The `index_blob_packfile_transaction()` function handles streaming a
blob from an fd to compute its object ID and conditionally writes the
object directly to a packfile if the INDEX_WRITE_OBJECT flag is set. A
subsequent commit will make these packfile object writes part of the
transaction interface. Consequently, having the object write be
conditional on this flag is a bit awkward.
In preparation for this change, introduce a dedicated
`hash_blob_stream()` helper that only computes the OID from a `struct
odb_write_stream`. This is invoked by `index_fd()` instead when the
INDEX_WRITE_OBJECT is not set. The object write performed via
`index_blob_packfile_transaction()` is made unconditional accordingly.
Signed-off-by: Justin Tobler <jltobler@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
The `read()` callback used by `struct odb_write_stream` currently
returns a pointer to an internal buffer along with the number of bytes
read. This makes buffer ownership unclear and provides no way to report
errors.
Update the interface to instead require the caller to provide a buffer,
and have the callback return the number of bytes written to it or a
negative value on error. While at it, also move the `struct
odb_write_stream` definition to "odb/streaming.h". Call sites are
updated accordingly.
Signed-off-by: Justin Tobler <jltobler@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
The odb_read_stream structure uses unsigned long for the size field,
which is 32-bit on Windows even in 64-bit builds. When streaming
objects larger than 4GB, the size would be truncated to zero or an
incorrect value, resulting in empty files being written to disk.
Change the size field in odb_read_stream to size_t and introduce
unpack_object_header_sz() to return sizes via size_t pointer. Since
object_info.sizep remains unsigned long for API compatibility, use
temporary variables where the types differ, with comments noting the
truncation limitation for code paths that still use unsigned long.
Widening the producers to size_t in this way introduces a handful of
silent size_t -> unsigned long narrowings on Windows, all in
builtin/pack-objects.c, where the consumers are still typed
unsigned long. Make those narrowings explicit with
cast_size_t_to_ulong() so they assert loudly the moment an object
actually exceeds ULONG_MAX bytes:
- oe_get_size_slow() returns unsigned long but holds a size_t
locally; cast at the return.
- write_reuse_object() passes a size_t into check_pack_inflate(),
whose expect parameter is unsigned long; cast at the call.
- check_object() routes a size_t through SET_SIZE() and
SET_DELTA_SIZE(), both of which take unsigned long via
oe_set_size() / oe_set_delta_size(); cast at the three call
sites in the OBJ_OFS_DELTA / OBJ_REF_DELTA branches and in the
non-delta default arm.
The cast-only treatment is deliberately a stop-gap. Properly
widening oe_set_size, oe_get_size_slow's return type,
check_pack_inflate's expect parameter, object_info.sizep,
patch_delta, and the OE_SIZE_BITS bit-fields cascades into a series
that is too large to be reviewable, so the proper widening is
deferred to a follow-up topic. Until then,
cast_size_t_to_ulong() at least makes the truncation explicit at
the source: it documents the boundary, and on a 64-bit non-Windows
platform it is a no-op.
This was originally authored by LordKiRon <https://github.com/LordKiRon>,
who preferred not to reveal their real name and therefore agreed that I
take over authorship.
Helped-by: Torsten Bögershausen <tboegi@web.de>
Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
The "odb.h" header currently includes the "odb/source.h" file. This is
somewhat roundabout though: most callers shouldn't have to care about
the `struct odb_source`, but should rather use the ODB-level functions.
Furthermore, it means that a couple of definitions have to live on the
source level even though they should be part of the generic interface.
Reverse the relation between "odb/source.h" and "odb.h" and move the
enums and typedefs that relate to the generic interfaces back into
"odb.h". Add the necessary includes to all files that rely on the
transitive include.
Suggested-by: Justin Tobler <jltobler@gmail.com>
Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Introduce a new callback function in `struct odb_source` to make the
function pluggable.
Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
The "files" backend is implemented as a pointer in the `struct
odb_source`. This contradicts our typical pattern for pluggable backends
like we use it for example in the ref store or for object database
streams, where we typically embed the generic base structure in the
specialized implementation. This pattern has a couple of small benefits:
- We avoid an extra allocation.
- We hide implementation details in the generic structure.
- We can easily downcast from a generic backend to the specialized
structure and vice versa because the offsets are known at compile
time.
- It becomes trivial to identify locations where we depend on backend
specific logic because the cast needs to be explicit.
Refactor our "files" object database source to do the same and embed the
`struct odb_source` in the `struct odb_source_files`.
There are still a bunch of sites in our code base where we do have to
access internals of the "files" backend. The intent is that those will
go away over time, but this will certainly take a while. Meanwhile,
provide a `odb_source_files_downcast()` function that can convert a
generic source into a "files" source.
As we only have a single source the downcast succeeds unconditionally
for now. Eventually though the intent is to make the cast `BUG()` in
case the caller requests to downcast a non-"files" backend to a "files"
backend.
Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Introduce a new "files" object database source. This source encapsulates
access to both loose object files and the packfile store, similar to how
the "files" backend for refs encapsulates access to loose refs and the
packed-refs file.
Note that for now the "files" source is still a direct member of a
`struct odb_source`. This architecture will be reversed in the next
commit so that the files source contains a `struct odb_source`.
Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
The packfile store is a member of `struct object_database`, which means
that we have a single store per database. This doesn't really make much
sense though: each source connected to the database has its own set of
packfiles, so there is a conceptual mismatch here. This hasn't really
caused much of a problem in the past, but with the advent of pluggable
object databases this is becoming more of a problem because some of the
sources may not even use packfiles in the first place.
Move the packfile store down by one level from the object database into
the object database source. This ensures that each source now has its
own packfile store, and we can eventually start to abstract it away
entirely so that the caller doesn't even know what kind of store it
uses.
Note that we only need to adjust a relatively small number of callers,
way less than one might expect. This is because most callers are using
`repo_for_each_pack()`, which handles enumeration of all packfiles that
exist in the repository. So for now, none of these callers need to be
adapted. The remaining callers that iterate through the packfiles
directly and that need adjustment are those that are a bit more tangled
with packfiles. These will be adjusted over time.
Note that this patch only moves the packfile store, and there is still a
bunch of functions that seemingly operate on a packfile store but that
end up iterating over all sources. These will be adjusted in subsequent
commits.
Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
In the preceding commits we have turned `struct odb_read_stream` into a
publicly visible structure. Furthermore, this structure now contains the
type and size of the object that we are about to stream. Consequently,
the out-pointers that we used before to propagate the type and size of
the streamed object are now somewhat redundant with the data contained
in the structure itself.
Drop these out-pointers and adapt callers accordingly.
Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
The "streaming" terminology is somewhat generic, so it may not be
immediately obvious that "streaming.{c,h}" is specific to the object
database. Rectify this by moving it into the "odb/" directory so that it
can be immediately attributed to the object subsystem.
Signed-off-by: Patrick Steinhardt <ps@pks.im>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Junio C Hamano