Commit Graph

113720 Commits

Author SHA1 Message Date
Johannes Schindelin
916dc0cf89 strbuf_realpath(): use platform-dependent API if available
Some platforms (e.g. Windows) provide API functions to resolve paths
much quicker. Let's offer a way to short-cut `strbuf_realpath()` on
those platforms.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
2020-10-15 22:31:23 +02:00
Johannes Schindelin
f9800fde4e mingw: demonstrate a git add issue with NTFS junctions
NTFS junctions are somewhat similar in spirit to Unix bind mounts: they
point to a different directory and are resolved by the filesystem
driver. As such, they appear to `lstat()` as if they are directories,
not as if they are symbolic links.

_Any_ user can create junctions, while symbolic links can only be
created by non-administrators in Developer Mode on Windows 10. Hence
NTFS junctions are much more common "in the wild" than NTFS symbolic
links.

It was reported in https://github.com/git-for-windows/git/issues/2481
that adding files via an absolute path that traverses an NTFS junction:
since 1e64d18 (mingw: do resolve symlinks in `getcwd()`), we resolve not
only symbolic links but also NTFS junctions when determining the
absolute path of the current directory. The same is not true for `git
add <file>`, where symbolic links are resolved in `<file>`, but not NTFS
junctions.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
2020-10-15 22:31:23 +02:00
Johannes Schindelin
25fb9835c4 Start the merging-rebase to v2.29.0-rc2
This commit starts the rebase of ce06eec3fb to 0675c6702155
2020-10-15 22:31:16 +02:00
Johannes Schindelin
e566521b14 Merge pull request #2850 from dscho/monitor-also-gnutls
Open tickets for new `gnutls` versions
2020-10-15 21:09:19 +02:00
Junio C Hamano
a5fa49ff0a Git 2.29-rc2
Signed-off-by: Junio C Hamano <gitster@pobox.com>
2020-10-15 11:58:37 -07:00
Johannes Schindelin
11f41b136b monitor-components: let's get notified about new GNU TLS versions
A common alternative to OpenSSL is GNU TLS. We already use it via GNU
Privacy Guard.

As 32-bit MSYS2 won't be updated anymore (see
https://www.msys2.org/news/#2020-05-17-32-bit-msys2-no-longer-actively-supported
for details), we have to build it ourselves.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
2020-10-15 15:39:36 +02:00
Johannes Schindelin
9b2f453b0d monitor-components: reduce checking frequency
There is very little reason for us to be overzealous and trying to be as
quick as possible in upgrading components as soon as they come out.

Let's save a couple electrons.

If need be, we can always trigger manual runs (thanks to the
`workflow_dispatch` event).

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
2020-10-15 15:37:28 +02:00
Johannes Schindelin
62fface9e8 Merge 'readme' into HEAD
Add a README.md for GitHub goodness.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
v2.29.0-rc1.windows.1
2020-10-09 18:29:48 +02:00
Johannes Schindelin
2341520514 Merge branch 'mirror-master-and-main'
For some transitional period, let's mirror `main` to `master`. In the
end, we want only `main`.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
2020-10-09 18:29:47 +02:00
Johannes Schindelin
8f60a319c5 Merge branch 'phase-out-reset-stdin'
This topic branch re-adds the deprecated --stdin/-z options to `git
reset`. Those patches were overridden by a different set of options in
the upstream Git project before we could propose `--stdin`.

We offered this in MinGit to applications that wanted a safer way to
pass lots of pathspecs to Git, and these applications will need to be
adjusted.

Instead of `--stdin`, `--pathspec-from-file=-` should be used, and
instead of `-z`, `--pathspec-file-nul`.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
2020-10-09 18:29:47 +02:00
Johannes Schindelin
1b998a2b35 Merge pull request #1354 from dscho/phase-out-show-ignored-directory-gracefully
Phase out `--show-ignored-directory` gracefully
2020-10-09 18:29:46 +02:00
Johannes Schindelin
1e39d1c35a Merge branch 'status-no-lock-index'
This branch allows third-party tools to call `git status
--no-lock-index` to avoid lock contention with the interactive Git usage
of the actual human user.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
2020-10-09 18:29:46 +02:00
Johannes Schindelin
81f810ddf5 Merge pull request #1170 from dscho/mingw-kill-process
Handle Ctrl+C in Git Bash nicely

