[PATCH v2 0/4] prepare for histogram diff

@@ -64,8 +64,6 @@ static int xdl_optimize_ctxs(xdfile_t *xdf1, xdfile_t *xdf2);
 
 
 static int xdl_init_classifier(xdlclassifier_t *cf, long size, long flags) {
-	long i;
-
 	cf->flags = flags;
 
 	cf->hbits = xdl_hashbits((unsigned int) size);

@@ -80,8 +78,7 @@ static int xdl_init_classifier(xdlclassifier_t *cf, long size, long flags) {
 		xdl_cha_free(&cf->ncha);
 		return -1;
 	}
-	for (i = 0; i < cf->hsize; i++)
-		cf->rchash[i] = NULL;
+	memset(cf->rchash, 0, cf->hsize * sizeof(xdlclass_t *));
 
 	cf->count = 0;
 

@@ -136,7 +133,7 @@ static int xdl_classify_record(xdlclassifier_t *cf, xrecord_t **rhash, unsigned
 static int xdl_prepare_ctx(mmfile_t *mf, long narec, xpparam_t const *xpp,
 			   xdlclassifier_t *cf, xdfile_t *xdf) {
 	unsigned int hbits;
-	long i, nrec, hsize, bsize;
+	long nrec, hsize, bsize;
 	unsigned long hav;
 	char const *blk, *cur, *top, *prev;
 	xrecord_t *crec;

@@ -164,8 +161,7 @@ static int xdl_prepare_ctx(mmfile_t *mf, long narec, xpparam_t const *xpp,
 		xdl_cha_free(&xdf->rcha);
 		return -1;
 	}
-	for (i = 0; i < hsize; i++)
-		rhash[i] = NULL;
+	memset(rhash, 0, hsize * sizeof(xrecord_t *));
 
 	nrec = 0;
 	if ((cur = blk = xdl_mmfile_first(mf, &bsize)) != NULL) {

@@ -143,24 +143,15 @@ static int xdl_prepare_ctx(mmfile_t *mf, long narec, xpparam_t const *xpp,
 	char *rchg;
 	long *rindex;
 
-	if (xdl_cha_init(&xdf->rcha, sizeof(xrecord_t), narec / 4 + 1) < 0) {
-
-		return -1;
-	}
-	if (!(recs = (xrecord_t **) xdl_malloc(narec * sizeof(xrecord_t *)))) {
-
-		xdl_cha_free(&xdf->rcha);
-		return -1;
-	}
+	if (xdl_cha_init(&xdf->rcha, sizeof(xrecord_t), narec / 4 + 1) < 0)
+		goto abort_rcha;
+	if (!(recs = (xrecord_t **) xdl_malloc(narec * sizeof(xrecord_t *))))
+		goto abort_recs;
 
 	hbits = xdl_hashbits((unsigned int) narec);
 	hsize = 1 << hbits;
-	if (!(rhash = (xrecord_t **) xdl_malloc(hsize * sizeof(xrecord_t *)))) {
-
-		xdl_free(recs);
-		xdl_cha_free(&xdf->rcha);
-		return -1;
-	}
+	if (!(rhash = (xrecord_t **) xdl_malloc(hsize * sizeof(xrecord_t *))))
+		goto abort_rhash;
 	memset(rhash, 0, hsize * sizeof(xrecord_t *));
 
 	nrec = 0;

@@ -175,63 +166,30 @@ static int xdl_prepare_ctx(mmfile_t *mf, long narec, xpparam_t const *xpp,
 			hav = xdl_hash_record(&cur, top, xpp->flags);
 			if (nrec >= narec) {
 				narec *= 2;
-				if (!(rrecs = (xrecord_t **) xdl_realloc(recs, narec * sizeof(xrecord_t *)))) {
-
-					xdl_free(rhash);
-					xdl_free(recs);
-					xdl_cha_free(&xdf->rcha);
-					return -1;
-				}
+				if (!(rrecs = (xrecord_t **) xdl_realloc(recs, narec * sizeof(xrecord_t *))))
+					goto abort_rrecs;
 				recs = rrecs;
 			}
-			if (!(crec = xdl_cha_alloc(&xdf->rcha))) {
-
-				xdl_free(rhash);
-				xdl_free(recs);
-				xdl_cha_free(&xdf->rcha);
-				return -1;
-			}
+			if (!(crec = xdl_cha_alloc(&xdf->rcha)))
+				goto abort_crec;
 			crec->ptr = prev;
 			crec->size = (long) (cur - prev);
 			crec->ha = hav;
 			recs[nrec++] = crec;
 
