When updating packages on the target device we ideally want to match 
user and group numbers from the existing file system. This patch encourages
opkg to lookup the uname/gname fields first and only use the hardcoded
numerical values if that fails.

Upstream-Status: Pending

RP 11/11/11

Index: trunk/libbb/unarchive.c
===================================================================
--- trunk.orig/libbb/unarchive.c	2011-11-11 15:52:59.761674091 +0000
+++ trunk/libbb/unarchive.c	2011-11-11 17:04:56.501574419 +0000
@@ -22,10 +22,13 @@
 #include <stdio.h>
 #include <errno.h>
 #include <stdlib.h>
+#include <stdbool.h>
 #include <string.h>
 #include <unistd.h>
 #include <utime.h>
 #include <libgen.h>
+#include <grp.h>
+#include <pwd.h>
 
 #include "libbb.h"
 
@@ -436,6 +439,42 @@
 	free(ar_entry);
 }
 
+static char uname_cache[32] = "";
+static uid_t uid_cache;
+
+static bool update_unamecache(char *uname) {
+	struct passwd *passwd;
+	if (!uname)
+		return FALSE;
+	if (!uname_cache[0] && strcmp(uname_cache, uname) == 0)
+		return TRUE;
+	passwd = getpwnam(uname);
+	if (passwd) {
+		uid_cache = passwd->pw_uid;
+		strncpy(uname, uname_cache, 32);
+		return TRUE;
+	}
+	return FALSE;
+}
+
+static char gname_cache[32] = "";
+static gid_t gid_cache;
+
+static bool update_gnamecache(char *gname) {
+	struct group *group;
+	if (!gname)
+		return FALSE;
+	if (!gname_cache[0] && strcmp(gname_cache, gname) == 0)
+		return TRUE;
+	group = getgrnam(gname);
+	if (group) {
+		gid_cache = group->gr_gid;
+		strncpy(gname, gname_cache, 32);
+		return TRUE;
+	}
+	return FALSE;
+}
+
 
 static file_header_t *
 get_header_tar(FILE *tar_stream)
@@ -515,8 +554,14 @@
 */
         tar_entry->mode = 07777 & strtol(tar.formated.mode, NULL, 8);
 
-	tar_entry->uid   = strtol(tar.formated.uid, NULL, 8);
-	tar_entry->gid   = strtol(tar.formated.gid, NULL, 8);
+	if (update_unamecache(tar.formated.uname))
+		tar_entry->uid = uid_cache;
+	else
+		tar_entry->uid = strtol(tar.formated.uid, NULL, 8);
+	if (update_gnamecache(tar.formated.gname))
+		tar_entry->gid = gid_cache;
+	else
+		tar_entry->gid = strtol(tar.formated.gid, NULL, 8);
 	tar_entry->size  = strtol(tar.formated.size, NULL, 8);
 	tar_entry->mtime = strtol(tar.formated.mtime, NULL, 8);