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
2020-10-09 18:29:45 +02:00
Johannes Schindelin
b525c2c559 Merge branch 'busybox-w32'
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
2020-10-09 18:29:45 +02:00
Johannes Schindelin
c8d1c4fdb3 Merge pull request #1897 from piscisaureus/symlink-attr
Specify symlink type in .gitattributes
2020-10-09 18:29:44 +02:00
Johannes Schindelin
bd5202fb6a Merge 'docker-volumes-are-no-symlinks'
This was pull request #1645 from ZCube/master

Support windows container.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
2020-10-09 18:29:44 +02:00
Johannes Schindelin
efd65a43a6 Merge branch 'kblees/kb/symlinks' 2020-10-09 18:29:43 +02:00
Johannes Schindelin
5fbfcc4505 Merge branch 'msys2' 2020-10-09 18:29:43 +02:00
Johannes Schindelin
bce123a665 Merge branch 'long-paths' 2020-10-09 18:29:42 +02:00
Johannes Schindelin
7ae4ed30b1 Merge branch 'gitk-and-git-gui-patches'
These are Git for Windows' Git GUI and gitk patches. We will have to
decide at some point what to do about them, but that's a little lower
priority (as Git GUI seems to be unmaintained for the time being, and
the gitk maintainer keeps a very low profile on the Git mailing list,
too).

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
2020-10-09 18:29:42 +02:00
Johannes Schindelin
4bf4db1eec mingw: really handle SIGINT
Previously, we did not install any handler for Ctrl+C, but now we really
want to because the MSYS2 runtime learned the trick to call the
ConsoleCtrlHandler when Ctrl+C was pressed.

With this, hitting Ctrl+C while `git log` is running will only terminate
the Git process, but not the pager. This finally matches the behavior on
Linux and on macOS.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
2020-10-09 18:29:40 +02:00
Johannes Schindelin
ead8bed561 mingw: kill child processes in a gentler way
The TerminateProcess() function does not actually leave the child
processes any chance to perform any cleanup operations. This is bad
insofar as Git itself expects its signal handlers to run.

A symptom is e.g. a left-behind .lock file that would not be left behind
if the same operation was run, say, on Linux.

To remedy this situation, we use an obscure trick: we inject a thread
into the process that needs to be killed and to let that thread run the
ExitProcess() function with the desired exit status. Thanks J Wyman for
describing this trick.

The advantage is that the ExitProcess() function lets the atexit
handlers run. While this is still different from what Git expects (i.e.
running a signal handler), in practice Git sets up signal handlers and
atexit handlers that call the same code to clean up after itself.

In case that the gentle method to terminate the process failed, we still
fall back to calling TerminateProcess(), but in that case we now also
make sure that processes spawned by the spawned process are terminated;
TerminateProcess() does not give the spawned process a chance to do so
itself.

Please note that this change only affects how Git for Windows tries to
terminate processes spawned by Git's own executables. Third-party
software that *calls* Git and wants to terminate it *still* need to make
sure to imitate this gentle method, otherwise this patch will not have
any effect.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
2020-10-09 18:29:40 +02:00
Johannes Schindelin
b18741ace8 mingw: add a Makefile target to copy test artifacts
The Makefile target `install-mingit-test-artifacts` simply copies stuff
and things directly into a MinGit directory, including an init.bat
script to set everything up so that the tests can be run in a cmd
window.

Sadly, Git's test suite still relies on a Perl interpreter even if
compiled with NO_PERL=YesPlease. We punt for now, installing a small
script into /usr/bin/perl that hands off to an existing Perl of a Git
for Windows SDK.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
2020-10-09 18:29:39 +02:00
Johannes Schindelin
dd1ffb917d t9200: skip tests when $PWD contains a colon
On Windows, the current working directory is pretty much guaranteed to
contain a colon. If we feed that path to CVS, it mistakes it for a
separator between host and port, though.

This has not been a problem so far because Git for Windows uses MSYS2's
Bash using a POSIX emulation layer that also pretends that the current
directory is a Unix path (at least as long as we're in a shell script).

However, that is rather limiting, as Git for Windows also explores other
ports of other Unix shells. One of those is BusyBox-w32's ash, which is
a native port (i.e. *not* using any POSIX emulation layer, and certainly
not emulating Unix paths).

So let's just detect if there is a colon in $PWD and punt in that case.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
2020-10-09 18:29:39 +02:00
Johannes Schindelin
0182e3fb28 t5813: allow for $PWD to be a Windows path
Git for Windows uses MSYS2's Bash to run the test suite, which comes
with benefits but also at a heavy price: on the plus side, MSYS2's
POSIX emulation layer allows us to continue pretending that we are on a
Unix system, e.g. use Unix paths instead of Windows ones, yet this is
bought at a rather noticeable performance penalty.