-			if (xdl_classify_record(cf, rhash, hbits, crec) < 0) {
-
-				xdl_free(rhash);
-				xdl_free(recs);
-				xdl_cha_free(&xdf->rcha);
-				return -1;
-			}
+			if (xdl_classify_record(cf, rhash, hbits, crec) < 0)
+				goto abort_classify;
 		}
 	}
 
-	if (!(rchg = (char *) xdl_malloc((nrec + 2) * sizeof(char)))) {
-
-		xdl_free(rhash);
-		xdl_free(recs);
-		xdl_cha_free(&xdf->rcha);
-		return -1;
-	}
+	if (!(rchg = (char *) xdl_malloc((nrec + 2) * sizeof(char))))
+		goto abort_rchg;
 	memset(rchg, 0, (nrec + 2) * sizeof(char));
 
-	if (!(rindex = (long *) xdl_malloc((nrec + 1) * sizeof(long)))) {
-
-		xdl_free(rchg);
-		xdl_free(rhash);
-		xdl_free(recs);
-		xdl_cha_free(&xdf->rcha);
-		return -1;
-	}
-	if (!(ha = (unsigned long *) xdl_malloc((nrec + 1) * sizeof(unsigned long)))) {
-
-		xdl_free(rindex);
-		xdl_free(rchg);
-		xdl_free(rhash);
-		xdl_free(recs);
-		xdl_cha_free(&xdf->rcha);
-		return -1;
-	}
+	if (!(rindex = (long *) xdl_malloc((nrec + 1) * sizeof(long))))
+		goto abort_rindex;
+	if (!(ha = (unsigned long *) xdl_malloc((nrec + 1) * sizeof(unsigned long))))
+		goto abort_ha;
 
 	xdf->nrec = nrec;
 	xdf->recs = recs;

@@ -245,6 +203,22 @@ static int xdl_prepare_ctx(mmfile_t *mf, long narec, xpparam_t const *xpp,
 	xdf->dend = nrec - 1;
 
 	return 0;
+
+abort_ha:
+	xdl_free(rindex);
+abort_rindex:
+	xdl_free(rchg);
+abort_rchg:
+abort_classify:
+abort_crec:
+abort_rrecs:
+	xdl_free(rhash);
+abort_rhash:
+	xdl_free(recs);
+abort_recs:
+	xdl_cha_free(&xdf->rcha);
+abort_rcha:
+	return -1;
 }
 
 

@@ -287,34 +287,11 @@ static int walk_common_sequence(struct hashmap *map, struct entry *first,
 static int fall_back_to_classic_diff(struct hashmap *map,
 		int line1, int count1, int line2, int count2)
 {
-	/*
-	 * This probably does not work outside Git, since
-	 * we have a very simple mmfile structure.
-	 *
-	 * Note: ideally, we would reuse the prepared environment, but
-	 * the libxdiff interface does not (yet) allow for diffing only
-	 * ranges of lines instead of the whole files.
-	 */
-	mmfile_t subfile1, subfile2;
 	xpparam_t xpp;
-	xdfenv_t env;
-
-	subfile1.ptr = (char *)map->env->xdf1.recs[line1 - 1]->ptr;
-	subfile1.size = map->env->xdf1.recs[line1 + count1 - 2]->ptr +
-		map->env->xdf1.recs[line1 + count1 - 2]->size - subfile1.ptr;
-	subfile2.ptr = (char *)map->env->xdf2.recs[line2 - 1]->ptr;
-	subfile2.size = map->env->xdf2.recs[line2 + count2 - 2]->ptr +
-		map->env->xdf2.recs[line2 + count2 - 2]->size - subfile2.ptr;
 	xpp.flags = map->xpp->flags & ~XDF_PATIENCE_DIFF;
-	if (xdl_do_diff(&subfile1, &subfile2, &xpp, &env) < 0)
-		return -1;
 
-	memcpy(map->env->xdf1.rchg + line1 - 1, env.xdf1.rchg, count1);
-	memcpy(map->env->xdf2.rchg + line2 - 1, env.xdf2.rchg, count2);
-
-	xdl_free_env(&env);
-
-	return 0;
+	return xdl_fall_back_diff(map->env, &xpp,
+				  line1, count1, line2, count2);
 }
 
