X-Git-Url: https://wimlib.net/git/?a=blobdiff_plain;f=src%2Flookup_table.c;h=3d2abf60539380b9ab3656cdfb72cff13f7d2777;hb=3b05052885168a50852b86609a89f29d1c0c6d97;hp=1950ab21a89bbbefb75fc56473ce64936d12753c;hpb=cc7b6ee47d4037ae8fa11b4c2d5154091d543704;p=wimlib

diff --git a/src/lookup_table.c b/src/lookup_table.c
index 1950ab21..3d2abf60 100644
--- a/src/lookup_table.c
+++ b/src/lookup_table.c
@@ -8,20 +8,18 @@
 /*
  * Copyright (C) 2012, 2013, 2014 Eric Biggers
  *
- * This file is part of wimlib, a library for working with WIM files.
+ * This file is free software; you can redistribute it and/or modify it under
+ * the terms of the GNU Lesser General Public License as published by the Free
+ * Software Foundation; either version 3 of the License, or (at your option) any
+ * later version.
  *
- * wimlib is free software; you can redistribute it and/or modify it under the
- * terms of the GNU General Public License as published by the Free
- * Software Foundation; either version 3 of the License, or (at your option)
- * any later version.
- *
- * wimlib is distributed in the hope that it will be useful, but WITHOUT ANY
- * WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR
- * A PARTICULAR PURPOSE. See the GNU General Public License for more
+ * This file is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
+ * FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License for more
  * details.
  *
- * You should have received a copy of the GNU General Public License
- * along with wimlib; if not, see http://www.gnu.org/licenses/.
+ * You should have received a copy of the GNU Lesser General Public License
+ * along with this file; if not, see http://www.gnu.org/licenses/.
  */
 
 #ifdef HAVE_CONFIG_H
@@ -35,6 +33,7 @@
 #include "wimlib/metadata.h"
 #include "wimlib/ntfs_3g.h"
 #include "wimlib/resource.h"
+#include "wimlib/unaligned.h"
 #include "wimlib/util.h"
 #include "wimlib/write.h"
 
@@ -245,20 +244,34 @@ finalize_lte(struct wim_lookup_table_entry *lte)
 }
 
 /*
- * Decrements the reference count for the lookup table entry @lte, which must be
- * inserted in the stream lookup table @table.
+ * Decrements the reference count of the single-instance stream @lte, which must
+ * be inserted in the stream lookup table @table.
+ *
+ * If the stream's reference count reaches 0, we may unlink it from @table and
+ * free it.  However, we retain streams with 0 reference count that originated
+ * from WIM files (RESOURCE_IN_WIM).  We do this for two reasons:
+ *
+ * 1. This prevents information about valid streams in a WIM file --- streams
+ *    which will continue to be present after appending to the WIM file --- from
+ *    being lost merely because we dropped all references to them.
+ *
+ * 2. Stream reference counts we read from WIM files can't be trusted.  It's
+ *    possible that a WIM has reference counts that are too low; WIMGAPI
+ *    sometimes creates WIMs where this is the case.  It's also possible that
+ *    streams have been referenced from an external WIM; those streams can
+ *    potentially have any reference count at all, either lower or higher than
+ *    would be expected for this WIM ("this WIM" meaning the owner of @table) if
+ *    it were a standalone WIM.
  *
- * If the reference count reaches 0, this may cause @lte to be destroyed.
- * However, we may retain entries with 0 reference count.  This does not affect
- * correctness, but it prevents the entries for valid streams in a WIM archive,
- * which will continue to be present after appending to the file, from being
- * lost merely because we dropped all references to them.
+ * So we can't take the reference counts too seriously.  But at least, we do
+ * recalculate by default when writing a new WIM file.
  */
 void
 lte_decrement_refcnt(struct wim_lookup_table_entry *lte,
 		     struct wim_lookup_table *table)
 {
-	wimlib_assert(lte->refcnt != 0);
+	if (unlikely(lte->refcnt == 0))  /* See comment above  */
+		return;
 
 	if (--lte->refcnt == 0) {
 		if (lte->unhashed) {
@@ -269,7 +282,8 @@ lte_decrement_refcnt(struct wim_lookup_table_entry *lte,
 			 * that there still may be open file descriptors to it.)
 			 * */
 			if (lte->resource_location == RESOURCE_IN_STAGING_FILE)
-				unlink(lte->staging_file_name);
+				unlinkat(lte->staging_dir_fd,
+					 lte->staging_file_name, 0);
 		#endif
 		} else {
 			if (!should_retain_lte(lte))
@@ -364,7 +378,7 @@ lookup_stream(const struct wim_lookup_table *table, const u8 hash[])
 	struct wim_lookup_table_entry *lte;
 	struct hlist_node *pos;
 
-	i = *(size_t*)hash % table->capacity;
+	i = load_size_t_unaligned(hash) % table->capacity;
 	hlist_for_each_entry(lte, pos, &table->array[i], hash_list)
 		if (hashes_equal(hash, lte->hash))
 			return lte;
@@ -564,7 +578,8 @@ struct wim_lookup_table_entry_disk {
 	/* Which part of the split WIM this stream is in; indexed from 1. */
 	le16 part_number;
 
-	/* Reference count of this stream over all WIM images. */
+	/* Reference count of this stream over all WIM images.  (But see comment
+	 * above lte_decrement_refcnt().)  */
 	le32 refcnt;
 
 	/* SHA1 message digest of the uncompressed data of this stream, or
@@ -1257,20 +1272,6 @@ write_wim_lookup_table_from_stream_list(struct list_head *stream_list,
 	return ret;
 }
 
-int
-lte_zero_real_refcnt(struct wim_lookup_table_entry *lte, void *_ignore)
-{
-	lte->real_refcnt = 0;
-	return 0;
-}
-
-int
-lte_zero_out_refcnt(struct wim_lookup_table_entry *lte, void *_ignore)
-{
-	lte->out_refcnt = 0;
-	return 0;
-}
-
 /* Allocate a stream entry for the contents of the buffer, or re-use an existing
  * entry in @lookup_table for the same stream.  */
 struct wim_lookup_table_entry *