Convert resolve_ref_unsafe to take a pointer to struct object_id by
converting one remaining caller to use struct object_id, removing the
temporary NULL pointer check in expand_ref, converting the declaration
and definition, and applying the following semantic patch:
@@
expression E1, E2, E3, E4;
@@
- resolve_ref_unsafe(E1, E2, E3.hash, E4)
+ resolve_ref_unsafe(E1, E2, &E3, E4)
@@
expression E1, E2, E3, E4;
@@
- resolve_ref_unsafe(E1, E2, E3->hash, E4)
+ resolve_ref_unsafe(E1, E2, E3, E4)
Signed-off-by: brian m. carlson <sandals@crustytoothpaste.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Convert peel_ref (and its corresponding backend) to struct object_id.
This transformation was done with an update to the declaration,
definition, comments, and test helper and the following semantic patch:
@@
expression E1, E2;
@@
- peel_ref(E1, E2.hash)
+ peel_ref(E1, &E2)
@@
expression E1, E2;
@@
- peel_ref(E1, E2->hash)
+ peel_ref(E1, E2)
Signed-off-by: brian m. carlson <sandals@crustytoothpaste.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Convert update_ref, refs_update_ref, and write_pseudoref to use struct
object_id. Update the existing callers as well. Remove update_ref_oid,
as it is no longer needed.
Signed-off-by: brian m. carlson <sandals@crustytoothpaste.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Convert delete_ref and refs_delete_ref to take a pointer to struct
object_id. Update the documentation accordingly, including referring to
null_oid in lowercase, as it is not a #define constant.
Signed-off-by: brian m. carlson <sandals@crustytoothpaste.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Check if the strbuf containing data to sort is empty before attempting
to trim a trailing newline character.
Signed-off-by: Rene Scharfe <l.s.r@web.de>
Reviewed-by: Jonathan Nieder <jrnieder@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Recent versions of "git rev-parse --parseopt" did not parse the
option specification that does not have the optional flags (*=?!)
correctly, which has been corrected.
* bc/rev-parse-parseopt-fix:
parse-options: only insert newline in help text if needed
parse-options: write blank line to correct output stream
t0040,t1502: Demonstrate parse_options bugs
git-rebase: don't ignore unexpected command line arguments
rev-parse parseopt: interpret any whitespace as start of help text
rev-parse parseopt: do not search help text for flag chars
t1502: demonstrate rev-parse --parseopt option mis-parsing
Many codepaths have been updated to squelch -Wimplicit-fallthrough
warnings from Gcc 7 (which is a good code hygiene).
* jk/fallthrough:
consistently use "fallthrough" comments in switches
curl_trace(): eliminate switch fallthrough
test-line-buffer: simplify command parsing
Many codepaths did not diagnose write failures correctly when disks
go full, due to their misuse of write_in_full() helper function,
which have been corrected.
* jk/write-in-full-fix:
read_pack_header: handle signed/unsigned comparison in read result
config: flip return value of store_write_*()
notes-merge: use ssize_t for write_in_full() return value
pkt-line: check write_in_full() errors against "< 0"
convert less-trivial versions of "write_in_full() != len"
avoid "write_in_full(fd, buf, len) != len" pattern
get-tar-commit-id: check write_in_full() return against 0
config: avoid "write_in_full(fd, buf, len) < len" pattern
A hotfix to a topic already in 'master'.
* kw/write-index-reduce-alloc:
read-cache: fix index corruption with index v4
Add t/helper/test-write-cache to .gitignore
When the option spec contains no switches or only hidden switches,
parse_options will emit an extra blank line at the end of help output so
that the help text will end in two blank lines instead of one.
When parse_options produces internal help output after an error has
occurred it will emit blank lines within the usage string to stdout
instead of stderr.
Update t/helper/test-parse-options.c to have a description body in the
usage string to exercise this second bug and mark tests as failing in
t0040.