 /*

@@ -402,3 +402,34 @@ int xdl_emit_hunk_hdr(long s1, long c1, long s2, long c2,
 
 	return 0;
 }
+
+int xdl_fall_back_diff(xdfenv_t *diff_env, xpparam_t const *xpp,
+		int line1, int count1, int line2, int count2)
+{
+	/*
+	 * This probably does not work outside Git, since
+	 * we have a very simple mmfile structure.
+	 *
+	 * Note: ideally, we would reuse the prepared environment, but
+	 * the libxdiff interface does not (yet) allow for diffing only
+	 * ranges of lines instead of the whole files.
+	 */
+	mmfile_t subfile1, subfile2;
+	xdfenv_t env;
+
+	subfile1.ptr = (char *)diff_env->xdf1.recs[line1 - 1]->ptr;
+	subfile1.size = diff_env->xdf1.recs[line1 + count1 - 2]->ptr +
+		diff_env->xdf1.recs[line1 + count1 - 2]->size - subfile1.ptr;
+	subfile2.ptr = (char *)diff_env->xdf2.recs[line2 - 1]->ptr;
+	subfile2.size = diff_env->xdf2.recs[line2 + count2 - 2]->ptr +
+		diff_env->xdf2.recs[line2 + count2 - 2]->size - subfile2.ptr;
+	if (xdl_do_diff(&subfile1, &subfile2, xpp, &env) < 0)
+		return -1;
+
+	memcpy(diff_env->xdf1.rchg + line1 - 1, env.xdf1.rchg, count1);
+	memcpy(diff_env->xdf2.rchg + line2 - 1, env.xdf2.rchg, count2);
+
+	xdl_free_env(&env);
+
+	return 0;
+}

@@ -41,6 +41,8 @@ int xdl_num_out(char *out, long val);
 long xdl_atol(char const *str, char const **next);
 int xdl_emit_hunk_hdr(long s1, long c1, long s2, long c2,
 		      const char *func, long funclen, xdemitcb_t *ecb);
+int xdl_fall_back_diff(xdfenv_t *diff_env, xpparam_t const *xpp,
+		       int line1, int count1, int line2, int count2);
 
 
 

@@ -0,0 +1,163 @@
+test_diff_frobnitz() {
+	cat >file1 <<\EOF
+#include <stdio.h>
+
+// Frobs foo heartily
+int frobnitz(int foo)
+{
+    int i;
+    for(i = 0; i < 10; i++)
+    {
+        printf("Your answer is: ");
+        printf("%d\n", foo);
+    }
+}
+
+int fact(int n)
+{
+    if(n > 1)
+    {
+        return fact(n-1) * n;
+    }
+    return 1;
+}
+
+int main(int argc, char **argv)
+{
+    frobnitz(fact(10));
+}
+EOF
+
+	cat >file2 <<\EOF
+#include <stdio.h>
+
+int fib(int n)
+{
+    if(n > 2)
+    {
+        return fib(n-1) + fib(n-2);
+    }
+    return 1;
+}
+
+// Frobs foo heartily
+int frobnitz(int foo)
+{
+    int i;
+    for(i = 0; i < 10; i++)
+    {
+        printf("%d\n", foo);
+    }
+}
+
+int main(int argc, char **argv)
+{
+    frobnitz(fib(10));
+}
+EOF
+
+	cat >expect <<\EOF
+diff --git a/file1 b/file2
+index 6faa5a3..e3af329 100644
+--- a/file1
++++ b/file2
+@@ -1,26 +1,25 @@
+ #include <stdio.h>
+ 
++int fib(int n)
++{
++    if(n > 2)
++    {
++        return fib(n-1) + fib(n-2);
++    }
++    return 1;
++}
++
+ // Frobs foo heartily
+ int frobnitz(int foo)
+ {
+     int i;
+     for(i = 0; i < 10; i++)
+     {
+-        printf("Your answer is: ");
+         printf("%d\n", foo);
+     }
+ }
+ 
+-int fact(int n)
+-{
+-    if(n > 1)
+-    {
+-        return fact(n-1) * n;
+-    }
+-    return 1;
+-}
+-
+ int main(int argc, char **argv)
+ {
+-    frobnitz(fact(10));
++    frobnitz(fib(10));
+ }
+EOF
+
+	STRATEGY=$1
+
+	test_expect_success "$STRATEGY diff" '
+		test_must_fail git diff --no-index "--$STRATEGY" file1 file2 > output &&
+		test_cmp expect output
+	'
+
+	test_expect_success "$STRATEGY diff output is valid" '
+		mv file2 expect &&
+		git apply < output &&
+		test_cmp expect file2
+	'
+}
+
+test_diff_unique() {
+	cat >uniq1 <<\EOF
+1
+2
+3
+4
+5
+6
+EOF
+
+	cat >uniq2 <<\EOF
+a
+b
+c
+d
+e
+f
+EOF
+
+	cat >expect <<\EOF
+diff --git a/uniq1 b/uniq2
+index b414108..0fdf397 100644
+--- a/uniq1
++++ b/uniq2
+@@ -1,6 +1,6 @@
+-1
+-2
+-3
+-4
+-5
+-6
++a
++b
++c
++d
++e
++f
+EOF
+
+	STRATEGY=$1
+
+	test_expect_success 'completely different files' '
+		test_must_fail git diff --no-index "--$STRATEGY" uniq1 uniq2 > output &&
+		test_cmp expect output
+	'
+}
+

