Update zlib_post_call() that adjusts the wrapper's notion of avail_in and
avail_out to what came back from zlib, so that the callers can feed
buffers larger than than 4GB to the API.
When underlying inflate/deflate stopped processing because we fed a buffer
larger than 4GB limit, detect that case, update the state variables, and
let the zlib function work another round.
Signed-off-by: Junio C Hamano <gitster@pobox.com>
The size of objects we read from the repository and data we try to put
into the repository are represented in "unsigned long", so that on larger
architectures we can handle objects that weigh more than 4GB.
But the interface defined in zlib.h to communicate with inflate/deflate
limits avail_in (how many bytes of input are we calling zlib with) and
avail_out (how many bytes of output from zlib are we ready to accept)
fields effectively to 4GB by defining their type to be uInt.
In many places in our code, we allocate a large buffer (e.g. mmap'ing a
large loose object file) and tell zlib its size by assigning the size to
avail_in field of the stream, but that will truncate the high octets of
the real size. The worst part of this story is that we often pass around
z_stream (the state object used by zlib) to keep track of the number of
used bytes in input/output buffer by inspecting these two fields, which
practically limits our callchain to the same 4GB limit.
Wrap z_stream in another structure git_zstream that can express avail_in
and avail_out in unsigned long. For now, just die() when the caller gives
a size that cannot be given to a single zlib call. In later patches in the
series, we would make git_inflate() and git_deflate() internally loop to
give callers an illusion that our "improved" version of zlib interface can
operate on a buffer larger than 4GB in one go.
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Wrap deflateInit, deflate, and deflateEnd for everybody, and the sole use
of deflateInit2 in remote-curl.c to tell the library to use gzip header
and trailer in git_deflate_init_gzip().
There is only one caller that cares about the status from deflateEnd().
Introduce git_deflate_end_gently() to let that sole caller retrieve the
status and act on it (i.e. die) for now, but we would probably want to
make inflate_end/deflate_end die when they ran out of memory and get
rid of the _gently() kind.
Signed-off-by: Junio C Hamano <gitster@pobox.com>
http-backend.c uses inflateInit2() to tell the library that it wants to
accept only gzip format. Wrap it in a helper function so that readers do
not have to wonder what the magic numbers 15 and 16 are for.
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Before refactoring the main part of the wrappers, first move the
logic to convert error status that come back from zlib to string
to a helper function.
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Programs using xmalloc() but not git_inflate() require -lz on the
linker command line because git_inflate() is in the same translation
unit as xmalloc().
Signed-off-by: Jonathan Nieder <jrnieder@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
