Move the check for short names out of is_special_dirent() and into
generate_obfuscated_name(). That way the check is more directly
associated with the algorithm that requires it.
Similarly, move the check for inode == 0, since that case has to do
with storing extended attributes (not files) in the name table.
As a result, is_special_dirent() is really only focused on whether a
given file is in the lost+found directory. Rename the function to
reflect its more specific purpose.
Signed-off-by: Alex Elder <aelder@xxxxxxx>
Updates (v3):
- The previous version did not properly skip the "lost+found"
directory itself; this one does.
- Created a new definition representing the name of the orphanage
directory. Encapsulate recognizing that directory into a new
macro, is_lost_found().
- Removed casts that eliminate a compile warning in calls to
libxfs_da_hashname(); will do them separately later if needed.
Updates (v4):
- Renamed is_lost_found() to be is_orphanage_dir(), and turned
it into an inline static function.
- Added parentheses around targets of the sizeof operation.
- Added a small bit of clarifying commentary in spots where
it was suggested.
---
db/metadump.c | 86
+++++++++++++++++++++++++++++++++++++++++-----------------
1 file changed, 62 insertions(+), 24 deletions(-)
Index: b/db/metadump.c
===================================================================
--- a/db/metadump.c
+++ b/db/metadump.c
@@ -1,5 +1,5 @@
/*
- * Copyright (c) 2007 Silicon Graphics, Inc.
+ * Copyright (c) 2007, 2011 SGI
* All Rights Reserved.
*
* This program is free software; you can redistribute it and/or
@@ -377,40 +377,63 @@ random_filename_char(void)
return c;
}
+#define ORPHANAGE "lost+found"
+#define ORPHANAGE_LEN (sizeof (ORPHANAGE) - 1)
+
+static inline int
+is_orphanage_dir(
+ struct xfs_mount *mp,
+ xfs_ino_t dir_ino,
+ size_t name_len,
+ uchar_t *name)
+{
+ return dir_ino == mp->m_sb.sb_rootino &&
+ name_len == ORPHANAGE_LEN &&
+ !memcmp(name, ORPHANAGE, ORPHANAGE_LEN);
+}
+
+/*
+ * Determine whether a name is one we shouldn't obfuscate because
+ * it's an orphan (or the "lost+found" directory itself). Note
+ * "cur_ino" is the inode for the directory currently being
+ * processed.
+ *
+ * Returns 1 if the name should NOT be obfuscated or 0 otherwise.
+ */
static int
-is_special_dirent(
+in_lost_found(
xfs_ino_t ino,
int namelen,
uchar_t *name)
{
static xfs_ino_t orphanage_ino = 0;
- char s[32];
+ char s[24]; /* 21 is enough (64 bits in decimal) */
int slen;
- /*
- * due to the XFS name hashing algorithm, we cannot obfuscate
- * names with 4 chars or less.
- */
- if (namelen <= 4)
- return 1;
+ /* Record the "lost+found" inode if we haven't done so already */
- if (ino == 0)
+ ASSERT(ino != 0);
+ if (!orphanage_ino && is_orphanage_dir(mp, cur_ino, namelen, name))
+ orphanage_ino = ino;
+
+ /* We don't obfuscate the "lost+found" directory itself */
+
+ if (ino == orphanage_ino)
+ return 1;
+
+ /* Most files aren't in "lost+found" at all */
+
+ if (cur_ino != orphanage_ino)
return 0;
/*
- * don't obfuscate lost+found nor any inodes within lost+found with
- * the inode number
+ * Within "lost+found", we don't obfuscate any file whose
+ * name is the same as its inode number. Any others are
+ * stray files and can be obfuscated.
*/
- if (cur_ino == mp->m_sb.sb_rootino && namelen == 10 &&
- memcmp(name, "lost+found", 10) == 0) {
- orphanage_ino = ino;
- return 1;
- }
- if (cur_ino != orphanage_ino)
- return 0;
+ slen = snprintf(s, sizeof (s), "%llu", (unsigned long long) ino);
- slen = sprintf(s, "%lld", (long long)ino);
- return (slen == namelen && memcmp(name, s, namelen) == 0);
+ return slen == namelen && !memcmp(name, s, namelen);
}
static void
@@ -426,13 +449,28 @@ generate_obfuscated_name(
xfs_dahash_t newhash;
uchar_t newname[NAME_MAX];
- if (is_special_dirent(ino, namelen, name))
- return;
+ /*
+ * Our obfuscation algorithm requires at least 5-character
+ * names, so don't bother if the name is too short. We
+ * work backward from a hash value to determine the last
+ * five bytes in a name required to produce a new name
+ * with the same hash.
+ */
+ if (namelen < 5)
+ return;
- hash = libxfs_da_hashname(name, namelen);
+ /*
+ * We don't obfuscate "lost+found" or any orphan files
+ * therein. When the name table is used for extended
+ * attributes, the inode number provided is 0, in which
+ * case we don't need to make this check.
+ */
+ if (ino && in_lost_found(ino, namelen, name))
+ return;
/* create a random name with the same hash value */
+ hash = libxfs_da_hashname(name, namelen);
do {
dup = 0;
newname[0] = '/';
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