Commits · 658022c41affc7d9b5bd9b84b1d75ec909b820c6 · lvzhengyang / git2

18 Jul, 2019 3 commits
- configuration: cvar -> configmap · 658022c4
```
`cvar` is an unhelpful name.  Refactor its usage to `configmap` for more
clarity.
```
  Patrick Steinhardt committed Jul 18, 2019
  658022c4 Browse Files
- Merge pull request #5156 from pks-t/pks/attr-macros-in-subdir · 343fb83a
```
gitattributes: ignore macros defined in subdirectories
```
  Patrick Steinhardt committed Jul 18, 2019
  343fb83a Browse Files
- Merge pull request #5168 from tiennou/clar/fix-data-suite-count · 368b9795
```
clar: correctly account for "data" suites when counting
```
  Patrick Steinhardt committed Jul 18, 2019
  368b9795 Browse Files
17 Jul, 2019 2 commits

Merge pull request #5170 from bk2204/packbuilder-efficient-realloc · 51124a5b
```
Allocate memory more efficiently when packing objects
```
Edward Thomson committed Jul 17, 2019
51124a5b Browse Files

pack-objects: allocate memory more efficiently · c4df926b

The packbuilder code allocates memory in chunks. When it needs to
allocate, it tries to add 1024 to the number of objects and multiply by
3/2. However, it actually multiplies by 1 instead, since it performs an
integral division in the expression "3 / 2" and only then multiplies by
the increased number of objects.

The current behavior causes the code to waste massive amounts of time
copying memory when it reallocates, causing inserting all non-blob
objects in the Linux repository into a new pack to take some
indeterminate time greater than 5 minutes instead of 52 seconds.

Correct this error by first dividing by two, and only then multiplying
by 3. We still check for overflow for the multiplication, which is the
only part that can overflow. This appears to be the only place in the
code base which has this problem.

committed Jul 17, 2019

c4df926b Browse Files

16 Jul, 2019 1 commit
- clar: correctly account for "data" suites when counting · 4cd8dfaa
```
Failing to do that makes clar miss the last of the suites, as all
duplicated "data" would have not been accounted for.
```
  Etienne Samson committed Jul 16, 2019
  4cd8dfaa Browse Files
12 Jul, 2019 10 commits

Merge pull request #5131 from pks-t/pks/fileops-mkdir-in-root · f92d495d
```
fileops: fix creation of directory in filesystem root
```
Patrick Steinhardt committed Jul 12, 2019
f92d495d Browse Files

attr_file: ignore macros defined in subdirectories · f8346905

Right now, we are unconditionally applying all macros found in a
gitatttributes file. But quoting gitattributes(5):

    Custom macro attributes can be defined only in top-level
    gitattributes files ($GIT_DIR/info/attributes, the .gitattributes
    file at the top level of the working tree, or the global or
    system-wide gitattributes files), not in .gitattributes files in
    working tree subdirectories. The built-in macro attribute "binary"
    is equivalent to:

So gitattribute files in subdirectories of the working tree may
explicitly _not_ contain macro definitions, but we do not currently
enforce this limitation.

This patch introduces a new parameter to the gitattributes parser that
tells whether macros are allowed in the current file or not. If set to
`false`, we will still parse macros, but silently ignore them instead of
adding them to the list of defined macros. Update all callers to
correctly determine whether the to-be-parsed file may contain macros or
not. Most importantly, when walking up the directory hierarchy, we will
only set it to `true` once it reaches the root directory of the repo
itself.

Add a test that verifies that we are indeed not applying macros from
subdirectories. Previous to these changes, the test would've failed.

committed Jul 12, 2019

f8346905 Browse Files

attr_file: refactor `parse_buffer` function · 97968529

The gitattributes code is one of our oldest and most-untouched codebases
in libgit2, and as such its code style doesn't quite match our current
best practices. Refactor the function `git_attr_file__parse_buffer` to
better match them.

committed Jul 12, 2019

97968529 Browse Files

attr_file: refactor `load_standalone` function · dbc7e4b1

The gitattributes code is one of our oldest and most-untouched codebases
in libgit2, and as such its code style doesn't quite match our current
best practices. Refactor the function `git_attr_file__lookup_standalone`
to better match them.

committed Jul 12, 2019

dbc7e4b1 Browse Files

attrcache: fix memory leak if inserting invalid macro to cache · be8f9bb1

A macro without any assignments is considered an invalid macro by the
attributes cache and is thus not getting added to the macro map at all.
But as `git_attr_cache__insert_macro` returns success with neither
free'ing nor adopting the macro into its map, this will cause a memory
leak.

