Current code makes pack-objects always do check_pack_crc() in
unpack_entry() even if right after that we find out there's a cached
version and pack access is not needed. Swap two code blocks, search
for cached version first, then check crc.
Signed-off-by: NNguyễn Thái Ngọc Duy <pclouds@gmail.com>
Signed-off-by: NJunio C Hamano <gitster@pobox.com>

When we read a sha1 file, we first look for a packed
version, then a loose version, and then re-check the pack
directory again before concluding that we cannot find it.
This lets us handle a process that is writing to the
repository simultaneously (e.g., receive-pack writing a new
pack followed by a ref update, or git-repack packing
existing loose objects into a new pack).

However, we do not do the same trick with has_sha1_file; we
only check the packed objects once, followed by loose
objects. This means that we might incorrectly report that we
do not have an object, even though we could find it if we
simply re-checked the pack directory.

By itself, this is usually not a big deal. The other process
is running simultaneously, so we may run has_sha1_file
before it writes, anyway. It is a race whether we see the
object or not.  However, we may also see other things
the writing process has done (like updating refs); and in
that case, we must be able to also see the new objects.

For example, imagine we are doing a for_each_ref iteration,
and somebody simultaneously pushes. Receive-pack may write
the pack and update a ref after we have examined the
objects/pack directory, but before the iteration gets to the
updated ref. When we do finally see the updated ref,
for_each_ref will call has_sha1_file to check whether the
ref is broken. If has_sha1_file returns the wrong answer, we
erroneously will think that the ref is broken.

For a normal iteration without DO_FOR_EACH_INCLUDE_BROKEN,
this means that the caller does not see the ref at all
(neither the old nor the new value).  So not only will we
fail to see the new value of the ref (which is acceptable,
since we are running simultaneously with the writer, and we
might well read the ref before the writer commits its
write), but we will not see the old value either. For
programs that act on reachability like pack-objects or
prune, this can cause data loss, as we may see the objects
referenced by the original ref value as dangling (and either
omit them from the pack, or delete them via prune).

There's no test included here, because the success case is
two processes running simultaneously forever. But you can
replicate the issue with:

  # base.sh
  # run this in one terminal; it creates and pushes
  # repeatedly to a repository
  git init parent &&
  (cd parent &&

    # create a base commit that will trigger us looking at
    # the objects/pack directory before we hit the updated ref
    echo content >file &&
    git add file &&
    git commit -m base &&

    # set the unpack limit abnormally low, which
    # lets us simulate full-size pushes using tiny ones
    git config receive.unpackLimit 1
  ) &&
  git clone parent child &&
  cd child &&
  n=0 &&
  while true; do
    echo $n >file && git add file && git commit -m $n &&
    git push origin HEAD:refs/remotes/child/master &&
    n=$(($n + 1))
  done

  # fsck.sh
  # now run this simultaneously in another terminal; it
  # repeatedly fscks, looking for us to consider the
  # newly-pushed ref broken. We cannot use for-each-ref
  # here, as it uses DO_FOR_EACH_INCLUDE_BROKEN, which
  # skips the has_sha1_file check (and if it wants
  # more information on the object, it will actually read
  # the object, which does the proper two-step lookup)
  cd parent &&
  while true; do
    broken=`git fsck 2>&1 | grep remotes/child`
    if test -n "$broken"; then
      echo $broken
      exit 1
    fi
  done

Without this patch, the fsck loop fails within a few seconds
(and almost instantly if the test repository actually has a
large number of refs). With it, the two can run
indefinitely.
Signed-off-by: NJeff King <peff@peff.net>
Signed-off-by: NJunio C Hamano <gitster@pobox.com>

Now that close_one_pack() has been introduced to handle file
descriptor pressure, it is not strictly necessary to close the
pack file descriptor in unuse_one_window() when we're under memory
pressure.

Jeff King provided a justification for leaving the pack file open:

   If you close packfile descriptors, you can run into racy situations
   where somebody else is repacking and deleting packs, and they go away
   while you are trying to access them. If you keep a descriptor open,
   you're fine; they last to the end of the process. If you don't, then
   they disappear from under you.