Add tests to t1502 to demonstrate both of these problems.
Signed-off-by: Brandon Casey <drafnel@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
The handle_command() function matches an incoming command
string with a sequence of starts_with() checks. But it also
surrounds these with a switch on the first character of the
command, which lets us jump to the right block of
starts_with() without going linearly through the list.
However, each case arm of the switch falls through to the
one below it. This is pointless (we know that a command
starting with 'b' does not need to check any of the commands
in the 'c' block), and it makes gcc's -Wimplicit-fallthrough
complain.
We could solve this by adding a break at the end of each
block. However, this optimization isn't helping anything.
Even if it does make matching faster (which is debatable),
this is code that is run only in the test suite, and each
run receives at most two of these "commands". We should
favor simplicity and readability over micro-optimizing.
Instead, let's drop the switch statement completely and
replace it with an if/else cascade.
Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
The return value of write_in_full() is either "-1", or the
requested number of bytes[1]. If we make a partial write
before seeing an error, we still return -1, not a partial
value. This goes back to f6aa66cb95 (write_in_full: really
write in full or return error on disk full., 2007-01-11).
So checking anything except "was the return value negative"
is pointless. And there are a couple of reasons not to do
so:
1. It can do a funny signed/unsigned comparison. If your
"len" is signed (e.g., a size_t) then the compiler will
promote the "-1" to its unsigned variant.
This works out for "!= len" (unless you really were
trying to write the maximum size_t bytes), but is a
bug if you check "< len" (an example of which was fixed
recently in config.c).
We should avoid promoting the mental model that you
need to check the length at all, so that new sites are
not tempted to copy us.
2. Checking for a negative value is shorter to type,
especially when the length is an expression.
3. Linus says so. In d34cf19b89 (Clean up write_in_full()
users, 2007-01-11), right after the write_in_full()
semantics were changed, he wrote:
I really wish every "write_in_full()" user would just
check against "<0" now, but this fixes the nasty and
stupid ones.
Appeals to authority aside, this makes it clear that
writing it this way does not have an intentional
benefit. It's a historical curiosity that we never
bothered to clean up (and which was undoubtedly
cargo-culted into new sites).
So let's convert these obviously-correct cases (this
includes write_str_in_full(), which is just a wrapper for
write_in_full()).
[1] A careful reader may notice there is one way that
write_in_full() can return a different value. If we ask
write() to write N bytes and get a return value that is
_larger_ than N, we could return a larger total. But
besides the fact that this would imply a totally broken
version of write(), it would already invoke undefined
behavior. Our internal remaining counter is an unsigned
size_t, which means that subtracting too many byte will
wrap it around to a very large number. So we'll instantly
begin reading off the end of the buffer, trying to write
gigabytes (or petabytes) of data.
Signed-off-by: Jeff King <peff@peff.net>
Reviewed-by: Jonathan Nieder <jrnieder@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
This is to address concerns raised by ThreadSanitizer on the mailing list
about threaded unprotected R/W access to map.size with my previous "disallow
rehash" change (0607e10009).
See:
https://public-inbox.org/git/adb37b70139fd1e2bac18bfd22c8b96683ae18eb.1502780344.git.martin.agren@gmail.com/
Add API to hashmap to disable item counting and thus automatic rehashing.
Also include API to later re-enable them.
When item counting is disabled, the map.size field is invalid. So to
prevent accidents, the field has been renamed and an accessor function
hashmap_get_size() has been added. All direct references to this
field have been been updated. And the name of the field changed
to map.private_size to communicate this.