Fix this by freeing the macro in the function if it's not going to be
added. This is perfectly fine to do, as callers assume that the
attrcache will have the macro adopted on success anyway.

committed Jul 12, 2019

be8f9bb1 Browse Files

attrcache: fix multiple memory leaks when inserting macros · 7277bf83

The function `git_attr_cache__insert_macro` is responsible for adopting
macros in the per-repo macro cache. When adding a macro that replaces an
already existing macro (e.g. because of re-parsing gitattributes files),
then we do not free the previous macro and thus cause a memory leak.

Fix this leak by first checking if the cache already has a macro defined
with the same name. If so, free it before replacing the cache entry with
the new instance.

committed Jul 12, 2019

7277bf83 Browse Files

tests: attr: verify that in-memory macros are respected · df417a43
```
Add some tests to ensure that the `git_attr_add_macro` function works as
expected.
```
Patrick Steinhardt committed Jul 12, 2019
df417a43 Browse Files
tests: attr: implement tests to verify attribute rewriting behaviour · 4a7f704f
```
Implement some tests that verify that we are correctly updating
gitattributes when rewriting or unlinking the corresponding files.
```
Patrick Steinhardt committed Jul 12, 2019
4a7f704f Browse Files

tests: attr: extract macro tests into their own suite · ed854aa0

As macros are a specific functionality in the gitattributes code, it
makes sense to extract them into their own test suite, too. This makes
finding macro-related tests easier.

committed Jul 12, 2019

ed854aa0 Browse Files

Merge pull request #5160 from pks-t/pks/win32-fuzzers · dacac9e1
```
win32: fix fuzzers and have CI build them
```
Patrick Steinhardt committed Jul 12, 2019
dacac9e1 Browse Files

11 Jul, 2019 17 commits

fileops: fix creation of directory in filesystem root · 5ae22a63

In commit 45f24e78 (git_repository_init: stop traversing at
windows root, 2019-04-12), we have fixed `git_futils_mkdir` to
correctly handle the case where we create a directory in
Windows-style filesystem roots like "C:\repo".

The problem here is an off-by-one: previously, to that commit,
we've been checking wether the parent directory's length is equal
to the root directory's length incremented by one. When we call
the function with "/example", then the parent directory's length
("/") is 1, but the root directory offset is 0 as the path is
directly rooted without a drive prefix. This resulted in `1 == 0 +
1`, which was true. With the change, we've stopped incrementing
the root directory length, and thus now compare `1 <= 0`, which
is false.

The previous way of doing it was kind of finicky any non-obvious,
which is also why the error was introduced. So instead of just
re-adding the increment, let's explicitly add a condition that
aborts finding the parent if the current parent path is "/".

Making this change causes Azure Pipelines to fail the testcase
repo::init::nonexistent_paths on Unix-based systems. This is because we
have just fixed creating directories in the filesystem root, which
previously didn't work. As Docker-based tests are running as root user,
we are thus able to create the non-existing path and will now succeed to
create the repository that was expected to actually fail.

Let's split this up into three different tests:

- A test to verify that we do not create repos in a non-existing parent
  directoy if the flag `GIT_REPOSITORY_INIT_MKPATH` is not set.

- A test to verify that we fail if the root directory does not exist. As
  there is a common root directory on Unix-based systems that always
  exist, we can only test for this on Windows-based systems.

- A test to verify that we fail if trying to create a repository in an
  unwriteable parent directory. We can only test this if not running
  tests as root user, as CAP_DAC_OVERRIDE will cause us to ignore
  permissions when creating files.

committed Jul 11, 2019

5ae22a63 Browse Files

Merge pull request #5134 from pks-t/pks/config-parser-separation · a6ad9e8a
```
Config parser separation
```
Patrick Steinhardt committed Jul 11, 2019
a6ad9e8a Browse Files

config_parse: provide parser init and dispose functions · dbeadf8a

Right now, all configuration file backends are expected to
directly mess with the configuration parser's internals in order
to set it up. Let's avoid doing that by implementing both a
`git_config_parser_init` and `git_config_parser_dispose` function
to clearly define the interface between configuration backends
and the parser.

