[SCM] Samba Shared Repository - branch master updated
Rusty Russell
rusty at samba.org
Sun Sep 26 19:18:58 MDT 2010
The branch, master has been updated
via 2dcf76c tdb: TDB_INCOMPATIBLE_HASH, to allow safe changing of default hash.
via ccac258 tdb: automatically identify Jenkins hash tdbs
via 3258cf3 tdb: add Bob Jenkins lookup3 hash as helper hash.
from 7afa7b8 s3-waf: rework static and shared list handling a little.
http://gitweb.samba.org/?p=samba.git;a=shortlog;h=master
- Log -----------------------------------------------------------------
commit 2dcf76c9247ff02a1779000dbbecdc418473ca41
Author: Rusty Russell <rusty at rustcorp.com.au>
Date: Fri Sep 24 15:45:11 2010 +0930
tdb: TDB_INCOMPATIBLE_HASH, to allow safe changing of default hash.
This flag to tdb_open/tdb_open_ex effects creation of a new database:
1) Uses the Jenkins lookup3 hash instead of the old gdbm hash if none is
specified,
2) Places a non-zero field in header->rwlocks, so older versions of TDB will
refuse to open it.
This means that the caller (ie Samba) can set this flag to safely
change the hash function. Versions of TDB from this one on will either
use the correct hash or refuse to open (if a different hash is specified).
Older TDB versions will see the nonzero rwlocks field and refuse to open
it under any conditions.
Signed-off-by: Rusty Russell <rusty at rustcorp.com.au>
commit ccac258d14dda7d8a994a7b80474ce6d85478a6d
Author: Rusty Russell <rusty at rustcorp.com.au>
Date: Fri Sep 24 15:39:43 2010 +0930
tdb: automatically identify Jenkins hash tdbs
If the caller to tdb_open_ex() doesn't specify a hash, and tdb_old_hash
doesn't match, try tdb_jenkins_hash.
This was Metze's idea: it makes life simpler, especially with the upcoming
TDB_INCOMPATIBLE_HASH flag.
Signed-off-by: Rusty Russell <rusty at rustcorp.com.au>
commit 3258cf3f11bf7c68a2e69e1808c4551cc899725a
Author: Rusty Russell <rusty at rustcorp.com.au>
Date: Fri Sep 24 15:34:06 2010 +0930
tdb: add Bob Jenkins lookup3 hash as helper hash.
This is a better hash than the default: shipping it with tdb makes it easy
for callers to use it as the hash by passing it to tdb_open_ex().
This version taken from CCAN and modified, which took it from
http://www.burtleburtle.net/bob/c/lookup3.c.
Signed-off-by: Rusty Russell <rusty at rustcorp.com.au>
-----------------------------------------------------------------------
Summary of changes:
lib/tdb/ABI/{tdb-1.2.4.sigs => tdb-1.2.5.sigs} | 1 +
lib/tdb/common/check.c | 2 +-
lib/tdb/common/hash.c | 380 ++++++++++++++++++++++++
lib/tdb/common/open.c | 74 +++--
lib/tdb/common/tdb_private.h | 2 +
lib/tdb/configure.ac | 2 +-
lib/tdb/include/tdb.h | 2 +
lib/tdb/wscript | 4 +-
8 files changed, 433 insertions(+), 34 deletions(-)
copy lib/tdb/ABI/{tdb-1.2.4.sigs => tdb-1.2.5.sigs} (98%)
create mode 100644 lib/tdb/common/hash.c
Changeset truncated at 500 lines:
diff --git a/lib/tdb/ABI/tdb-1.2.4.sigs b/lib/tdb/ABI/tdb-1.2.5.sigs
similarity index 98%
copy from lib/tdb/ABI/tdb-1.2.4.sigs
copy to lib/tdb/ABI/tdb-1.2.5.sigs
index 043790d..1e01f3b 100644
--- a/lib/tdb/ABI/tdb-1.2.4.sigs
+++ b/lib/tdb/ABI/tdb-1.2.5.sigs
@@ -24,6 +24,7 @@ tdb_get_logging_private: void *(struct tdb_context *)
tdb_get_seqnum: int (struct tdb_context *)
tdb_hash_size: int (struct tdb_context *)
tdb_increment_seqnum_nonblock: void (struct tdb_context *)
+tdb_jenkins_hash: unsigned int (TDB_DATA *)
tdb_lockall: int (struct tdb_context *)
