Commit Graph

58196 Commits

Author SHA1 Message Date
Elijah Newren
7f45ab2dca dir: replace double pathspec matching with single in treat_directory()
treat_directory() had a call to both do_match_pathspec() and
match_pathspec().  These calls have migrated through the code somewhat
since their introduction, but we don't actually need both.  Replace the
two calls with one, and while at it, move the check earlier in order to
reduce the need for callers of fill_directory() to do post-filtering of
results.

The next patch will address post-filtering more forcefully and provide
more relevant history and context.

Signed-off-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-04-01 11:11:31 -07:00
Elijah Newren
1684644489 dir: include DIR_KEEP_UNTRACKED_CONTENTS handling in treat_directory()
Handling DIR_KEEP_UNTRACKED_CONTENTS within treat_directory() instead of
as a post-processing step in read_directory():
  * allows us to directly access and remove the relevant entries instead
    of needing to calculate which ones need to be removed
  * keeps the logic for directory handling in one location (and puts it
    closer the the logic for stripping out extra ignored entries, which
    seems logical).

Signed-off-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-04-01 11:11:31 -07:00
Elijah Newren
8d92fb2927 dir: replace exponential algorithm with a linear one
dir's read_directory_recursive() naturally operates recursively in order
to walk the directory tree.  Treating of directories is sometimes weird
because there are so many different permutations about how to handle
directories.  Some examples:

   * 'git ls-files -o --directory' only needs to know that a directory
     itself is untracked; it doesn't need to recurse into it to see what
     is underneath.

   * 'git status' needs to recurse into an untracked directory, but only
     to determine whether or not it is empty.  If there are no files
     underneath, the directory itself will be omitted from the output.
     If it is not empty, only the directory will be listed.

   * 'git status --ignored' needs to recurse into untracked directories
     and report all the ignored entries and then report the directory as
     untracked -- UNLESS all the entries under the directory are
     ignored, in which case we don't print any of the entries under the
     directory and just report the directory itself as ignored.  (Note
     that although this forces us to walk all untracked files underneath
     the directory as well, we strip them from the output, except for
     users like 'git clean' who also set DIR_KEEP_TRACKED_CONTENTS.)

   * For 'git clean', we may need to recurse into a directory that
     doesn't match any specified pathspecs, if it's possible that there
     is an entry underneath the directory that can match one of the
     pathspecs.  In such a case, we need to be careful to omit the
     directory itself from the list of paths (see commit 404ebceda0
     ("dir: also check directories for matching pathspecs", 2019-09-17))

Part of the tension noted above is that the treatment of a directory can
change based on the files within it, and based on the various settings
in dir->flags.  Trying to keep this in mind while reading over the code,
it is easy to think in terms of "treat_directory() tells us what to do
with a directory, and read_directory_recursive() is the thing that
recurses".  Since we need to look into a directory to know how to treat
it, though, it is quite easy to decide to (also) recurse into the
directory from treat_directory() by adding a read_directory_recursive()
call.  Adding such a call is actually fine, IF we make sure that
read_directory_recursive() does not also recurse into that same
directory.

Unfortunately, commit df5bcdf83a ("dir: recurse into untracked dirs
for ignored files", 2017-05-18), added exactly such a case to the code,
meaning we'd have two calls to read_directory_recursive() for an
untracked directory.  So, if we had a file named
   one/two/three/four/five/somefile.txt
and nothing in one/ was tracked, then 'git status --ignored' would
call read_directory_recursive() twice on the directory 'one/', and
each of those would call read_directory_recursive() twice on the
directory 'one/two/', and so on until read_directory_recursive() was
called 2^5 times for 'one/two/three/four/five/'.

Avoid calling read_directory_recursive() twice per level by moving a
lot of the special logic into treat_directory().

Since dir.c is somewhat complex, extra cruft built up around this over
time.  While trying to unravel it, I noticed several instances where the
first call to read_directory_recursive() would return e.g.
path_untracked for some directory and a later one would return e.g.
path_none, despite the fact that the directory clearly should have been
considered untracked.  The code happened to work due to the side-effect
from the first invocation of adding untracked entries to dir->entries;
this allowed it to get the correct output despite the supposed override
in return value by the later call.