Here is the relevant output from ThreadSanitizer showing the problem:
WARNING: ThreadSanitizer: data race (pid=10554)
Read of size 4 at 0x00000082d488 by thread T2 (mutexes: write M16):
#0 hashmap_add hashmap.c:209
#1 hash_dir_entry_with_parent_and_prefix name-hash.c:302
#2 handle_range_dir name-hash.c:347
#3 handle_range_1 name-hash.c:415
#4 lazy_dir_thread_proc name-hash.c:471
#5 <null> <null>
Previous write of size 4 at 0x00000082d488 by thread T1 (mutexes: write M31):
#0 hashmap_add hashmap.c:209
#1 hash_dir_entry_with_parent_and_prefix name-hash.c:302
#2 handle_range_dir name-hash.c:347
#3 handle_range_1 name-hash.c:415
#4 handle_range_dir name-hash.c:380
#5 handle_range_1 name-hash.c:415
#6 lazy_dir_thread_proc name-hash.c:471
#7 <null> <null>
Martin gives instructions for running TSan on test t3008 in this post:
https://public-inbox.org/git/CAN0heSoJDL9pWELD6ciLTmWf-a=oyxe4EXXOmCKvsG5MSuzxsA@mail.gmail.com/
Signed-off-by: Jeff Hostetler <jeffhost@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
This new binary was introduced in commit 3921a0b ("perf: add test for
writing the index", 2017-08-21), but a .gitignore entry was not added
for it. Add that entry.
Signed-off-by: Jonathan Tan <jonathantanmy@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
We used to spend more than necessary cycles allocating and freeing
piece of memory while writing each index entry out. This has been
optimized.
* kw/write-index-reduce-alloc:
read-cache: avoid allocating every ondisk entry when writing
read-cache: fix memory leak in do_write_index
perf: add test for writing the index
Code clean-up to avoid mixing values read from the .gitmodules file
and values read from the .git/config file.
* bw/submodule-config-cleanup:
submodule: remove gitmodules_config
unpack-trees: improve loading of .gitmodules
submodule-config: lazy-load a repository's .gitmodules file
submodule-config: move submodule-config functions to submodule-config.c
submodule-config: remove support for overlaying repository config
diff: stop allowing diff to have submodules configured in .git/config
submodule: remove submodule_config callback routine
unpack-trees: don't respect submodule.update
submodule: don't rely on overlayed config when setting diffopts
fetch: don't overlay config with submodule-config
submodule--helper: don't overlay config in update-clone
submodule--helper: don't overlay config in remote_submodule_branch
add, reset: ensure submodules can be added or reset
submodule: don't use submodule_from_name
t7411: check configuration parsing errors
A performance test for writing the index to be able to
determine if changes to allocating ondisk structure help.
Signed-off-by: Kevin Willford <kewillf@microsoft.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Many uses of comparision callback function the hashmap API uses
cast the callback function type when registering it to
hashmap_init(), which defeats the compile time type checking when
the callback interface changes (e.g. gaining more parameters).
The callback implementations have been updated to take "void *"
pointers and cast them to the type they expect instead.
* sb/hashmap-cleanup:
t/helper/test-hashmap: use custom data instead of duplicate cmp functions
name-hash.c: drop hashmap_cmp_fn cast
submodule-config.c: drop hashmap_cmp_fn cast
remote.c: drop hashmap_cmp_fn cast
patch-ids.c: drop hashmap_cmp_fn cast
convert/sub-process: drop cast to hashmap_cmp_fn
config.c: drop hashmap_cmp_fn cast
builtin/describe: drop hashmap_cmp_fn cast
builtin/difftool.c: drop hashmap_cmp_fn cast
attr.c: drop hashmap_cmp_fn cast
Conversion from uchar[20] to struct object_id continues.
* bc/object-id:
sha1_name: convert uses of 40 to GIT_SHA1_HEXSZ
sha1_name: convert GET_SHA1* flags to GET_OID*
sha1_name: convert get_sha1* to get_oid*
Convert remaining callers of get_sha1 to get_oid.
builtin/unpack-file: convert to struct object_id
bisect: convert bisect_checkout to struct object_id
builtin/update_ref: convert to struct object_id
sequencer: convert to struct object_id
remote: convert struct push_cas to struct object_id
submodule: convert submodule config lookup to use object_id
builtin/merge-tree: convert remaining caller of get_sha1 to object_id
builtin/fsck: convert remaining caller of get_sha1 to object_id
The parameter to basename(3) and dirname(3) traditionally had the type
"char *", but on OpenBSD it's been "const char *" for years. That
causes (at least) Clang to throw an incompatible-pointer-types warning
for test-path-utils, where we try to pass around pointers to these
functions.
