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-rw-r--r--fs/ext4/hash.c268
1 files changed, 268 insertions, 0 deletions
diff --git a/fs/ext4/hash.c b/fs/ext4/hash.c
new file mode 100644
index 000000000..e22dcfab3
--- /dev/null
+++ b/fs/ext4/hash.c
@@ -0,0 +1,268 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * linux/fs/ext4/hash.c
+ *
+ * Copyright (C) 2002 by Theodore Ts'o
+ */
+
+#include <linux/fs.h>
+#include <linux/compiler.h>
+#include <linux/bitops.h>
+#include "ext4.h"
+
+#define DELTA 0x9E3779B9
+
+static void TEA_transform(__u32 buf[4], __u32 const in[])
+{
+ __u32 sum = 0;
+ __u32 b0 = buf[0], b1 = buf[1];
+ __u32 a = in[0], b = in[1], c = in[2], d = in[3];
+ int n = 16;
+
+ do {
+ sum += DELTA;
+ b0 += ((b1 << 4)+a) ^ (b1+sum) ^ ((b1 >> 5)+b);
+ b1 += ((b0 << 4)+c) ^ (b0+sum) ^ ((b0 >> 5)+d);
+ } while (--n);
+
+ buf[0] += b0;
+ buf[1] += b1;
+}
+
+/* F, G and H are basic MD4 functions: selection, majority, parity */
+#define F(x, y, z) ((z) ^ ((x) & ((y) ^ (z))))
+#define G(x, y, z) (((x) & (y)) + (((x) ^ (y)) & (z)))
+#define H(x, y, z) ((x) ^ (y) ^ (z))
+
+/*
+ * The generic round function. The application is so specific that
+ * we don't bother protecting all the arguments with parens, as is generally
+ * good macro practice, in favor of extra legibility.
+ * Rotation is separate from addition to prevent recomputation
+ */
+#define ROUND(f, a, b, c, d, x, s) \
+ (a += f(b, c, d) + x, a = rol32(a, s))
+#define K1 0
+#define K2 013240474631UL
+#define K3 015666365641UL
+
+/*
+ * Basic cut-down MD4 transform. Returns only 32 bits of result.
+ */
+static __u32 half_md4_transform(__u32 buf[4], __u32 const in[8])
+{
+ __u32 a = buf[0], b = buf[1], c = buf[2], d = buf[3];
+
+ /* Round 1 */
+ ROUND(F, a, b, c, d, in[0] + K1, 3);
+ ROUND(F, d, a, b, c, in[1] + K1, 7);
+ ROUND(F, c, d, a, b, in[2] + K1, 11);
+ ROUND(F, b, c, d, a, in[3] + K1, 19);
+ ROUND(F, a, b, c, d, in[4] + K1, 3);
+ ROUND(F, d, a, b, c, in[5] + K1, 7);
+ ROUND(F, c, d, a, b, in[6] + K1, 11);
+ ROUND(F, b, c, d, a, in[7] + K1, 19);
+
+ /* Round 2 */
+ ROUND(G, a, b, c, d, in[1] + K2, 3);
+ ROUND(G, d, a, b, c, in[3] + K2, 5);
+ ROUND(G, c, d, a, b, in[5] + K2, 9);
+ ROUND(G, b, c, d, a, in[7] + K2, 13);
+ ROUND(G, a, b, c, d, in[0] + K2, 3);
+ ROUND(G, d, a, b, c, in[2] + K2, 5);
+ ROUND(G, c, d, a, b, in[4] + K2, 9);
+ ROUND(G, b, c, d, a, in[6] + K2, 13);
+
+ /* Round 3 */
+ ROUND(H, a, b, c, d, in[3] + K3, 3);
+ ROUND(H, d, a, b, c, in[7] + K3, 9);
+ ROUND(H, c, d, a, b, in[2] + K3, 11);
+ ROUND(H, b, c, d, a, in[6] + K3, 15);
+ ROUND(H, a, b, c, d, in[1] + K3, 3);
+ ROUND(H, d, a, b, c, in[5] + K3, 9);
+ ROUND(H, c, d, a, b, in[0] + K3, 11);
+ ROUND(H, b, c, d, a, in[4] + K3, 15);
+
+ buf[0] += a;
+ buf[1] += b;
+ buf[2] += c;
+ buf[3] += d;
+
+ return buf[1]; /* "most hashed" word */
+}
+#undef ROUND
+#undef K1
+#undef K2
+#undef K3
+#undef F
+#undef G
+#undef H
+
+/* The old legacy hash */
+static __u32 dx_hack_hash_unsigned(const char *name, int len)
+{
+ __u32 hash, hash0 = 0x12a3fe2d, hash1 = 0x37abe8f9;
+ const unsigned char *ucp = (const unsigned char *) name;
+
+ while (len--) {
+ hash = hash1 + (hash0 ^ (((int) *ucp++) * 7152373));
+
+ if (hash & 0x80000000)
+ hash -= 0x7fffffff;
+ hash1 = hash0;
+ hash0 = hash;
+ }
+ return hash0 << 1;
+}
+
+static __u32 dx_hack_hash_signed(const char *name, int len)
+{