I am somewhat concerned that there are still bugs and maybe even
testcases with the wrong expectation.  I have tried to carefully
document treat_directory() since it becomes more complex after this
change (though much of this complexity came from elsewhere that probably
deserved better comments to begin with).  However, much of my work felt
more like a game of whackamole while attempting to make the code match
the existing regression tests than an attempt to create an
implementation that matched some clear design.  That seems wrong to me,
but the rules of existing behavior had so many special cases that I had
a hard time coming up with some overarching rules about what correct
behavior is for all cases, forcing me to hope that the regression tests
are correct and sufficient.  Such a hope seems likely to be ill-founded,
given my experience with dir.c-related testcases in the last few months:

  Examples where the documentation was hard to parse or even just wrong:
   * 3aca58045f (git-clean.txt: do not claim we will delete files with
                   -n/--dry-run, 2019-09-17)
   * 09487f2cba (clean: avoid removing untracked files in a nested git
                   repository, 2019-09-17)
   * e86bbcf987 (clean: disambiguate the definition of -d, 2019-09-17)
  Examples where testcases were declared wrong and changed:
   * 09487f2cba (clean: avoid removing untracked files in a nested git
                   repository, 2019-09-17)
   * e86bbcf987 (clean: disambiguate the definition of -d, 2019-09-17)
   * a2b13367fe (Revert "dir.c: make 'git-status --ignored' work within
                   leading directories", 2019-12-10)
  Examples where testcases were clearly inadequate:
   * 502c386ff9 (t7300-clean: demonstrate deleting nested repo with an
                   ignored file breakage, 2019-08-25)
   * 7541cc5302 (t7300: add testcases showing failure to clean specified
                   pathspecs, 2019-09-17)
   * a5e916c745 (dir: fix off-by-one error in match_pathspec_item,
                   2019-09-17)
   * 404ebceda0 (dir: also check directories for matching pathspecs,
                   2019-09-17)
   * 09487f2cba (clean: avoid removing untracked files in a nested git
                   repository, 2019-09-17)
   * e86bbcf987 (clean: disambiguate the definition of -d, 2019-09-17)
   * 452efd11fb (t3011: demonstrate directory traversal failures,
                   2019-12-10)
   * b9670c1f5e (dir: fix checks on common prefix directory, 2019-12-19)
  Examples where "correct behavior" was unclear to everyone:
    https://lore.kernel.org/git/20190905154735.29784-1-newren@gmail.com/
  Other commits of note:
   * 902b90cf42 (clean: fix theoretical path corruption, 2019-09-17)

However, on the positive side, it does make the code much faster.  For
the following simple shell loop in an empty repository:

  for depth in $(seq 10 25)
  do
    dirs=$(for i in $(seq 1 $depth) ; do printf 'dir/' ; done)
    rm -rf dir
    mkdir -p $dirs
    >$dirs/untracked-file
    /usr/bin/time --format="$depth: %e" git status --ignored >/dev/null
  done

I saw the following timings, in seconds (note that the numbers are a
little noisy from run-to-run, but the trend is very clear with every
run):

    10: 0.03
    11: 0.05
    12: 0.08
    13: 0.19
    14: 0.29
    15: 0.50
    16: 1.05
    17: 2.11
    18: 4.11
    19: 8.60
    20: 17.55
    21: 33.87
    22: 68.71
    23: 140.05
    24: 274.45
    25: 551.15

For the above run, using strace I can look for the number of untracked
directories opened and can verify that it matches the expected
2^($depth+1)-2 (the sum of 2^1 + 2^2 + 2^3 + ... + 2^$depth).

After this fix, with strace I can verify that the number of untracked
directories that are opened drops to just $depth, and the timings all
drop to 0.00.  In fact, it isn't until a depth of 190 nested directories
that it sometimes starts reporting a time of 0.01 seconds and doesn't
consistently report 0.01 seconds until there are 240 nested directories.
The previous code would have taken
  17.55 * 2^220 / (60*60*24*365) = 9.4 * 10^59 YEARS
to have completed the 240 nested directories case.  It's not often
that you get to speed something up by a factor of 3*10^69.

Signed-off-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-04-01 11:10:38 -07:00
Derrick Stolee
0bbd0e8b52 dir: refactor treat_directory to clarify control flow
The logic in treat_directory() is handled by a multi-case
switch statement, but this switch is very asymmetrical, as
the first two cases are simple but the third is more
complicated than the rest of the method. In fact, the third
case includes a "break" statement that leads to the block
of code outside the switch statement. That is the only way
to reach that block, as the switch handles all possible
values from directory_exists_in_index();

Extract the switch statement into a series of "if" statements.
This simplifies the trivial cases, while clarifying how to
reach the "show_other_directories" case. This is particularly
important as the "show_other_directories" case will expand
in a later change.

Helped-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
Signed-off-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-04-01 11:10:38 -07:00
Elijah Newren
2df179d3df dir: fix confusion based on variable tense
Despite having contributed several fixes in this area, I have for months
(years?) assumed that the "exclude" variable was a directive; this
caused me to think of it as a different mode we operate in and left me
confused as I tried to build up a mental model around why we'd need such
a directive.  I mostly tried to ignore it while focusing on the pieces I
was trying to understand.