tdb_lockall_mark: int (struct tdb_context *)
tdb_lockall_nonblock: int (struct tdb_context *)
diff --git a/lib/tdb/common/check.c b/lib/tdb/common/check.c
index b1b98d4..58c9c26 100644
--- a/lib/tdb/common/check.c
+++ b/lib/tdb/common/check.c
@@ -39,7 +39,7 @@ static bool tdb_check_header(struct tdb_context *tdb, tdb_off_t *recovery)
if (hdr.version != TDB_VERSION)
goto corrupt;
- if (hdr.rwlocks != 0)
+ if (hdr.rwlocks != 0 && hdr.rwlocks != TDB_HASH_RWLOCK_MAGIC)
goto corrupt;
tdb_header_hash(tdb, &h1, &h2);
diff --git a/lib/tdb/common/hash.c b/lib/tdb/common/hash.c
new file mode 100644
index 0000000..c07297e
--- /dev/null
+++ b/lib/tdb/common/hash.c
@@ -0,0 +1,380 @@
+ /*
+ Unix SMB/CIFS implementation.
+
+ trivial database library
+
+ Copyright (C) Rusty Russell 2010
+
+ ** NOTE! The following LGPL license applies to the tdb
+ ** library. This does NOT imply that all of Samba is released
+ ** under the LGPL
+
+ This library 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.
+
+ This library 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 Lesser General Public
+ License along with this library; if not, see <http://www.gnu.org/licenses/>.
+*/
+#include "tdb_private.h"
+
+/* This is based on the hash algorithm from gdbm */
+unsigned int tdb_old_hash(TDB_DATA *key)
+{
+ uint32_t value; /* Used to compute the hash value. */
+ uint32_t i; /* Used to cycle through random values. */
+
+ /* Set the initial value from the key size. */
+ for (value = 0x238F13AF * key->dsize, i=0; i < key->dsize; i++)
+ value = (value + (key->dptr[i] << (i*5 % 24)));
+
+ return (1103515243 * value + 12345);
+}
+
+#ifndef WORDS_BIGENDIAN
+# define HASH_LITTLE_ENDIAN 1
+# define HASH_BIG_ENDIAN 0
+#else
+# define HASH_LITTLE_ENDIAN 0
+# define HASH_BIG_ENDIAN 1
+#endif
+
+/*
+-------------------------------------------------------------------------------
+lookup3.c, by Bob Jenkins, May 2006, Public Domain.
+
+These are functions for producing 32-bit hashes for hash table lookup.
+hash_word(), hashlittle(), hashlittle2(), hashbig(), mix(), and final()
+are externally useful functions. Routines to test the hash are included
+if SELF_TEST is defined. You can use this free for any purpose. It's in
+the public domain. It has no warranty.
+
+You probably want to use hashlittle(). hashlittle() and hashbig()
+hash byte arrays. hashlittle() is is faster than hashbig() on
+little-endian machines. Intel and AMD are little-endian machines.
+On second thought, you probably want hashlittle2(), which is identical to
+hashlittle() except it returns two 32-bit hashes for the price of one.
+You could implement hashbig2() if you wanted but I haven't bothered here.
+
+If you want to find a hash of, say, exactly 7 integers, do
+ a = i1; b = i2; c = i3;
+ mix(a,b,c);
+ a += i4; b += i5; c += i6;
+ mix(a,b,c);
+ a += i7;
+ final(a,b,c);
+then use c as the hash value. If you have a variable length array of
+4-byte integers to hash, use hash_word(). If you have a byte array (like
+a character string), use hashlittle(). If you have several byte arrays, or
+a mix of things, see the comments above hashlittle().
+
+Why is this so big? I read 12 bytes at a time into 3 4-byte integers,
+then mix those integers. This is fast (you can do a lot more thorough
+mixing with 12*3 instructions on 3 integers than you can with 3 instructions
+on 1 byte), but shoehorning those bytes into integers efficiently is messy.
