buck: set Bundle-Version for :jgit_bin

Run git describe during the build to determine the lineage of this
working directory and stamp this information into the binary.

Change-Id: I0ad24125c31e4280ccf900bac4065924087b05aa

org.eclipse.jgit.pgm/BUCK

@@ -1,3 +1,5 @@
+include_defs('//tools/git.defs')
+
 java_library(
   name = 'pgm',
   srcs = glob(['src/**']),
@@ -27,8 +29,14 @@ genrule(
 
 genrule(
   name = 'jgit',
-  cmd = 'cat $SRCDIR/jgit.sh $(location :jgit_jar) >$OUT;' +
-        'chmod a+x $OUT',
+  cmd = ''.join([
+    'mkdir $TMP/META-INF &&',
+    'cp $(location :binary_manifest) $TMP/META-INF/MANIFEST.MF &&',
+    'cp $(location :jgit_jar) $TMP/jgit.jar &&',
+    'cd $TMP && zip $TMP/jgit.jar META-INF/MANIFEST.MF &&',
+    'cat $SRCDIR/jgit.sh $TMP/jgit.jar >$OUT &&',
+    'chmod a+x $OUT',
+  ]),
   srcs = ['jgit.sh'],
   out = 'jgit',
   visibility = ['PUBLIC'],
@@ -36,10 +44,27 @@ genrule(
 
 java_binary(
   name = 'jgit_jar',
-  main_class = 'org.eclipse.jgit.pgm.Main',
   deps = [
     ':pgm',
     '//lib:slf4j-simple',
     '//lib:tukaani-xz',
   ],
+  blacklist = [
+    'META-INF/DEPENDENCIES',
+    'META-INF/maven/.*',
+  ],
+)
+
+genrule(
+  name = 'binary_manifest',
+  cmd = ';'.join(['echo "%s: %s" >>$OUT' % e for e in [
+    ('Manifest-Version', '1.0'),
+    ('Main-Class', 'org.eclipse.jgit.pgm.Main'),
+    ('Bundle-Version', git_version()),
+    ('Implementation-Title', 'JGit Command Line Interface'),
+    ('Implementation-Vendor', 'Eclipse.org - JGit'),
+    ('Implementation-Vendor-URL', 'http://www.eclipse.org/jgit/'),
+    ('Implementation-Vendor-Id', 'org.eclipse.jgit'),
+  ]] + ['echo >>$OUT']),
+  out = 'MANIFEST.MF',
 )

tools/git.defs

@@ -0,0 +1,9 @@
+def git_version():
+  import subprocess
+  cmd = ['git', 'describe', '--always', '--match', 'v[0-9].*', '--dirty']
+  p = subprocess.Popen(cmd, stdout = subprocess.PIPE)
+  v = p.communicate()[0].strip()
+  r = p.returncode
+  if r != 0:
+    raise subprocess.CalledProcessError(r, ' '.join(cmd))
+  return v