Ideally, we would make the `git_config_parser` structure
definition private to its implementation. But as that would
require an additional memory allocation that was not required
before we just live with it being visible to others.

committed Jul 11, 2019

dbeadf8a Browse Files

config_file: refactor error handling in `config_write` · 32157526

Error handling in `config_write` is rather convoluted and does
not match our current code style. Refactor it to make it easier
to understand.

committed Jul 11, 2019

32157526 Browse Files

config_file: internalize `git_config_file` struct · 820fa1a3

With the previous commits, we have finally separated the config
parsing logic from the specific configuration file backend. Due
to that, we can now move the `git_config_file` structure into the
config file backend's implementation so that no other code may
accidentally start using it again. Furthermore, we rename the
structure to `diskfile` to make it obvious that it is internal,
only, and to unify it with naming scheme of the other diskfile
structures.

committed Jul 11, 2019

820fa1a3 Browse Files

config_parse: remove use of `git_config_file` · 6e6da75f

The config parser code needs to keep track of the current parsed
file's name so that we are able to provide proper error messages
to the user. Right now, we do that by storing a `git_config_file`
in the parser structure, but as that is a specific backend and
the parser aims to be generic, it is a layering violation.

Switch over to use a simple string to fix that.

committed Jul 11, 2019

6e6da75f Browse Files

config_file: embed file in diskfile parse data · 54d350e0

The config file code needs to keep track of the actual
`git_config_file` structure, as it not only contains the path
of the current configuration file, but it also keeps tracks of
all includes of that file. Right now, we keep track of that
structure via the `git_config_parser`, but as that's supposed to
be a backend generic implementation of configuration parsing it's
a layering violation to have it in there.

Switch over the config file backend to use its own config file
structure that's embedded in the backend parse data. This allows
us to switch over the generic config parser to avoid using the
`git_config_file` structure.

committed Jul 11, 2019

54d350e0 Browse Files

config_parse: rename `data` parameter to `payload` for clarity · 76749dfb

By convention, parameters that get passed to callbacks are
usually named `payload` in our codebase. Rename the `data`
parameters in the configuration parser callbacks to `payload` to
avoid confusion.

committed Jul 11, 2019

76749dfb Browse Files

Merge pull request #5132 from pks-t/pks/config-stat-cache · ba9725a2
```
config_file: implement stat cache to avoid repeated rehashing
```
Patrick Steinhardt committed Jul 11, 2019
ba9725a2 Browse Files

config_file: avoid re-reading files on write · 2ba7020f

When we rewrite the configuration file due to any of its values
being modified, we call `config_refresh` to update the in-memory
representation of our config file backend. This is needlessly
wasteful though, as `config_refresh` will always open the on-disk
representation to reads the file contents while we already know
the complete file contents at this point in time as we have just
written it to disk.

Implement a new function `config_refresh_from_buffer` that will
refresh the backend's config entries from a buffer instead of
from the config file itself. Note that this will thus _not_
update the backend's timestamp, which will cause us to re-read
the buffer when performing a read operation on it. But this is
still an improvement as we now lazily re-read the contents, and
most importantly we will avoid constantly re-reading the contents
if we perform multiple write operations.

The following strace demonstrates this if we're re-writing a key
multiple times. It uses our config example with `config_set`
changed to update the file 10 times with different keys:

And now with the optimization of `config_refresh_from_buffer`:

As can be seen, this is quite a lot of `open` calls less.

committed Jul 11, 2019

2ba7020f Browse Files

config_file: split out function that sets config entries · a0dc3027

Updating a config file backend's config entries is a bit more
involved, as it requires clearing of the old config entries as
well as handling locking correctly. As we will need this
functionality in a future patch to refresh config entries from a
buffer, let's extract this into its own function
`config_set_entries`.

committed Jul 11, 2019

a0dc3027 Browse Files

config_file: split out function that reads entries from a buffer · 985f5cdf

The `config_read` function currently performs both reading the
on-disk config file as well as parsing the retrieved buffer
contents. To optimize how we refresh our config entries from an
in-memory buffer, we need to be able to directly parse buffers,
though, without involving any on-disk files at all.