+*/
+
+#define hashsize(n) ((uint32_t)1<<(n))
+#define hashmask(n) (hashsize(n)-1)
+#define rot(x,k) (((x)<<(k)) | ((x)>>(32-(k))))
+
+/*
+-------------------------------------------------------------------------------
+mix -- mix 3 32-bit values reversibly.
+
+This is reversible, so any information in (a,b,c) before mix() is
+still in (a,b,c) after mix().
+
+If four pairs of (a,b,c) inputs are run through mix(), or through
+mix() in reverse, there are at least 32 bits of the output that
+are sometimes the same for one pair and different for another pair.
+This was tested for:
+* pairs that differed by one bit, by two bits, in any combination
+ of top bits of (a,b,c), or in any combination of bottom bits of
+ (a,b,c).
+* "differ" is defined as +, -, ^, or ~^. For + and -, I transformed
+ the output delta to a Gray code (a^(a>>1)) so a string of 1's (as
+ is commonly produced by subtraction) look like a single 1-bit
+ difference.
+* the base values were pseudorandom, all zero but one bit set, or
+ all zero plus a counter that starts at zero.
+
+Some k values for my "a-=c; a^=rot(c,k); c+=b;" arrangement that
+satisfy this are
+ 4 6 8 16 19 4
+ 9 15 3 18 27 15
+ 14 9 3 7 17 3
+Well, "9 15 3 18 27 15" didn't quite get 32 bits diffing
+for "differ" defined as + with a one-bit base and a two-bit delta. I
+used http://burtleburtle.net/bob/hash/avalanche.html to choose
+the operations, constants, and arrangements of the variables.
+
+This does not achieve avalanche. There are input bits of (a,b,c)
+that fail to affect some output bits of (a,b,c), especially of a. The
+most thoroughly mixed value is c, but it doesn't really even achieve
+avalanche in c.
+
+This allows some parallelism. Read-after-writes are good at doubling
+the number of bits affected, so the goal of mixing pulls in the opposite
+direction as the goal of parallelism. I did what I could. Rotates
+seem to cost as much as shifts on every machine I could lay my hands
+on, and rotates are much kinder to the top and bottom bits, so I used
+rotates.
+-------------------------------------------------------------------------------
+*/
+#define mix(a,b,c) \
+{ \
+ a -= c; a ^= rot(c, 4); c += b; \
+ b -= a; b ^= rot(a, 6); a += c; \
+ c -= b; c ^= rot(b, 8); b += a; \
+ a -= c; a ^= rot(c,16); c += b; \
+ b -= a; b ^= rot(a,19); a += c; \
+ c -= b; c ^= rot(b, 4); b += a; \
+}
+
+/*
+-------------------------------------------------------------------------------
+final -- final mixing of 3 32-bit values (a,b,c) into c
+
+Pairs of (a,b,c) values differing in only a few bits will usually
+produce values of c that look totally different. This was tested for
+* pairs that differed by one bit, by two bits, in any combination
+ of top bits of (a,b,c), or in any combination of bottom bits of
+ (a,b,c).
+* "differ" is defined as +, -, ^, or ~^. For + and -, I transformed
+ the output delta to a Gray code (a^(a>>1)) so a string of 1's (as
+ is commonly produced by subtraction) look like a single 1-bit
+ difference.
+* the base values were pseudorandom, all zero but one bit set, or
+ all zero plus a counter that starts at zero.
+
+These constants passed:
+ 14 11 25 16 4 14 24
+ 12 14 25 16 4 14 24
+and these came close:
+ 4 8 15 26 3 22 24
+ 10 8 15 26 3 22 24
+ 11 8 15 26 3 22 24
+-------------------------------------------------------------------------------
+*/
+#define final(a,b,c) \
+{ \
+ c ^= b; c -= rot(b,14); \
+ a ^= c; a -= rot(c,11); \
+ b ^= a; b -= rot(a,25); \
+ c ^= b; c -= rot(b,16); \
+ a ^= c; a -= rot(c,4); \
+ b ^= a; b -= rot(a,14); \
+ c ^= b; c -= rot(b,24); \
+}
+
+
+/*
+-------------------------------------------------------------------------------
+hashlittle() -- hash a variable-length key into a 32-bit value
+ k : the key (the unaligned variable-length array of bytes)
+ length : the length of the key, counting by bytes
+ val2 : IN: can be any 4-byte value OUT: second 32 bit hash.
