signed-off-by: Felipe Contreras <felipe.contreras@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
fast-export: add support to delete refs

Signed-off-by: Felipe Contreras <felipe.contreras@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
transport-helper: add support to delete branches

For remote-helpers that use 'export' to push.

Signed-off-by: Felipe Contreras <felipe.contreras@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
transport-helper: remove unnecessary strbuf resets

Signed-off-by: Felipe Contreras <felipe.contreras@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
git.c: treat RUN_SETUP_GENTLY and RUN_SETUP as mutually exclusive

This saves us a few branches when RUN_SETUP is set up.

Signed-off-by: Luis R. Rodriguez <mcgrof@suse.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
mergetools: add vimdiff3 mode

It's similar to the default, except that the other windows are hidden.
This ensures that removed/added colors are still visible on the main
merge window, but the other windows not visible.

Specially useful with merge.conflictstyle=diff3.

Signed-off-by: Felipe Contreras <felipe.contreras@gmail.com>
Acked-by: David Aguilar <davvid@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
mergetool: run prompt only if guessed tool

It's annoying to see the prompt:

  Hit return to start merge resolution tool (foo):

Every time the user does 'git mergetool' even if the user already
configured 'foo' as the wanted tool.

Display this prompt only when the user hasn't explicitly configured a
tool.

Signed-off-by: Felipe Contreras <felipe.contreras@gmail.com>
Acked-by: David Aguilar <davvid@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
merge: enable defaulttoupstream by default

There's no point in this:

% git merge
fatal: No commit specified and merge.defaultToUpstream not set.

We know the most likely scenario is that the user wants to merge the
upstream, and if not, he can set merge.defaultToUpstream to false.

Signed-off-by: Felipe Contreras <felipe.contreras@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
blame: fix broken time_buf paddings in relative timestamp

Command `git blame --date relative` aligns the date field with a
fixed-width (defined by blame_date_width), and if time_str is shorter
than that, it adds spaces for padding.  But there are two bugs in the
following codes:

        time_len = strlen(time_str);
        ...
        memset(time_buf + time_len, ' ', blame_date_width - time_len);

 1. The type of blame_date_width is size_t, which is unsigned.  If
    time_len is greater than blame_date_width, the result of
    "blame_date_width - time_len" will never be a negative number, but a
    really big positive number, and will cause memory overwrite.

    This bug can be triggered if either l10n message for function
    show_date_relative() in date.c is longer than 30 characters, then
    `git blame --date relative` may exit abnormally.

 2. When show blame information with relative time, the UTF-8 characters
    in time_str will break the alignment of columns after the date field.
    This is because the time_buf padding with spaces should have a
    constant display width, not a fixed strlen size.  So we should call
    utf8_strwidth() instead of strlen() for width calibration.

Helped-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
Helped-by: Eric Sunshine <sunshine@sunshineco.com>
Signed-off-by: Jiang Xin <worldhello.net@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>