git-p4: add p4 submit hooks

The git command "commit" supports a number of hooks that support
changing the behavior of the commit command.  The git-p4.py program only
has one existing hook, "p4-pre-submit".  This command occurs early in
the process.  There are no hooks in the process flow for modifying
the P4 changelist text programmatically.

Adds 3 new hooks to git-p4.py to the submit option.

The new hooks are:
* p4-prepare-changelist - Execute this hook after the changelist file
  has been created. The hook will be executed even if the
  --prepare-p4-only option is set.  This hook ignores the --no-verify
  option in keeping with the existing behavior of git commit.

* p4-changelist - Execute this hook after the user has edited the
  changelist. Do not execute this hook if the user has selected the
  --prepare-p4-only option. This hook will honor the --no-verify,
  following the conventions of git commit.

* p4-post-changelist - Execute this hook after the P4 submission process
  has completed successfully. This hook takes no parameters and is
  executed regardless of the --no-verify option.  It's return value will
  not be checked.

The calls to the new hooks: p4-prepare-changelist, p4-changelist,
and p4-post-changelist should all be called inside the try-finally
block.

Signed-off-by: Ben Keene <seraphire@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

Documentation/git-p4.txt

@@ -387,6 +387,41 @@ It can be bypassed with the `--no-verify` command line option.
 
 One usage scenario is to run unit tests in the hook.
 
+p4-prepare-changelist
+~~~~~~~~~~~~~~~~~~~~~
+
+The `p4-prepare-changelist` hook is executed right after preparing
+the default changelist message and before the editor is started.
+It takes one parameter, the name of the file that contains the
+changelist text. Exiting with a non-zero status from the script
+will abort the process.
+
+The purpose of the hook is to edit the message file in place,
+and it is not supressed by the `--no-verify` option. This hook
+is called even if `--prepare-p4-only` is set.
+
+p4-changelist
+~~~~~~~~~~~~~
+
+The `p4-changelist` hook is executed after the changelist
+message has been edited by the user. It can be bypassed with the
+`--no-verify` option. It takes a single parameter, the name
+of the file that holds the proposed changelist text. Exiting
+with a non-zero status causes the command to abort.
+
+The hook is allowed to edit the changelist file and can be used
+to normalize the text into some project standard format. It can
+also be used to refuse the Submit after inspect the message file.
+
+p4-post-changelist
+~~~~~~~~~~~~~~~~~~
+
+The `p4-post-changelist` hook is invoked after the submit has
+successfully occured in P4. It takes no parameters and is meant
+primarily for notification and cannot affect the outcome of the
+git p4 submit action.
+
+
 
 Rebase options
 ~~~~~~~~~~~~~~

Documentation/githooks.txt

@@ -515,6 +515,52 @@ The exit status determines whether git will use the data from the
 hook to limit its search.  On error, it will fall back to verifying
 all files and folders.
 
+p4-changelist
+~~~~~~~~~~~~~
+
+This hook is invoked by `git-p4 submit`.
+
+The `p4-changelist` hook is executed after the changelist
+message has been edited by the user. It can be bypassed with the
+`--no-verify` option. It takes a single parameter, the name
+of the file that holds the proposed changelist text. Exiting
+with a non-zero status causes the command to abort.
+
+The hook is allowed to edit the changelist file and can be used
+to normalize the text into some project standard format. It can
+also be used to refuse the Submit after inspect the message file.
+
+Run `git-p4 submit --help` for details.
+
+p4-prepare-changelist
+~~~~~~~~~~~~~~~~~~~~~
+
+This hook is invoked by `git-p4 submit`.
+
+The `p4-prepare-changelist` hook is executed right after preparing
+the default changelist message and before the editor is started.
+It takes one parameter, the name of the file that contains the
+changelist text. Exiting with a non-zero status from the script
+will abort the process.
+
+The purpose of the hook is to edit the message file in place,
+and it is not supressed by the `--no-verify` option. This hook
+is called even if `--prepare-p4-only` is set.
+
+Run `git-p4 submit --help` for details.
+
+p4-post-changelist
+~~~~~~~~~~~~~~~~~~
+
+This hook is invoked by `git-p4 submit`.
+
+The `p4-post-changelist` hook is invoked after the submit has
+successfully occured in P4. It takes no parameters and is meant
+primarily for notification and cannot affect the outcome of the
+git p4 submit action.
+
+Run `git-p4 submit --help` for details.
+
 p4-pre-submit
 ~~~~~~~~~~~~~
 

git-p4.py

@@ -1589,7 +1589,7 @@ def __init__(self):
                 optparse.make_option("--disable-p4sync", dest="disable_p4sync", action="store_true",
                                      help="Skip Perforce sync of p4/master after submit or shelve"),
                 optparse.make_option("--no-verify", dest="no_verify", action="store_true",
-                                     help="Bypass p4-pre-submit"),
+                                     help="Bypass p4-pre-submit and p4-changelist hooks"),
         ]
         self.description = """Submit changes from git to the perforce depot.\n
     The `p4-pre-submit` hook is executed if it exists and is executable. It
@@ -1598,6 +1598,28 @@ def __init__(self):
     from this script prevents `git-p4 submit` from launching.
 
     One usage scenario is to run unit tests in the hook.
+
+    The `p4-prepare-changelist` hook is executed right after preparing the default
+    changelist message and before the editor is started. It takes one parameter,
+    the name of the file that contains the changelist text. Exiting with a non-zero
+    status from the script will abort the process.
+
+    The purpose of the hook is to edit the message file in place, and it is not
+    supressed by the `--no-verify` option. This hook is called even if
+    `--prepare-p4-only` is set.
+
+    The `p4-changelist` hook is executed after the changelist message has been
+    edited by the user. It can be bypassed with the `--no-verify` option. It
+    takes a single parameter, the name of the file that holds the proposed
+    changelist text. Exiting with a non-zero status causes the command to abort.
+
+    The hook is allowed to edit the changelist file and can be used to normalize
+    the text into some project standard format. It can also be used to refuse the
+    Submit after inspect the message file.
+
+    The `p4-post-changelist` hook is invoked after the submit has successfully
+    occured in P4. It takes no parameters and is meant primarily for notification
+    and cannot affect the outcome of the git p4 submit action.
     """
 
         self.usage += " [name of git branch to submit into perforce depot]"
@@ -2105,6 +2127,10 @@ def applyCommit(self, id):
         submitted = False
 
         try:
+            # Allow the hook to edit the changelist text before presenting it
+            # to the user.
+            if not run_git_hook("p4-prepare-changelist", [fileName]):
+                return False
 
             if self.prepare_p4_only:
                 #
@@ -2144,6 +2170,12 @@ def applyCommit(self, id):
                 return True
 
             if self.edit_template(fileName):
+                if not self.no_verify:
+                    if not run_git_hook("p4-changelist", [fileName]):
+                        print("The p4-changelist hook failed.")
+                        sys.stdout.flush()
+                        return False
+
                 # read the edited message and submit
                 tmpFile = open(fileName, "rb")
                 message = tmpFile.read()
@@ -2181,6 +2213,7 @@ def applyCommit(self, id):
 
                 submitted = True
 
+                run_git_hook("p4-post-changelist")
         finally:
             # Revert changes if we skip this patch
             if not submitted or self.shelve: