This poor transport was forgotten in the recent sideband support.

This updates all the `foreach()` type functions across the library
that take callbacks from the user to have a consistent behavior.
The rules are:

* A callback terminates the loop by returning any non-zero value
* Once the callback returns non-zero, it will not be called again
  (i.e. the loop stops all iteration regardless of state)
* If the callback returns non-zero, the parent fn returns GIT_EUSER
* Although the parent returns GIT_EUSER, no error will be set in
  the library and `giterr_last()` will return NULL if called.

This commit makes those changes across the library and adds tests
for most of the iteration APIs to make sure that they follow the
above rules.

SSL isn't the only way that a transport can be encrypted. The new name
will make it easier to merge the SSH support.

Instad of each transport having its own function and logic to get to
its refs, store them directly in transport.

Leverage the new gitno_buffer to make the parsing and storing of the
refs use common code and get rid of the git_protocol struct.

This allows us to add capabilitites to both at the same time, keeps
them in sync and removes a lot of code.

gitno_buffer now uses a callback to fill its buffer, allowing us to
use the same interface for git and http (which uses callbacks).

For the transition, http is going to keep its own logic until the
git/common code catches up with the implied multi_ack that http
has. This also has the side-effect of making the code cleaner and more
correct regardingt he protocol.

Not everyone who indexes a packfile wants to put it in the standard
git repository location.

Sometimes it's useful not to perform the check. Allow it to be
configurable.

This should help us free some resources, though the libraries do keep
some buffers allocated regardless.

Add specific functions that use OpenSSL instead of GnuTLS

If it's not available, an error saying so will be returned when trying
to use a https:// URL.

This also unifies a lot of the network code to use git_transport in
many places instead of an socket descriptor.

gitno_connect() can return an error or socket, which is fine on most
platforms where sockets are file descriptors (signed int), but on Windows,
SOCKET is an unsigned type, which is problematic when we are trying to
test if the socket was actually a negative error code.

This fix seperates the error code and socket in gitno_connect(), and fixes
the error handling in do_connect() functions to compensate. It appears
that git_connect() and the git-transport do_connect() functions had bugs
in the non-windows cases too (leaking sockets, and not properly reporting
connection error, respectively) so I went ahead and fixed those too.

When e.g. a repository isn't found, the server sends an error saying
so. Put that error message in our error buffer.

Trying to send every single line immediately won't give us any speed
improvement and duplicates the code we need for other transports. Make
the git transport use the same buffer functions as HTTP.

This changes the git_remote_download() API, but the existing one is
silly, so you don't get to complain.

The new API allows to know how much data has been downloaded, how many
objects we expect in total and how many we've processed.

This fixes all the warnings on win64 except those in deps, which
come from the regex code.

This also includes droping `git_buf_lasterror` because it makes no sense
in the new system. Note that in most of the places were it has been
dropped, the code needs cleanup. I.e. GIT_ENOMEM is going away, so
instead it should return a generic `-1` and obviously not throw
anything.

Signed-off-by: schu <schu-github@schulog.org>

The buffer wasn't getting freed if the last difference was a deletion.

MSVC doesn't think %zd is a valid specifier.

This converts virtually all of the places that allocate GIT_PATH_MAX
buffers on the stack for manipulating paths to use git_buf objects
instead.  The patch is pretty careful not to touch the public API
for libgit2, so there are a few places that still use GIT_PATH_MAX.

This extends and changes some details of the git_buf implementation
to add a couple of extra functions and to make error handling easier.

This includes serious alterations to all the path.c functions, and
several of the fileops.c ones, too.  Also, there are a number of new
functions that parallel existing ones except that use a git_buf
instead of a stack-based buffer (such as git_config_find_global_r
that exists alongsize git_config_find_global).

This also modifies the win32 version of p_realpath to allocate whatever
buffer size is needed to accommodate the realpath instead of hardcoding
a GIT_PATH_MAX limit, but that change needs to be tested still.

- Hide the remaining transports code
- Drop `git_headarray`, switch to using a callback to list refs. Makes
the code cleaner.

Ensure that all memory related functions (malloc, calloc, strdup, free,
etc) are using their respective `git__` wrappers.

The following files now have 0444 permissions:

- loose objects
- pack indexes
- pack files
- packs downloaded by fetch
- packs downloaded by the HTTP transport

And the following files now have 0666 permissions:

- config files
- repository indexes
- reflogs
- refs

This brings libgit2 more in line with Git.

Note that git_filebuf_commit() and git_filebuf_commit_at() have both
gained a new mode parameter.

The latter change fixes an important issue where filebufs created with
GIT_FILEBUF_TEMPORARY received 0600 permissions (due to mkstemp(3)
usage). Now we chmod() the file before renaming it into place.

Tests have been added to confirm that new commit, tag, and tree
objects are created with the right permissions. I don't have access to
Windows, so for now I've guarded the tests with "#ifndef GIT_WIN32".

Signed-off-by: Carlos Martín Nieto <carlos@cmartin.tk>

Unfortunately, we can't use the function in fetch.c due to chunked
encoding and keep-alive connections.

Signed-off-by: Carlos Martín Nieto <carlos@cmartin.tk>

Signed-off-by: Carlos Martín Nieto <carlos@cmartin.tk>

Signed-off-by: Carlos Martín Nieto <carlos@cmartin.tk>

Signed-off-by: Carlos Martín Nieto <carlos@cmartin.tk>