win32_apply.c: Never externally back extracted SYSTEM registry files

diff --git a/src/win32_apply.c b/src/win32_apply.c
index 7800e5994a5adf0aecda4532d32fc4a455c99359..5669e44160b23f190ccc3d1be1850c4f5750c95c 100644 (file)
--- a/src/win32_apply.c
+++ b/src/win32_apply.c
@@ -36,6 +36,7 @@
 #include "wimlib/reparse.h"
 #include "wimlib/textfile.h"
 #include "wimlib/xml.h"
+#include "wimlib/wildcard.h"
 #include "wimlib/wimboot.h"
 
 struct win32_apply_ctx {
@@ -296,12 +297,11 @@ load_prepopulate_pats(struct win32_apply_ctx *ctx)
        return 0;
 }
 
-/* Returns %true if the path to @dentry matches a pattern in [PrepopulateList]
- * of WimBootCompress.ini.  Otherwise returns %false.
- *
- * @dentry must have had its full path calculated.  */
+/* Returns %true if the specified absolute path to a file in the WIM image
+ * matches a pattern in [PrepopulateList] of WimBootCompress.ini.  Otherwise
+ * returns %false.  */
 static bool
-in_prepopulate_list(struct wim_dentry *dentry,
+in_prepopulate_list(const wchar_t *path, size_t path_nchars,
                    const struct win32_apply_ctx *ctx)
 {
        const struct string_set *pats = ctx->wimboot.prepopulate_pats;
@@ -309,8 +309,32 @@ in_prepopulate_list(struct wim_dentry *dentry,
        if (!pats || !pats->num_strings)
                return false;
 
-       return match_pattern_list(dentry->_full_path,
-                                 wcslen(dentry->_full_path), pats);
+       return match_pattern_list(path, path_nchars, pats);
+}
+
+/* Returns %true if the specified absolute path to a file in the WIM image can
+ * be subject to external backing when extracted.  Otherwise returns %false.  */
+static bool
+can_externally_back_path(const wchar_t *path, size_t path_nchars,
+                        const struct win32_apply_ctx *ctx)
+{
+       if (in_prepopulate_list(path, path_nchars, ctx))
+               return false;
+
+       /* Since we attempt to modify the SYSTEM registry after it's extracted
+        * (see end_wimboot_extraction()), it can't be extracted as externally
+        * backed.  This extends to associated files such as SYSTEM.LOG that
+        * also must be writable in order to write to the registry.  Normally,
+        * SYSTEM is in [PrepopulateList], and the SYSTEM.* files match patterns
+        * in [ExclusionList] and therefore are not captured in the WIM at all.
+        * However, a WIM that wasn't specifically captured in "WIMBoot mode"
+        * may contain SYSTEM.* files.  So to make things "just work", hard-code
+        * the pattern.  */
+       if (match_path(path, path_nchars, L"\\Windows\\System32\\config\\SYSTEM*",
+                      OS_PREFERRED_PATH_SEPARATOR, false))
+               return false;
+
+       return true;
 }
 
 static const wchar_t *
@@ -361,7 +385,8 @@ win32_will_externally_back(struct wim_dentry *dentry, struct apply_ctx *_ctx)
        if (ret)
                return ret;
 
-       if (in_prepopulate_list(dentry, ctx))
+       if (!can_externally_back_path(dentry->_full_path,
+                                     wcslen(dentry->_full_path), ctx))
                return WIM_BACKING_EXCLUDED;
 
        return 0;