+ __u32 hash, hash0 = 0x12a3fe2d, hash1 = 0x37abe8f9;
+ const signed char *scp = (const signed char *) name;
+
+ while (len--) {
+ hash = hash1 + (hash0 ^ (((int) *scp++) * 7152373));
+
+ if (hash & 0x80000000)
+ hash -= 0x7fffffff;
+ hash1 = hash0;
+ hash0 = hash;
+ }
+ return hash0 << 1;
+}
+
+static void str2hashbuf_signed(const char *msg, int len, __u32 *buf, int num)
+{
+ __u32 pad, val;
+ int i;
+ const signed char *scp = (const signed char *) msg;
+
+ pad = (__u32)len | ((__u32)len << 8);
+ pad |= pad << 16;
+
+ val = pad;
+ if (len > num*4)
+ len = num * 4;
+ for (i = 0; i < len; i++) {
+ val = ((int) scp[i]) + (val << 8);
+ if ((i % 4) == 3) {
+ *buf++ = val;
+ val = pad;
+ num--;
+ }
+ }
+ if (--num >= 0)
+ *buf++ = val;
+ while (--num >= 0)
+ *buf++ = pad;
+}
+
+static void str2hashbuf_unsigned(const char *msg, int len, __u32 *buf, int num)
+{
+ __u32 pad, val;
+ int i;
+ const unsigned char *ucp = (const unsigned char *) msg;
+
+ pad = (__u32)len | ((__u32)len << 8);
+ pad |= pad << 16;
+
+ val = pad;
+ if (len > num*4)
+ len = num * 4;
+ for (i = 0; i < len; i++) {
+ val = ((int) ucp[i]) + (val << 8);
+ if ((i % 4) == 3) {
+ *buf++ = val;
+ val = pad;
+ num--;
+ }
+ }
+ if (--num >= 0)
+ *buf++ = val;
+ while (--num >= 0)
+ *buf++ = pad;
+}
+
+/*
+ * Returns the hash of a filename. If len is 0 and name is NULL, then
+ * this function can be used to test whether or not a hash version is
+ * supported.
+ *
+ * The seed is an 4 longword (32 bits) "secret" which can be used to
+ * uniquify a hash. If the seed is all zero's, then some default seed
+ * may be used.
+ *
+ * A particular hash version specifies whether or not the seed is
+ * represented, and whether or not the returned hash is 32 bits or 64
+ * bits. 32 bit hashes will return 0 for the minor hash.
+ */
+int ext4fs_dirhash(const char *name, int len, struct dx_hash_info *hinfo)
+{
+ __u32 hash;
+ __u32 minor_hash = 0;
+ const char *p;
+ int i;
+ __u32 in[8], buf[4];
+ void (*str2hashbuf)(const char *, int, __u32 *, int) =
+ str2hashbuf_signed;
+
+ /* Initialize the default seed for the hash checksum functions */
+ buf[0] = 0x67452301;
+ buf[1] = 0xefcdab89;
+ buf[2] = 0x98badcfe;
+ buf[3] = 0x10325476;
+
+ /* Check to see if the seed is all zero's */
+ if (hinfo->seed) {
+ for (i = 0; i < 4; i++) {
+ if (hinfo->seed[i]) {
+ memcpy(buf, hinfo->seed, sizeof(buf));
+ break;
+ }
+ }
+ }
+
+ switch (hinfo->hash_version) {
+ case DX_HASH_LEGACY_UNSIGNED:
+ hash = dx_hack_hash_unsigned(name, len);
+ break;
+ case DX_HASH_LEGACY:
+ hash = dx_hack_hash_signed(name, len);
+ break;
+ case DX_HASH_HALF_MD4_UNSIGNED:
+ str2hashbuf = str2hashbuf_unsigned;
+ case DX_HASH_HALF_MD4:
+ p = name;
+ while (len > 0) {
+ (*str2hashbuf)(p, len, in, 8);
+ half_md4_transform(buf, in);
+ len -= 32;
+ p += 32;
+ }
+ minor_hash = buf[2];
+ hash = buf[1];
+ break;
+ case DX_HASH_TEA_UNSIGNED:
+ str2hashbuf = str2hashbuf_unsigned;
+ case DX_HASH_TEA:
+ p = name;
+ while (len > 0) {
+ (*str2hashbuf)(p, len, in, 4);
+ TEA_transform(buf, in);
+ len -= 16;
+ p += 16;
+ }
+ hash = buf[0];
+ minor_hash = buf[1];
+ break;
+ default:
+ hinfo->hash = 0;
+ return -1;
+ }
+ hash = hash & ~1;
+ if (hash == (EXT4_HTREE_EOF_32BIT << 1))
+ hash = (EXT4_HTREE_EOF_32BIT - 1) << 1;
+ hinfo->hash = hash;
+ hinfo->minor_hash = minor_hash;
+ return 0;
+}
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