scmutil: introduce a new backuppath() to replace origpath()

scmutil: introduce a new backuppath() to replace origpath()

Unlike most functions in our codebase, origpath() takes a path that is
relative to cwd. This commit introduces a replacement for
origpath(). The new function takes a path that is relative to the repo
root. There is a lot of duplication between the two, but I intend to
remove origpath() within the next few commits, so it won't be a
maintenance burden.

origpath() is also a little weird in that it returns either a a
cwd-relative path or an absolute path. It needs to be able to return a
path outside the repo, so it makes sense that it can return an
absolute path. However, it would be simpler to always return an
absolute path. The new function does that.

Differential Revision: https://phab.mercurial-scm.org/D5851

--- a/mercurial/scmutil.py	Mon Feb 04 09:21:40 2019 -0800
+++ b/mercurial/scmutil.py	Mon Feb 04 20:46:33 2019 -0800
@@ -838,6 +838,41 @@
         return None
     return vfs.vfs(repo.wvfs.join(origbackuppath))
 
+def backuppath(ui, repo, filepath):
+    '''customize where working copy backup files (.orig files) are created
+
+    Fetch user defined path from config file: [ui] origbackuppath = <path>
+    Fall back to default (filepath with .orig suffix) if not specified
+
+    filepath is repo-relative
+
+    Returns an absolute path
+    '''
+    origvfs = getorigvfs(ui, repo)
+    if origvfs is None:
+        return repo.wjoin(filepath + ".orig")
+
+    origbackupdir = origvfs.dirname(filepath)
+    if not origvfs.isdir(origbackupdir) or origvfs.islink(origbackupdir):
+        ui.note(_('creating directory: %s\n') % origvfs.join(origbackupdir))
+
+        # Remove any files that conflict with the backup file's path
+        for f in reversed(list(util.finddirs(filepath))):
+            if origvfs.isfileorlink(f):
+                ui.note(_('removing conflicting file: %s\n')
+                        % origvfs.join(f))
+                origvfs.unlink(f)
+                break
+
+        origvfs.makedirs(origbackupdir)
+
+    if origvfs.isdir(filepath) and not origvfs.islink(filepath):
+        ui.note(_('removing conflicting directory: %s\n')
+                % origvfs.join(filepath))
+        origvfs.rmtree(filepath, forcibly=True)
+
+    return origvfs.join(filepath)
+
 def origpath(ui, repo, filepath):
     '''customize where .orig files are created