egencache: Add comment preserving to --update-use-local-desc.

diff --git a/bin/egencache b/bin/egencache
index 5ae15bc4f5663ccd9ddafe112b4dc5aa4adf3bca..b0d727e963a253b7a6f46abc5b189503d127502c 100755 (executable)
--- a/bin/egencache
+++ b/bin/egencache
@@ -98,6 +98,9 @@ def parse_args(args):
        parser.add_option_group(update)
 
        uld = optparse.OptionGroup(parser, '--update-use-local-desc options')
+       uld.add_option("--preserve-comments",
+               action="store_true",
+               help="preserve the comments from the existing use.local.desc file")
        uld.add_option("--use-local-desc-output",
                help="output file for use.local.desc data (or '-' for stdout)",
                dest="uld_output")
@@ -161,6 +164,9 @@ def parse_args(args):
                except NameError:
                        parser.error('--update-use-local-desc requires python with USE=xml!')
 
+       if options.uld_output == '-' and options.preserve_comments:
+               parser.error('--preserve-comments can not be used when outputting to stdout')
+
        return parser, options, args
 
 class GenCache(object):
@@ -313,10 +319,12 @@ class GenCache(object):
                                        level=logging.ERROR, noiselevel=-1)
 
 class GenUseLocalDesc(object):
-       def __init__(self, portdb, output=None):
+       def __init__(self, portdb, output=None,
+                       preserve_comments=False):
                self.returncode = os.EX_OK
                self._portdb = portdb
                self._output = output
+               self._preserve_comments = preserve_comments
        
        def run(self):
                repo_path = self._portdb.porttrees[0]
@@ -333,18 +341,36 @@ class GenUseLocalDesc(object):
                        else:
                                desc_path = self._output
 
+                       if self._preserve_comments:
+                               output_mode = 'r+'
+                       else:
+                               output_mode = 'w'
+
                        try:
-                               output = open(desc_path, 'w')
+                               output = open(desc_path, output_mode)
                        except IOError as e:
                                writemsg_level(
-                                       "ERROR: failed to open output file: %s\n" % (e,),
+                                       "ERROR: failed to open output file %s: %s\n" % (output_mode,e,),
                                        level=logging.ERROR, noiselevel=-1)
                                self.returncode |= 2
                                return
                else:
                        output = sys.stdout
 
-               output.write('''
+               if self._preserve_comments:
+                       while True:
+                               l = output.readline()
+                               # Seek through comments, until the first non-comment.
+                               # If we hit empty line, then great.
+                               # Otherwise, we need to seek back and add an empty line.
+                               if not l.startswith('#'):
+                                       if l.rstrip() != '':
+                                               output.seek(-len(l), os.SEEK_CUR)
+                                               output.write('\n')
+                                       break
+                       output.truncate()
+               else:   
+                       output.write('''
 # This file is deprecated as per GLEP 56 in favor of metadata.xml. Please add
 # your descriptions to your package's metadata.xml ONLY.
 # * generated automatically using egencache *
@@ -498,7 +524,8 @@ def egencache_main(args):
 
        if options.update_use_local_desc:
                gen_desc = GenUseLocalDesc(portdb,
-                       output=options.uld_output)
+                       output=options.uld_output,
+                       preserve_comments=options.preserve_comments)
                gen_desc.run()
                ret.append(gen_desc.returncode)
 

diff --git a/man/egencache.1 b/man/egencache.1
index ec5121eee4d3901b4fbf3bbcb0c8af346f5c0dc5..f32427bbecd58c4f2397078172fdef83b6f1102e 100644 (file)
--- a/man/egencache.1
+++ b/man/egencache.1
@@ -41,15 +41,19 @@ Also see the related \fB\-\-load\-average\fR option.
 .BR \-\-load\-average=LOAD
 Specifies that maximum load allowed when spawning multiple jobs.
 .TP
+.BR "\-\-portdir=PORTDIR"
+Override the portage tree location.
+.TP
+.BR "\-\-preserve\-comments"
+Preserve the comments found in the output use.local.desc file. This requires
+the output file to exist before egencache is called.
+.TP
 .BR "\-\-repo=REPO"
 Name of the repo to operate on (default repo is located at \fBPORTDIR\fR).
 The name should correspond the value of a \fBrepo_name\fR entry (see
 \fBportage\fR(5)) from one of the repositories that is configured via the
 \fBPORTDIR\fR or \fBPORTDIR_OVERLAY\fR variables (see \fBmake.conf\fR(5)).
 .TP
-.BR "\-\-portdir=PORTDIR"
-Override the portage tree location.
-.TP
 .BR "\-\-rsync"
 When used together with the \fB\-\-update\fR action, this enables a workaround
 for cases in which the content of a cache entry changes and neither the file