git-archimport: allow remapping branch names

This patch adds support to archimport for remapping the branch
names to match those used in git more closely.  This is useful
for projects that migrate to git (as opposed to users that want
to use git on Arch-based projects).  For example, one can choose
an Arch branch name and call it "master".

The new command-line syntax works even if there is a colon in
a branch name, since only the part after the last colon is taken
to be the git name (git does not allow colons in branch names).

The new feature is implemented so that archives rotated every
year can also be remapped into a single git archive.

Signed-off-by: Paolo Bonzini  <bonzini@gnu.org>
Signed-off-by: Junio C Hamano <junkio@cox.net>

Documentation/git-archimport.txt

@@ -10,7 +10,7 @@ SYNOPSIS
 --------
 [verse]
 'git-archimport' [-h] [-v] [-o] [-a] [-f] [-T] [-D depth] [-t tempdir]
-               <archive/branch> [ <archive/branch> ]
+               <archive/branch>[:<git-branch>] ...
 
 DESCRIPTION
 -----------
@@ -39,6 +39,19 @@ directory. To follow the development of a project that uses Arch, rerun
 `git-archimport` with the same parameters as the initial import to perform 
 incremental imports.
 
+While git-archimport will try to create sensible branch names for the
+archives that it imports, it is also possible to specify git branch names
+manually.  To do so, write a git branch name after each <archive/branch>
+parameter, separated by a colon.  This way, you can shorten the Arch
+branch names and convert Arch jargon to git jargon, for example mapping a
+"PROJECT--devo--VERSION" branch to "master".
+
+Associating multiple Arch branches to one git branch is possible; the
+result will make the most sense only if no commits are made to the first
+branch, after the second branch is created.  Still, this is useful to
+convert Arch repositories that had been rotated periodically.
+
+
 MERGES
 ------
 Patch merge data from Arch is used to mark merges in git as well. git 
@@ -73,7 +86,9 @@ OPTIONS
 	Use this for compatibility with old-style branch names used by
 	earlier versions of git-archimport.  Old-style branch names
 	were category--branch, whereas new-style branch names are
-	archive,category--branch--version.
+	archive,category--branch--version.  In both cases, names given
+	on the command-line will override the automatically-generated
+	ones.
 
 -D <depth>::
 	Follow merge ancestry and attempt to import trees that have been

git-archimport.perl

@@ -89,7 +89,11 @@ END
 # values associated with keys:
 #   =1 - Arch version / git 'branch' detected via abrowse on a limit
 #   >1 - Arch version / git 'branch' of an auxiliary branch we've merged
-my %arch_branches = map { $_ => 1 } @ARGV;
+my %arch_branches = map { my $branch = $_; $branch =~ s/:[^:]*$//; $branch => 1 } @ARGV;
+
+# $branch_name_map:
+# maps arch branches to git branch names
+my %branch_name_map = map { m/^(.*):([^:]*)$/; $1 => $2 } grep { m/:/ } @ARGV;
 
 $ENV{'TMPDIR'} = $opt_t if $opt_t; # $ENV{TMPDIR} will affect tempdir() calls:
 my $tmp = tempdir('git-archimport-XXXXXX', TMPDIR => 1, CLEANUP => 1);
@@ -104,6 +108,7 @@ END
     closedir DIR
 }
 
+my $default_archive;		# default Arch archive
 my %reachable = ();             # Arch repositories we can access
 my %unreachable = ();           # Arch repositories we can't access :<
 my @psets  = ();                # the collection
@@ -303,7 +308,34 @@ sub old_style_branchname {
     return $ret;
 }
 