   For normal object access, this isn't that big a deal; we just rescan
   the packs and retry. But if you are packing yourself (e.g., because
   you are a pack-objects started by upload-pack for a clone or fetch),
   it's much harder to recover (and we print some warnings).

Let's do so (or uh, not do so).
Signed-off-by: NBrandon Casey <drafnel@gmail.com>
Signed-off-by: NJunio C Hamano <gitster@pobox.com>

When the number of open packs exceeds pack_max_fds, unuse_one_window()
is called repeatedly to attempt to release the least-recently-used
pack windows, which, as a side-effect, will also close a pack file
after closing its last open window.  If a pack file has been opened,
but no windows have been allocated into it, it will never be selected
by unuse_one_window() and hence its file descriptor will not be
closed.  When this happens, git may exceed the number of file
descriptors permitted by the system.

This latter situation can occur in show-ref or receive-pack during ref
advertisement.  During ref advertisement, receive-pack will iterate
over every ref in the repository and advertise it to the client after
ensuring that the ref exists in the local repository.  If the ref is
located inside a pack, then the pack is opened to ensure that it
exists, but since the object is not actually read from the pack, no
mmap windows are allocated.  When the number of open packs exceeds
pack_max_fds, unuse_one_window() will not be able to find any windows to
free and will not be able to close any packs.  Once the per-process
file descriptor limit is exceeded, receive-pack will produce a warning,
not an error, for each pack it cannot open, and will then most likely
fail with an error to spawn rev-list or index-pack like:

   error: cannot create standard input pipe for rev-list: Too many open files
   error: Could not run 'git rev-list'

This may also occur during upload-pack when refs are packed (in the
packed-refs file) and the number of packs that must be opened to
verify that these packed refs exist exceeds the file descriptor
limit.  If the refs are loose, then upload-pack will read each ref
from the object database (if the object is in a pack, allocating one
or more mmap windows for it) in order to peel tags and advertise the
underlying object.  But when the refs are packed and peeled,
upload-pack will use the peeled sha1 in the packed-refs file and
will not need to read from the pack files, so no mmap windows will
be allocated and just like with receive-pack, unuse_one_window()
will never select these opened packs to close.

When we have file descriptor pressure, we just need to find an open
pack to close.  We can leave the existing mmap windows open.  If
additional windows need to be mapped into the pack file, it will be
reopened when necessary.  If the pack file has been rewritten in the
mean time, open_packed_git_1() should notice when it compares the file
size or the pack's sha1 checksum to what was previously read from the
pack index, and reject it.

Let's introduce a new function close_one_pack() designed specifically
for this purpose to search for and close the least-recently-used pack,
where LRU is defined as (in order of preference):

   * pack with oldest mtime and no allocated mmap windows
   * pack with the least-recently-used windows, i.e. the pack
     with the oldest most-recently-used window, where none of
     the windows are in use
   * pack with the least-recently-used windows
Signed-off-by: NBrandon Casey <drafnel@gmail.com>
Signed-off-by: NJunio C Hamano <gitster@pobox.com>

Sparse issues some "Using plain integer as NULL pointer" warnings.
Each warning relates to the use of an '{0}' initialiser expression
in the declaration of an 'struct object_info'. The first field of
this structure has pointer type. Thus, in order to suppress these
warnings, we replace the initialiser expression with '{NULL}'.
Signed-off-by: NRamsay Jones <ramsay@ramsay1.demon.co.uk>
Acked-by: NJeff King <peff@peff.net>
Signed-off-by: NJunio C Hamano <gitster@pobox.com>

We take in a "struct object_info" which contains pointers to
storage for items the caller cares about. But then rather
than pass the whole object to the low-level loose/packed
helper functions, we pass the individual pointers.

Let's pass the whole struct instead, which will make adding
more items later easier.
Signed-off-by: NJeff King <peff@peff.net>
Signed-off-by: NJunio C Hamano <gitster@pobox.com>

Each caller of sha1_object_info_extended sets up an
object_info struct to tell the function which elements of
the object it wants to get. Until now, getting the type of
the object has always been required (and it is returned via
the return type rather than a pointer in object_info).

