t1514: Add tests of shortening refnames in strict/loose mode

These tests verify the correct behavior of "git rev-parse --abbrev-ref"
in both "strict" and "loose" modes. Really, it tests the correct behavior
of refs.c:shorten_unambiguous_ref() with its 'strict' argument set to
either true of false.

Signed-off-by: Johan Herland <johan@herland.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
t1514: Demonstrate failure to correctly shorten "refs/remotes/origin/HEAD"

There is currently a bug in refs.c:shorten_unambiguous_ref() that causes
"refs/remotes/origin/HEAD" to be shortened to "origin/HEAD" instead of
"origin" (which is expected from matching against the "refs/remotes/%.*s"
pattern from refs.c:ref_rev_parse_rules) when it is not a symbolic ref.

Signed-off-by: Johan Herland <johan@herland.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
shorten_unambiguous_ref(): Fix shortening refs/remotes/origin/HEAD to origin

When expanding shorthand refs to full ref names (e.g. in dwim_ref()),
we use the ref_rev_parse_rules list of expansion patterns. This list
allows "origin" to be expanded into "refs/remotes/origin/HEAD", by
using the "refs/remotes/%.*s/HEAD" pattern from that list.

shorten_unambiguous_ref() exists to provide the reverse operation:
turning a full ref name into a shorter (but still unambiguous) name.
It does so by matching the given refname against each pattern from
the ref_rev_parse_rules list (in reverse), and extracting the short-
hand name from the matching rule.

However, when given "refs/remotes/origin/HEAD" it fails to shorten it
into "origin", because we misuse the sscanf() function when matching
"refs/remotes/origin/HEAD" against "refs/remotes/%.*s/HEAD": We end
up calling sscanf like this:

  sscanf("refs/remotes/origin/HEAD", "refs/remotes/%s/HEAD", short_name)

In this case, sscanf() will match the initial "refs/remotes/" part, and
then match the remainder of the refname against the "%s", and place it
("origin/HEAD") into short_name. The part of the pattern following the
"%s" format is never verified, because sscanf() apparently does not
need to do that (it has performed the one expected format extraction,
and will return 1 correspondingly; see [1] for more details).

This patch replaces the misuse of sscanf() with a fairly simple function
that manually matches the refname against patterns, and extracts the
shorthand name.

[1]: If we assume that sscanf() does not do a verification pass prior
to format extraction, there is AFAICS _no_ way for sscanf() - having
already done one or more format extractions - to indicate to its caller
that the input fails to match the trailing part of the format string.
In other words, AFAICS, the scanf() family of function will only verify
matching input up to and including the last format specifier in the
format string. Any data following the last format specifier will not be
verified. Yet another reason to consider the scanf functions harmful...

Cc: Bert Wesarg <bert.wesarg@googlemail.com>
Improved-by: Junio C Hamano <gitster@pobox.com>
Signed-off-by: Johan Herland <johan@herland.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
t1514: refname shortening is done after dereferencing symbolic refs

Signed-off-by: Junio C Hamano <gitster@pobox.com>
fast-{import,export}: use get_sha1_hex() to read from marks file

It's wrong to call get_sha1() if they should be SHA-1s, plus
inefficient.

Signed-off-by: Felipe Contreras <felipe.contreras@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
tests: at-combinations: simplify setup

The test is setting up an upstream branch, but there's a much simpler
way of doing that: git branch -u.

Signed-off-by: Ramkumar Ramachandra <artagnon@gmail.com>
Signed-off-by: Felipe Contreras <felipe.contreras@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
tests: at-combinations: check ref names directly

Some committishes might point to the same commit, but through a
different ref, that's why it's better to check directly for the ref,
rather than the commit message.

We can do that by calling rev-parse --symbolic-full-name, and to
differentiate the old from the new behavior we add an extra argument to
the check() helper.

Signed-off-by: Ramkumar Ramachandra <artagnon@gmail.com>
Signed-off-by: Felipe Contreras <felipe.contreras@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
SQUASH??? style fixups
tests: at-combinations: improve nonsense()

In some circumstances 'git log' might fail, but not because the @
parsing failed. For example: 'git rev-parse' might succeed and return a
bad object, and then 'git log' would fail.

