Restore legacy behavior on %ghost %config erasure, mostlyrpm-4.11.0.1-release

- Make rpmfiConfigConflict() consider any existing %ghost %config
  as "modified". This causes them to be left alone on erasure to match
  long-standing rpm behavior (whether the behavior is intended or not...)
  Ghost config testcase passes again, talk about flip-flop. Sigh.
- Legacy behavior had an extra twist which we are intentionally NOT
  restoring: if a non-empty %ghost exists at build-time, its digest
  is stored in the header despite the file not being present in
  the payload. With previous versions of rpm, the contents of an
  existing  %ghost %config would be compared to the one in header and
  resulting in different behavior on erasure: if the contents matched
  that of build-time, the file would be removed, otherwise it would
  be preserved. Ghosts remembering their identity from previous life
  goes a little bit too far into the land of paranormal for me...
(cherry picked from commit 233e4573d1d21a36d06874fea6c594428033802e)

1 files changed, 15 insertions, 2 deletions

diff --git a/lib/rpmfi.c b/lib/rpmfi.c
index 012219807..7f7ef2a7f 100644
--- a/lib/rpmfi.c
+++ b/lib/rpmfi.c
@@ -661,8 +661,8 @@ int rpmfiConfigConflictIndex(rpmfi fi, int ix)
     struct stat sb;
     int rc = 0;
 
-    /* Non-configs and ghosts are not config conflicts.  */
-    if (!(flags & RPMFILE_CONFIG) || (flags & RPMFILE_GHOST))
+    /* Non-configs are not config conflicts. */
+    if (!(flags & RPMFILE_CONFIG))
 	return 0;
 
     /* Only links and regular files can be %config, this is kinda moot */
@@ -676,6 +676,19 @@ int rpmfiConfigConflictIndex(rpmfi fi, int ix)
     if (lstat(fn, &sb))
 	goto exit;
 
+    /*
+     * Preserve legacy behavior: an existing %ghost %config is considered
+     * "modified" but unlike regular %config, its never removed and
+     * never backed up. Whether this actually makes sense is a whole
+     * another question, but this is very long-standing behavior that
+     * people might be depending on. The resulting FA_ALTNAME etc action
+     * is special-cased in FSM to avoid actually creating backups on ghosts.
+     */
+    if (flags & RPMFILE_GHOST) {
+	rc = 1;
+	goto exit;
+    }
+
     /* Files of different types obviously are not identical */
     diskWhat = rpmfiWhatis((rpm_mode_t)sb.st_mode);
     if (diskWhat != newWhat) {