Extract a new function `config_read_buffer` that sets up the
parsing logic and then parses config entries from a buffer, only.
Have `config_read` use it to avoid duplicated logic.

committed Jul 11, 2019

985f5cdf Browse Files

config_file: move refresh into `write` function · 3e1c137a

We are quite lazy in how we refresh our config file backend when
updating any of its keys: instead of just updating our in-memory
representation of the keys, we just discard the old set of keys
and then re-read the config file contents from disk. This refresh
currently happens separately at every callsite of `config_write`,
but it is clear that we _always_ want to refresh if we have
written the config file to disk. If we didn't, then we'd run
around with an outdated config file backend that does not
represent what we have on disk.

By moving the refresh into `config_write`, we are also able to
optimize the case where the config file is currently locked.
Before, we would've tried to re-read the file even if we have
only updated its cached contents without touching the on-disk
file. Thus we'd have unnecessarily stat'd the file, even though
we know that it shouldn't have been modified in the meantime due
to its lock.

committed Jul 11, 2019

3e1c137a Browse Files

config_file: implement stat cache to avoid repeated rehashing · d7f58eab

To decide whether a config file has changed, we always hash its
complete contents. This is unnecessarily expensive, as
well-behaved filesystems will always update stat information for
files which have changed. So before computing the hash, we should
first check whether the stat info has actually changed for either
the configuration file or any of its includes. This avoids having
to re-read the configuration file and its includes every time
when we check whether it's been modified.

Tracing the for-each-ref example previous to this commit, one can
see that we repeatedly re-open both the repo configuration as
well as the global configuration:

	$ strace lg2 for-each-ref |& grep config
	access("/home/pks/.gitconfig", F_OK)    = -1 ENOENT (No such file or directory)
	access("/home/pks/.config/git/config", F_OK) = 0
	access("/etc/gitconfig", F_OK)          = -1 ENOENT (No such file or directory)
	stat("/tmp/repo/.git/config", {st_mode=S_IFREG|0644, st_size=92, ...}) = 0
	access("/tmp/repo/.git/config", F_OK)   = 0
	stat("/tmp/repo/.git/config", {st_mode=S_IFREG|0644, st_size=92, ...}) = 0
	open("/tmp/repo/.git/config", O_RDONLY|O_CLOEXEC) = 3
	stat("/home/pks/.gitconfig", 0x7ffd15c05290) = -1 ENOENT (No such file or directory)
	access("/home/pks/.gitconfig", F_OK)    = -1 ENOENT (No such file or directory)
	stat("/home/pks/.config/git/config", {st_mode=S_IFREG|0644, st_size=1154, ...}) = 0
	access("/home/pks/.config/git/config", F_OK) = 0
	stat("/home/pks/.config/git/config", {st_mode=S_IFREG|0644, st_size=1154, ...}) = 0
	open("/home/pks/.config/git/config", O_RDONLY|O_CLOEXEC) = 3
	stat("/tmp/repo/.git/config", {st_mode=S_IFREG|0644, st_size=92, ...}) = 0
	open("/tmp/repo/.git/config", O_RDONLY|O_CLOEXEC) = 3
	stat("/home/pks/.gitconfig", 0x7ffd15c051f0) = -1 ENOENT (No such file or directory)
	stat("/home/pks/.config/git/config", {st_mode=S_IFREG|0644, st_size=1154, ...}) = 0
	open("/home/pks/.config/git/config", O_RDONLY|O_CLOEXEC) = 3
	stat("/tmp/repo/.git/config", {st_mode=S_IFREG|0644, st_size=92, ...}) = 0
	open("/tmp/repo/.git/config", O_RDONLY|O_CLOEXEC) = 3
	stat("/home/pks/.gitconfig", 0x7ffd15c05090) = -1 ENOENT (No such file or directory)
	stat("/home/pks/.config/git/config", {st_mode=S_IFREG|0644, st_size=1154, ...}) = 0
	open("/home/pks/.config/git/config", O_RDONLY|O_CLOEXEC) = 3
	stat("/tmp/repo/.git/config", {st_mode=S_IFREG|0644, st_size=92, ...}) = 0
	open("/tmp/repo/.git/config", O_RDONLY|O_CLOEXEC) = 3
	stat("/home/pks/.gitconfig", 0x7ffd15c05090) = -1 ENOENT (No such file or directory)
	stat("/home/pks/.config/git/config", {st_mode=S_IFREG|0644, st_size=1154, ...}) = 0
	open("/home/pks/.config/git/config", O_RDONLY|O_CLOEXEC) = 3
	stat("/tmp/repo/.git/config", {st_mode=S_IFREG|0644, st_size=92, ...}) = 0
	open("/tmp/repo/.git/config", O_RDONLY|O_CLOEXEC) = 3
	stat("/home/pks/.gitconfig", 0x7ffd15c05090) = -1 ENOENT (No such file or directory)
	stat("/home/pks/.config/git/config", {st_mode=S_IFREG|0644, st_size=1154, ...}) = 0
	open("/home/pks/.config/git/config", O_RDONLY|O_CLOEXEC) = 3