Avoid this warning (which is fatal in DEVELOPER mode) by ignoring the
promise of OpenBSD's implementations to keep input strings unmodified
and enclosing them in POSIX-compatible wrappers.
Signed-off-by: Rene Scharfe <l.s.r@web.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Now that the submodule-config subsystem can lazily read the gitmodules
file we no longer need to explicitly pre-read the gitmodules by calling
'gitmodules_config()' so let's remove it.
Signed-off-by: Brandon Williams <bmwill@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
All callers have been migrated to explicitly read any configuration they
need. The support for handling it automatically in submodule-config is
no longer needed.
Signed-off-by: Brandon Williams <bmwill@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
* bc/object-id:
sha1_name: convert uses of 40 to GIT_SHA1_HEXSZ
sha1_name: convert GET_SHA1* flags to GET_OID*
sha1_name: convert get_sha1* to get_oid*
Convert remaining callers of get_sha1 to get_oid.
builtin/unpack-file: convert to struct object_id
bisect: convert bisect_checkout to struct object_id
builtin/update_ref: convert to struct object_id
sequencer: convert to struct object_id
remote: convert struct push_cas to struct object_id
submodule: convert submodule config lookup to use object_id
builtin/merge-tree: convert remaining caller of get_sha1 to object_id
builtin/fsck: convert remaining caller of get_sha1 to object_id
tag: convert gpg_verify_tag to use struct object_id
commit: convert lookup_commit_graft to struct object_id
Update the hashmap API so that data to customize the behaviour of
the comparison function can be specified at the time a hashmap is
initialized.
* sb/hashmap-customize-comparison:
hashmap: migrate documentation from Documentation/technical into header
patch-ids.c: use hashmap correctly
hashmap.h: compare function has access to a data field
With the new field that is passed to the compare function, we can pass
through flags there instead of having multiple compare functions.
Also drop the cast to hashmap_cmp_fn.
Signed-off-by: Stefan Beller <sbeller@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
When using the hashmap a common need is to have access to caller provided
data in the compare function. A couple of times we abuse the keydata field
to pass in the data needed. This happens for example in patch-ids.c.
This patch changes the function signature of the compare function
to have one more void pointer available. The pointer given for each
invocation of the compare function must be defined in the init function
of the hashmap and is just passed through.
Documentation of this new feature is deferred to a later patch.
This is a rather mechanical conversion, just adding the new pass-through
parameter. However while at it improve the naming of the fields of all
compare functions used by hashmaps by ensuring unused parameters are
prefixed with 'unused_' and naming the parameters what they are (instead
of 'unused' make it 'unused_keydata').
Signed-off-by: Stefan Beller <sbeller@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Fix configuration codepath to pay proper attention to commondir
that is used in multi-worktree situation, and isolate config API
into its own header file.
* bw/config-h:
config: don't implicitly use gitdir or commondir
config: respect commondir
setup: teach discover_git_directory to respect the commondir
config: don't include config.h by default
config: remove git_config_iter
config: create config.h
Remove the unused wildopts placeholder struct from being passed to all
wildmatch() invocations, or rather remove all the boilerplate NULL
parameters.
This parameter was added back in commit 9b3497cab9 ("wildmatch: rename
constants and update prototype", 2013-01-01) as a placeholder for
future use. Over 4 years later nothing has made use of it, let's just
remove it. It can be added in the future if we find some reason to
start using such a parameter.
Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Stop including config.h by default in cache.h. Instead only include
config.h in those files which require use of the config system.