@@ -3,166 +3,10 @@
 test_description='patience diff algorithm'
 
 . ./test-lib.sh
+. "$TEST_DIRECTORY"/lib-diff-patience.sh
 
-cat >file1 <<\EOF
-#include <stdio.h>
+test_diff_frobnitz "patience"
 
-// Frobs foo heartily
-int frobnitz(int foo)
-{
-    int i;
-    for(i = 0; i < 10; i++)
-    {
-        printf("Your answer is: ");
-        printf("%d\n", foo);
-    }
-}
-
-int fact(int n)
-{
-    if(n > 1)
-    {
-        return fact(n-1) * n;
-    }
-    return 1;
-}
-
-int main(int argc, char **argv)
-{
-    frobnitz(fact(10));
-}
-EOF
-
-cat >file2 <<\EOF
-#include <stdio.h>
-
-int fib(int n)
-{
-    if(n > 2)
-    {
-        return fib(n-1) + fib(n-2);
-    }
-    return 1;
-}
-
-// Frobs foo heartily
-int frobnitz(int foo)
-{
-    int i;
-    for(i = 0; i < 10; i++)
-    {
-        printf("%d\n", foo);
-    }
-}
-
-int main(int argc, char **argv)
-{
-    frobnitz(fib(10));
-}
-EOF
-
-cat >expect <<\EOF
-diff --git a/file1 b/file2
-index 6faa5a3..e3af329 100644
---- a/file1
-+++ b/file2
-@@ -1,26 +1,25 @@
- #include <stdio.h>
- 
-+int fib(int n)
-+{
-+    if(n > 2)
-+    {
-+        return fib(n-1) + fib(n-2);
-+    }
-+    return 1;
-+}
-+
- // Frobs foo heartily
- int frobnitz(int foo)
- {
-     int i;
-     for(i = 0; i < 10; i++)
-     {
--        printf("Your answer is: ");
-         printf("%d\n", foo);
-     }
- }
- 
--int fact(int n)
--{
--    if(n > 1)
--    {
--        return fact(n-1) * n;
--    }
--    return 1;
--}
--
- int main(int argc, char **argv)
- {
--    frobnitz(fact(10));
-+    frobnitz(fib(10));
- }
-EOF
-
-test_expect_success 'patience diff' '
-
-	test_must_fail git diff --no-index --patience file1 file2 > output &&
-	test_cmp expect output
-
-'
-
-test_expect_success 'patience diff output is valid' '
-
-	mv file2 expect &&
-	git apply < output &&
-	test_cmp expect file2
-
-'
-
-cat >uniq1 <<\EOF
-1
-2
-3
-4
-5
-6
-EOF
-
-cat >uniq2 <<\EOF
-a
-b
-c
-d
-e
-f
-EOF
-
-cat >expect <<\EOF
-diff --git a/uniq1 b/uniq2
-index b414108..0fdf397 100644
---- a/uniq1
-+++ b/uniq2
-@@ -1,6 +1,6 @@
--1
--2
--3
--4
--5
--6
-+a
-+b
-+c
-+d
-+e
-+f
-EOF
-
-test_expect_success 'completely different files' '
-
-	test_must_fail git diff --no-index --patience uniq1 uniq2 > output &&
-	test_cmp expect output
-
-'
+test_diff_unique "patience"
 
 test_done

@@ -64,8 +64,6 @@ static int xdl_optimize_ctxs(xdfile_t *xdf1, xdfile_t *xdf2);
 
 
 static int xdl_init_classifier(xdlclassifier_t *cf, long size, long flags) {
-	long i;
-
 	cf->flags = flags;
 
 	cf->hbits = xdl_hashbits((unsigned int) size);