The layer we want to test is revision parsing, so let's test that
directly.

Signed-off-by: Ramkumar Ramachandra <artagnon@gmail.com>
Signed-off-by: Felipe Contreras <felipe.contreras@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
tests: at-combinations: increase coverage

Add more tests exercising documented functionality.

[fc: commit message and extra tests]

Signed-off-by: Ramkumar Ramachandra <artagnon@gmail.com>
Signed-off-by: Felipe Contreras <felipe.contreras@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
tests: at-combinations: @{N} versus HEAD@{N}

All the tests so far check that @{N} is the same as HEAD@{N} (for
positive N). However, this is not always the case; write a couple of
tests for this.

[fc: simplify some wording]

Signed-off-by: Ramkumar Ramachandra <artagnon@gmail.com>
Signed-off-by: Felipe Contreras <felipe.contreras@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
sha1_name: remove no-op

'at' is always 0, since we can reach this point only if
!len && reflog_len, and len=at when reflog is assigned.

Signed-off-by: Felipe Contreras <felipe.contreras@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
sha1_name: remove unnecessary braces

Signed-off-by: Felipe Contreras <felipe.contreras@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
sha1_name: don't waste cycles in the @-parsing loop

The @-parsing loop unnecessarily checks for the sequence "@{" from len -
2 unnecessarily. We can safely check from len - 4.

[fc: remove cruft]

Signed-off-by: Felipe Contreras <felipe.contreras@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
sha1_name: reorganize get_sha1_basic()

Through the years the functionality to handle @{-N} and @{u} has moved
around the code, and as a result, code that once made sense, doesn't any
more.

There is no need to call this function recursively with the branch of
@{-N} substituted because dwim_{ref,log} already replaces it.

However, there's one corner-case where @{-N} resolves to a detached
HEAD, in which case we wouldn't get any ref back.

So we parse the nth-prior manually, and deal with it depending on
weather it's a SHA-1, or a ref.

Signed-off-by: Felipe Contreras <felipe.contreras@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
sha1_name: check @{-N} errors sooner

It's trivial to check for them in the @{N} parsing loop.

[fc: style]

Signed-off-by: Felipe Contreras <felipe.contreras@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
sha1_name: refactor reinterpret()

This code essentially replaces part of ref with another ref, for example
'@{-1}@{u}' is replaced with 'master@{u}', but this can be reused for
other purposes other than nth prior checkouts.

Signed-off-by: Felipe Contreras <felipe.contreras@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Add new @ shortcut for HEAD

Typing 'HEAD' is tedious, especially when we can use '@' instead.

The reason for choosing '@' is that it follows naturally from the
ref@op syntax (e.g. HEAD@{u}), except we have no ref, and no
operation, and when we don't have those, it makes sens to assume
'HEAD'.

So now we can use 'git show @~1', and all that goody goodness.

Until now '@' was a valid name, but it conflicts with this idea, so
let's make it invalid. Probably very few people, if any, used this name.

Signed-off-by: Felipe Contreras <felipe.contreras@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
sha1_name: compare variable with constant, not constant with variable

And restructure the if/else to factor out the common "is len positive?"
test into a single conditional.

Signed-off-by: Felipe Contreras <felipe.contreras@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Merge branch 'fc/transport-helper-error-reporting' into jch

Update transport helper to report errors and maintain ref hierarchy
used to keep track of remote helper state better.

* fc/transport-helper-error-reporting:
  t5801: "VAR=VAL shell_func args" is forbidden
  transport-helper: update remote helper namespace
  transport-helper: trivial code shuffle
  transport-helper: warn when refspec is not used
  transport-helper: clarify pushing without refspecs
  transport-helper: update refspec documentation
  transport-helper: clarify *:* refspec
  transport-helper: improve push messages
  transport-helper: mention helper name when it dies
  transport-helper: report errors properly

# Conflicts:
# 	t/t5801-remote-helpers.sh