+Returns a 32-bit value. Every bit of the key affects every bit of
+the return value. Two keys differing by one or two bits will have
+totally different hash values. Note that the return value is better
+mixed than val2, so use that first.
+
+The best hash table sizes are powers of 2. There is no need to do
+mod a prime (mod is sooo slow!). If you need less than 32 bits,
+use a bitmask. For example, if you need only 10 bits, do
+ h = (h & hashmask(10));
+In which case, the hash table should have hashsize(10) elements.
+
+If you are hashing n strings (uint8_t **)k, do it like this:
+ for (i=0, h=0; i<n; ++i) h = hashlittle( k[i], len[i], h);
+
+By Bob Jenkins, 2006. bob_jenkins at burtleburtle.net. You may use this
+code any way you wish, private, educational, or commercial. It's free.
+
+Use for hash table lookup, or anything where one collision in 2^^32 is
+acceptable. Do NOT use for cryptographic purposes.
+-------------------------------------------------------------------------------
+*/
+
+static uint32_t hashlittle( const void *key, size_t length )
+{
+ uint32_t a,b,c; /* internal state */
+ union { const void *ptr; size_t i; } u; /* needed for Mac Powerbook G4 */
+
+ /* Set up the internal state */
+ a = b = c = 0xdeadbeef + ((uint32_t)length);
+
+ u.ptr = key;
+ if (HASH_LITTLE_ENDIAN && ((u.i & 0x3) == 0)) {
+ const uint32_t *k = (const uint32_t *)key; /* read 32-bit chunks */
+#ifdef VALGRIND
+ const uint8_t *k8;
+#endif
+
+ /*------ all but last block: aligned reads and affect 32 bits of (a,b,c) */
+ while (length > 12)
+ {
+ a += k[0];
+ b += k[1];
+ c += k[2];
+ mix(a,b,c);
+ length -= 12;
+ k += 3;
+ }
+
+ /*----------------------------- handle the last (probably partial) block */
+ /*
+ * "k[2]&0xffffff" actually reads beyond the end of the string, but
+ * then masks off the part it's not allowed to read. Because the
+ * string is aligned, the masked-off tail is in the same word as the
+ * rest of the string. Every machine with memory protection I've seen
+ * does it on word boundaries, so is OK with this. But VALGRIND will
+ * still catch it and complain. The masking trick does make the hash
+ * noticably faster for short strings (like English words).
+ */
+#ifndef VALGRIND
+
+ switch(length)
+ {
+ case 12: c+=k[2]; b+=k[1]; a+=k[0]; break;
+ case 11: c+=k[2]&0xffffff; b+=k[1]; a+=k[0]; break;
+ case 10: c+=k[2]&0xffff; b+=k[1]; a+=k[0]; break;
+ case 9 : c+=k[2]&0xff; b+=k[1]; a+=k[0]; break;
+ case 8 : b+=k[1]; a+=k[0]; break;
+ case 7 : b+=k[1]&0xffffff; a+=k[0]; break;
+ case 6 : b+=k[1]&0xffff; a+=k[0]; break;
+ case 5 : b+=k[1]&0xff; a+=k[0]; break;
+ case 4 : a+=k[0]; break;
+ case 3 : a+=k[0]&0xffffff; break;
+ case 2 : a+=k[0]&0xffff; break;
+ case 1 : a+=k[0]&0xff; break;
+ case 0 : return c; /* zero length strings require no mixing */
+ }
+
+#else /* make valgrind happy */
+
+ k8 = (const uint8_t *)k;
+ switch(length)
+ {
+ case 12: c+=k[2]; b+=k[1]; a+=k[0]; break;
+ case 11: c+=((uint32_t)k8[10])<<16; /* fall through */