Then I finally traced this variable all back to a call to is_excluded(),
meaning it was actually functioning as an adjective.  In particular, it
was a checked property ("Does this path match a rule in .gitignore?"),
rather than a mode passed in from the caller.  Change the variable name
to match the part of speech used by the function called to define it,
which will hopefully make these bits of code slightly clearer to the
next reader.

Signed-off-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-04-01 11:10:38 -07:00
Elijah Newren
0126d1415a dir: fix broken comment
Signed-off-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-04-01 11:10:38 -07:00
Elijah Newren
cd129eed98 dir: consolidate treat_path() and treat_one_path()
Commit 16e2cfa909 ("read_directory(): further split treat_path()",
2010-01-08) split treat_one_path() out of treat_path(), because
treat_leading_path() would not have access to a dirent but wanted to
re-use as much of treat_path() as possible.  Not re-using all of
treat_path() caused other bugs, as noted in commit b9670c1f5e ("dir:
fix checks on common prefix directory", 2019-12-19).  Finally, in commit
ad6f2157f9 ("dir: restructure in a way to avoid passing around a
struct dirent", 2020-01-16), dirents were removed from treat_path() and
other functions entirely.

Since the only reason for splitting these functions was the lack of a
dirent -- which no longer applies to either function -- and since the
split caused problems in the past resulting in us not using
treat_one_path() separately anymore, just undo the split.

Signed-off-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-04-01 11:10:38 -07:00
Elijah Newren
446f46d8c7 dir: fix simple typo in comment
Signed-off-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-04-01 11:10:38 -07:00
Elijah Newren
7260c7b66e t3000: add more testcases testing a variety of ls-files issues
This adds seven new ls-files tests.  While currently all seven test
pass, my earlier rounds of restructuring dir.c to replace an exponential
algorithm with a linear one passed all the tests in the testsuite but
failed six of these seven new tests.  Add these tests to increase our
case coverage.

Signed-off-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-04-01 11:10:38 -07:00
Elijah Newren
ce5c61a3f5 t7063: more thorough status checking
It turns out the t7063 has some testcases that even without using the
untracked cache cover situations that nothing else in the testsuite
handles.  Checking the results of
  git status --porcelain
both with and without the untracked cache, and comparing both against
our expected results helped uncover a critical bug in some dir.c
restructuring.

Unfortunately, it's not easy to run status and tell it to ignore the
untracked cache; the only knob we have is core.untrackedCache=false,
which is used to instruct git to *delete* the untracked cache (which
might also ignore the untracked cache when it operates, but that isn't
specified in the docs).

Create a simple helper that will create a clone of the index that is
missing the untracked cache bits, and use it to compare that the results
with the untracked cache match the results we get without the untracked
cache.

Signed-off-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-04-01 11:10:38 -07:00
Junio C Hamano
0822e66b5d Git 2.25.2
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-03-17 15:06:37 -07:00
Beat Bolli
65588b0b2e unicode: update the width tables to Unicode 13.0
Now that Unicode 13.0 has been announced[0], update the character
width tables to the new version.

[0] https://home.unicode.org/announcing-the-unicode-standard-version-13-0/

Signed-off-by: Beat Bolli <dev+git@drbeat.li>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-03-17 15:06:37 -07:00
Junio C Hamano
7be274b0ff Merge branch 'js/ci-windows-update' into maint
Updates to the CI settings.

* js/ci-windows-update:
  Azure Pipeline: switch to the latest agent pools
  ci: prevent `perforce` from being quarantined
  t/lib-httpd: avoid using macOS' sed
2020-03-17 15:02:26 -07:00
Junio C Hamano
9a75ecda1b Merge branch 'jk/run-command-formatfix' into maint
Code style cleanup.

* jk/run-command-formatfix:
  run-command.h: fix mis-indented struct member
2020-03-17 15:02:26 -07:00
Junio C Hamano
221887a492 Merge branch 'jk/doc-credential-helper' into maint
Docfix.

* jk/doc-credential-helper:
  doc: move credential helper info into gitcredentials(7)
2020-03-17 15:02:26 -07:00
Junio C Hamano
32fc2c6dd6 Merge branch 'js/mingw-open-in-gdb' into maint
Dev support.

* js/mingw-open-in-gdb:
  mingw: add a helper function to attach GDB to the current process
2020-03-17 15:02:25 -07:00
Junio C Hamano
fe0d2c8ddb Merge branch 'js/test-unc-fetch' into maint
Test updates.

* js/test-unc-fetch:
  t5580: test cloning without file://, test fetching via UNC paths
2020-03-17 15:02:25 -07:00
Junio C Hamano
618db3621a Merge branch 'js/test-write-junit-xml-fix' into maint
Testfix.

