reiserfslib: add basic extended attribute helpers

Signed-off-by: Jeff Mahoney <jeffm@suse.com>

4 files changed, 147 insertions, 2 deletions

diff --git a/include/reiserfs_fs.h b/include/reiserfs_fs.h
index cb84fa8..fc39d7a 100644
--- a/include/reiserfs_fs.h
+++ b/include/reiserfs_fs.h
@@ -1402,6 +1402,32 @@ struct buffer_info {
 #define MAX_DIRECT_ITEM_LEN(size) ((size) - BLKH_SIZE - 2*IH_SIZE - SD_SIZE - UNFM_P_SIZE)
 #define MAX_INDIRECT_ITEM_LEN(size) MAX_ITEM_LEN(size)
 
+/* Extended attributes */
+/* Magic value in header */
+#define REISERFS_XATTR_MAGIC 0x52465841 /* "RFXA" */
+
+struct reiserfs_xattr_header {
+	__le32 h_magic;
+	__le32 h_hash;
+};
+
+/* ACLs */
+#define REISERFS_ACL_VERSION 0x0001
+struct reiserfs_acl_entry {
+	__le16	e_tag;
+	__le16	e_perm;
+	__le32	e_id;
+};
+
+struct reiserfs_acl_entry_short {
+	__le16	e_tag;
+	__le16	e_perm;
+};
+
+struct reiserfs_acl_header {
+	__le32	a_version;
+};
+
 /***************************************************************************/
 /*                    FUNCTION DECLARATIONS                                */
 /***************************************************************************/
diff --git a/include/reiserfs_lib.h b/include/reiserfs_lib.h
index 3513071..e00099c 100644
--- a/include/reiserfs_lib.h
+++ b/include/reiserfs_lib.h
@@ -431,5 +431,8 @@ int can_we_format_it(char *device_name, int force);
 		return 0;\
 	}\
 
-
+/* xattr.c */
+__u32 reiserfs_xattr_hash(const char *msg, int len);
+int reiserfs_check_xattr(const void *body, int len);
+int reiserfs_acl_count(size_t size);
 #endif /* REISERFSPROGS_LIB_H */
diff --git a/reiserfscore/Makefile.am b/reiserfscore/Makefile.am
index f9b1e61..a140a23 100644
--- a/reiserfscore/Makefile.am
+++ b/reiserfscore/Makefile.am
@@ -2,7 +2,7 @@ lib_LTLIBRARIES = libreiserfscore.la
 
 libreiserfscore_la_SOURCES = do_balan.c fix_node.c hashes.c ibalance.c \
 			     lbalance.c prints.c stree.c node_formats.c \
-			     reiserfslib.c bitmap.c journal.c includes.h
+			     reiserfslib.c bitmap.c journal.c xattr.c includes.h
 libreiserfscore_la_LIBADD = ../lib/libmisc.la
 
 pkgconfigdir = $(libdir)/pkgconfig
diff --git a/reiserfscore/xattr.c b/reiserfscore/xattr.c
new file mode 100644
index 0000000..8ad81f3
--- /dev/null
+++ b/reiserfscore/xattr.c
@@ -0,0 +1,116 @@
+#include <sys/types.h>
+#include <stdio.h>
+#include <errno.h>
+#include <sys/acl.h>
+#include "reiserfs_lib.h"
+
+static inline unsigned short from32to16(unsigned int x)
+{
+	/* add up 16-bit and 16-bit for 16+c bit */
+	x = (x & 0xffff) + (x >> 16);
+	/* add up carry.. */
+	x = (x & 0xffff) + (x >> 16);
+	return x;
+}
+
+static unsigned int do_csum(const unsigned char *buff, int len)
+{
+	int odd;
+	unsigned int result = 0;
+
+	if (len <= 0)
+		goto out;
+	odd = 1 & (unsigned long) buff;
+	if (odd) {
+#ifdef __LITTLE_ENDIAN
+		result += (*buff << 8);
+#else
+		result = *buff;
+#endif
+		len--;
+		buff++;
+	}
+	if (len >= 2) {
+		if (2 & (unsigned long) buff) {
+			result += *(unsigned short *) buff;
+			len -= 2;
+			buff += 2;
+		}
+		if (len >= 4) {
+			const unsigned char *end = buff + ((unsigned)len & ~3);
+			unsigned int carry = 0;
+			do {
+				unsigned int w = *(unsigned int *) buff;
+				buff += 4;
+				result += carry;
+				result += w;
+				carry = (w > result);
+			} while (buff < end);
+			result += carry;
+			result = (result & 0xffff) + (result >> 16);
+		}
+		if (len & 2) {
+			result += *(unsigned short *) buff;
+			buff += 2;
+		}
+	}
+	if (len & 1)
+#ifdef __LITTLE_ENDIAN
+		result += *buff;
+#else
+		result += (*buff << 8);
+#endif
+	result = from32to16(result);
+	if (odd)
+		result = ((result >> 8) & 0xff) | ((result & 0xff) << 8);
+out:
+	return result;
+}
+
+__wsum csum_partial(const void *buff, int len, __wsum wsum)
+{
+	unsigned int sum = (__force unsigned int)wsum;
+	unsigned int result = do_csum(buff, len);
+
+	/* add in old sum, and carry.. */
+	result += sum;
+	if (sum > result)
+		result += 1;
+	return (__force __wsum)result;
+}
+
+inline __u32 reiserfs_xattr_hash(const char *msg, int len)
+{
+	return csum_partial(msg, len, 0);
+}
+
+
+int reiserfs_check_xattr(const void *body, int len)
+{
+	const struct reiserfs_xattr_header *xah = body;
+	int hdrsz = sizeof(struct reiserfs_xattr_header);
+	__u32 hash;
+
+	if (len < hdrsz)
+		return -EINVAL;
+
+	hash = reiserfs_xattr_hash(body + hdrsz, len - hdrsz);
+	return xah->h_magic == cpu_to_le32(REISERFS_XATTR_MAGIC) &&
+	       le32_to_cpu(xah->h_hash) == hash;
+}
+
+int reiserfs_acl_count(size_t size)
+{
+	ssize_t s;
+	size -= sizeof(struct reiserfs_acl_header);
+	s = size - 4 * sizeof(struct reiserfs_acl_entry_short);
+	if (s < 0) {
+		if (size % sizeof(struct reiserfs_acl_entry_short))
+			return -1;
+		return size / sizeof(struct reiserfs_acl_entry_short);
+	} else {
+		if (s % sizeof(struct reiserfs_acl_entry))
+			return -1;
+		return s / sizeof(struct reiserfs_acl_entry) + 4;
+	}
+}