With the change, we only do stats for those files and open them a
single time, only:

	$ strace lg2 for-each-ref |& grep config
	access("/home/pks/.gitconfig", F_OK)    = -1 ENOENT (No such file or directory)
	access("/home/pks/.config/git/config", F_OK) = 0
	access("/etc/gitconfig", F_OK)          = -1 ENOENT (No such file or directory)
	stat("/tmp/repo/.git/config", {st_mode=S_IFREG|0644, st_size=92, ...}) = 0
	access("/tmp/repo/.git/config", F_OK)   = 0
	stat("/tmp/repo/.git/config", {st_mode=S_IFREG|0644, st_size=92, ...}) = 0
	stat("/tmp/repo/.git/config", {st_mode=S_IFREG|0644, st_size=92, ...}) = 0
	open("/tmp/repo/.git/config", O_RDONLY|O_CLOEXEC) = 3
	stat("/home/pks/.gitconfig", 0x7ffe70540d20) = -1 ENOENT (No such file or directory)
	access("/home/pks/.gitconfig", F_OK)    = -1 ENOENT (No such file or directory)
	stat("/home/pks/.config/git/config", {st_mode=S_IFREG|0644, st_size=1154, ...}) = 0
	access("/home/pks/.config/git/config", F_OK) = 0
	stat("/home/pks/.config/git/config", {st_mode=S_IFREG|0644, st_size=1154, ...}) = 0
	stat("/home/pks/.config/git/config", {st_mode=S_IFREG|0644, st_size=1154, ...}) = 0
	open("/home/pks/.config/git/config", O_RDONLY|O_CLOEXEC) = 3
	stat("/tmp/repo/.git/config", {st_mode=S_IFREG|0644, st_size=92, ...}) = 0
	stat("/home/pks/.gitconfig", 0x7ffe70540ca0) = -1 ENOENT (No such file or directory)
	stat("/home/pks/.gitconfig", 0x7ffe70540c80) = -1 ENOENT (No such file or directory)
	stat("/home/pks/.config/git/config", {st_mode=S_IFREG|0644, st_size=1154, ...}) = 0
	stat("/tmp/repo/.git/config", {st_mode=S_IFREG|0644, st_size=92, ...}) = 0
	stat("/home/pks/.gitconfig", 0x7ffe70540b40) = -1 ENOENT (No such file or directory)
	stat("/home/pks/.gitconfig", 0x7ffe70540b20) = -1 ENOENT (No such file or directory)
	stat("/home/pks/.config/git/config", {st_mode=S_IFREG|0644, st_size=1154, ...}) = 0
	stat("/tmp/repo/.git/config", {st_mode=S_IFREG|0644, st_size=92, ...}) = 0
	stat("/home/pks/.gitconfig", 0x7ffe70540b40) = -1 ENOENT (No such file or directory)
	stat("/home/pks/.gitconfig", 0x7ffe70540b20) = -1 ENOENT (No such file or directory)
	stat("/home/pks/.config/git/config", {st_mode=S_IFREG|0644, st_size=1154, ...}) = 0
	stat("/tmp/repo/.git/config", {st_mode=S_IFREG|0644, st_size=92, ...}) = 0
	stat("/home/pks/.gitconfig", 0x7ffe70540b40) = -1 ENOENT (No such file or directory)
	stat("/home/pks/.gitconfig", 0x7ffe70540b20) = -1 ENOENT (No such file or directory)
	stat("/home/pks/.config/git/config", {st_mode=S_IFREG|0644, st_size=1154, ...}) = 0