Signed-off-by: Brandon Williams <bmwill@google.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Just because the files backend can't retain reflogs for deleted
references is no reason that they shouldn't be supported by the
virtual method interface. Also, `delete_ref()` and `refs_delete_ref()`
have already gained `msg` parameters. Now let's add them to
`delete_refs()` and `refs_delete_refs()`.
Signed-off-by: Michael Haggerty <mhagger@alum.mit.edu>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
* bc/object-id: (53 commits)
object: convert parse_object* to take struct object_id
tree: convert parse_tree_indirect to struct object_id
sequencer: convert do_recursive_merge to struct object_id
diff-lib: convert do_diff_cache to struct object_id
builtin/ls-tree: convert to struct object_id
merge: convert checkout_fast_forward to struct object_id
sequencer: convert fast_forward_to to struct object_id
builtin/ls-files: convert overlay_tree_on_cache to object_id
builtin/read-tree: convert to struct object_id
sha1_name: convert internals of peel_onion to object_id
upload-pack: convert remaining parse_object callers to object_id
revision: convert remaining parse_object callers to object_id
revision: rename add_pending_sha1 to add_pending_oid
http-push: convert process_ls_object and descendants to object_id
refs/files-backend: convert many internals to struct object_id
refs: convert struct ref_update to use struct object_id
ref-filter: convert some static functions to struct object_id
Convert struct ref_array_item to struct object_id
Convert the verify_pack callback to struct object_id
Convert lookup_tag to struct object_id
...
Some platforms have ulong that is smaller than time_t, and our
historical use of ulong for timestamp would mean they cannot
represent some timestamp that the platform allows. Invent a
separate and dedicated timestamp_t (so that we can distingiuish
timestamps and a vanilla ulongs, which along is already a good
move), and then declare uintmax_t is the type to be used as the
timestamp_t.
* js/larger-timestamps:
archive-tar: fix a sparse 'constant too large' warning
use uintmax_t for timestamps
date.c: abort if the system time cannot handle one of our timestamps
timestamp_t: a new data type for timestamps
PRItime: introduce a new "printf format" for timestamps
parse_timestamp(): specify explicitly where we parse timestamps
t0006 & t5000: skip "far in the future" test when time_t is too limited
t0006 & t5000: prepare for 64-bit timestamps
ref-filter: avoid using `unsigned long` for catch-all data type
"git gc" did not interact well with "git worktree"-managed
per-worktree refs.
* nd/worktree-kill-parse-ref:
refs: kill set_worktree_head_symref()
worktree.c: kill parse_ref() in favor of refs_resolve_ref_unsafe()
refs: introduce get_worktree_ref_store()
refs: add REFS_STORE_ALL_CAPS
refs.c: make submodule ref store hashmap generic
environment.c: fix potential segfault by get_git_common_dir()
Convert parse_tree_indirect to take a pointer to struct object_id.
Update all the callers. This transformation was achieved using the
following semantic patch and manual updates to the declaration and
definition. Update builtin/checkout.c manually as well, since it uses a
ternary expression not handled by the semantic patch.
@@
expression E1;
@@
- parse_tree_indirect(E1.hash)
+ parse_tree_indirect(&E1)
@@
expression E1;
@@
- parse_tree_indirect(E1->hash)
+ parse_tree_indirect(E1)
Signed-off-by: brian m. carlson <sandals@crustytoothpaste.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Convert the sha1 member of struct cache_tree to struct object_id by
changing the definition and applying the following semantic patch, plus
the standard object_id transforms:
@@
struct cache_tree E1;
@@
- E1.sha1
+ E1.oid.hash
@@
struct cache_tree *E1;
@@
- E1->sha1
+ E1->oid.hash
Fix up one reference to active_cache_tree which was not automatically
caught by Coccinelle. These changes are prerequisites for converting
parse_object.
