fmt-merge-msg: show those involved in a merged series

As we already walk the history of the branch that gets merged to
come up with a short log, let's label it with names of the primary
authors, so that the user who summarizes the merge can easily give
credit to them in the log message.

Also infer the names of "lieutents" to help integrators at higher
level of the food-chain to give credit to them, by counting:

 * The committer of the 'tip' commit that is merged
 * The committer of merge commits that are merged

Often the first one gives the owner of the history being pulled, but
his last pull from his sublieutenants may have been a fast-forward,
in which case the first one would not be.  The latter rule will
count the integrator of the history, so together it might be a
reasonable heuristics.

There are two special cases:

 - The "author" credit is omitted when the series is written solely
   by the same author who is making the merge. The name can be seen
   on the "Author" line of the "git log" output to view the log
   message anyway.

 - The "lieutenant" credit is omitted when there is only one key
   committer in the merged branch and it is the committer who is
   making the merge. Typically this applies to the case where the
   developer merges his own branch.

Signed-off-by: Junio C Hamano <gitster@pobox.com>
push: Provide situational hints for non-fast-forward errors

Pushing a non-fast-forward update to a remote repository will result in
an error, but the hint text doesn't provide the correct resolution in
every case. Give better resolution advice in three push scenarios:

1) If you push your current branch and it triggers a non-fast-forward
error, you should merge remote changes with 'git pull' before pushing
again.

2) If you push to a shared repository others push to, and your local
tracking branches are not kept up to date, the 'matching refs' default
will generate non-fast-forward errors on outdated branches. If this is
your workflow, the 'matching refs' default is not for you. Consider
setting the 'push.default' configuration variable to 'current' or
'upstream' to ensure only your current branch is pushed.

3) If you explicitly specify a ref that is not your current branch or
push matching branches with ':', you will generate a non-fast-forward
error if any pushed branch tip is out of date. You should checkout the
offending branch and merge remote changes before pushing again.

Teach transport.c to recognize these scenarios and configure push.c
to hint for them. If 'git push's default behavior changes or we
discover more scenarios, extension is easy. Standardize on the
advice API and add three new advice variables, 'pushNonFFCurrent',
'pushNonFFDefault', and 'pushNonFFMatching'. Setting any of these
to 'false' will disable their affiliated advice. Setting
'pushNonFastForward' to false will disable all three, thus preserving the
config option for users who already set it, but guaranteeing new
users won't disable push advice accidentally.

Based-on-patch-by: Junio C Hamano <gitster@pobox.com>
Signed-off-by: Christopher Tiwald <christiwald@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
clean up struct ref's nonfastforward field

Each ref structure contains a "nonfastforward" field which
is set during push to show whether the ref rewound history.
Originally this was a single bit, but it was changed in
f25950f (push: Provide situational hints for non-fast-forward
errors) to an enum differentiating a non-ff of the current
branch versus another branch.

However, we never actually set the member according to the
enum values, nor did we ever read it expecting anything but
a boolean value. But we did use the side effect of declaring
the enum constants to store those values in a totally
different integer variable. The code as-is isn't buggy, but
the enum declaration inside "struct ref" is somewhat
misleading.

Let's convert nonfastforward back into a single bit, and
then define the NON_FF_* constants closer to where they
would be used (they are returned via the "int *nonfastforward"
parameter to transport_push, so we can define them there).

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
am -3: list the paths that needed 3-way fallback

When applying a patch that was based on an older release with "am -3", I
often wonder changes to which files need to be reviewed with extra care to
spot mismerges, but there is no good indication.

The paths that needed 3-way fallback can easily be obtained by comparing
the synthesized (partial) base tree and the current HEAD and noticing only
additions and modifications (removals only show the sparseness of the fake
ancestor tree, which is not useful information at all).  List them in the
usual --name-status format.

Signed-off-by: Junio C Hamano <gitster@pobox.com>
am: support --include option

am supports a number of pass-through options
to apply, like --exclude and --directory. Add
--include to this list.

