It's currently the responsibility of the caller to give
fill_sha1_file() enough bytes to write into, leading them to
manually compute the required lengths. Instead, let's just
write into a strbuf so that it's impossible to get this
wrong.

The alt_odb caller already has a strbuf, so this makes
things strictly simpler. The other caller, sha1_file_name(),
uses a static PATH_MAX buffer and dies when it would
overflow. We can convert this to a static strbuf, which
means our allocation cost is amortized (and as a bonus, we
no longer have to worry about PATH_MAX being too short for
normal use).

This does introduce some small overhead in fill_sha1_file(),
as each strbuf_addchar() will check whether it needs to
grow. However, between the optimization in fec501da
(strbuf_addch: avoid calling strbuf_grow, 2015-04-16) and
the fact that this is not generally called in a tight loop
(after all, the next step is typically to access the file!)
this probably doesn't matter. And even if it did, the right
place to micro-optimize is inside fill_sha1_file(), by
calling a single strbuf_grow() there.
Signed-off-by: NJeff King <peff@peff.net>
Signed-off-by: NJunio C Hamano <gitster@pobox.com>

We pre-size the scratch buffer to hold a loose object
filename of the form "xx/yyyy...", which leads to allocation
code that is hard to verify. We have to use some magic
numbers during the initial allocation, and then writers must
blindly assume that the buffer is big enough. Using a strbuf
makes it more clear that we cannot overflow.

Unfortunately, we do still need some magic numbers to grow
our strbuf before calling fill_sha1_path(), but the strbuf
growth is much closer to the point of use. This makes it
easier to see that it's correct, and opens the possibility
of pushing it even further down if fill_sha1_path() learns
to work on strbufs.
Signed-off-by: NJeff King <peff@peff.net>
Signed-off-by: NJunio C Hamano <gitster@pobox.com>

This function forms a sha1 as "xx/yyyy...", but skips over
the slot for the slash rather than writing it, leaving it to
the caller to do so. It also does not bother to put in a
trailing NUL, even though every caller would want it (we're
forming a path which by definition is not a directory, so
the only thing to do with it is feed it to a system call).

Let's make the lives of our callers easier by just writing
out the internal "/" and the NUL.
Signed-off-by: NJeff King <peff@peff.net>
Signed-off-by: NJunio C Hamano <gitster@pobox.com>

The alternate_object_database struct uses a single buffer
both for storing the path to the alternate, and as a scratch
buffer for forming object names. This is efficient (since
otherwise we'd end up storing the path twice), but it makes
life hard for callers who just want to know the path to the
alternate. They have to remember to stop reading after
"alt->name - alt->base" bytes, and to subtract one for the
trailing '/'.

It would be much simpler if they could simply access a
NUL-terminated path string. We could encapsulate this in a
function which puts a NUL in the scratch buffer and returns
the string, but that opens up questions about the lifetime
of the result. The first time another caller uses the
alternate, the scratch buffer may get other data tacked onto
it.

Let's instead just store the root path separately from the
scratch buffer. There aren't enough alternates being stored
for the duplicated data to matter for performance, and this
keeps things simple and safe for the callers.
Signed-off-by: NJeff King <peff@peff.net>
Signed-off-by: NJunio C Hamano <gitster@pobox.com>

The alternate_object_database struct holds a path to the
alternate objects, but we also use that buffer as scratch
space for forming loose object filenames. Let's pull that
logic into a helper function so that we can more easily
modify it.
Signed-off-by: NJeff King <peff@peff.net>
Signed-off-by: NJunio C Hamano <gitster@pobox.com>

Allocating a struct alternate_object_database is tricky, as
we must over-allocate the buffer to provide scratch space,
and then put in particular '/' and NUL markers.

Let's encapsulate this in a function so that the complexity
doesn't leak into callers (and so that we can modify it
later).
Signed-off-by: NJeff King <peff@peff.net>
Signed-off-by: NJunio C Hamano <gitster@pobox.com>

The submodule code wants to temporarily add an alternate
object store to our in-memory alt_odb list, but does it
manually. Let's provide a helper so it can reuse the code in
link_alt_odb_entry().

While we're adding our new add_to_alternates_memory(), let's
document add_to_alternates_file(), as the two are related.
Signed-off-by: NJeff King <peff@peff.net>
Signed-off-by: NJunio C Hamano <gitster@pobox.com>

The string handling in link_alt_odb_entry() is mostly an
artifact of the original version, which took the path as a
ptr/len combo, and did not have a NUL-terminated string
until we created one in the alternate_object_database
struct.  But since 5bdf0a84 (sha1_file: normalize alt_odb
path before comparing and storing, 2011-09-07), the first
thing we do is put the path into a strbuf, which gives us
some easy opportunities for cleanup.

In particular:

  - we call strlen(pathbuf.buf), which is silly; we can look
    at pathbuf.len.