This can involve actually opening a loose object file to
determine its type, or following delta chains to determine a
packed file's base type. These effects produce a measurable
slow-down when doing a "cat-file --batch-check" that does
not include %(objecttype).

This patch adds a "typep" query to struct object_info, so
that it can be optionally queried just like size and
disk_size. As a result, the return type of the function is
no longer the object type, but rather 0/-1 for success/error.

As there are only three callers total, we just fix up each
caller rather than keep a compatibility wrapper:

  1. The simpler sha1_object_info wrapper continues to
     always ask for and return the type field.

  2. The istream_source function wants to know the type, and
     so always asks for it.

  3. The cat-file batch code asks for the type only when
     %(objecttype) is part of the format string.

On linux.git, the best-of-five for running:

  $ git rev-list --objects --all >objects
  $ time git cat-file --batch-check='%(objectsize:disk)'

on a fully packed repository goes from:

  real    0m8.680s
  user    0m8.160s
  sys     0m0.512s

to:

  real    0m7.205s
  user    0m6.580s
  sys     0m0.608s
Signed-off-by: NJeff King <peff@peff.net>
Signed-off-by: NJunio C Hamano <gitster@pobox.com>

Currently, packed_object_info can save some work by not
calculating the size or disk_size of the object if the
caller is not interested. However, it always calculates the
true object type, whether the caller cares or not, and only
optionally returns the easy-to-get "representation type".

Let's swap these types. The function will now return the
representation type (or OBJ_BAD on failure), and will only
optionally fill in the true type.

There should be no behavior change yet, as the only caller,
sha1_object_info_extended, will always feed it a type
pointer.
Signed-off-by: NJeff King <peff@peff.net>
Signed-off-by: NJunio C Hamano <gitster@pobox.com>

To calculate the type of a packed object, we must walk down
its delta chain until we hit a true base object with a real
type. Most of the code in packed_object_info is for handling
this case.

Let's hoist it out into a separate helper function, which
will make it easier to make the type-lookup optional in the
future (and keep our indentation level sane).
Signed-off-by: NJeff King <peff@peff.net>
Signed-off-by: NJunio C Hamano <gitster@pobox.com>

Until recently, the only items to request from
sha1_object_info_extended were type and size. This meant
that we always had to open a loose object file to determine
one or the other.  But with the addition of the disk_size
query, it's possible that we can fulfill the query without
even opening the object file at all. However, since the
function interface always returns the type, we have no way
of knowing whether the caller cares about it or not.

This patch only modified sha1_loose_object_info to make type
lookup optional using an out-parameter, similar to the way
the size is handled (and the return value is "0" or "-1" for
success or error, respectively).

There should be no functional change yet, though, as
sha1_object_info_extended, the only caller, will always ask
for a type.
Signed-off-by: NJeff King <peff@peff.net>
Signed-off-by: NJunio C Hamano <gitster@pobox.com>

The value we get from each low-level object_info function
(e.g., loose, packed) is actually the object type (or -1 for
error). Let's explicitly call it "type", which will make
further refactorings easier to read.
Signed-off-by: NJeff King <peff@peff.net>
Signed-off-by: NJunio C Hamano <gitster@pobox.com>

Using sha1_object_info_extended, a caller can find out the
type of an object, its size, and information about where it
is stored. In addition to the object's "true" size, it can
also be useful to know the size that the object takes on
disk (e.g., to generate statistics about which refs consume
space).

This patch adds a "disk_sizep" field to "struct object_info",
and fills it in during sha1_object_info_extended if it is
non-NULL.
Signed-off-by: NJeff King <peff@peff.net>
Signed-off-by: NJunio C Hamano <gitster@pobox.com>

The sha1_object_info_extended function expects the caller to
provide a "struct object_info" which contains pointers to
"query" items that will be filled in. The purpose of
providing pointers rather than storing the response directly
in the struct is so that callers can choose not to incur the
expense in finding particular fields that they do not care
about.

Right now the only query item is "sizep", and all callers
set it explicitly to choose whether or not to query it; they
can then leave the rest of the struct uninitialized.