* js/test-write-junit-xml-fix:
  tests: fix --write-junit-xml with subshells
2020-03-17 15:02:25 -07:00
Junio C Hamano
50e1b4166f Merge branch 'en/simplify-check-updates-in-unpack-trees' into maint
Code simplification.

* en/simplify-check-updates-in-unpack-trees:
  unpack-trees: exit check_updates() early if updates are not wanted
2020-03-17 15:02:25 -07:00
Junio C Hamano
fda2baffd2 Merge branch 'jc/doc-single-h-is-for-help' into maint
Both "git ls-remote -h" and "git grep -h" give short usage help,
like any other Git subcommand, but it is not unreasonable to expect
that the former would behave the same as "git ls-remote --head"
(there is no other sensible behaviour for the latter).  The
documentation has been updated in an attempt to clarify this.

* jc/doc-single-h-is-for-help:
  Documentation: clarify that `-h` alone stands for `help`
2020-03-17 15:02:24 -07:00
Junio C Hamano
41d910ea6c Merge branch 'hd/show-one-mergetag-fix' into maint
"git show" and others gave an object name in raw format in its
error output, which has been corrected to give it in hex.

* hd/show-one-mergetag-fix:
  show_one_mergetag: print non-parent in hex form.
2020-03-17 15:02:24 -07:00
Junio C Hamano
2d7247af6f Merge branch 'am/mingw-poll-fix' into maint
MinGW's poll() emulation has been improved.

* am/mingw-poll-fix:
  mingw: workaround for hangs when sending STDIN
2020-03-17 15:02:24 -07:00
Junio C Hamano
4e730fcd18 Merge branch 'hi/gpg-use-check-signature' into maint
"git merge signed-tag" while lacking the public key started to say
"No signature", which was utterly wrong.  This regression has been
reverted.

* hi/gpg-use-check-signature:
  Revert "gpg-interface: prefer check_signature() for GPG verification"
2020-03-17 15:02:23 -07:00
Junio C Hamano
76ccbdaf97 Merge branch 'ds/partial-clone-fixes' into maint
Fix for a bug revealed by a recent change to make the protocol v2
the default.

* ds/partial-clone-fixes:
  partial-clone: avoid fetching when looking for objects
  partial-clone: demonstrate bugs in partial fetch
2020-03-17 15:02:23 -07:00
Junio C Hamano
569b89842d Merge branch 'en/t3433-rebase-stat-dirty-failure' into maint
The merge-recursive machinery failed to refresh the cache entry for
a merge result in a couple of places, resulting in an unnecessary
merge failure, which has been fixed.

* en/t3433-rebase-stat-dirty-failure:
  merge-recursive: fix the refresh logic in update_file_flags
  t3433: new rebase testcase documenting a stat-dirty-like failure
2020-03-17 15:02:23 -07:00
Junio C Hamano
16a4bf1035 Merge branch 'en/check-ignore' into maint
"git check-ignore" did not work when the given path is explicitly
marked as not ignored with a negative entry in the .gitignore file.

* en/check-ignore:
  check-ignore: fix documentation and implementation to match
2020-03-17 15:02:23 -07:00
Junio C Hamano
3246495a5c Merge branch 'jk/push-option-doc-markup-fix' into maint
Doc markup fix.

* jk/push-option-doc-markup-fix:
  doc/config/push: use longer "--" line for preformatted example
2020-03-17 15:02:22 -07:00
Junio C Hamano
56f97d5896 Merge branch 'jk/doc-diff-parallel' into maint
Update to doc-diff.

* jk/doc-diff-parallel:
  doc-diff: use single-colon rule in rendering Makefile
2020-03-17 15:02:22 -07:00
Junio C Hamano
1a4abcbb3b Merge branch 'jh/notes-fanout-fix' into maint
The code to automatically shrink the fan-out in the notes tree had
an off-by-one bug, which has been killed.

* jh/notes-fanout-fix:
  notes.c: fix off-by-one error when decreasing notes fanout
  t3305: check notes fanout more carefully and robustly
2020-03-17 15:02:22 -07:00
Junio C Hamano
7e84f4608f Merge branch 'jk/index-pack-dupfix' into maint
The index-pack code now diagnoses a bad input packstream that
records the same object twice when it is used as delta base; the
code used to declare a software bug when encountering such an
input, but it is an input error.

* jk/index-pack-dupfix:
  index-pack: downgrade twice-resolved REF_DELTA to die()
2020-03-17 15:02:22 -07:00
Junio C Hamano
fa24bbe864 Merge branch 'js/rebase-i-with-colliding-hash' into maint
"git rebase -i" identifies existing commits in its todo file with
their abbreviated object name, which could become ambigous as it
goes to create new commits, and has a mechanism to avoid ambiguity
in the main part of its execution.  A few other cases however were
not covered by the protection against ambiguity, which has been
corrected.

