Commit Graph

45983 Commits

Author SHA1 Message Date
Richard Hansen
c1b0d3a010 mergetool: take the "-O" out of $orderfile
This will make it easier for a future commit to convert a relative
orderfile pathname to either absolute or relative to the top-level
directory.  It also improves code readability.

Signed-off-by: Richard Hansen <hansenr@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-01-10 13:22:20 -08:00
Richard Hansen
b9ebb65926 t7610: add test case for rerere+mergetool+subdir bug
If rerere is enabled and mergetool is run from a subdirectory,
mergetool always prints "No files need merging".  Add an expected
failure test case for this situation.

Signed-off-by: Richard Hansen <hansenr@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-01-10 13:22:20 -08:00
Richard Hansen
bd9714f253 t7610: spell 'git reset --hard' consistently
Signed-off-by: Richard Hansen <hansenr@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-01-10 13:22:20 -08:00
Richard Hansen
fef6c06d64 t7610: don't assume the checked-out commit
Always check out the required commit at the beginning of the test so
that a failure in a previous test does not cause the test to work off
of the wrong commit.

This is a step toward making the tests more independent so that if one
test fails it doesn't cause subsequent tests to fail.

Signed-off-by: Richard Hansen <hansenr@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-01-10 13:22:20 -08:00
Richard Hansen
61b76d2de3 t7610: always work on a test-specific branch
Create and use a test-specific branch when the test might create a
commit.  This is not always necessary for correctness, but it improves
debuggability by ensuring a commit created by test #N shows up on the
testN branch, not the branch for test #N-1.

Signed-off-by: Richard Hansen <hansenr@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-01-10 13:22:20 -08:00
Richard Hansen
e866ff851a t7610: delete some now-unnecessary 'git reset --hard' lines
Tests now always run 'git reset --hard' at the end (even if they
fail), so it's no longer necessary to run 'git reset --hard' at the
beginning of a test.

Signed-off-by: Richard Hansen <hansenr@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-01-10 13:22:20 -08:00
Richard Hansen
c3ad3126b8 t7610: run 'git reset --hard' after each test to clean up
Use test_when_finished to run 'git reset --hard' after each test so
that the repository is left in a saner state for the next test.

This is a step toward making the tests more independent so that if one
test fails it doesn't cause subsequent tests to fail.

Signed-off-by: Richard Hansen <hansenr@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-01-10 13:22:20 -08:00
Richard Hansen
b696ac9aaf t7610: don't rely on state from previous test
If the repository must be in a particular state (beyond what is
already done by the 'setup' test case) before the test can run, make
the necessary repository changes in the test script even if it means
duplicating some lines of code from the previous test case.

This is a step toward making the tests more independent so that if one
test fails it doesn't cause subsequent tests to fail.

Signed-off-by: Richard Hansen <hansenr@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-01-10 13:22:20 -08:00
Richard Hansen
614eb27f02 t7610: use test_when_finished for cleanup tasks
This is a step toward making the tests more independent so that if one
test fails it doesn't cause subsequent tests to fail.

Signed-off-by: Richard Hansen <hansenr@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-01-10 13:22:20 -08:00
Richard Hansen
157acfcf35 t7610: move setup code to the 'setup' test case
Multiple test cases depend on these hunks, so move them to the 'setup'
test case.  This is a step toward making the tests more independent so
that if one test fails it doesn't cause subsequent tests to fail.

Signed-off-by: Richard Hansen <hansenr@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-01-10 13:22:19 -08:00
Richard Hansen
ecfdf0bd2f t7610: update branch names to match test number
Rename the testNN branches so that NN matches the test number.  This
should make it easier to troubleshoot test issues.  Use $test_count to
keep this future-proof.

Signed-off-by: Richard Hansen <hansenr@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-01-10 13:22:19 -08:00
Richard Hansen
11873b438f rev-parse doc: pass "--" to rev-parse in the --prefix example
The "--" argument avoids "ambiguous argument: unknown revision or
path not in the working tree" errors when a pathname argument refers
to a non-existent file.

The "--" passed explicitly to set was removed because rev-parse
outputs the "--" argument that it is given.

Signed-off-by: Richard Hansen <hansenr@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-01-10 13:22:19 -08:00
Stefan Beller
384f1a167b unpack-trees: factor progress setup out of check_updates
This makes check_updates shorter and easier to understand.

Signed-off-by: Stefan Beller <sbeller@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-01-10 11:53:33 -08:00
Stefan Beller
c4bfc7728b unpack-trees: remove unneeded continue
The continue is the last statement in the loop, so not needed.
This situation arose in 700e66d66 (2010-07-30, unpack-trees: let
read-tree -u remove index entries outside sparse area) when statements
after the continue were removed.

Signed-off-by: Stefan Beller <sbeller@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-01-10 11:51:19 -08:00
Stefan Beller
30ac275b1c unpack-trees: move checkout state into check_updates
The checkout state was introduced via 16da134b1f
(read-trees: refactor the unpack_trees() part, 2006-07-30). An attempt to
refactor the checkout state was done in b56aa5b268 (unpack-trees: pass
checkout state explicitly to check_updates(), 2016-09-13), but we can
go even further.

The `struct checkout state` is not used in unpack_trees apart from
initializing it, so move it into the function that makes use of it,
which is `check_updates`.

Signed-off-by: Stefan Beller <sbeller@google.com>
Reviewed-by: René Scharfe <l.s.r@web.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-01-10 11:51:14 -08:00
Richard Hansen
314caebe21 .mailmap: record canonical email for Richard Hansen
When I changed employers my work address changed from rhansen@bbn.com
to hansenr@google.com.  Rather than map my old work address to my new,
map them both to my permanent personal email address.  (I will still
use my work address in commits I submit so that my employer gets some
credit.)

Signed-off-by: Richard Hansen <hansenr@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-01-10 11:13:11 -08:00
Stefan Beller
2d81c48fa7 pathspec: give better message for submodule related pathspec error
Every once in a while someone complains to the mailing list to have
run into this weird assertion[1]. The usual response from the mailing
list is link to old discussions[2], and acknowledging the problem
stating it is known.

This patch accomplishes two things:

  1. Switch assert() to die("BUG") to give a more readable message.

  2. Take one of the cases where we hit a BUG and turn it into a normal
     "there was something wrong with the input" message.

     This assertion triggered for cases where there wasn't a programming
     bug, but just bogus input. In particular, if the user asks for a
     pathspec that is inside a submodule, we shouldn't assert() or
     die("BUG"); we should tell the user their request is bogus.

     The only reason we did not check for it, is the expensive nature
     of such a check, so callers avoid setting the flag
     PATHSPEC_STRIP_SUBMODULE_SLASH_EXPENSIVE. However when we die due
     to bogus input, the expense of CPU cycles spent outweighs the user
     wondering what went wrong, so run that check unconditionally before
     dying with a more generic error message.

Note: There is a case (e.g. "git -C submodule add .") in which we call
strip_submodule_slash_expensive, as git-add requests it via the flag
PATHSPEC_STRIP_SUBMODULE_SLASH_EXPENSIVE, but the assert used to
trigger nevertheless, because the flag PATHSPEC_LITERAL was not set,
such that we executed

	if (item->nowildcard_len < prefixlen)
		item->nowildcard_len = prefixlen;

and prefixlen was not adapted (e.g. it was computed from "submodule/")
So in the die_inside_submodule_path function we also need handle paths,
that were stripped before, i.e. are the exact submodule path. This
is why the conditions in die_inside_submodule_path are slightly
different than in strip_submodule_slash_expensive.