Signed-off-by: Johannes Berg <johannes@sipsolutions.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
push: error out when the "upstream" semantics does not make sense

The user can say "git push" without specifying any refspec.  When using
the "upstream" semantics via the push.default configuration, the user
wants to update the "upstream" branch of the current branch, which is the
branch at a remote repository the current branch is set to integrate with,
with this command.

However, there are cases that such a "git push" that uses the "upstream"
semantics does not make sense:

 - The current branch does not have branch.$name.remote configured.  By
   definition, "git push" that does not name where to push to will not
   know where to push to.  The user may explicitly say "git push $there",
   but again, by definition, no branch at repository $there is set to
   integrate with the current branch in this case and we wouldn't know
   which remote branch to update.

 - The current branch does have branch.$name.remote configured, but it
   does not specify branch.$name.merge that names what branch at the
   remote this branch integrates with. "git push" knows where to push in
   this case (or the user may explicitly say "git push $remote" to tell us
   where to push), but we do not know which remote branch to update.

 - The current branch does have its remote and upstream branch configured,
   but the user said "git push $there", where $there is not the remote
   named by "branch.$name.remote".  By definition, no branch at repository
   $there is set to integrate with the current branch in this case, and
   this push is not meant to update any branch at the remote repository
   $there.

The first two cases were already checked correctly, but the third case was
not checked and we ended up updating the branch named branch.$name.merge
at repository $there, which was totally bogus.

Signed-off-by: Junio C Hamano <gitster@pobox.com>
compat/mingw.[ch]: Change return type of exec functions to int

The POSIX standard specifies a return type of int for all six exec
functions. In addition, all exec functions return -1 on error, and
simply do not return on success. However, the current emulation of
the exec functions on mingw are declared with a void return type.

This would cause a problem should any code attempt to call the
exec function in a non-void context. In particular, if an exec
function were used in a conditional it would fail to compile.

In order to improve the fidelity of the emulation, we change the
return type of the mingw_execv[p] functions to int and return -1
on error.

Signed-off-by: Ramsay Jones <ramsay@ramsay1.demon.co.uk>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
run-command: treat inaccessible directories as ENOENT

When execvp reports EACCES, it can be one of two things:

  1. We found a file to execute, but did not have
     permissions to do so.

  2. We did not have permissions to look in some directory
     in the $PATH.

In the former case, we want to consider this a
permissions problem and report it to the user as such (since
getting this for something like "git foo" is likely a
configuration error).

In the latter case, there is a good chance that the
inaccessible directory does not contain anything of
interest. Reporting "permission denied" is confusing to the
user (and prevents our usual "did you mean...?" lookup). It
also prevents git from trying alias lookup, since we do so
only when an external command does not exist (not when it
exists but has an error).

This patch detects EACCES from execvp, checks whether we are
in case (2), and if so converts errno to ENOENT. This
behavior matches that of "bash" (but not of simpler shells
that use execvp more directly, like "dash").

Test stolen from Junio.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Avoid bug in Solaris xpg4/sed as used in submodule

The sed provided by Solaris in /usr/xpg4/bin has a bug whereby an
unanchored regex using * for zero or more repetitions sees two
separate matches fed to the substitution engine in some cases.

This is evidenced by:

$ for sed in /usr/xpg4/bin/sed /usr/bin/sed /opt/csw/gnu/sed; do \
echo 'ab' | $sed -e 's|[a]*|X|g'; \
done
XXbX
XbX
XbX

This bug was triggered during a git submodule clone operation as
exercised in the setup stage of t5526-fetch-submodules when using the
default SANE_TOOL_PATH for Solaris.  It led to paths such as
..../.. being used in the submodule .git gitdir reference.

Using the expression 's|\([^/]*\(/*\)\)|..\2|g' provides the desired
result with all three three tested sed implementations but is harder
to read.  As we do not need to handle fully qualified paths though,
the expression could actually be [^/]+ which isn't properly handled
either.  Instead, use [^/][^/]*, as suggested by Andreas Schwab, which
works on all three tested sed implementations.