* js/rebase-i-with-colliding-hash:
  rebase -i: also avoid SHA-1 collisions with missingCommitsCheck
  rebase -i: re-fix short SHA-1 collision
  parse_insn_line(): improve error message when parsing failed
2020-03-17 15:02:21 -07:00
Junio C Hamano
a7a2e12b6e Merge branch 'jk/clang-sanitizer-fixes' into maint
C pedantry ;-) fix.

* jk/clang-sanitizer-fixes:
  obstack: avoid computing offsets from NULL pointer
  xdiff: avoid computing non-zero offset from NULL pointer
  avoid computing zero offsets from NULL pointer
  merge-recursive: use subtraction to flip stage
  merge-recursive: silence -Wxor-used-as-pow warning
2020-03-17 15:02:21 -07:00
Junio C Hamano
93d0892891 Merge branch 'dt/submodule-rm-with-stale-cache' into maint
Running "git rm" on a submodule failed unnecessarily when
.gitmodules is only cache-dirty, which has been corrected.

* dt/submodule-rm-with-stale-cache:
  git rm submodule: succeed if .gitmodules index stat info is zero
2020-03-17 15:02:21 -07:00
Junio C Hamano
dae477777e Merge branch 'pb/recurse-submodule-in-worktree-fix' into maint
The "--recurse-submodules" option of various subcommands did not
work well when run in an alternate worktree, which has been
corrected.

* pb/recurse-submodule-in-worktree-fix:
  submodule.c: use get_git_dir() instead of get_git_common_dir()
  t2405: clarify test descriptions and simplify test
  t2405: use git -C and test_commit -C instead of subshells
  t7410: rename to t2405-worktree-submodule.sh
2020-03-17 15:02:21 -07:00
Junio C Hamano
758d0773ba Merge branch 'es/outside-repo-errmsg-hints' into maint
An earlier update to show the location of working tree in the error
message did not consider the possibility that a git command may be
run in a bare repository, which has been corrected.

* es/outside-repo-errmsg-hints:
  prefix_path: show gitdir if worktree unavailable
  prefix_path: show gitdir when arg is outside repo
2020-03-17 15:02:20 -07:00
Junio C Hamano
f0c344ce57 Merge branch 'js/builtin-add-i-cmds' into maint
Minor bugfixes to "git add -i" that has recently been rewritten in C.

* js/builtin-add-i-cmds:
  built-in add -i: accept open-ended ranges again
  built-in add -i: do not try to `patch`/`diff` an empty list of files
2020-03-17 15:02:20 -07:00
Emily Shaffer
5c20398699 prefix_path: show gitdir if worktree unavailable
If there is no worktree at present, we can still hint the user about
Git's current directory by showing them the absolute path to the Git
directory. Even though the Git directory doesn't make it as easy to
locate the worktree in question, it can still help a user figure out
what's going on while developing a script.

This fixes a segmentation fault introduced in e0020b2f
("prefix_path: show gitdir when arg is outside repo", 2020-02-14).

Signed-off-by: Emily Shaffer <emilyshaffer@google.com>
[jc: added minimum tests, with help from Szeder Gábor]
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-03-15 09:35:46 -07:00
Harald van Dijk
237a28173f show_one_mergetag: print non-parent in hex form.
When a mergetag names a non-parent, which can occur after a shallow
clone, its hash was previously printed as raw data. Print it in hex form
instead.

Signed-off-by: Harald van Dijk <harald@gigawatt.nl>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-03-02 12:34:00 -08:00
Junio C Hamano
0106b1d4be Revert "gpg-interface: prefer check_signature() for GPG verification"
This reverts commit 72b006f4bf, which
breaks the end-user experience when merging a signed tag without
having the public key.  We should report "can't check because we
have no public key", but the code with this change claimed that
there was no signature.
2020-02-28 09:43:17 -08:00
Alexandr Miloslavskiy
94f4d01932 mingw: workaround for hangs when sending STDIN
Explanation
-----------
The problem here is flawed `poll()` implementation. When it tries to
see if pipe can be written without blocking, it eventually calls
`NtQueryInformationFile()` and tests `WriteQuotaAvailable`. However,
the meaning of quota was misunderstood. The value of quota is reduced
when either some data was written to a pipe, *or* there is a pending
read on the pipe. Therefore, if there is a pending read of size >= than
the pipe's buffer size, poll() will think that pipe is not writable and
will hang forever, usually that means deadlocking both pipe users.