[1] https://www.google.com/search?q=item-%3Enowildcard_len
[2] http://git.661346.n2.nabble.com/assert-failed-in-submodule-edge-case-td7628687.html
    https://www.spinics.net/lists/git/msg249473.html

Helped-by: Jeff King <peff@peff.net>
Helped-by: Junio C Hamano <gitster@pobox.com>
Signed-off-by: Stefan Beller <sbeller@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-01-09 15:19:22 -08:00
Johannes Schindelin
ac191470c7 sequencer (rebase -i): differentiate between comments and 'noop'
In the upcoming patch, we will support rebase -i's progress
reporting. The progress skips comments but counts 'noop's.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-01-09 14:57:30 -08:00
Johannes Schindelin
b3fdd581ae sequencer (rebase -i): implement the 'drop' command
The parsing part of a 'drop' command is almost identical to parsing a
'pick', while the operation is the same as that of a 'noop'.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-01-09 14:57:30 -08:00
Johannes Schindelin
9d7bf3cf99 sequencer (rebase -i): allow rescheduling commands
The interactive rebase has the very special magic that a cherry-pick
that exits with a status different from 0 and 1 signifies a failure to
even record that a cherry-pick was started.

This can happen e.g. when a fast-forward fails because it would
overwrite untracked files.

In that case, we must reschedule the command that we thought we already
had at least started successfully.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-01-09 14:57:30 -08:00
Johannes Schindelin
ca6c6b45dd sequencer (rebase -i): respect strategy/strategy_opts settings
The sequencer already has an idea about using different merge
strategies. We just piggy-back on top of that, using rebase -i's
own settings, when running the sequencer in interactive rebase mode.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-01-09 14:57:30 -08:00
Johannes Schindelin
796c7972c7 sequencer (rebase -i): respect the rebase.autostash setting
Git's `rebase` command inspects the `rebase.autostash` config setting
to determine whether it should stash any uncommitted changes before
rebasing and re-apply them afterwards.

As we introduce more bits and pieces to let the sequencer act as
interactive rebase's backend, here is the part that adds support for
the autostash feature.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-01-09 14:57:30 -08:00
Johannes Schindelin
795160457d sequencer (rebase -i): run the post-rewrite hook, if needed
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-01-09 14:57:30 -08:00
Johannes Schindelin
ca98c6d487 sequencer (rebase -i): record interrupted commits in rewritten, too
When continuing after a `pick` command failed, we want that commit
to show up in the rewritten-list (and its notes to be rewritten), too.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-01-09 14:57:30 -08:00
Johannes Schindelin
25cb8df97c sequencer (rebase -i): copy commit notes at end
When rebasing commits that have commit notes attached, the interactive
rebase rewrites those notes faithfully at the end. The sequencer must
do this, too, if it wishes to do interactive rebase's job.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-01-09 14:57:30 -08:00
Johannes Schindelin
8ab37ef21f sequencer (rebase -i): set the reflog message consistently
We already used the same reflog message as the scripted version of rebase
-i when finishing. With this commit, we do that also for all the commands
before that.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-01-09 14:57:30 -08:00
Johannes Schindelin
96e832a5fd sequencer (rebase -i): refactor setting the reflog message
This makes the code DRYer, with the obvious benefit that we can enhance
the code further in a single place.

We can also reuse the functionality elsewhere by calling this new
function.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-01-09 14:57:30 -08:00
Johannes Schindelin
bcbb68be2e sequencer (rebase -i): allow fast-forwarding for edit/reword
The sequencer already knew how to fast-forward instead of
cherry-picking, if possible.

We want to continue to do this, of course, but in case of the 'reword'
command, we will need to call `git commit` after fast-forwarding.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-01-09 14:57:30 -08:00
Johannes Schindelin
04efc8b57c sequencer (rebase -i): implement the 'reword' command
This is now trivial, as all the building blocks are in place: all we need
to do is to flip the "edit" switch when committing.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-01-09 14:57:30 -08:00
Johannes Schindelin
4a5146f9d2 sequencer (rebase -i): leave a patch upon error
When doing an interactive rebase, we want to leave a 'patch' file for
further inspection by the user (even if we never tried to actually apply
that patch, since we're cherry-picking instead).

