[meld] vc: Add ability to check if version control repos are valid

[Kai Willadsen <kaiw src gnome org>]

commit c1ce5ba8bf2b693aa190920d3e01eb2b7b58d47e
Author: Peter Tyser <ptyser gmail com>
Date:   Tue Aug 17 23:47:59 2010 -0500

    vc: Add ability to check if version control repos are valid
    
    Sometimes meld may be ran in a directory that contains invalid or
    corrupt version control information.  (eg run 'mkdir .svn; meld .' in a
    git repository).  Previously meld would not gracefully handle invalid
    repositories.  This patch attempts to add a quick sanity check
    to most version control systems.  The checks are meant to be
    as quick as possible to reduce startup time.
    
    Signed-off-by: Peter Tyser <ptyser gmail com>

 meld/vc/_vc.py       |    4 ++++
 meld/vc/bzr.py       |    5 +++++
 meld/vc/cvs.py       |    5 +++++
 meld/vc/darcs.py     |    6 ++++++
 meld/vc/git.py       |    5 +++++
 meld/vc/mercurial.py |    5 +++++
 meld/vc/monotone.py  |    5 +++++
 meld/vc/svn.py       |    5 +++++
 meld/vc/tla.py       |    6 ++++++
 meld/vcview.py       |   18 ++++++++++++------
 10 files changed, 58 insertions(+), 6 deletions(-)
---
diff --git a/meld/vc/_vc.py b/meld/vc/_vc.py
index 27844d6..621a527 100644
--- a/meld/vc/_vc.py
+++ b/meld/vc/_vc.py
@@ -141,6 +141,10 @@ class Vc(object):
     def listdir_filter(self, entries):
         return [f for f in entries if f != self.VC_DIR]
 
+    # Determine if a directory is a valid git/svn/hg/cvs/etc repository
+    def valid_repo(self):
+        return True
+
     def listdir(self, start):
         if start=="": start="."
         cfiles = []
diff --git a/meld/vc/bzr.py b/meld/vc/bzr.py
index f6de97c..3ad7720 100644
--- a/meld/vc/bzr.py
+++ b/meld/vc/bzr.py
@@ -57,6 +57,11 @@ class Vc(_vc.CachedVc):
         return [self.CMD] + self.CMDARGS + ["revert"]
     def resolved_command(self):
         return [self.CMD] + self.CMDARGS + ["resolve"]
+    def valid_repo(self):
+        if _vc.call([self.CMD, "check"]):
+            return False
+        else:
+            return True
     def get_working_directory(self, workdir):
         return self.root
 
diff --git a/meld/vc/cvs.py b/meld/vc/cvs.py
index 4cde7be..14071e0 100644
--- a/meld/vc/cvs.py
+++ b/meld/vc/cvs.py
@@ -49,6 +49,11 @@ class Vc(_vc.Vc):
         return [self.CMD,"rm","-f"]
     def revert_command(self):
         return [self.CMD,"update","-C"]
+    def valid_repo(self):
+        if _vc.call([self.CMD, "version"]):
+            return False
+        else:
+            return True
 
     def _get_dirsandfiles(self, directory, dirs, files):
 
diff --git a/meld/vc/darcs.py b/meld/vc/darcs.py
index 6853dd0..6c1070c 100644
--- a/meld/vc/darcs.py
+++ b/meld/vc/darcs.py
@@ -70,6 +70,12 @@ class Vc(_vc.CachedVc):
         # untested
         return [self.CMD, "resolve"]
 