  - even though we have a strbuf, we don't maintain its
    "len" field when chomping extra slashes from the
    end, and instead keep a separate "pfxlen" variable. We
    can fix this and then drop "pfxlen" entirely.

  - we don't check whether the path is usable until after we
    allocate the new struct, making extra cleanup work for
    ourselves. Since we have a NUL-terminated string, we can
    bump the "is it usable" checks higher in the function.
    While we're at it, we can move that logic to its own
    helper, which makes the flow of link_alt_odb_entry()
    easier to follow.
Signed-off-by: NJeff King <peff@peff.net>
Signed-off-by: NJunio C Hamano <gitster@pobox.com>

When we add a new alternate to the list, we try to normalize
out any redundant "..", etc. However, we do not look at the
return value of normalize_path_copy(), and will happily
continue with a path that could not be normalized. Worse,
the normalizing process is done in-place, so we are left
with whatever half-finished working state the normalizing
function was in.

Fortunately, this cannot cause us to read past the end of
our buffer, as that working state will always leave the
NUL from the original path in place. And we do tend to
notice problems when we check is_directory() on the path.
But you can see the nonsense that we feed to is_directory
with an entry like:

  this/../../is/../../way/../../too/../../deep/../../to/../../resolve

in your objects/info/alternates, which yields:

  error: object directory
  /to/e/deep/too/way//ects/this/../../is/../../way/../../too/../../deep/../../to/../../resolve
  does not exist; check .git/objects/info/alternates.

We can easily fix this just by checking the return value.
But that makes it hard to generate a good error message,
since we're normalizing in-place and our input value has
been overwritten by cruft.

Instead, let's provide a strbuf helper that does an in-place
normalize, but restores the original contents on error. This
uses a second buffer under the hood, which is slightly less
efficient, but this is not a performance-critical code path.

The strbuf helper can also properly set the "len" parameter
of the strbuf before returning. Just doing:

  normalize_path_copy(buf.buf, buf.buf);

will shorten the string, but leave buf.len at the original
length. That may be confusing to later code which uses the
strbuf.
Signed-off-by: NJeff King <peff@peff.net>
Signed-off-by: NJunio C Hamano <gitster@pobox.com>

These tests are just trying to show that we allow recursion
up to a certain depth, but not past it. But the counting is
a bit non-intuitive, and rather than test at the edge of the
breakage, we test "OK" cases in the middle of the chain.
Let's explain what's going on, and explicitly test the
switch between "OK" and "too deep".
Signed-off-by: NJeff King <peff@peff.net>
Signed-off-by: NJunio C Hamano <gitster@pobox.com>

Our usual style when working with subdirectories is to chdir
inside a subshell or to use "git -C", which means we do not
have to constantly return to the main test directory. Let's
convert this old test, which does not follow that style.
Signed-off-by: NJeff King <peff@peff.net>
Signed-off-by: NJunio C Hamano <gitster@pobox.com>

Our normal test style these days puts the opening quote of
the body on the description line, and indents the body with
a single tab. This ancient test did not follow this.
Signed-off-by: NJeff King <peff@peff.net>
Signed-off-by: NJunio C Hamano <gitster@pobox.com>

Besides being our normal style, this correctly checks for an
error exit() versus signal death.
Signed-off-by: NJeff King <peff@peff.net>
Signed-off-by: NJunio C Hamano <gitster@pobox.com>

This function makes sure that "git fsck" does not report any
errors. But "--full" has been the default since f29cd393
(fsck: default to "git fsck --full", 2009-10-20), and we can
use the exit code (instead of counting the lines) since
e2b4f635 (fsck: exit with non-zero status upon errors,
2007-03-05).

So we can just use "git fsck", which is shorter and more
flexible (e.g., we can use "git -C").
Signed-off-by: NJeff King <peff@peff.net>
Signed-off-by: NJunio C Hamano <gitster@pobox.com>

This function was never used since its inception in dd05ea17
(test case for transitive info/alternates, 2006-05-07).
Which is just as well, since it mutates the repo state in a
way that would invalidate further tests, without cleaning up
after itself. Let's get rid of it so that nobody is tempted
to use it.
Signed-off-by: NJeff King <peff@peff.net>
Signed-off-by: NJunio C Hamano <gitster@pobox.com>

* maint:
  Git 2.10.1

Signed-off-by: NJunio C Hamano <gitster@pobox.com>

Doc update to clarify what "log -3 --reverse" does.

* pb/rev-list-reverse-with-count:
  rev-list-options: clarify the usage of --reverse

The codepath in "git fsck" to detect malformed tree objects has
been updated not to die but keep going after detecting them.

* dt/tree-fsck:
  fsck: handle bad trees like other errors
  tree-walk: be more specific about corrupt tree errors

An author name, that spelled a backslash-quoted double quote in the
human readable part "My \"double quoted\" name", was not unquoted
correctly while applying a patch from a piece of e-mail.

