Be more intelligent about storing file user and group names

- User and group names contain an enormous amount of redundancy: typically
  most files and directories are owned by root:root. Store the each unique
  name just once into global cache and store indexes to the cache into
  rpmfi user + group arrays. This saves several megabytes of memory on
  a transaction of non-trivial size...
- The cache implementation is dumb, but it's not noticeably slower than
  uncached version, copying megs of strings around is not cheap either.
  Easy enough to replace with a hash-table or such if performace becomes
  and issue...

1 files changed, 8 insertions, 2 deletions

diff --git a/lib/rpmfi_internal.h b/lib/rpmfi_internal.h
index 60d3458e1..291f78454 100644
--- a/lib/rpmfi_internal.h
+++ b/lib/rpmfi_internal.h
@@ -18,6 +18,12 @@ struct sharedFileInfo_s {
     int isRemoved;
 };
 
+/* 
+ * This limits maximum unique user + group names from packages to 65535,
+ * should be plenty but easy to bump if ever needed.
+ */
+typedef uint16_t ugidx_t;
+
 /**
  * A package filename set.
  */
@@ -52,8 +58,8 @@ struct rpmfi_s {
 /*?null?*/
     const rpm_ino_t * finodes;	/*!< File inodes(s) (from header) */
 
-    const char ** fuser;	/*!< File owner(s) (from header) */
-    const char ** fgroup;	/*!< File group(s) (from header) */
+    ugidx_t *fuser;		/*!< Index to file owner(s) cache */
+    ugidx_t *fgroup;		/*!< Index to file group(s) cache */
 
     char * fstates;		/*!< File state(s) (from header) */