-*git_branchname = $opt_o ? *old_style_branchname : *tree_dirname;
+*git_default_branchname = $opt_o ? *old_style_branchname : *tree_dirname;
+
+# retrieve default archive, since $branch_name_map keys might not include it
+sub get_default_archive {
+    if (!defined $default_archive) {
+        $default_archive = safe_pipe_capture($TLA,'my-default-archive');
+        chomp $default_archive;
+    }
+    return $default_archive;
+}
+
+sub git_branchname {
+    my $revision = shift;
+    my $name = extract_versionname($revision);
+
+    if (exists $branch_name_map{$name}) {
+	return $branch_name_map{$name};
+
+    } elsif ($name =~ m#^([^/]*)/(.*)$#
+	     && $1 eq get_default_archive()
+	     && exists $branch_name_map{$2}) {
+	# the names given in the command-line lacked the archive.
+	return $branch_name_map{$2};
+
+    } else {
+	return git_default_branchname($revision);
+    }
+}
 
 sub process_patchset_accurate {
     my $ps = shift;
@@ -333,19 +365,23 @@ sub process_patchset_accurate {
         if ($ps->{tag} && (my $branchpoint = eval { ptag($ps->{tag}) })) {
 
             # find where we are supposed to branch from
-            system('git-checkout','-f','-b',$ps->{branch},
-                            $branchpoint) == 0 or die "$! $?\n";
-
+	    if (! -e "$git_dir/refs/heads/$ps->{branch}") {
+		system('git-branch',$ps->{branch},$branchpoint) == 0 or die "$! $?\n";
+
+		# We trust Arch with the fact that this is just a tag,
+		# and it does not affect the state of the tree, so
+		# we just tag and move on.  If the user really wants us
+		# to consolidate more branches into one, don't tag because
+		# the tag name would be already taken.
+		tag($ps->{id}, $branchpoint);
+		ptag($ps->{id}, $branchpoint);
+		print " * Tagged $ps->{id} at $branchpoint\n";
+	    }
+	    system('git-checkout','-f',$ps->{branch}) == 0 or die "$! $?\n";
+
             # remove any old stuff that got leftover:
             my $rm = safe_pipe_capture('git-ls-files','--others','-z');
             rmtree(split(/\0/,$rm)) if $rm;
-
-            # If we trust Arch with the fact that this is just 
-            # a tag, and it does not affect the state of the tree
-            # then we just tag and move on
-            tag($ps->{id}, $branchpoint);
-            ptag($ps->{id}, $branchpoint);
-            print " * Tagged $ps->{id} at $branchpoint\n";
             return 0;
         } else {
             warn "Tagging from unknown id unsupported\n" if $ps->{tag};
@@ -385,14 +421,19 @@ sub process_patchset_fast {
                 unless $branchpoint;
 
             # find where we are supposed to branch from
-            system('git-checkout','-b',$ps->{branch},$branchpoint);
-
-            # If we trust Arch with the fact that this is just 
-            # a tag, and it does not affect the state of the tree
-            # then we just tag and move on
-            tag($ps->{id}, $branchpoint);
-            ptag($ps->{id}, $branchpoint);
-            print " * Tagged $ps->{id} at $branchpoint\n";
+	    if (! -e "$git_dir/refs/heads/$ps->{branch}") {
+		system('git-branch',$ps->{branch},$branchpoint) == 0 or die "$! $?\n";
+
+		# We trust Arch with the fact that this is just a tag,
+		# and it does not affect the state of the tree, so
+		# we just tag and move on.  If the user really wants us
+		# to consolidate more branches into one, don't tag because
+		# the tag name would be already taken.
+		tag($ps->{id}, $branchpoint);
+		ptag($ps->{id}, $branchpoint);
+		print " * Tagged $ps->{id} at $branchpoint\n";
+            }
+            system('git-checkout',$ps->{branch}) == 0 or die "$! $?\n";
             return 0;
         } 
         die $! if $?;
@@ -830,8 +871,9 @@ sub tag {
     if ($opt_o) {
         $tag =~ s|/|--|g;
     } else {
-        # don't use subdirs for tags yet, it could screw up other porcelains
-        $tag =~ s|/|,|g;
+	my $patchname = $tag;
+	$patchname =~ s/.*--//;
+        $tag = git_branchname ($tag) . '--' . $patchname;
     }
 
     if ($commit) {