Add support for alternate SHA1 library implementations.

This one includes the Mozilla SHA1 implementation sent in by Edgar Toernig.
It's dual-licenced under MPL-1.1 or GPL, so in the context of git, we
obviously use the GPL version. 

Side note: the Mozilla SHA1 implementation is about twice as fast as the
default openssl one on my G5, but the default openssl one has optimized
x86 assembly language on x86. So choose wisely.

Makefile

@@ -29,22 +29,22 @@ LIB_H=cache.h object.h
 
 LIBS = $(LIB_FILE)
 LIBS += -lz
-LIBS += -lssl
+
+ifdef MOZILLA_SHA1
+  SHA1_HEADER="mozilla-sha1/sha1.h"
+  LIB_OBJS += mozilla-sha1/sha1.o
+else
+  SHA1_HEADER=<openssl/sha.h>
+  LIBS += -lssl
+endif
+
+CFLAGS += '-DSHA1_HEADER=$(SHA1_HEADER)'
 
 $(LIB_FILE): $(LIB_OBJS)
 	$(AR) rcs $@ $(LIB_OBJS)
 
 init-db: init-db.o
 
-fsck-cache: fsck-cache.o $(LIB_FILE) object.o commit.o tree.o blob.o
-	$(CC) $(CFLAGS) -o fsck-cache fsck-cache.o $(LIBS)
-
-rev-tree: rev-tree.o $(LIB_FILE) object.o commit.o tree.o blob.o
-	$(CC) $(CFLAGS) -o rev-tree rev-tree.o $(LIBS)
-
-merge-base: merge-base.o $(LIB_FILE) object.o commit.o tree.o blob.o
-	$(CC) $(CFLAGS) -o merge-base merge-base.o $(LIBS)
-
 %: %.o $(LIB_FILE)
 	$(CC) $(CFLAGS) -o $@ $< $(LIBS)
 
@@ -77,7 +77,7 @@ unpack-file.o: $(LIB_H)
 write-tree.o: $(LIB_H)
 
 clean:
-	rm -f *.o $(PROG) $(LIB_FILE)
+	rm -f *.o mozilla-sha1/*.o $(PROG) $(LIB_FILE)
 