@@ -80,8 +78,7 @@ static int xdl_init_classifier(xdlclassifier_t *cf, long size, long flags) {
 		xdl_cha_free(&cf->ncha);
 		return -1;
 	}
-	for (i = 0; i < cf->hsize; i++)
-		cf->rchash[i] = NULL;
+	memset(cf->rchash, 0, cf->hsize * sizeof(xdlclass_t *));
 
 	cf->count = 0;
 

@@ -136,7 +133,7 @@ static int xdl_classify_record(xdlclassifier_t *cf, xrecord_t **rhash, unsigned
 static int xdl_prepare_ctx(mmfile_t *mf, long narec, xpparam_t const *xpp,
 			   xdlclassifier_t *cf, xdfile_t *xdf) {
 	unsigned int hbits;
-	long i, nrec, hsize, bsize;
+	long nrec, hsize, bsize;
 	unsigned long hav;
 	char const *blk, *cur, *top, *prev;
 	xrecord_t *crec;

@@ -164,8 +161,7 @@ static int xdl_prepare_ctx(mmfile_t *mf, long narec, xpparam_t const *xpp,
 		xdl_cha_free(&xdf->rcha);
 		return -1;
 	}
-	for (i = 0; i < hsize; i++)
-		rhash[i] = NULL;
+	memset(rhash, 0, hsize * sizeof(xrecord_t *));
 
 	nrec = 0;
 	if ((cur = blk = xdl_mmfile_first(mf, &bsize)) != NULL) {

@@ -287,34 +287,11 @@ static int walk_common_sequence(struct hashmap *map, struct entry *first,
 static int fall_back_to_classic_diff(struct hashmap *map,
 		int line1, int count1, int line2, int count2)
 {
-	/*
-	 * This probably does not work outside Git, since
-	 * we have a very simple mmfile structure.
-	 *
-	 * Note: ideally, we would reuse the prepared environment, but
-	 * the libxdiff interface does not (yet) allow for diffing only
-	 * ranges of lines instead of the whole files.
-	 */
-	mmfile_t subfile1, subfile2;
 	xpparam_t xpp;
-	xdfenv_t env;
-
-	subfile1.ptr = (char *)map->env->xdf1.recs[line1 - 1]->ptr;
-	subfile1.size = map->env->xdf1.recs[line1 + count1 - 2]->ptr +
-		map->env->xdf1.recs[line1 + count1 - 2]->size - subfile1.ptr;
-	subfile2.ptr = (char *)map->env->xdf2.recs[line2 - 1]->ptr;
-	subfile2.size = map->env->xdf2.recs[line2 + count2 - 2]->ptr +
-		map->env->xdf2.recs[line2 + count2 - 2]->size - subfile2.ptr;
 	xpp.flags = map->xpp->flags & ~XDF_PATIENCE_DIFF;
-	if (xdl_do_diff(&subfile1, &subfile2, &xpp, &env) < 0)
-		return -1;
 
-	memcpy(map->env->xdf1.rchg + line1 - 1, env.xdf1.rchg, count1);
-	memcpy(map->env->xdf2.rchg + line2 - 1, env.xdf2.rchg, count2);
-
-	xdl_free_env(&env);
-
-	return 0;
+	return xdl_fall_back_diff(map->env, &xpp,
+				  line1, count1, line2, count2);
 }
 