However, as we add new query items, each caller will have to
be updated to explicitly turn off the new ones (by setting
them to NULL).  Instead, let's teach each caller to
zero-initialize the struct, so that they do not have to
learn about each new query item added.
Signed-off-by: NJeff King <peff@peff.net>
Signed-off-by: NJunio C Hamano <gitster@pobox.com>

When we try to load an object from disk and fail, our
general strategy is to see if we can get it from somewhere
else (e.g., a loose object). That lets users fix corruption
problems by copying known-good versions of objects into the
object database.

We already handle the case where we were not able to read
the delta from disk. However, when we find that the delta we
read does not apply, we simply die.  This case is harder to
trigger, as corruption in the delta data itself would
trigger a crc error from zlib.  However, a corruption that
pointed us at the wrong delta base might cause it.

We can do the same "fail and try to find the object
elsewhere" trick instead of dying. This not only gives us a
chance to recover, but also puts us on code paths that will
alert the user to the problem (with the current message,
they do not even know which sha1 caused the problem).

Note that unlike some other pack corruptions, we do not
recover automatically from this case when doing a repack.
There is nothing apparently wrong with the delta, as it
points to a valid, accessible object, and we realize the
error only when the resulting size does not match up. And in
theory, one could even have a case where the corrupted size
is the same, and the problem would only be noticed by
recomputing the sha1.

We can get around this by recomputing the deltas with
--no-reuse-delta, which our test does (and this is probably
good advice for anyone recovering from pack corruption).
Signed-off-by: NJeff King <peff@peff.net>
Signed-off-by: NJunio C Hamano <gitster@pobox.com>

5f44324d (core: log offset pack data accesses happened - 2011-07-06)
provides a way to observe pack access patterns via a config
switch. Setting an environment variable looks more obvious than a
config var, especially when you just need to _observe_, and more
inline with other tracing knobs we have.

Document it as it may be useful for remote troubleshooting.
Signed-off-by: NNguyễn Thái Ngọc Duy <pclouds@gmail.com>
Signed-off-by: NJunio C Hamano <gitster@pobox.com>

sha1_object_info() returns -1 (OBJ_BAD) if it cannot find the object
for some reason, which suggests that it wants the _caller_ to report
this error.  However, part of its work happens in
sha1_loose_object_info, which _does_ report errors itself.  This is
doubly strange because:

* packed_object_info(), which is the other half of the duo, does _not_
  report this.

* In the event that an object is packed and pruned while
  sha1_object_info_extended() goes looking for it, we would
  erroneously show the error -- even though the code of the latter
  function purports to handle this case gracefully.

* A caller might invoke sha1_object_info() to find the type of an
  object even if that object is not known to exist.

Silence this error.  The others remain untouched as a corrupt object
is a much more grave error than it merely being absent.
Signed-off-by: NThomas Rast <trast@inf.ethz.ch>
Signed-off-by: NJunio C Hamano <gitster@pobox.com>

Signed-off-by: NFelipe Contreras <felipe.contreras@gmail.com>
Signed-off-by: NJunio C Hamano <gitster@pobox.com>

In the !delta_data error path of unpack_entry(), we run free(base).
This became a window for use-after-free() in abe601bb (sha1_file:
remove recursion in unpack_entry, 2013-03-27), as follows:

Before abe601bb, we got the 'base' from cache_or_unpack_entry(..., 0);
keep_cache=0 tells it to also remove that entry.  So the 'base' is at
this point not cached, and freeing it in the error path is the right
thing.

After abe601bb, the structure changed: we use a three-phase approach
where phase 1 finds the innermost base or a base that is already in
the cache.  In phase 3 we therefore know that all bases we unpack are
not part of the delta cache yet.  (Observe that we pop from the cache
in phase 1, so this is also true for the very first base.)  So we make
no further attempts to look up the bases in the cache, and just call
add_delta_base_cache() on every base object we have assembled.

But the !delta_data error path remained unchanged, and now calls
free() on a base that has already been entered in the cache.  This
means that there is a use-after-free if we later use the same base
again.