The new expression is semantically different than the original one.
It will not place a leading '..' on a fully qualified path as the
original expression did.  All of the paths being passed through this
regex are relative and did not rely on this behaviour so it's a safe
change.

Signed-off-by: Ben Walton <bwalton@artsci.utoronto.ca>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Fix httpd tests that broke when non-ff push advice changed

Signed-off-by: Christopher Tiwald <christiwald@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Do not use SHELL_PATH from build system in prepare_shell_cmd on Windows

The recent change to use SHELL_PATH instead of "sh" to spawn shell commands
is not suited for Windows:

- The default setting, "/bin/sh", does not work when git has to run the
  shell because it is a POSIX style path, but not a proper Windows style
  path.

- If it worked, it would hard-code a position in the files system where
  the shell is expected, making git (more precisely, the POSIX toolset that
  is needed alongside git) non-relocatable. But we cannot sacrifice
  relocatability on Windows.

- Apart from that, even though the Makefile leaves SHELL_PATH set to
  "/bin/sh" for the Windows builds, the build system passes a mangled path
  to the compiler, and something like "D:/Src/msysgit/bin/sh" is used,
  which is doubly bad because it points to where /bin/sh resolves to on
  the system where git was built.

- Finally, the system's CreateProcess() function that is used under
  mingw.c's hood does not work with forward slashes and cannot find the
  shell.

Undo the earlier change on Windows.

Signed-off-by: Johannes Sixt <j6t@kdbg.org>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
Merge branch 'jc/fmt-merge-msg-people'

The "fmt-merge-msg" command learns to list the primary contributors
involved in the side topic you are merging.

* jc/fmt-merge-msg-people:
  fmt-merge-msg: show those involved in a merged series
Merge branch 'jb/am-include'

"git am" learned the "--include" option, which is an opposite of existing
the "--exclude" option.

By Johannes Berg
* jb/am-include:
  am: support --include option
Merge branch 'jc/am-report-3way'

When "git am -3" needs to fall back to an application to a synthesized
preimage followed by a 3-way merge, the paths that needed such treatment
are now reported to the end user, so that the result in them can be
eyeballed with extra care.

* jc/am-report-3way:
  am -3: list the paths that needed 3-way fallback
Merge branch 'jc/push-upstream-sanity'

Fix broken 'push to upstream' implementation.  "git push $there" without
refspec, when the current branch is set to push to a remote different from
$there, used to push to $there using the upstream information to a remote
unreleated to $there.

* jc/push-upstream-sanity:
  push: error out when the "upstream" semantics does not make sense
Merge branch 'jk/run-command-eacces'

When PATH contains an unreadable directory, alias expansion code did not
kick in, and failed with an error that said "git-subcmd" was not found.

By Jeff King (1) and Ramsay Jones (1)
* jk/run-command-eacces:
  run-command: treat inaccessible directories as ENOENT
  compat/mingw.[ch]: Change return type of exec functions to int
Merge branch 'bw/submodule-sed-solaris'

By Ben Walton
* bw/submodule-sed-solaris:
  Avoid bug in Solaris xpg4/sed as used in submodule
Merge branch 'ct/advise-push-default'

Break down the cases in which "git push" fails due to non-ff into
three categories, and give separate advise messages for each case.

By Christopher Tiwald (2) and Jeff King (1)
* ct/advise-push-default:
  Fix httpd tests that broke when non-ff push advice changed
  clean up struct ref's nonfastforward field
  push: Provide situational hints for non-fast-forward errors
Merge branch 'js/spawn-via-shell-path-fix'

Mops up an unfortunate fallout from bw/spawn-via-shell-path topic.

By Johannes Sixt
* js/spawn-via-shell-path-fix:
  Do not use SHELL_PATH from build system in prepare_shell_cmd on Windows
RelNotes: the third batch

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