Signed-off-by: brian m. carlson <sandals@crustytoothpaste.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Git's source code assumes that unsigned long is at least as precise as
time_t. Which is incorrect, and causes a lot of problems, in particular
where unsigned long is only 32-bit (notably on Windows, even in 64-bit
versions).
So let's just use a more appropriate data type instead. In preparation
for this, we introduce the new `timestamp_t` data type.
By necessity, this is a very, very large patch, as it has to replace all
timestamps' data type in one go.
As we will use a data type that is not necessarily identical to `time_t`,
we need to be very careful to use `time_t` whenever we interact with the
system functions, and `timestamp_t` everywhere else.
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
"git checkout" that handles a lot of paths has been optimized by
reducing the number of unnecessary checks of paths in the
has_dir_name() function.
* jh/add-index-entry-optim:
read-cache: speed up has_dir_name (part 2)
read-cache: speed up has_dir_name (part 1)
read-cache: speed up add_index_entry during checkout
p0006-read-tree-checkout: perf test to time read-tree
read-cache: add strcmp_offset function
The manual parsing code is replaced with a call to refs_resolve_ref_unsafe().
The manual parsing code must die because only refs/files-backend.c
should do that.
Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Currently, Git's source code treats all timestamps as if they were
unsigned longs. Therefore, it is okay to write "%lu" when printing them.
There is a substantial problem with that, though: at least on Windows,
time_t is *larger* than unsigned long, and hence we will want to switch
away from the ill-specified `unsigned long` data type.
So let's introduce the pseudo format "PRItime" (currently simply being
defined to "lu") to make it easier to change the data type used for
timestamps.
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Currently, Git's source code represents all timestamps as `unsigned
long`. In preparation for using a more appropriate data type, let's
introduce a symbol `parse_timestamp` (currently being defined to
`strtoul`) where appropriate, so that we can later easily switch to,
say, use `strtoull()` instead.
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Git's source code refers to timestamps as unsigned long, which is
ill-defined, as there is no guarantee about the number of bits that
data type has.
In preparation of switching to another data type that is large enough
to hold "far in the future" dates, we need to prepare the t0006-date.sh
script for the case where we *still* cannot format those dates if the
system library uses 32-bit time_t.
Signed-off-by: Johannes Schindelin <Johannes.Schindelin@gmx.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Git's source code refers to timestamps as unsigned longs. On 32-bit
platforms, as well as on Windows, unsigned long is not large enough to
capture dates that are "absurdly far in the future".
It is perfectly valid by the C standard, of course, for the `long` data
type to refer to 32-bit integers. That is why the `time_t` data type
exists: so that it can be 64-bit even if `long` is 32-bit. Git's source
code simply uses an incorrect data type for timestamps, is all.
The earlier quick fix 6b9c38e14c (t0006: skip "far in the future" test
when unsigned long is not long enough, 2016-07-11) papered over this
issue simply by skipping the respective test cases on platforms where
they would fail due to the data type in use.
This quick fix, however, tests for *long* to be 64-bit or not. What we
need, though, is a test that says whether *whatever data type we use for
timestamps* is 64-bit or not.
The same quick fix was used to handle the similar problem where Git's
source code uses `unsigned long` to represent size, instead of `size_t`,
conflating the two issues.
So let's just add another prerequisite to test specifically whether
timestamps are represented by a 64-bit data type or not. Later, after we
switch to a larger data type, we can flip that prerequisite to test
`time_t` instead of `long`.
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Hotfix for a topic that is already in 'master'.
* jh/memihash-opt:
p0004: make perf test executable
t3008: skip lazy-init test on a single-core box
test-online-cpus: helper to return cpu count
name-hash: fix buffer overrun
Clean up fallouts from recent tightening of the set-up sequence,
where Git barfs when repository information is accessed without
first ensuring that it was started in a repository.
* jk/no-looking-at-dotgit-outside-repo:
test-read-cache: setup git dir
has_sha1_file: don't bother if we are not in a repository