I have studied the problem and found that Windows pipes track two values:
`QuotaUsed` and `BytesInQueue`. The code in `poll()` apparently wants to
know `BytesInQueue` instead of quota. Unfortunately, `BytesInQueue` can
only be requested from read end of the pipe, while `poll()` receives
write end.

The git's implementation of `poll()` was copied from gnulib, which also
contains a flawed implementation up to today.

I also had a look at implementation in cygwin, which is also broken in a
subtle way. It uses this code in `pipe_data_available()`:
	fpli.WriteQuotaAvailable = (fpli.OutboundQuota - fpli.ReadDataAvailable)
However, `ReadDataAvailable` always returns 0 for the write end of the pipe,
turning the code into an obfuscated version of returning pipe's total
buffer size, which I guess will in turn have `poll()` always say that pipe
is writable. The commit that introduced the code doesn't say anything about
this change, so it could be some debugging code that slipped in.

These are the typical sizes used in git:
0x2000 - default read size in `strbuf_read()`
0x1000 - default read size in CRT, used by `strbuf_getwholeline()`
0x2000 - pipe buffer size in compat\mingw.c

As a consequence, as soon as child process uses `strbuf_read()`,
`poll()` in parent process will hang forever, deadlocking both
processes.

This results in two observable behaviors:
1) If parent process begins sending STDIN quickly (and usually that's
   the case), then first `poll()` will succeed and first block will go
   through. MAX_IO_SIZE_DEFAULT is 8MB, so if STDIN exceeds 8MB, then
   it will deadlock.
2) If parent process waits a little bit for any reason (including OS
   scheduler) and child is first to issue `strbuf_read()`, then it will
   deadlock immediately even on small STDINs.

The problem is illustrated by `git stash push`, which will currently
read the entire patch into memory and then send it to `git apply` via
STDIN. If patch exceeds 8MB, git hangs on Windows.

Possible solutions
------------------
1) Somehow obtain `BytesInQueue` instead of `QuotaUsed`
   I did a pretty thorough search and didn't find any ways to obtain
   the value from write end of the pipe.
2) Also give read end of the pipe to `poll()`
   That can be done, but it will probably invite some dirty code,
   because `poll()`
   * can accept multiple pipes at once
   * can accept things that are not pipes
   * is expected to have a well known signature.
3) Make `poll()` always reply "writable" for write end of the pipe
   Afterall it seems that cygwin (accidentally?) does that for years.
   Also, it should be noted that `pump_io_round()` writes 8MB blocks,
   completely ignoring the fact that pipe's buffer size is only 8KB,
   which means that pipe gets clogged many times during that single
   write. This may invite a deadlock, if child's STDERR/STDOUT gets
   clogged while it's trying to deal with 8MB of STDIN. Such deadlocks
   could be defeated with writing less than pipe's buffer size per
   round, and always reading everything from STDOUT/STDERR before
   starting next round. Therefore, making `poll()` always reply
   "writable" shouldn't cause any new issues or block any future
   solutions.
4) Increase the size of the pipe's buffer
   The difference between `BytesInQueue` and `QuotaUsed` is the size
   of pending reads. Therefore, if buffer is bigger than size of reads,
   `poll()` won't hang so easily. However, I found that for example
   `strbuf_read()` will get more and more hungry as it reads large inputs,
   eventually surpassing any reasonable pipe buffer size.

Chosen solution
---------------
Make `poll()` always reply "writable" for write end of the pipe.
Hopefully one day someone will find a way to implement it properly.

Reproduction
------------
printf "%8388608s" X >large_file.txt
git stash push --include-untracked -- large_file.txt

I have decided not to include this as test to avoid slowing down the
test suite. I don't expect the specific problem to come back, and
chances are that `git stash push` will be reworked to avoid sending the
entire patch via STDIN.

Signed-off-by: Alexandr Miloslavskiy <alexandr.miloslavskiy@syntevo.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-02-27 14:23:29 -08:00
Junio C Hamano
1ff466c018 Documentation: clarify that -h alone stands for help
We seem to be getting new users who get confused every 20 months or
so with this "-h consistently wants to give help, but the commands
to which `-h` may feel like a good short-form option want it to mean
something else." compromise.

Let's make sure that the readers know that `git cmd -h` (with no
other arguments) is a way to get usage text, even for commands like
ls-remote and grep.

Also extend the description that is already in gitcli.txt, as it is
clear that users still get confused with the current text.

Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-02-27 14:14:01 -08:00
Johannes Schindelin
7f487ce062 Azure Pipeline: switch to the latest agent pools
It would seem that at least the `vs2015-win2012r2` pool (which we use
via its old name, `Hosted`) is about to be phased out. Let's switch
before that.