There *are* some more native ports of Unix shells out there, though,
most notably BusyBox-w32's ash. These native ports do not use any POSIX
emulation layer (or at most a *very* thin one, choosing to avoid
features such as fork() that are expensive to emulate on Windows), and
they use native Windows paths (usually with forward slashes instead of
backslashes, which is perfectly legal in almost all use cases).

And here comes the problem: with a $PWD looking like, say,
C:/git-sdk-64/usr/src/git/t/trash directory.t5813-proto-disable-ssh
Git's test scripts get quite a bit confused, as their assumptions have
been shattered. Not only does this path contain a colon (oh no!), it
also does not start with a slash.

This is a problem e.g. when constructing a URL as t5813 does it:
ssh://remote$PWD. Not only is it impossible to separate the "host" from
the path with a $PWD as above, even prefixing $PWD by a slash won't
work, as /C:/git-sdk-64/... is not a valid path.

As a workaround, detect when $PWD does not start with a slash on
Windows, and simply strip the drive prefix, using an obscure feature of
Windows paths: if an absolute Windows path starts with a slash, it is
implicitly prefixed by the drive prefix of the current directory. As we
are talking about the current directory here, anyway, that strategy
works.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
2020-10-09 18:29:39 +02:00
Johannes Schindelin
97e51afae3 t5605: special-case hardlink test for BusyBox-w32
When t5605 tries to verify that files are hardlinked (or that they are
not), it uses the `-links` option of the `find` utility.

BusyBox' implementation does not support that option, and BusyBox-w32's
lstat() does not even report the number of hard links correctly (for
performance reasons).

So let's just switch to a different method that actually works on
Windows.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
2020-10-09 18:29:39 +02:00
Johannes Schindelin
eeb8cebc2f t5532: workaround for BusyBox on Windows
While it may seem super convenient to some old Unix hands to simpy
require Perl to be available when running the test suite, this is a
major hassle on Windows, where we want to verify that Perl is not,
actually, required in a NO_PERL build.

As a super ugly workaround, we "install" a script into /usr/bin/perl
reading like this:

	#!/bin/sh

	# We'd much rather avoid requiring Perl altogether when testing
	# an installed Git. Oh well, that's why we cannot have nice
	# things.
	exec c:/git-sdk-64/usr/bin/perl.exe "$@"

The problem with that is that BusyBox assumes that the #! line in a
script refers to an executable, not to a script. So when it encounters
the line #!/usr/bin/perl in t5532's proxy-get-cmd, it barfs.

Let's help this situation by simply executing the Perl script with the
"interpreter" specified explicitly.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
2020-10-09 18:29:39 +02:00
Johannes Schindelin
9fe366e0a1 t5003: use binary file from t/diff-lib/
At some stage, t5003-archive-zip wants to add a file that is not ASCII.
To that end, it uses /bin/sh. But that file may actually not exist (it
is too easy to forget that not all the world is Unix/Linux...)! Besides,
we already have perfectly fine binary files intended for use solely by
the tests. So let's use one of them instead.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
2020-10-09 18:29:39 +02:00
Johannes Schindelin
8d823d51cc t0021: use Windows path when appropriate
Since c6b0831c9c (docs: warn about possible '=' in clean/smudge filter
process values, 2016-12-03), t0021 writes out a file with quotes in its
name, and MSYS2's path conversion heuristics mistakes that to mean that
we are not talking about a path here.

Therefore, we need to use Windows paths, as the test-helper is a Win32
program that would otherwise have no idea where to look for the file.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
2020-10-09 18:29:39 +02:00
Johannes Schindelin
3bef949745 test-lib: add BUSYBOX prerequisite
When running with BusyBox, we will want to avoid calling executables on
the PATH that are implemented in BusyBox itself.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
2020-10-09 18:29:39 +02:00
Johannes Schindelin
e05ed6f0b2 tests (mingw): remove Bash-specific pwd option
The -W option is only understood by MSYS2 Bash's pwd command. We already
make sure to override `pwd` by `builtin pwd -W` for MINGW, so let's not
double the effort here.

This will also help when switching the shell to another one (such as
BusyBox' ash) whose pwd does *not* understand the -W option.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
2020-10-09 18:29:39 +02:00
Johannes Schindelin
2b1c076858 mingw: only use Bash-ism builtin pwd -W when available
Traditionally, Git for Windows' SDK uses Bash as its default shell.
However, other Unix shells are available, too. Most notably, the Win32
port of BusyBox comes with `ash` whose `pwd` command already prints
Windows paths as Git for Windows wants them, while there is not even a
`builtin` command.