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-01-09 14:57:30 -08:00
Johannes Schindelin
4b83ce9f67 sequencer (rebase -i): update refs after a successful rebase
An interactive rebase operates on a detached HEAD (to keep the reflog
of the original branch relatively clean), and updates the branch only
at the end.

Now that the sequencer learns to perform interactive rebases, it also
needs to learn the trick to update the branch before removing the
directory containing the state of the interactive rebase.

We introduce a new head_ref variable in a wider scope than necessary at
the moment, to allow for a later patch that prints out "Successfully
rebased and updated <ref>".

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-01-09 14:57:30 -08:00
Johannes Schindelin
52865279ee sequencer (rebase -i): the todo can be empty when continuing
When the last command of an interactive rebase fails, the user needs to
resolve the problem and then continue the interactive rebase. Naturally,
the todo script is empty by then. So let's not complain about that!

To that end, let's move that test out of the function that parses the
todo script, and into the more high-level function read_populate_todo().
This is also necessary by now because the lower-level parse_insn_buffer()
has no idea whether we are performing an interactive rebase or not.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-01-09 14:57:29 -08:00
Johannes Schindelin
4258a6da90 sequencer (rebase -i): skip some revert/cherry-pick specific code path
When a cherry-pick continues without a "todo script", the intention is
simply to pick a single commit.

However, when an interactive rebase is continued without a "todo
script", it means that the last command has been completed and that we
now need to clean up.

This commit guards the revert/cherry-pick specific steps so that they
are not executed in rebase -i mode.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-01-09 14:57:29 -08:00
Johannes Schindelin
5263220967 sequencer (rebase -i): remove CHERRY_PICK_HEAD when no longer needed
The scripted version of the interactive rebase already does that.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-01-09 14:57:29 -08:00
Johannes Schindelin
9d93ccd1d2 sequencer (rebase -i): allow continuing with staged changes
When an interactive rebase is interrupted, the user may stage changes
before continuing, and we need to commit those changes in that case.

Please note that the nested "if" added to the sequencer_continue() is
not combined into a single "if" because it will be extended with an
"else" clause in a later patch in this patch series.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-01-09 14:57:29 -08:00
Johannes Schindelin
0473f28ad7 sequencer (rebase -i): write an author-script file
When the interactive rebase aborts, it writes out an author-script file
to record the author information for the current commit. As we are about
to teach the sequencer how to perform the actions behind an interactive
rebase, it needs to write those author-script files, too.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-01-09 14:57:29 -08:00
Johannes Schindelin
414697a9d8 sequencer (rebase -i): implement the short commands
For users' convenience, most rebase commands can be abbreviated, e.g.
'p' instead of 'pick' and 'x' instead of 'exec'. Let's teach the
sequencer to handle those abbreviated commands just fine.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-01-09 14:57:29 -08:00
Johannes Schindelin
6e98de72c0 sequencer (rebase -i): add support for the 'fixup' and 'squash' commands
This is a huge patch, and at the same time a huge step forward to
execute the performance-critical parts of the interactive rebase in a
builtin command.

Since 'fixup' and 'squash' are not only similar, but also need to know
about each other (we want to reduce a series of fixups/squashes into a
single, final commit message edit, from the user's point of view), we
really have to implement them both at the same time.

Most of the actual work is done by the existing code path that already
handles the "pick" and the "edit" commands; We added support for other
features (e.g. to amend the commit message) in the patches leading up to
this one, yet there are still quite a few bits in this patch that simply
would not make sense as individual patches (such as: determining whether
there was anything to "fix up" in the "todo" script, etc).

In theory, it would be possible to reuse the fast-forward code path also
for the fixup and the squash code paths, but in practice this would make
the code less readable. The end result cannot be fast-forwarded anyway,
therefore let's just extend the cherry-picking code path for now.

Since the sequencer parses the entire `git-rebase-todo` script in one go,
fixup or squash commands without a preceding pick can be reported early
(in git-rebase--interactive, we could only report such errors just before
executing the fixup/squash).