So remove that free(); we are still going to use that data.
Reported-by: NNguyễn Thái Ngọc Duy <pclouds@gmail.com>
Signed-off-by: NThomas Rast <trast@inf.ethz.ch>
Signed-off-by: NJunio C Hamano <gitster@pobox.com>

It's possible for read_istream to return an error, in which
case we just end up in an infinite loop (aside from EOF, we
do not even look at the result, but just feed it straight
into our running hash).
Signed-off-by: NJeff King <peff@peff.net>
Signed-off-by: NJunio C Hamano <gitster@pobox.com>

Similar to the recursion in packed_object_info(), this leads to
problems on stack-space-constrained systems in the presence of long
delta chains.

We proceed in three phases:

1. Dig through the delta chain, saving each delta object's offsets and
   size on an ad-hoc stack.

2. Unpack the base object at the bottom.

3. Unpack and apply the deltas from the stack.
Signed-off-by: NThomas Rast <trast@student.ethz.ch>
Signed-off-by: NJunio C Hamano <gitster@pobox.com>

The delta base cache lookup and test were shared.  Refactor them;
we'll need both parts again.  Also, we'll use the clearing routine
later.
Signed-off-by: NThomas Rast <trast@student.ethz.ch>
Signed-off-by: NJunio C Hamano <gitster@pobox.com>

If two processes are racing to create the same directory tree, they
will both see that the directory doesn't exist, both try to mkdir(),
and one of them will fail.  This is okay, as we only care that the
directory gets created.  So, we add a check for EEXIST from mkdir,
and continue when the directory exists, taking the same codepath as
the case where the earlier stat() succeeds and finds a directory.
Signed-off-by: NSteven Walter <stevenrwalter@gmail.com>
Signed-off-by: NJunio C Hamano <gitster@pobox.com>

packed_object_info() and packed_delta_info() were mutually recursive.
The former would handle ordinary types and defer deltas to the latter;
the latter would use the former to resolve the delta base.

This arrangement, however, leads to trouble with threaded index-pack
and long delta chains on platforms where thread stacks are small, as
happened on OS X (512kB thread stacks by default) with the chromium
repo.

The task of the two functions is not all that hard to describe without
any recursion, however.  It proceeds in three steps:

- determine the representation type and size, based on the outermost
  object (delta or not)

- follow through the delta chain, if any

- determine the object type from what is found at the end of the delta
  chain

The only complication stems from the error recovery.  If parsing fails
at any step, we want to mark that object (within the pack) as bad and
try getting the corresponding SHA1 from elsewhere.  If that also
fails, we want to repeat this process back up the delta chain until we
find a reasonable solution or conclude that there is no way to
reconstruct the object.  (This is conveniently checked by t5303.)

To achieve that within the pack, we keep track of the entire delta
chain in a stack.  When things go sour, we process that stack from the
top, marking entries as bad and attempting to re-resolve by sha1.  To
avoid excessive malloc(), the stack starts out with a small
stack-allocated array.  The choice of 64 is based on the default of
pack.depth, which is 50, in the hope that it covers "most" delta
chains without any need for malloc().

It's much harder to make the actual re-resolving by sha1 nonrecursive,
so we skip that.  If you can't afford *that* recursion, your
corruption problems are more serious than your stack size problems.
Reported-by: NStefan Zager <szager@google.com>
Signed-off-by: NThomas Rast <trast@student.ethz.ch>
Signed-off-by: NJunio C Hamano <gitster@pobox.com>

prepare_packed_git_one() is modified to allow count-objects to hook a
report function to so we don't need to duplicate the pack searching
logic in count-objects.c. When report_pack_garbage is NULL, the
overhead is insignificant.

