read_packed_refs: use a strbuf for reading lines

Current code uses a fixed PATH_MAX-sized buffer for reading
packed-refs lines. This is a reasonable guess, in the sense
that git generally cannot work with refs larger than
PATH_MAX.  However, there are a few cases where it is not
great:

  1. Some systems may have a low value of PATH_MAX, but can
     actually handle larger paths in practice. Fixing this
     code path probably isn't enough to make them work
     completely with long refs, but it is a step in the
     right direction.

  2. We use fgets, which will happily give us half a line on
     the first read, and then the rest of the line on the
     second. This is probably OK in practice, because our
     refline parser is careful enough to look for the
     trailing newline on the first line. The second line may
     look like a peeled line to us, but since "^" is illegal
     in refnames, it is not likely to come up.

     Still, it does not hurt to be more careful.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
read_packed_refs: pass strbuf to parse_ref_line

Now that we have a strbuf in read_packed_refs, we can pass
it straight to the line parser, which saves us an extra
strlen.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
read_packed_refs: use skip_prefix instead of static array

We want to recognize the packed-refs header and skip to the
"traits" part of the line. We currently do it by feeding
sizeof() a static const array to strncmp. However, it's a
bit simpler to just skip_prefix, which expresses the
intention more directly, and without remembering to account
for the NUL-terminator in each sizeof() call.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
commit: loosen ident checks when generating template

When we generate the commit-message template, we try to
report an author or committer ident that will be of interest
to the user: an author that does not match the committer, or
a committer that was auto-configured.

When doing so, if we encounter what we consider to be a
bogus ident, we immediately die. This is a bad idea, because
our use of the idents here is purely informational.  Any
ident rules should be enforced elsewhere, because commits
that do not invoke the editor will not even hit this code
path (e.g., "git commit -mfoo" would work, but "git commit"
would not). So at best, we are redundant with other checks,
and at worse, we actively prevent commits that should
otherwise be allowed.

We should therefore do the minimal parsing we can to get a
value and not do any validation (i.e., drop the call to
sane_ident_split()).

In theory we could notice when even our minimal parsing
fails to work, and do the sane thing for each check (e.g.,
if we have an author but can't parse the committer, assume
they are different and print the author). But we can
actually simplify this even further.

We know that the author and committer strings we are parsing
have been generated by us earlier in the program, and
therefore they must be parseable. We could just call
split_ident_line without even checking its return value,
knowing that it will put _something_ in the name/mail
fields. Of course, to protect ourselves against future
changes to the code, it makes sense to turn this into an
assert, so we are not surprised if our assumption fails.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
commit: always populate GIT_AUTHOR_* variables

To figure out the author ident for a commit, we call
determine_author_info(). This function collects information
from the environment, other commits (in the case of
"--amend" or "-c/-C"), and the "--author" option. It then
uses fmt_ident to generate the final ident string that goes
into the commit object. fmt_ident is therefore responsible
for any quality or validation checks on what is allowed to
go into a commit.

Before returning, though, we call split_ident_line on the
result, and feed the individual components to hooks via the
GIT_AUTHOR_* variables. Furthermore, we do extra validation
by feeding the split to sane_ident_split(), which is pickier
than fmt_ident (in particular, it will complain about an empty
email field).  If this parsing or validation fails, we skip
updating the environment variables.

This is bad, because it means that hooks may silently see a
different ident than what we are putting into the commit. We
should drop the extra sane_ident_split checks entirely, and
take whatever fmt_ident has fed us (and what will go into
the commit object).

If parsing fails, we should actually abort here rather than
continuing (and feeding the hooks bogus data). However,
split_ident_line should never fail here. The ident was just
generated by fmt_ident, so we know that it's sane. We can
use assert_split_ident to double-check this.