* kd/mailinfo-quoted-string:
  mailinfo: unescape quoted-pair in header fields
  t5100-mailinfo: replace common path prefix with variable

Clean-up for a recently graduated topic.

* mh/diff-indent-heuristic:
  xdiff: rename "struct group" to "struct xdlgroup"

* dt/mailinfo:
  add David Turner's Two Sigma address

"git gui" l10n to Portuguese.

* va/git-gui-i18n:
  git-gui: l10n: add Portuguese translation
  git-gui i18n: mark strings for translation

The original command line syntax for "git merge", which was "git
merge <msg> HEAD <parent>...", has been deprecated for quite some
time, and "git gui" was the last in-tree user of the syntax.  This
is finally fixed, so that we can move forward with the deprecation.

* rs/git-gui-use-modern-git-merge-syntax:
  git-gui: stop using deprecated merge syntax

Codepaths that read from an on-disk loose object were too loose in
validating what they are reading is a proper object file and
sometimes read past the data they read from the disk, which has
been corrected.  H/t to Gustavo Grieco for reporting.

* jc/verify-loose-object-header:
  unpack_sha1_header(): detect malformed object header
  streaming: make sure to notice corrupt object

"git init" tried to record core.worktree in the repository's
'config' file when GIT_WORK_TREE environment variable was set and
it was different from where GIT_DIR appears as ".git" at its top,
but the logic was faulty when .git is a "gitdir:" file that points
at the real place, causing trouble in working trees that are
managed by "git worktree".  This has been corrected.

* nd/init-core-worktree-in-multi-worktree-world:
  init: kill git_link variable
  init: do not set unnecessary core.worktree
  init: kill set_git_dir_init()
  init: call set_git_dir_init() from within init_db()
  init: correct re-initialization from a linked worktree

"gitweb" can spawn "highlight" to show blob contents with
(programming) language-specific syntax highlighting, but only
when the language is known.  "highlight" can however be told
to make the guess itself by giving it "--force" option, which
has been enabled.

* ik/gitweb-force-highlight:
  gitweb: use highlight's shebang detection
  gitweb: remove unused guess_file_syntax() parameter

Code cleanup.

* rs/copy-array:
  use COPY_ARRAY
  add COPY_ARRAY

Signed-off-by: NJunio C Hamano <gitster@pobox.com>

In the codepath that comes up with the hostname to be used in an
e-mail when the user didn't tell us, we looked at ai_canonname
field in struct addrinfo without making sure it is not NULL first.

* jk/ident-ai-canonname-could-be-null:
  ident: handle NULL ai_canonname

Documentation around tools to import from CVS was fairly outdated.

* jk/doc-cvs-update:
  docs/cvs-migration: mention cvsimport caveats
  docs/cvs-migration: update link to cvsps homepage
  docs/cvsimport: prefer cvs-fast-export to parsecvs

"git pack-objects --include-tag" was taught that when we know that
we are sending an object C, we want a tag B that directly points at
C but also a tag A that points at the tag B.  We used to miss the
intermediate tag B in some cases.

* jk/pack-tag-of-tag:
  pack-objects: walk tag chains for --include-tag
  t5305: simplify packname handling
  t5305: use "git -C"
  t5305: drop "dry-run" of unpack-objects
  t5305: move cleanup into test block

* maint:
  Prepare for 2.10.1

Signed-off-by: NJunio C Hamano <gitster@pobox.com>

"git worktree", even though it used the default_abbrev setting that
ought to be affected by core.abbrev configuration variable, ignored
the variable setting.  The command has been taught to read the
default set of configuration variables to correct this.

* jc/worktree-config:
  worktree: honor configuration variables

In the codepath that comes up with the hostname to be used in an
e-mail when the user didn't tell us, we looked at ai_canonname
field in struct addrinfo without making sure it is not NULL first.

* jk/ident-ai-canonname-could-be-null:
  ident: handle NULL ai_canonname

When "git fetch" tries to find where the history of the repository
it runs in has diverged from what the other side has, it has a
mechanism to avoid digging too deep into irrelevant side branches.
This however did not work well over the "smart-http" transport due
to a design bug, which has been fixed.

* jt/fetch-pack-in-vain-count-with-stateless:
  fetch-pack: do not reset in_vain on non-novel acks

A low-level function verify_packfile() was meant to show errors
that were detected without dying itself, but under some conditions
it didn't and died instead, which has been fixed.

* jk/verify-packfile-gently:
  verify_packfile: check pack validity before accessing data

When "git format-patch --stdout" output is placed as an in-body
header and it uses the RFC2822 header folding, "git am" failed to
put the header line back into a single logical line.  The
underlying "git mailinfo" was taught to handle this properly.

* jt/mailinfo-fold-in-body-headers:
  mailinfo: handle in-body header continuations
  mailinfo: make is_scissors_line take plain char *
  mailinfo: separate in-body header processing

Signed-off-by: NJunio C Hamano <gitster@pobox.com>