The garbage is reported with warning() instead of error() in packed
garbage case because it's not an error to have garbage. Loose garbage
is still reported as errors and will be converted to warnings later.
Signed-off-by: NNguyễn Thái Ngọc Duy <pclouds@gmail.com>
Signed-off-by: NJunio C Hamano <gitster@pobox.com>

The current loop does

	while (...) {
		if (it is not an .idx file)
			continue;
		process .idx file;
	}

and is reordered to

	while (...) {
		if (it is an .idx file) {
			process .idx file;
		}
	}

This makes it easier to add new extension file processing.
Signed-off-by: NNguyễn Thái Ngọc Duy <pclouds@gmail.com>
Signed-off-by: NJunio C Hamano <gitster@pobox.com>

Change link_alt_odb_entries() to take the length of the "alt"
parameter rather than a pointer to the end of the "alt" string.  This
is the more common calling convention and simplifies the code a tiny
bit.
Signed-off-by: NMichael Haggerty <mhagger@alum.mit.edu>
Signed-off-by: NJeff King <peff@peff.net>

Change link_alt_odb_entry() to take a NUL-terminated string instead of
(char *, len).  Use string_list_split_in_place() rather than inline
code in link_alt_odb_entries().

This approach saves some code and also avoids the (probably harmless)
error of passing a non-NUL-terminated string to is_absolute_path().
Signed-off-by: NMichael Haggerty <mhagger@alum.mit.edu>
Signed-off-by: NJeff King <peff@peff.net>

Not all platforms have getrlimit(), but there are other ways to see
the maximum number of files that a process can have open.  If
getrlimit() is unavailable, fall back to sysconf(_SC_OPEN_MAX) if
available, and use OPEN_MAX from <limits.h>.
Signed-off-by: NJoachim Schmitz <jojo@schmitz-digital.de>
Signed-off-by: NJunio C Hamano <gitster@pobox.com>

pfxlen can be longer than the path in objdir when relative_base
contains the path to gits object directory.  Here we are interested
in checking if ent->base[] (the part that corresponds to .git/objects)
is the same string as objdir, and the code NUL-terminated ent->base[]
to

	LEADING PATH\0XX/XXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXXX\0

in preparation for these "duplicate check" step (before we return
from the function, the first NUL is turned into '/' so that we can
fill XX when probing for loose objects).  All we need to do is to
compare the string with the path to our object directory.
Signed-off-by: NHeiko Voigt <hvoigt@hvoigt.net>
Signed-off-by: NJunio C Hamano <gitster@pobox.com>

Since we allow to link other object databases when loading a submodules
database we should also load possible alternates.
Signed-off-by: NHeiko Voigt <hvoigt@hvoigt.net>
Signed-off-by: NJunio C Hamano <gitster@pobox.com>

When write_loose_object() finds that it is unable to
create a temporary file, it complains, for instance:

    unable to create temporary sha1 filename : Too many open files

That extra space was supposed to be the name of the file,
and will be an empty string if the git_mkstemps_mode() fails.

The name of the temporary file is unimportant; delete it.
Signed-off-by: NPete Wyckoff <pw@padd.com>
Signed-off-by: NJunio C Hamano <gitster@pobox.com>

The error handling routines add a newline.  Remove
the duplicate ones in error messages.
Signed-off-by: NPete Wyckoff <pw@padd.com>
Signed-off-by: NJunio C Hamano <gitster@pobox.com>

Traditionally, all the callers of check_sha1_signature() first
called read_sha1_file() to prepare the whole object data in core,
and called this function.  The function is used to revalidate what
we read from the object database actually matches the object name we
used to ask for the data from the object database.

Update the API to allow callers to pass NULL as the object data, and
have the function read and hash the object data using streaming API
to recompute the object name, without having to hold everything in
core at the same time.  This is most useful in parse_object() that
parses a blob object, because this caller does not have to keep the
actual blob data around in memory after a "struct blob" is returned.
Signed-off-by: NNguyễn Thái Ngọc Duy <pclouds@gmail.com>
Signed-off-by: NJunio C Hamano <gitster@pobox.com>

Because git's object format requires us to specify the
number of bytes in the object in its header, we must know
the size before streaming a blob into the object database.
This is not a problem when adding a regular file, as we can
get the size from stat(). However, when filters are in use
(such as autocrlf, or the ident, filter, or eol
gitattributes), we have no idea what the ultimate size will
be.

The current code just punts on the whole issue and ignores
filter configuration entirely for files larger than
core.bigfilethreshold. This can generate confusing results
if you use filters for large binary files, as the filter
will suddenly stop working as the file goes over a certain
size.  Rather than try to handle unknown input sizes with
streaming, this patch just turns off the streaming
optimization when filters are in use.