 backup: clean
 	cd .. ; tar czvf dircache.tar.gz dir-cache

cache.h

@@ -14,7 +14,7 @@
 #include <sys/param.h>
 #include <netinet/in.h>
 
-#include <openssl/sha.h>
+#include SHA1_HEADER
 #include <zlib.h>
 
 /*

mozilla-sha1/sha1.c

@@ -0,0 +1,152 @@
+/* 
+ * The contents of this file are subject to the Mozilla Public
+ * License Version 1.1 (the "License"); you may not use this file
+ * except in compliance with the License. You may obtain a copy of
+ * the License at http://www.mozilla.org/MPL/
+ * 
+ * Software distributed under the License is distributed on an "AS
+ * IS" basis, WITHOUT WARRANTY OF ANY KIND, either express or
+ * implied. See the License for the specific language governing
+ * rights and limitations under the License.
+ * 
+ * The Original Code is SHA 180-1 Reference Implementation (Compact version)
+ * 
+ * The Initial Developer of the Original Code is Paul Kocher of
+ * Cryptography Research.  Portions created by Paul Kocher are 
+ * Copyright (C) 1995-9 by Cryptography Research, Inc.  All
+ * Rights Reserved.
+ * 
+ * Contributor(s):
+ *
+ *     Paul Kocher
+ * 
+ * Alternatively, the contents of this file may be used under the
+ * terms of the GNU General Public License Version 2 or later (the
+ * "GPL"), in which case the provisions of the GPL are applicable 
+ * instead of those above.  If you wish to allow use of your 
+ * version of this file only under the terms of the GPL and not to
+ * allow others to use your version of this file under the MPL,
+ * indicate your decision by deleting the provisions above and
+ * replace them with the notice and other provisions required by
+ * the GPL.  If you do not delete the provisions above, a recipient
+ * may use your version of this file under either the MPL or the
+ * GPL.
+ */
+
+#include "sha1.h"
+
+static void shaHashBlock(SHA_CTX *ctx);
+
+void SHA1_Init(SHA_CTX *ctx) {
+  int i;
+
+  ctx->lenW = 0;
+  ctx->sizeHi = ctx->sizeLo = 0;
+
+  /* Initialize H with the magic constants (see FIPS180 for constants)
+   */
+  ctx->H[0] = 0x67452301;
+  ctx->H[1] = 0xefcdab89;
+  ctx->H[2] = 0x98badcfe;
+  ctx->H[3] = 0x10325476;
+  ctx->H[4] = 0xc3d2e1f0;
+
+  for (i = 0; i < 80; i++)
+    ctx->W[i] = 0;
+}
+
+
+void SHA1_Update(SHA_CTX *ctx, void *_dataIn, int len) {
+  unsigned char *dataIn = _dataIn;
+  int i;
+
+  /* Read the data into W and process blocks as they get full
+   */
+  for (i = 0; i < len; i++) {
+    ctx->W[ctx->lenW / 4] <<= 8;
+    ctx->W[ctx->lenW / 4] |= (unsigned int)dataIn[i];
+    if ((++ctx->lenW) % 64 == 0) {
+      shaHashBlock(ctx);
+      ctx->lenW = 0;
+    }
+    ctx->sizeLo += 8;
+    ctx->sizeHi += (ctx->sizeLo < 8);
+  }
+}
+
+
+void SHA1_Final(unsigned char hashout[20], SHA_CTX *ctx) {
+  unsigned char pad0x80 = 0x80;
+  unsigned char pad0x00 = 0x00;
+  unsigned char padlen[8];
+  int i;
+
+  /* Pad with a binary 1 (e.g. 0x80), then zeroes, then length
+   */
+  padlen[0] = (unsigned char)((ctx->sizeHi >> 24) & 255);
+  padlen[1] = (unsigned char)((ctx->sizeHi >> 16) & 255);
+  padlen[2] = (unsigned char)((ctx->sizeHi >> 8) & 255);
+  padlen[3] = (unsigned char)((ctx->sizeHi >> 0) & 255);
+  padlen[4] = (unsigned char)((ctx->sizeLo >> 24) & 255);
+  padlen[5] = (unsigned char)((ctx->sizeLo >> 16) & 255);
+  padlen[6] = (unsigned char)((ctx->sizeLo >> 8) & 255);
+  padlen[7] = (unsigned char)((ctx->sizeLo >> 0) & 255);
+  SHA1_Update(ctx, &pad0x80, 1);
+  while (ctx->lenW != 56)
+    SHA1_Update(ctx, &pad0x00, 1);
+  SHA1_Update(ctx, padlen, 8);
+
+  /* Output hash
+   */
+  for (i = 0; i < 20; i++) {
+    hashout[i] = (unsigned char)(ctx->H[i / 4] >> 24);
+    ctx->H[i / 4] <<= 8;
+  }
+
+  /*
+   *  Re-initialize the context (also zeroizes contents)
+   */
+  SHA1_Init(ctx);
+}
+
+
+#define SHA_ROT(X,n) (((X) << (n)) | ((X) >> (32-(n))))
+
+static void shaHashBlock(SHA_CTX *ctx) {
+  int t;
+  unsigned int A,B,C,D,E,TEMP;
+
+  for (t = 16; t <= 79; t++)
+    ctx->W[t] =
+      SHA_ROT(ctx->W[t-3] ^ ctx->W[t-8] ^ ctx->W[t-14] ^ ctx->W[t-16], 1);
+
+  A = ctx->H[0];
+  B = ctx->H[1];
+  C = ctx->H[2];
+  D = ctx->H[3];
+  E = ctx->H[4];
+
+  for (t = 0; t <= 19; t++) {
+    TEMP = SHA_ROT(A,5) + (((C^D)&B)^D)     + E + ctx->W[t] + 0x5a827999;
+    E = D; D = C; C = SHA_ROT(B, 30); B = A; A = TEMP;
+  }
+  for (t = 20; t <= 39; t++) {
+    TEMP = SHA_ROT(A,5) + (B^C^D)           + E + ctx->W[t] + 0x6ed9eba1;
+    E = D; D = C; C = SHA_ROT(B, 30); B = A; A = TEMP;
+  }
+  for (t = 40; t <= 59; t++) {
+    TEMP = SHA_ROT(A,5) + ((B&C)|(D&(B|C))) + E + ctx->W[t] + 0x8f1bbcdc;
+    E = D; D = C; C = SHA_ROT(B, 30); B = A; A = TEMP;
+  }
+  for (t = 60; t <= 79; t++) {
+    TEMP = SHA_ROT(A,5) + (B^C^D)           + E + ctx->W[t] + 0xca62c1d6;
+    E = D; D = C; C = SHA_ROT(B, 30); B = A; A = TEMP;
+  }
+
+  ctx->H[0] += A;
+  ctx->H[1] += B;
+  ctx->H[2] += C;
+  ctx->H[3] += D;
+  ctx->H[4] += E;
+}
+

mozilla-sha1/sha1.h

@@ -0,0 +1,45 @@
+/* 
+ * The contents of this file are subject to the Mozilla Public
+ * License Version 1.1 (the "License"); you may not use this file
+ * except in compliance with the License. You may obtain a copy of
+ * the License at http://www.mozilla.org/MPL/
+ * 
+ * Software distributed under the License is distributed on an "AS
+ * IS" basis, WITHOUT WARRANTY OF ANY KIND, either express or
+ * implied. See the License for the specific language governing
+ * rights and limitations under the License.
+ * 
+ * The Original Code is SHA 180-1 Header File
+ * 
+ * The Initial Developer of the Original Code is Paul Kocher of
+ * Cryptography Research.  Portions created by Paul Kocher are 
+ * Copyright (C) 1995-9 by Cryptography Research, Inc.  All
+ * Rights Reserved.
+ * 
+ * Contributor(s):
+ *
+ *     Paul Kocher
+ * 
+ * Alternatively, the contents of this file may be used under the
+ * terms of the GNU General Public License Version 2 or later (the
+ * "GPL"), in which case the provisions of the GPL are applicable 
+ * instead of those above.  If you wish to allow use of your 
+ * version of this file only under the terms of the GPL and not to
+ * allow others to use your version of this file under the MPL,
+ * indicate your decision by deleting the provisions above and
+ * replace them with the notice and other provisions required by
+ * the GPL.  If you do not delete the provisions above, a recipient
+ * may use your version of this file under either the MPL or the
+ * GPL.
+ */
+
+typedef struct {
+  unsigned int H[5];
+  unsigned int W[80];
+  int lenW;
+  unsigned int sizeHi,sizeLo;
+} SHA_CTX;
+
+void SHA1_Init(SHA_CTX *ctx);
+void SHA1_Update(SHA_CTX *ctx, void *dataIn, int len);
+void SHA1_Final(unsigned char hashout[20], SHA_CTX *ctx);