Therefore, let's be careful not to override `pwd` unless we know that
the `builtin` command is available.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
2020-10-09 18:29:39 +02:00
Johannes Schindelin
b71d856a3e tests: use the correct path separator with BusyBox
BusyBox-w32 is a true Win32 application, i.e. it does not come with a
POSIX emulation layer.

That also means that it does *not* use the Unix convention of separating
the entries in the PATH variable using colons, but semicolons.

However, there are also BusyBox ports to Windows which use a POSIX
emulation layer such as Cygwin's or MSYS2's runtime, i.e. using colons
as PATH separators.

As a tell-tale, let's use the presence of semicolons in the PATH
variable: on Unix, it is highly unlikely that it contains semicolons,
and on Windows (without POSIX emulation), it is virtually guaranteed, as
everybody should have both $SYSTEMROOT and $SYSTEMROOT/system32 in their
PATH.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
2020-10-09 18:29:39 +02:00
Johannes Schindelin
a2044df37e tests: only override sort & find if there are usable ones in /usr/bin/
The idea is to allow running the test suite on MinGit with BusyBox
installed in /mingw64/bin/sh.exe. In that case, we will want to exclude
sort & find (and other Unix utilities) from being bundled.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
2020-10-09 18:29:39 +02:00
Johannes Schindelin
22c8f0dc61 tests: move test PNGs into t/diff-lib/
We already have a directory where we store files intended for use by
multiple test scripts. The same directory is a better home for the
test-binary-*.png files than t/.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
2020-10-09 18:29:39 +02:00
Johannes Schindelin
21585b0655 gitattributes: mark .png files as binary
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
2020-10-09 18:29:39 +02:00
Johannes Schindelin
0831a6a0a7 tests: use t/diff-lib/* consistently
The idea of copying README and COPYING into t/diff-lib/ was to step away
from using files from outside t/ in tests. Let's really make sure that
we use the files from t/diff-lib/ instead of other versions of those
files.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
2020-10-09 18:29:39 +02:00
Johannes Schindelin
85f607bd44 tests(mingw): if iconv is unavailable, use test-helper --iconv
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
2020-10-09 18:29:39 +02:00
Johannes Schindelin
b2458f71e0 test-tool: learn to act as a drop-in replacement for iconv
It is convenient to assume that everybody who wants to build & test Git
has access to a working `iconv` executable (after all, we already pretty
much require libiconv).

However, that limits esoteric test scenarios such as Git for Windows',
where an end user installation has to ship with `iconv` for the sole
purpose of being testable. That payload serves no other purpose.

So let's just have a test helper (to be able to test Git, the test
helpers have to be available, after all) to act as `iconv` replacement.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
2020-10-09 18:29:39 +02:00
Bert Belder
9f49c5c92c Win32: symlink: add test for symlink attribute
To verify that the symlink is resolved correctly, we use the fact that
`git.exe` is a native Win32 program, and that `git.exe config -f <path>`
therefore uses the native symlink resolution.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
2020-10-09 18:29:38 +02:00
Johannes Schindelin
082d0b5930 mingw: Windows Docker volumes are *not* symbolic links
... even if they may look like them.

As looking up the target of the "symbolic link" (just to see whether it
starts with `/ContainerMappedDirectories/`) is pretty expensive, we
do it when we can be *really* sure that there is a possibility that this
might be the case.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: JiSeop Moon <zcube@zcube.kr>
2020-10-09 18:29:38 +02:00
Johannes Schindelin
f75d345a3b mingw: special-case index entries for symlinks with buggy size
In https://github.com/git-for-windows/git/pull/2637, we fixed a bug
where symbolic links' target path sizes were recorded incorrectly in the
index. The downside of this fix was that every user with tracked
symbolic links in their checkouts would see them as modified in `git
status`, but not in `git diff`, and only a `git add <path>` (or `git add
-u`) would "fix" this.

Let's do better than that: we can detect that situation and simply
pretend that a symbolic link with a known bad size (or a size that just
happens to be that bad size, a _very_ unlikely scenario because it would
overflow our buffers due to the trailing NUL byte) means that it needs
to be re-checked as if we had just checked it out.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
2020-10-09 18:29:38 +02:00
Johannes Schindelin
e4df5751fc tests: replace mingw_test_cmp with a helper in C
This helper is slightly more performant than the script with MSYS2's
Bash. And a lot more readable.