+ case 10: c+=((uint32_t)k8[9])<<8; /* fall through */
+ case 9 : c+=k8[8]; /* fall through */
+ case 8 : b+=k[1]; a+=k[0]; break;
+ case 7 : b+=((uint32_t)k8[6])<<16; /* fall through */
+ case 6 : b+=((uint32_t)k8[5])<<8; /* fall through */
+ case 5 : b+=k8[4]; /* fall through */
+ case 4 : a+=k[0]; break;
+ case 3 : a+=((uint32_t)k8[2])<<16; /* fall through */
+ case 2 : a+=((uint32_t)k8[1])<<8; /* fall through */
+ case 1 : a+=k8[0]; break;
+ case 0 : return c;
+ }
+
+#endif /* !valgrind */
+
+ } else if (HASH_LITTLE_ENDIAN && ((u.i & 0x1) == 0)) {
+ const uint16_t *k = (const uint16_t *)key; /* read 16-bit chunks */
+ const uint8_t *k8;
+
+ /*--------------- all but last block: aligned reads and different mixing */
+ while (length > 12)
+ {
+ a += k[0] + (((uint32_t)k[1])<<16);
+ b += k[2] + (((uint32_t)k[3])<<16);
+ c += k[4] + (((uint32_t)k[5])<<16);
+ mix(a,b,c);
+ length -= 12;
+ k += 6;
+ }
+
+ /*----------------------------- handle the last (probably partial) block */
+ k8 = (const uint8_t *)k;
+ switch(length)
+ {
+ case 12: c+=k[4]+(((uint32_t)k[5])<<16);
+ b+=k[2]+(((uint32_t)k[3])<<16);
+ a+=k[0]+(((uint32_t)k[1])<<16);
+ break;
+ case 11: c+=((uint32_t)k8[10])<<16; /* fall through */
+ case 10: c+=k[4];
+ b+=k[2]+(((uint32_t)k[3])<<16);
+ a+=k[0]+(((uint32_t)k[1])<<16);
+ break;
+ case 9 : c+=k8[8]; /* fall through */
+ case 8 : b+=k[2]+(((uint32_t)k[3])<<16);
+ a+=k[0]+(((uint32_t)k[1])<<16);
+ break;
+ case 7 : b+=((uint32_t)k8[6])<<16; /* fall through */
+ case 6 : b+=k[2];
+ a+=k[0]+(((uint32_t)k[1])<<16);
+ break;
+ case 5 : b+=k8[4]; /* fall through */
+ case 4 : a+=k[0]+(((uint32_t)k[1])<<16);
+ break;
+ case 3 : a+=((uint32_t)k8[2])<<16; /* fall through */
+ case 2 : a+=k[0];
+ break;
+ case 1 : a+=k8[0];
+ break;
+ case 0 : return c; /* zero length requires no mixing */
+ }
+
+ } else { /* need to read the key one byte at a time */
+ const uint8_t *k = (const uint8_t *)key;
+
+ /*--------------- all but the last block: affect some 32 bits of (a,b,c) */
+ while (length > 12)
+ {
+ a += k[0];
+ a += ((uint32_t)k[1])<<8;
+ a += ((uint32_t)k[2])<<16;
+ a += ((uint32_t)k[3])<<24;
+ b += k[4];
+ b += ((uint32_t)k[5])<<8;
+ b += ((uint32_t)k[6])<<16;
+ b += ((uint32_t)k[7])<<24;
+ c += k[8];
+ c += ((uint32_t)k[9])<<8;
+ c += ((uint32_t)k[10])<<16;
+ c += ((uint32_t)k[11])<<24;
+ mix(a,b,c);
+ length -= 12;
+ k += 12;
+ }
+
+ /*-------------------------------- last block: affect all 32 bits of (c) */
+ switch(length) /* all the case statements fall through */
+ {
+ case 12: c+=((uint32_t)k[11])<<24;
+ case 11: c+=((uint32_t)k[10])<<16;
+ case 10: c+=((uint32_t)k[9])<<8;
+ case 9 : c+=k[8];
+ case 8 : b+=((uint32_t)k[7])<<24;
+ case 7 : b+=((uint32_t)k[6])<<16;
+ case 6 : b+=((uint32_t)k[5])<<8;
+ case 5 : b+=k[4];
+ case 4 : a+=((uint32_t)k[3])<<24;
+ case 3 : a+=((uint32_t)k[2])<<16;
+ case 2 : a+=((uint32_t)k[1])<<8;
+ case 1 : a+=k[0];
+ break;
+ case 0 : return c;
+ }
+ }
+
+ final(a,b,c);