 /*

@@ -402,3 +402,34 @@ int xdl_emit_hunk_hdr(long s1, long c1, long s2, long c2,
 
 	return 0;
 }
+
+int xdl_fall_back_diff(xdfenv_t *diff_env, xpparam_t const *xpp,
+		int line1, int count1, int line2, int count2)
+{
+	/*
+	 * This probably does not work outside Git, since
+	 * we have a very simple mmfile structure.
+	 *
+	 * Note: ideally, we would reuse the prepared environment, but
+	 * the libxdiff interface does not (yet) allow for diffing only
+	 * ranges of lines instead of the whole files.
+	 */
+	mmfile_t subfile1, subfile2;
+	xdfenv_t env;
+
+	subfile1.ptr = (char *)diff_env->xdf1.recs[line1 - 1]->ptr;
+	subfile1.size = diff_env->xdf1.recs[line1 + count1 - 2]->ptr +
+		diff_env->xdf1.recs[line1 + count1 - 2]->size - subfile1.ptr;
+	subfile2.ptr = (char *)diff_env->xdf2.recs[line2 - 1]->ptr;
+	subfile2.size = diff_env->xdf2.recs[line2 + count2 - 2]->ptr +
+		diff_env->xdf2.recs[line2 + count2 - 2]->size - subfile2.ptr;
+	if (xdl_do_diff(&subfile1, &subfile2, xpp, &env) < 0)
+		return -1;
+
+	memcpy(diff_env->xdf1.rchg + line1 - 1, env.xdf1.rchg, count1);
+	memcpy(diff_env->xdf2.rchg + line2 - 1, env.xdf2.rchg, count2);
+
+	xdl_free_env(&env);
+
+	return 0;
+}

@@ -41,6 +41,8 @@ int xdl_num_out(char *out, long val);
 long xdl_atol(char const *str, char const **next);
 int xdl_emit_hunk_hdr(long s1, long c1, long s2, long c2,
 		      const char *func, long funclen, xdemitcb_t *ecb);
+int xdl_fall_back_diff(xdfenv_t *diff_env, xpparam_t const *xpp,
+		       int line1, int count1, int line2, int count2);
 
 
 

@@ -143,24 +143,21 @@ static int xdl_prepare_ctx(mmfile_t *mf, long narec, xpparam_t const *xpp,
 	char *rchg;
 	long *rindex;
 
-	if (xdl_cha_init(&xdf->rcha, sizeof(xrecord_t), narec / 4 + 1) < 0) {
+	ha = NULL;
+	rindex = NULL;
+	rchg = NULL;
+	rhash = NULL;
+	recs = NULL;
 
-		return -1;
-	}
-	if (!(recs = (xrecord_t **) xdl_malloc(narec * sizeof(xrecord_t *)))) {
-
-		xdl_cha_free(&xdf->rcha);
-		return -1;
-	}
+	if (xdl_cha_init(&xdf->rcha, sizeof(xrecord_t), narec / 4 + 1) < 0)
+		goto abort;
+	if (!(recs = (xrecord_t **) xdl_malloc(narec * sizeof(xrecord_t *))))
+		goto abort;
 
 	hbits = xdl_hashbits((unsigned int) narec);
 	hsize = 1 << hbits;
-	if (!(rhash = (xrecord_t **) xdl_malloc(hsize * sizeof(xrecord_t *)))) {
-
-		xdl_free(recs);
-		xdl_cha_free(&xdf->rcha);
-		return -1;
-	}
+	if (!(rhash = (xrecord_t **) xdl_malloc(hsize * sizeof(xrecord_t *))))
+		goto abort;
 	memset(rhash, 0, hsize * sizeof(xrecord_t *));
 
 	nrec = 0;

@@ -175,63 +172,30 @@ static int xdl_prepare_ctx(mmfile_t *mf, long narec, xpparam_t const *xpp,
 			hav = xdl_hash_record(&cur, top, xpp->flags);
 			if (nrec >= narec) {
 				narec *= 2;
-				if (!(rrecs = (xrecord_t **) xdl_realloc(recs, narec * sizeof(xrecord_t *)))) {
-
-					xdl_free(rhash);
-					xdl_free(recs);
-					xdl_cha_free(&xdf->rcha);
-					return -1;
-				}
+				if (!(rrecs = (xrecord_t **) xdl_realloc(recs, narec * sizeof(xrecord_t *))))
+					goto abort;
 				recs = rrecs;
 			}
-			if (!(crec = xdl_cha_alloc(&xdf->rcha))) {
-
-				xdl_free(rhash);
-				xdl_free(recs);
-				xdl_cha_free(&xdf->rcha);
-				return -1;
-			}
+			if (!(crec = xdl_cha_alloc(&xdf->rcha)))
+				goto abort;
 			crec->ptr = prev;
 			crec->size = (long) (cur - prev);
 			crec->ha = hav;
 			recs[nrec++] = crec;
 