To accommodate t1050, which wants to compare files weighing in with 3MB
(falling outside of t1050's malloc limit of 1.5MB), we simply lift the
allocation limit by setting the environment variable GIT_ALLOC_LIMIT to
zero when calling the helper.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
2020-10-09 18:29:38 +02:00
Bert Belder
b93b6edf83 mingw: allow to specify the symlink type in .gitattributes
On Windows, symbolic links have a type: a "file symlink" must point at
a file, and a "directory symlink" must point at a directory. If the
type of symlink does not match its target, it doesn't work.

Git does not record the type of symlink in the index or in a tree. On
checkout it'll guess the type, which only works if the target exists
at the time the symlink is created. This may often not be the case,
for example when the link points at a directory inside a submodule.

By specifying `symlink=file` or `symlink=dir` the user can specify what
type of symlink Git should create, so Git doesn't have to rely on
unreliable heuristics.

Signed-off-by: Bert Belder <bertbelder@gmail.com>
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
2020-10-09 18:29:38 +02:00
JiSeop Moon
ec4b9c2db7 mingw: move the file_attr_to_st_mode() function definition
In preparation for making this function a bit more complicated (to allow
for special-casing the `ContainerMappedDirectories` in Windows
containers, which look like a symbolic link, but are not), let's move it
out of the header.

Signed-off-by: JiSeop Moon <zcube@zcube.kr>
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
2020-10-09 18:29:38 +02:00
Johannes Schindelin
50a7290c7b mingw: emulate stat() a little more faithfully
When creating directories via `safe_create_leading_directories()`, we
might encounter an already-existing directory which is not
readable by the current user. To handle that situation, Git's code calls
`stat()` to determine whether we're looking at a directory.

In such a case, `CreateFile()` will fail, though, no matter what, and
consequently `mingw_stat()` will fail, too. But POSIX semantics seem to
still allow `stat()` to go forward.

So let's call `mingw_lstat()` for the rescue if we fail to get a file
handle due to denied permission in `mingw_stat()`, and fill the stat
info that way.

We need to be careful to not allow this to go forward in case that we're
looking at a symbolic link: to resolve the link, we would still have to
create a file handle, and we just found out that we cannot. Therefore,
`stat()` still needs to fail with `EACCES` in that case.

This fixes https://github.com/git-for-windows/git/issues/2531.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
2020-10-09 18:29:38 +02:00
Johannes Schindelin
76d90ac86c test-lib: avoid unnecessary Perl invocation
It is a bit strange, and even undesirable, to require Perl just to run
the test suite even when NO_PERL was set.

This patch does not fix this problem by any stretch of imagination.
However, it fixes *the* Perl invocation that *every single* test script
has to run.

While at it, it makes the source code also more grep'able, as the code
that unsets some, but not all, GIT_* environment variables just became a
*lot* more explicit. And all that while still reducing the total number
of lines.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
2020-10-09 18:29:38 +02:00
Johannes Schindelin
9e0667e023 Introduce helper to create symlinks that knows about index_state
On Windows, symbolic links actually have a type depending on the target:
it can be a file or a directory.

In certain circumstances, this poses problems, e.g. when a symbolic link
is supposed to point into a submodule that is not checked out, so there
is no way for Git to auto-detect the type.

To help with that, we will add support over the course of the next
commits to specify that symlink type via the Git attributes. This
requires an index_state, though, something that Git for Windows'
`symlink()` replacement cannot know about because the function signature
is defined by the POSIX standard and not ours to change.

So let's introduce a helper function to create symbolic links that
*does* know about the index_state.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
2020-10-09 18:29:38 +02:00
JiSeop Moon
4a174f19f8 mingw: when running in a Windows container, try to rename() harder
It is a known issue that a rename() can fail with an "Access denied"
error at times, when copying followed by deleting the original file
works. Let's just fall back to that behavior.

Signed-off-by: JiSeop Moon <zcube@zcube.kr>
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
2020-10-09 18:29:38 +02:00
Johannes Schindelin
3200d67df5 mingw: try to create symlinks without elevated permissions
With Windows 10 Build 14972 in Developer Mode, a new flag is supported
by CreateSymbolicLink() to create symbolic links even when running
outside of an elevated session (which was previously required).

This new flag is called SYMBOLIC_LINK_FLAG_ALLOW_UNPRIVILEGED_CREATE and
has the numeric value 0x02.

Previous Windows 10 versions will not understand that flag and return an
ERROR_INVALID_PARAMETER, therefore we have to be careful to try passing
that flag only when the build number indicates that it is supported.

For more information about the new flag, see this blog post:
https://blogs.windows.com/buildingapps/2016/12/02/symlinks-windows-10/

This patch is loosely based on the patch submitted by Samuel D. Leslie
as https://github.com/git-for-windows/git/pull/1184.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
2020-10-09 18:29:38 +02:00