While at it, use the newer pool names as suggested at
https://docs.microsoft.com/en-us/azure/devops/pipelines/agents/hosted?view=azure-devops#use-a-microsoft-hosted-agent

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-02-27 09:58:43 -08:00
Johannes Schindelin
5ed9fc3fc8 ci: prevent perforce from being quarantined
The most recent Azure Pipelines macOS agents enable what Apple calls
"System Integrity Protection". This makes `p4d -V` hang: there is some
sort of GUI dialog waiting for the user to acknowledge that the copied
binaries are legit and may be executed, but on build agents, there is no
user who could acknowledge that.

Let's ask Homebrew specifically to _not_ quarantine the Perforce
binaries.

Helped-by: Aleksandr Chebotov
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-02-27 09:58:42 -08:00
Johannes Schindelin
eafff6e41e t/lib-httpd: avoid using macOS' sed
Among other differences relative to GNU sed, macOS' sed always ends its
output with a trailing newline, even if the input did not have such a
trailing newline.

Surprisingly, this makes three httpd-based tests fail on macOS: t5616,
t5702 and t5703. ("Surprisingly" because those tests have been around
for some time, but apparently nobody runs them on macOS with a working
Apache2 setup.)

The reason is that we use `sed` in those tests to filter the response of
the web server. Apart from the fact that we use GNU constructs (such as
using a space after the `c` command instead of a backslash and a
newline), we have another problem: macOS' sed LF-only newlines while
webservers are supposed to use CR/LF ones.

Even worse, t5616 uses `sed` to replace a binary part of the response
with a new binary part (kind of hoping that the replaced binary part
does not contain a 0x0a byte which would be interpreted as a newline).

To that end, it calls on Perl to read the binary pack file and
hex-encode it, then calls on `sed` to prefix every hex digit pair with a
`\x` in order to construct the text that the `c` statement of the `sed`
invocation is supposed to insert. So we call Perl and sed to construct a
sed statement. The final nail in the coffin is that macOS' sed does not
even interpret those `\x<hex>` constructs.

Let's just replace all of that by Perl snippets. With Perl, at least, we
do not have to deal with GNU vs macOS semantics, we do not have to worry
about unwanted trailing newlines, and we do not have to spawn commands
to construct arguments for other commands to be spawned (i.e. we can
avoid a whole lot of shell scripting complexity).

The upshot is that this fixes t5616, t5702 and t5703 on macOS with
Apache2.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-02-27 09:58:41 -08:00
Derrick Stolee
3e96c66805 partial-clone: avoid fetching when looking for objects
When using partial clone, find_non_local_tags() in builtin/fetch.c
checks each remote tag to see if its object also exists locally. There
is no expectation that the object exist locally, but this function
nevertheless triggers a lazy fetch if the object does not exist. This
can be extremely expensive when asking for a commit, as we are
completely removed from the context of the non-existent object and
thus supply no "haves" in the request.

6462d5eb9a (fetch: remove fetch_if_missing=0, 2019-11-05) removed a
global variable that prevented these fetches in favor of a bitflag.
However, some object existence checks were not updated to use this flag.

Update find_non_local_tags() to use OBJECT_INFO_SKIP_FETCH_OBJECT in
addition to OBJECT_INFO_QUICK. The _QUICK option only prevents
repreparing the pack-file structures. We need to be extremely careful
about supplying _SKIP_FETCH_OBJECT when we expect an object to not exist
due to updated refs.

This resolves a broken test in t5616-partial-clone.sh.

Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-02-22 09:23:08 -08:00
Derrick Stolee
d0badf8797 partial-clone: demonstrate bugs in partial fetch
While testing partial clone, I noticed some odd behavior. I was testing
a way of running 'git init', followed by manually configuring the remote
for partial clone, and then running 'git fetch'. Astonishingly, I saw
the 'git fetch' process start asking the server for multiple rounds of
pack-file downloads! When tweaking the situation a little more, I
discovered that I could cause the remote to hang up with an error.

Add two tests that demonstrate these two issues.

In the first test, we find that when fetching with blob filters from
a repository that previously did not have any tags, the 'git fetch
--tags origin' command fails because the server sends "multiple
filter-specs cannot be combined". This only happens when using
protocol v2.

In the second test, we see that a 'git fetch origin' request with
several ref updates results in multiple pack-file downloads. This must
be due to Git trying to fault-in the objects pointed by the refs. What
makes this matter particularly nasty is that this goes through the
do_oid_object_info_extended() method, so there are no "haves" in the
negotiation. This leads the remote to send every reachable commit and
tree from each new ref, providing a quadratic amount of data transfer!
This test is fixed if we revert 6462d5eb9a (fetch: remove
fetch_if_missing=0, 2019-11-05), but that revert causes other test
failures. The real fix will need more care.