Note that we also teach that assertion to check that we
found a date (it always should, but until now, no caller
cared whether we found a date or not). Checking the return
value of sane_ident_split is enough to ensure we have the
name/email pointers set, and checking date_begin is enough
to know that all of the date/tz variables are set.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
pkt-line: allow writing of LARGE_PACKET_MAX buffers

When we send out pkt-lines with refnames, we use a static
1000-byte buffer. This means that the maximum size of a ref
over the git protocol is around 950 bytes (the exact size
depends on the protocol line being written, but figure on a sha1
plus some boilerplate).

This is enough for any sane workflow, but occasionally odd
things happen (e.g., a bug may create a ref "foo/foo/foo/..."
accidentally).  With the current code, you cannot even use
"push" to delete such a ref from a remote.

Let's switch to using a strbuf, with a hard-limit of
LARGE_PACKET_MAX (which is specified by the protocol).  This
matches the size of the readers, as of 74543a0 (pkt-line:
provide a LARGE_PACKET_MAX static buffer, 2013-02-20).
Versions of git older than that will complain about our
large packets, but it's really no worse than the current
behavior. Right now the sender barfs with "impossibly long
line" trying to send the packet, and afterwards the reader
will barf with "protocol error: bad line length %d", which
is arguably better anyway.

Note that we're not really _solving_ the problem here, but
just bumping the limits. In theory, the length of a ref is
unbounded, and pkt-line can only represent sizes up to
65531 bytes. So we are just bumping the limit, not removing
it.  But hopefully 64K should be enough for anyone.

As a bonus, by using a strbuf for the formatting we can
eliminate an unnecessary copy in format_buf_write.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Show number of TODO items for interactive rebase

During 'rebase -i', one wrong edit in a long rebase session
might inadvertently drop commits/items. This change shows
the total number of TODO items in the comments after the
list. After performing the rebase edit, total item counts
can be compared to make sure that no changes have been lost
in the edit.

Signed-off-by: Onno Kortmann <onno@gmx.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
put string-list API documentation in one place

Until recently (v1.8.0-rc0~46^2~5, 2012-09-12), the string-list API
was documented in detail in Documentation/technical/api-string-list.txt
and the header file contained section markers and some short reminders
but little other documentation.

Since then, the header has acquired some more comments that are mostly
identical to the documentation from technical/.  In principle that
should help convenience, since it means one less hop for someone
reading the header to find API documentation.  In practice,
unfortunately, it is hard to remember that there is documentation in
two places, and the comprehensive documentation of some functions in
the header makes it too easy to forget that the other functions are
documented at all (and where).

Add a comment pointing to Documentation/technical/ and remove the
comments that duplicate what is written there.  Longer term, we may
want to move all of the technical docs to header files and generate
printer-ready API documentation another way, but that is a larger
change for another day.

Short reminders in the header file are still okay.

Reported-by: Stefan Beller <sbeller@google.com>
Signed-off-by: Jonathan Nieder <jrnieder@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Merge branch 'jn/dedup-doc-header' into pu

We would want to have an easy way for developers to learn about
APIs, and also a way to encourage them to keep the API
documentation up to date when they make changes.  Having header
comments and API documentation duplicated in two different places
risked them going out of sync.

This removes the duplicates by dropping comments from the header;
it is just for discussion at this moment.

* jn/dedup-doc-header:
  put string-list API documentation in one place
  put strbuf API documentation in one place
Merge branch 'jk/always-allow-large-packets' into pu

* jk/always-allow-large-packets:
  pkt-line: allow writing of LARGE_PACKET_MAX buffers
Merge branch 'jk/read-packed-refs-without-path-max' into pu

* jk/read-packed-refs-without-path-max:
  read_packed_refs: use skip_prefix instead of static array
  read_packed_refs: pass strbuf to parse_ref_line
  read_packed_refs: use a strbuf for reading lines
Merge branch 'jk/commit-date-approxidate' into pu

* jk/commit-date-approxidate:
  commit: always populate GIT_AUTHOR_* variables
  commit: loosen ident checks when generating template
Merge branch 'ok/rebase-i-count-todo' into pu

* ok/rebase-i-count-todo:
  Show number of TODO items for interactive rebase