+    def valid_repo(self):
+        if _vc.call([self.CMD, "query", "tags"]):
+            return False
+        else:
+            return True
+
     def get_working_directory(self, workdir):
         return self.root
 
diff --git a/meld/vc/git.py b/meld/vc/git.py
index 4cc2cd4..82c6c23 100644
--- a/meld/vc/git.py
+++ b/meld/vc/git.py
@@ -66,6 +66,11 @@ class Vc(_vc.CachedVc):
         return [self.CMD,"rm"]
     def revert_command(self):
         return [self.CMD,"checkout"]
+    def valid_repo(self):
+        if _vc.call([self.CMD, "branch"]):
+            return False
+        else:
+            return True
     def get_working_directory(self, workdir):
         if workdir.startswith("/"):
             return self.root
diff --git a/meld/vc/mercurial.py b/meld/vc/mercurial.py
index 0879636..77665cc 100644
--- a/meld/vc/mercurial.py
+++ b/meld/vc/mercurial.py
@@ -59,6 +59,11 @@ class Vc(_vc.Vc):
         return [self.CMD,"rm"]
     def revert_command(self):
         return [self.CMD,"revert"]
+    def valid_repo(self):
+        if _vc.call([self.CMD, "root"]):
+            return False
+        else:
+            return True
     def get_working_directory(self, workdir):
         return self.root
 
diff --git a/meld/vc/monotone.py b/meld/vc/monotone.py
index 69cde5f..7d504c8 100644
--- a/meld/vc/monotone.py
+++ b/meld/vc/monotone.py
@@ -143,6 +143,11 @@ class Vc(_vc.CachedVc):
         return [self.CMD,"revert"]
     def resolved_command(self):
         return [self.CMD,"resolved"]
+    def valid_repo(self):
+        if _vc.call([self.CMD, "list", "tags"]):
+            return False
+        else:
+            return True
     def get_working_directory(self, workdir):
         return self.root
 
diff --git a/meld/vc/svn.py b/meld/vc/svn.py
index 5091578..8b49ab1 100644
--- a/meld/vc/svn.py
+++ b/meld/vc/svn.py
@@ -63,6 +63,11 @@ class Vc(_vc.Vc):
         return [self.CMD,"revert"]
     def resolved_command(self):
         return [self.CMD,"resolved"]
+    def valid_repo(self):
+        if _vc.call([self.CMD, "info"]):
+            return False
+        else:
+            return True
 
     def _get_matches(self, directory):
         """return a list of tuples (file_path, status_code, revision)"""
diff --git a/meld/vc/tla.py b/meld/vc/tla.py
index f66fdac..82744a0 100644
--- a/meld/vc/tla.py
+++ b/meld/vc/tla.py
@@ -85,6 +85,12 @@ class Vc(_vc.CachedVc):
         # Will only work on later versions of tla
         return [self.CMD, "undo", "--"]
 
+    def valid_repo(self):
+        if _vc.call([self.CMD, "tree-version"]):
+            return False
+        else:
+            return True
+
     def get_working_directory(self, workdir):
         return self.root
 
diff --git a/meld/vcview.py b/meld/vcview.py
index c8800b5..a58cdce 100644
--- a/meld/vcview.py
+++ b/meld/vcview.py
@@ -233,17 +233,23 @@ class VcView(melddoc.MeldDoc, gnomeglade.Component):
         default_active = 0
         # Try to keep the same VC plugin active on refresh()
         for idx, avc in enumerate(vcs):
-            if (self.vc is not None and
-                self.vc.__class__ == avc.__class__):
-                default_active = idx
-
-            # See if the necessary version control command exists.  If not,
-            # make the version control choice non-selectable.
+            # See if the necessary version control command exists.  If so,
+            # make sure what we're diffing is a valid respository.  If either
+            # check fails don't let the user select the that version control
+            # tool and display a basic error message in the drop-down menu.
             err_str = ""
             if vc._vc.call(["which", avc.CMD]):
                 # TRANSLATORS: this is an error message when a version control
                 # application isn't installed or can't be found
                 err_str = _("%s Not Installed" % avc.CMD)
+            elif not avc.valid_repo():
+                # TRANSLATORS: this is an error message when a version
+                # controlled repository is invalid or corrupted
+                err_str = _("Invalid Repository")
+            else:
+                if (self.vc is not None and
+                     self.vc.__class__ == avc.__class__):
+                     default_active = idx
 
             if err_str:
                 self.combobox_vcs.get_model().append( \