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-01-09 14:57:29 -08:00
Johannes Schindelin
1df6df0c18 sequencer (rebase -i): write the 'done' file
In the interactive rebase, commands that were successfully processed are
not simply discarded, but appended to the 'done' file instead. This is
used e.g. to display the current state to the user in the output of
`git status` or the progress.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-01-09 14:57:29 -08:00
Johannes Schindelin
556907f1e1 sequencer (rebase -i): learn about the 'verbose' mode
When calling `git rebase -i -v`, the user wants to see some statistics
after the commits were rebased. Let's show some.

The strbuf we use to perform that task will be used for other things
in subsequent commits, hence it is declared and initialized in a wider
scope than strictly needed here.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-01-09 14:57:29 -08:00
Johannes Schindelin
311af5266b sequencer (rebase -i): implement the 'exec' command
The 'exec' command is a little special among rebase -i's commands, as it
does *not* have a SHA-1 as first parameter. Instead, everything after the
`exec` command is treated as command-line to execute.

Let's reuse the arg/arg_len fields of the todo_item structure (which hold
the oneline for pick/edit commands) to point to the command-line.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-01-09 14:57:29 -08:00
Johannes Schindelin
56dc3ab04b sequencer (rebase -i): implement the 'edit' command
This patch is a straight-forward reimplementation of the `edit`
operation of the interactive rebase command.

Well, not *quite* straight-forward: when stopping, the `edit`
command wants to write the `patch` file (which is not only the
patch, but includes the commit message and author information). To
that end, this patch requires the earlier work that taught the
log-tree machinery to respect the `file` setting of
rev_info->diffopt to write to a file stream different than stdout.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-01-09 14:57:29 -08:00
Johannes Schindelin
25c4366782 sequencer (rebase -i): implement the 'noop' command
The 'noop' command is probably the most boring of all rebase -i commands
to support in the sequencer.

Which makes it an excellent candidate for this first stab to add support
for rebase -i's commands to the sequencer.

For the moment, let's also treat empty lines and commented-out lines as
'noop'; We will refine that handling later in this patch series.

To make it easier to identify "classes" of todo_commands (such as:
determine whether a command is pick-like, i.e. handles a single commit),
let's enforce a certain order of said commands.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-01-09 14:57:29 -08:00
Johannes Schindelin
845839575d sequencer: support a new action: 'interactive rebase'
This patch introduces a new action for the sequencer. It really does not
do a whole lot of its own right now, but lays the ground work for
patches to come. The intention, of course, is to finally make the
sequencer the work horse of the interactive rebase (the original idea
behind the "sequencer" concept).

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-01-09 14:57:29 -08:00
Johannes Schindelin
23aa51420c sequencer: use a helper to find the commit message
It is actually not safe to look for a commit message by looking for the
first empty line and skipping it.

The find_commit_subject() function looks more carefully, so let's use
it. Since we are interested in the entire commit message, we re-compute
the string length after verifying that the commit subject is not empty
(in which case the entire commit message would be empty, something that
should not happen but that we want to handle gracefully).

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-01-09 14:57:29 -08:00
Johannes Schindelin
a70d8f8067 sequencer: move "else" keyword onto the same line as preceding brace
It is the current coding style of the Git project to write

	if (...) {
		...
	} else {
		...
	}

instead of putting the closing brace and the "else" keyword on separate
lines.

Pointed out by Junio Hamano.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-01-09 14:57:29 -08:00
Johannes Schindelin
637666c822 sequencer: avoid unnecessary curly braces
This was noticed while addressing Junio Hamano's concern that some
"else" operators were on separate lines than the preceding closing
brace.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-01-09 14:57:29 -08:00
Jeff King
46df6906f3 execv_dashed_external: wait for child on signal death
When you hit ^C to interrupt a git command going to a pager,
this usually leaves the pager running. But when a dashed
external is in use, the pager ends up in a funny state and
quits (but only after eating one more character from the
terminal!). This fixes it.

Explaining the reason will require a little background.

When git runs a pager, it's important for the git process to
hang around and wait for the pager to finish, even though it
has no more data to feed it. This is because git spawns the
pager as a child, and thus the git process is the session
leader on the terminal. After it dies, the pager will finish
its current read from the terminal (eating the one
character), and then get EIO trying to read again.

When you hit ^C, that sends SIGINT to git and to the pager,
and it's a similar situation.  The pager ignores it, but the
git process needs to hang around until the pager is done. We
addressed that long ago in a3da882120 (pager: do
wait_for_pager on signal death, 2009-01-22).

But when you have a dashed external (or an alias pointing to
a builtin, which will re-exec git for the builtin), there's
an extra process in the mix. For instance, running:

  $ git -c alias.l=log l

will end up with a process tree like:

  git (parent)
    \
     git-log (child)
      \
       less (pager)

If you hit ^C, SIGINT goes to all of them. The pager ignores
it, and the child git process will end up in wait_for_pager().
But the parent git process will die, and the usual EIO
trouble happens.

So we really want the parent git process to wait_for_pager(),
but of course it doesn't know anything about the pager at
all, since it was started by the child.  However, we can
have it wait on the git-log child, which in turn is waiting
on the pager. And that's what this patch does.

There are a few design decisions here worth explaining:

  1. The new feature is attached to run-command's
     clean_on_exit feature. Partly this is convenience,
     since that feature already has a signal handler that
     deals with child cleanup.

     But it's also a meaningful connection. The main reason
     that dashed externals use clean_on_exit is to bind the
     two processes together. If somebody kills the parent
     with a signal, we propagate that to the child (in this
     instance with SIGINT, we do propagate but it doesn't
     matter because the original signal went to the whole
     process group). Likewise, we do not want the parent
     to go away until the child has done so.

     In a traditional Unix world, we'd probably accomplish
     this binding by just having the parent execve() the
     child directly. But since that doesn't work on Windows,
     everything goes through run_command's more spawn-like
     interface.

  2. We do _not_ automatically waitpid() on any
     clean_on_exit children. For dashed externals this makes
     sense; we know that the parent is doing nothing but
     waiting for the child to exit anyway. But with other
     children, it's possible that the child, after getting
     the signal, could be waiting on the parent to do
     something (like closing a descriptor). If we were to
     wait on such a child, we'd end up in a deadlock. So
     this errs on the side of caution, and lets callers
     enable the feature explicitly.

  3. When we send children the cleanup signal, we send all
     the signals first, before waiting on any children. This
     is to avoid the case where one child might be waiting
     on another one to exit, causing a deadlock. We inform
     all of them that it's time to die before reaping any.

     In practice, there is only ever one dashed external run
     from a given process, so this doesn't matter much now.
     But it future-proofs us if other callers start using
     the wait_after_clean mechanism.

There's no automated test here, because it would end up racy
and unportable. But it's easy to reproduce the situation by
running the log command given above and hitting ^C.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-01-09 13:41:40 -08:00
Jeff King
246f0edec0 execv_dashed_external: stop exiting with negative code
When we try to exec a git sub-command, we pass along the
status code from run_command(). But that may return -1 if we
ran into an error with pipe() or execve(). This tends to
work (and end up as 255 due to twos-complement wraparound
and truncation), but in general it's probably a good idea to
avoid negative exit codes for portability.

We can easily translate to the normal generic "128" code we
get when syscalls cause us to die.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-01-09 13:41:35 -08:00
Jeff King
2b296c93d4 execv_dashed_external: use child_process struct
When we run a dashed external, we use the one-liner
run_command_v_opt() to do so. Let's switch to using a
child_process struct, which has two advantages:

  1. We can drop all of the allocation and cleanup code for
     building our custom argv array, and just rely on the
     builtin argv_array (at the minor cost of doing a few
     extra mallocs).

  2. We have access to the complete range of child_process
     options, not just the ones that the "_opt()" form can
     forward.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2017-01-09 13:41:33 -08:00