The tests are ordered in this way because if I swap the test order the
tag test will succeed instead of fail. I believe this is because somehow
we need the srv.bare repo to not have any tags when we clone, but then
have tags in our next fetch.

Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-02-22 09:23:08 -08:00
Jeff King
539052f42f run-command.h: fix mis-indented struct member
An accidental conversion of a tab to 4 spaces snuck into 4c4066d95d
(run-command: move doc to run-command.h, 2019-11-17), messing up the
alignment when you have the project-recommended 8-width tabstops. Let's
revert that line.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-02-22 09:05:34 -08:00
Elijah Newren
fb1c18fc46 merge-recursive: fix the refresh logic in update_file_flags
If we need to delete a higher stage entry in the index to place the file
at stage 0, then we'll lose that file's stat information.  In such
situations we may still be able to detect that the file on disk is the
version we want (as noted by our comment in the code:
  /* do not overwrite file if already present */
), but we do still need to update the mtime since we are creating a new
cache_entry for that file.  Update the logic used to determine whether
we refresh a file's mtime.

Signed-off-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-02-19 10:13:31 -08:00
Elijah Newren
73113c5922 t3433: new rebase testcase documenting a stat-dirty-like failure
A user discovered a case where they had a stack of 20 simple commits to
rebase, and the rebase would succeed in picking the first commit and
then error out with a pair of "Could not execute the todo command" and
"Your local changes to the following files would be overwritten by
merge" messages.

Their steps actually made use of the -i flag, but I switched it over to
-m to make it simpler to trigger the bug.  With that flag, it bisects
back to commit 68aa495b59 (rebase: implement --merge via the
interactive machinery, 2018-12-11), but that's misleading.  If you
change the -m flag to --keep-empty, then the problem persists and will
bisect back to 356ee4659b (sequencer: try to commit without forking
'git commit', 2017-11-24)

After playing with the testcase for a bit, I discovered that added
--exec "sleep 1" to the command line makes the rebase succeed, making me
suspect there is some kind of discard and reloading of caches that lead
us to believe that something is stat dirty, but I didn't succeed in
digging any further than that.

Signed-off-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-02-19 10:13:27 -08:00
Elijah Newren
7ec8125fba check-ignore: fix documentation and implementation to match
check-ignore has two different modes, and neither of these modes has an
implementation that matches the documentation.  These modes differ in
whether they just print paths or whether they also print the final
pattern matched by the path.  The fix is different for both modes, so
I'll discuss both separately.

=== First (default) mode ===

The first mode is documented as:

    For each pathname given via the command-line or from a file via
    --stdin, check whether the file is excluded by .gitignore (or other
    input files to the exclude mechanism) and output the path if it is
    excluded.

However, it fails to do this because it did not account for negated
patterns.  Commands other than check-ignore verify exclusion rules via
calling

   ... -> treat_one_path() -> is_excluded() -> last_matching_pattern()

while check-ignore has a call path of the form:

   ... -> check_ignore()                    -> last_matching_pattern()

The fact that the latter does not include the call to is_excluded()
means that it is susceptible to to messing up negated patterns (since
that is the only significant thing is_excluded() adds over
last_matching_pattern()).  Unfortunately, we can't make it just call
is_excluded(), because the same codepath is used by the verbose mode
which needs to know the matched pattern in question.  This brings us
to...

=== Second (verbose) mode ===

The second mode, known as verbose mode, references the first in the
documentation and says:

    Also output details about the matching pattern (if any) for each
    given pathname. For precedence rules within and between exclude
    sources, see gitignore(5).

The "Also" means it will print patterns that match the exclude rules as
noted for the first mode, and also print which pattern matches.  Unless
more information is printed than just pathname and pattern (which is not
done), this definition is somewhat ill-defined and perhaps even
self-contradictory for negated patterns: A path which matches a negated
exclude pattern is NOT excluded and thus shouldn't be printed by the
former logic, while it certainly does match one of the explicit patterns
and thus should be printed by the latter logic.

=== Resolution ==

Since the second mode exists to find out which pattern matches given
paths, and showing the user a pattern that begins with a '!' is
sufficient for them to figure out whether the pattern is excluded, the
existing behavior is desirable -- we just need to update the
documentation to match the implementation (i.e. it is about printing
which pattern is matched by paths, not about showing which paths are
excluded).

For the first or default mode, users just want to know whether a pattern
is excluded.  As such, the existing documentation is desirable; change
the implementation to match the documented behavior.

Finally, also adjust a few tests in t0008 that were caught up by this
discrepancy in how negated paths were handled.

Signed-off-by: Elijah Newren <newren@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-02-18 15:28:58 -08:00