This has a slight performance regression in a very specific
case: if you have autocrlf on, but no gitattributes, a large
binary file will avoid the streaming code path because we
don't know beforehand whether it will need conversion or
not. But if you are handling large binary files, you should
be marking them as such via attributes (or at least not
using autocrlf, and instead marking your text files as
such). And the flip side is that if you have a large
_non_-binary file, there is a correctness improvement;
before we did not apply the conversion at all.

The first half of the new t1051 script covers these failures
on input. The second half tests the matching output code
paths. These already work correctly, and do not need any
adjustment.
Signed-off-by: NJeff King <peff@peff.net>
Signed-off-by: NJunio C Hamano <gitster@pobox.com>

Since 3ba7a065 (A loose object is not corrupt if it
cannot be read due to EMFILE), "git fsck" on a repository with an empty
loose object file complains with the error message

  fatal: failed to read object <sha1>: Invalid argument

This comes from a failure of mmap on this empty file, which sets errno to
EINVAL. Instead of calling xmmap on empty file, we display a clean error
message ourselves, and return a NULL pointer. The new message is

  error: object file .git/objects/09/<rest-of-sha1> is empty
  fatal: loose object <sha1> (stored in .git/objects/09/<rest-of-sha1>) is corrupt

The second line was already there before the regression in 3ba7a065,
and the first is an additional message, that should help diagnosing the
problem for the user.
Signed-off-by: NMatthieu Moy <Matthieu.Moy@imag.fr>
Signed-off-by: NJunio C Hamano <gitster@pobox.com>

Commit f7c22cc6 (always start looking up objects in the last used pack
first - 2007-05-30) introduce a static packed_git* pointer as an
optimization.  The kept pointer however may become invalid if
free_pack_by_name() happens to free that particular pack.

Current code base does not access packs after calling
free_pack_by_name() so it should not be a problem. Anyway, move the
pointer out so that free_pack_by_name() can reset it to avoid running
into troubles in future.
Signed-off-by: NNguyễn Thái Ngọc Duy <pclouds@gmail.com>
Acked-by: NNicolas Pitre <nico@fluxnic.net>
Signed-off-by: NJunio C Hamano <gitster@pobox.com>

The new helper function implements the logic to find the offset for the
object in one pack and fill a pack_entry structure. The next patch will
restructure the loop and will call the helper from two places.
Signed-off-by: NNguyễn Thái Ngọc Duy <pclouds@gmail.com>
Acked-by: NNicolas Pitre <nico@fluxnic.net>
Signed-off-by: NJunio C Hamano <gitster@pobox.com>

On Solaris the system headers define the "tmpfile" name, which'll
cause Git compiled with Sun Studio 12 Update 1 to whine about us
redefining the name:

    "pack-write.c", line 76: warning: name redefined by pragma redefine_extname declared static: tmpfile     (E_PRAGMA_REDEFINE_STATIC)
    "sha1_file.c", line 2455: warning: name redefined by pragma redefine_extname declared static: tmpfile    (E_PRAGMA_REDEFINE_STATIC)
    "fast-import.c", line 858: warning: name redefined by pragma redefine_extname declared static: tmpfile   (E_PRAGMA_REDEFINE_STATIC)
    "builtin/index-pack.c", line 175: warning: name redefined by pragma redefine_extname declared static: tmpfile    (E_PRAGMA_REDEFINE_STATIC)

Just renaming the "tmpfile" variable to "tmp_file" in the relevant
places is the easiest way to fix this.
Signed-off-by: NÆvar Arnfjörð Bjarmason <avarab@gmail.com>
Signed-off-by: NJunio C Hamano <gitster@pobox.com>

This extends the earlier approach to stream a large file directly from the
filesystem to its own packfile, and allows "git add" to send large files
directly into a single pack. Older code used to spawn fast-import, but the
new bulk-checkin API replaces it.
Signed-off-by: NJunio C Hamano <gitster@pobox.com>

Signed-off-by: NRamkumar Ramachandra <artagnon@gmail.com>
Signed-off-by: NJunio C Hamano <gitster@pobox.com>