The following benchmark has been performed with and without the
stat cache in a best-of-ten run:

```

int lg2_repro(git_repository *repo, int argc, char **argv)
{
	git_config *cfg;
	int32_t dummy;
	int i;

	UNUSED(argc);
	UNUSED(argv);

	check_lg2(git_repository_config(&cfg, repo),
			"Could not obtain config", NULL);

	for (i = 1; i < 100000; ++i)
		git_config_get_int32(&dummy, cfg, "foo.bar");

	git_config_free(cfg);
	return 0;
}
```

Without stat cache:

	$ time lg2 repro
	real    0m1.528s
	user    0m0.568s
	sys     0m0.944s

With stat cache:

	$ time lg2 repro
	real    0m0.526s
	user    0m0.268s
	sys     0m0.258s

This benchmark shows a nearly three-fold performance improvement.

This change requires that we check our configuration stress tests
as we're now in fact becoming more racy. If somebody is writing a
configuration file at nearly the same time (there is a window of
100ns on Windows-based systems), then it might be that we realize
that this file has actually changed and thus may not re-read it.
This will only happen if either an external process is rewriting
the configuration file or if the same process has multiple
`git_config` structures pointing to the same time, where one of
both is being used to write and the other one is used to read
values.

committed Jul 11, 2019

d7f58eab Browse Files

config: use `git_config_file` in favor of `struct config_file` · d0868646
Patrick Steinhardt committed Jul 11, 2019

d0868646 Browse Files

examples: implement config example · 8ee3d39a

Implement a new example that resembles git-config(1). Right now,
this example can both read and set configuration keys, only.

committed Jul 11, 2019

8ee3d39a Browse Files

cmake: report whether we are using sub-second stat information · df54c7fb

Depending on the platform and on build options, we may or may not
build libgit2 with support for nanoseconds when using `stat`
calls. It's currently unclear though whether sub-second stat
information is used at all.

Add feature info for this to tell at configure time whether it's
being used or not.

committed Jul 11, 2019

df54c7fb Browse Files

05 Jul, 2019 7 commits

ci: build fuzzers on Powershell based build jobs · eb27fb9b

In order to guarantee that our fuzzers build just fine on the Windows
platform, let's enable building fuzzers on all Powershell-based builds.

committed Jul 05, 2019

eb27fb9b Browse Files

fuzzers: clean up header includes · 3c966fb4

There's multiple headers included in our fuzzers that aren't required at
all. Furthermore, some of them are not available on Win32, causing
builds to fail. Remove them to fix this.

committed Jul 05, 2019

3c966fb4 Browse Files

fuzzers: use `git_buf_printf` instead of `snprintf` · 9d43d45b

The `snprintf` function does not exist on Win32, it only has
`_snprintf_s` available. Let's just avoid any cross-platform hassle and
use our own `git_buf` functionality instead.

committed Jul 05, 2019

9d43d45b Browse Files

fuzzers: use POSIX emulation layer to unlink files · a6b2fffd

Use `p_unlink` instead of `unlink` to remove the generated packfiles in
our packfile fuzzer. Like this, we do not have to worry about using
proper includes that are known on all platforms, especially Win32.

committed Jul 05, 2019

a6b2fffd Browse Files

fuzzers: make printf formatters cross-platform compatible · 69055813

The `printf` formatters in our standalone fuzzing driver are currently
using the "%m" specifier, which is a GNU extension that prints the error
message for the error code in `errno`. As we're using libgit2 functions
in both cases anyway, let's just use `git_error_last` instead to make
this valid on all platforms.

committed Jul 05, 2019

69055813 Browse Files

fuzzers: implement `mkdtemp` alternative for Win32 · 48d56328

The `mkdtemp` function is not available on Windows, so our download_refs
fuzzer will fail to compile on Windows. Provide an alternative
implementation to fix it.

committed Jul 05, 2019

48d56328 Browse Files

Merge pull request #5143 from libgit2/ethomson/warnings · 398412cc
```
ci: build with ENABLE_WERROR on Windows
```
Patrick Steinhardt committed Jul 05, 2019
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