+ return c;
+}
+
+unsigned int tdb_jenkins_hash(TDB_DATA *key)
+{
+ return hashlittle(key->dptr, key->dsize);
+}
diff --git a/lib/tdb/common/open.c b/lib/tdb/common/open.c
index a964994..66539c3 100644
--- a/lib/tdb/common/open.c
+++ b/lib/tdb/common/open.c
@@ -30,20 +30,6 @@
/* all contexts, to ensure no double-opens (fcntl locks don't nest!) */
static struct tdb_context *tdbs = NULL;
-
-/* This is based on the hash algorithm from gdbm */
-static unsigned int default_tdb_hash(TDB_DATA *key)
-{
- uint32_t value; /* Used to compute the hash value. */
- uint32_t i; /* Used to cycle through random values. */
-
- /* Set the initial value from the key size. */
- for (value = 0x238F13AF * key->dsize, i=0; i < key->dsize; i++)
- value = (value + (key->dptr[i] << (i*5 % 24)));
-
- return (1103515243 * value + 12345);
-}
-
/* We use two hashes to double-check they're using the right hash function. */
void tdb_header_hash(struct tdb_context *tdb,
uint32_t *magic1_hash, uint32_t *magic2_hash)
@@ -51,7 +37,7 @@ void tdb_header_hash(struct tdb_context *tdb,
TDB_DATA hash_key;
uint32_t tdb_magic = TDB_MAGIC;
- hash_key.dptr = (unsigned char *)TDB_MAGIC_FOOD;
+ hash_key.dptr = discard_const_p(unsigned char, TDB_MAGIC_FOOD);
hash_key.dsize = sizeof(TDB_MAGIC_FOOD);
*magic1_hash = tdb->hash_fn(&hash_key);
@@ -84,6 +70,11 @@ static int tdb_new_database(struct tdb_context *tdb, int hash_size)
tdb_header_hash(tdb, &newdb->magic1_hash, &newdb->magic2_hash);
+ /* Make sure older tdbs (which don't check the magic hash fields)
+ * will refuse to open this TDB. */
+ if (tdb->flags & TDB_INCOMPATIBLE_HASH)
+ newdb->rwlocks = TDB_HASH_RWLOCK_MAGIC;
+
if (tdb->flags & TDB_INTERNAL) {
tdb->map_size = size;
tdb->map_ptr = (char *)newdb;
@@ -150,6 +141,26 @@ static void null_log_fn(struct tdb_context *tdb, enum tdb_debug_level level, con
{
}
+static bool check_header_hash(struct tdb_context *tdb,
+ bool default_hash, uint32_t *m1, uint32_t *m2)
+{
+ tdb_header_hash(tdb, m1, m2);
+ if (tdb->header.magic1_hash == *m1 &&
+ tdb->header.magic2_hash == *m2) {
+ return true;
+ }
+
+ /* If they explicitly set a hash, always respect it. */
+ if (!default_hash)
+ return false;
+
+ /* Otherwise, try the other inbuilt hash. */
+ if (tdb->hash_fn == tdb_old_hash)
+ tdb->hash_fn = tdb_jenkins_hash;
+ else
+ tdb->hash_fn = tdb_old_hash;
+ return check_header_hash(tdb, false, m1, m2);
+}
struct tdb_context *tdb_open_ex(const char *name, int hash_size, int tdb_flags,
int open_flags, mode_t mode,
@@ -162,9 +173,8 @@ struct tdb_context *tdb_open_ex(const char *name, int hash_size, int tdb_flags,
unsigned char *vp;
uint32_t vertest;
unsigned v;
- uint32_t magic1_hash;
- uint32_t magic2_hash;
const char *hash_alg;
+ uint32_t magic1, magic2;
if (!(tdb = (struct tdb_context *)calloc(1, sizeof *tdb))) {
/* Can't log this */
@@ -189,10 +199,15 @@ struct tdb_context *tdb_open_ex(const char *name, int hash_size, int tdb_flags,
--
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