setup.c: stop prefix_pathspec() from looping past the end of string

The code assumes that the string ends at either `)` or `,`, and does
not handle the case where strcspn() returns length due to end of
string.  So specifying ":(top" as pathspec will cause the loop to go
past the end of string.

Signed-off-by: Andrew Wong <andrew.kw.w@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
git p4 test: make sure P4CONFIG relative path works

This adds a test for the fix in bf1d68f (git-p4: use absolute
directory for PWD env var, 2011-12-09).  It is necessary to
set PWD to an absolute path so that p4 can find files referenced
by non-absolute paths, like the value of the P4CONFIG environment
variable.

P4 does not open files directly; it builds a path by prepending
the contents of the PWD environment variable.

Signed-off-by: Pete Wyckoff <pw@padd.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
setup.c: check that the pathspec magic ends with ")"

The previous code did not diagnose an incorrectly spelled ":(top"
as an error.

Signed-off-by: Andrew Wong <andrew.kw.w@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
test-lib: factor out $GIT_UNZIP setup

We set up the $GIT_UNZIP variable and lazy prereq in
multiple places (and the next patch is about to add another
one). Let's factor it out to avoid repeating ourselves.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
archive: handle commits with an empty tree

git-archive relies on get_pathspec to convert its argv into
a list of pathspecs. When get_pathspec is given an empty
argv list, it returns a single pathspec, the empty string,
to indicate that everything matches. When we feed this to
our path_exists function, we typically see that the pathspec
turns up at least one item in the tree, and we are happy.

But when our tree is empty, we erroneously think it is
because the pathspec is too limited, when in fact it is
simply that there is nothing to be found in the tree. This
is a weird corner case, but the correct behavior is almost
certainly to produce an empty archive, not to exit with an
error.

This patch teaches git-archive to create empty archives when
there is no pathspec given (we continue to complain if a
pathspec is given, since it obviously is not matched). It
also confirms that the tar and zip writers produce sane
output in this instance.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
git p4 test: should honor symlink in p4 client root

This test fails when the p4 client root includes
a symlink.  It complains:

    Path /vol/bar/projects/foo/... is not under client root /p/foo

and dumps a traceback.

Signed-off-by: Pete Wyckoff <pw@padd.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
git p4: avoid expanding client paths in chdir

The generic chdir() helper sets the PWD environment
variable, as that is what is used by p4 to know its
current working directory.  Normally the shell would
do this, but in git-p4, we must do it by hand.

However, when the path contains a symbolic link,
os.getcwd() will return the physical location.  If the
p4 client specification includes symlinks, setting PWD
to the physical location causes p4 to think it is not
inside the client workspace.  It complains, e.g.

    Path /vol/bar/projects/foo/... is not under client root /p/foo

One workaround is to use AltRoots in the p4 client specification,
but it is cleaner to handle it directly in git-p4.

Other uses of chdir still require setting PWD to an
absolute path so p4 features like P4CONFIG work.  See
bf1d68f (git-p4: use absolute directory for PWD env
var, 2011-12-09).

[ pw: tweak patch and commit message ]

Thanks-to: John Keeping <john@keeping.me.uk>
Signed-off-by: Pete Wyckoff <pw@padd.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Merge branch 'pw/p4-symlinked-root' into next

* pw/p4-symlinked-root:
  git p4: avoid expanding client paths in chdir
  git p4 test: should honor symlink in p4 client root
  git p4 test: make sure P4CONFIG relative path works
Merge branch 'aw/setup-prefix-pathspec' into next

* aw/setup-prefix-pathspec:
  setup.c: check that the pathspec magic ends with ")"
  setup.c: stop prefix_pathspec() from looping past the end of string
Merge branch 'jk/empty-archive' into next

"git archive" reports a failure when asked to create an archive out
of an empty tree.  It would be more intuitive to give an empty
archive back in such a case.

* jk/empty-archive:
  archive: handle commits with an empty tree
  test-lib: factor out $GIT_UNZIP setup