-			if (xdl_classify_record(cf, rhash, hbits, crec) < 0) {
-
-				xdl_free(rhash);
-				xdl_free(recs);
-				xdl_cha_free(&xdf->rcha);
-				return -1;
-			}
+			if (xdl_classify_record(cf, rhash, hbits, crec) < 0)
+				goto abort;
 		}
 	}
 
-	if (!(rchg = (char *) xdl_malloc((nrec + 2) * sizeof(char)))) {
-
-		xdl_free(rhash);
-		xdl_free(recs);
-		xdl_cha_free(&xdf->rcha);
-		return -1;
-	}
+	if (!(rchg = (char *) xdl_malloc((nrec + 2) * sizeof(char))))
+		goto abort;
 	memset(rchg, 0, (nrec + 2) * sizeof(char));
 
-	if (!(rindex = (long *) xdl_malloc((nrec + 1) * sizeof(long)))) {
-
-		xdl_free(rchg);
-		xdl_free(rhash);
-		xdl_free(recs);
-		xdl_cha_free(&xdf->rcha);
-		return -1;
-	}
-	if (!(ha = (unsigned long *) xdl_malloc((nrec + 1) * sizeof(unsigned long)))) {
-
-		xdl_free(rindex);
-		xdl_free(rchg);
-		xdl_free(rhash);
-		xdl_free(recs);
-		xdl_cha_free(&xdf->rcha);
-		return -1;
-	}
+	if (!(rindex = (long *) xdl_malloc((nrec + 1) * sizeof(long))))
+		goto abort;
+	if (!(ha = (unsigned long *) xdl_malloc((nrec + 1) * sizeof(unsigned long))))
+		goto abort;
 
 	xdf->nrec = nrec;
 	xdf->recs = recs;

@@ -245,6 +209,15 @@ static int xdl_prepare_ctx(mmfile_t *mf, long narec, xpparam_t const *xpp,
 	xdf->dend = nrec - 1;
 
 	return 0;
+
+abort:
+	xdl_free(ha);
+	xdl_free(rindex);
+	xdl_free(rchg);
+	xdl_free(rhash);
+	xdl_free(recs);
+	xdl_cha_free(&xdf->rcha);
+	return -1;
 }
 
 

@@ -0,0 +1,165 @@
+#!/bin/sh
+
+test_diff_frobnitz() {
+	cat >file1 <<\EOF
+#include <stdio.h>
+
+// Frobs foo heartily
+int frobnitz(int foo)
+{
+    int i;
+    for(i = 0; i < 10; i++)
+    {
+        printf("Your answer is: ");
+        printf("%d\n", foo);
+    }
+}
+
+int fact(int n)
+{
+    if(n > 1)
+    {
+        return fact(n-1) * n;
+    }
+    return 1;
+}
+
+int main(int argc, char **argv)
+{
+    frobnitz(fact(10));
+}
+EOF
+
+	cat >file2 <<\EOF
+#include <stdio.h>
+
+int fib(int n)
+{
+    if(n > 2)
+    {
+        return fib(n-1) + fib(n-2);
+    }
+    return 1;
+}
+
+// Frobs foo heartily
+int frobnitz(int foo)
+{
+    int i;
+    for(i = 0; i < 10; i++)
+    {
+        printf("%d\n", foo);
+    }
+}
+
+int main(int argc, char **argv)
+{
+    frobnitz(fib(10));
+}
+EOF
+
+	cat >expect <<\EOF
+diff --git a/file1 b/file2
+index 6faa5a3..e3af329 100644
+--- a/file1
++++ b/file2
+@@ -1,26 +1,25 @@
+ #include <stdio.h>
+ 
++int fib(int n)
++{
++    if(n > 2)
++    {
++        return fib(n-1) + fib(n-2);
++    }
++    return 1;
++}
++
+ // Frobs foo heartily
+ int frobnitz(int foo)
+ {
+     int i;
+     for(i = 0; i < 10; i++)
+     {
+-        printf("Your answer is: ");
+         printf("%d\n", foo);
+     }
+ }
+ 
+-int fact(int n)
+-{
+-    if(n > 1)
+-    {
+-        return fact(n-1) * n;
+-    }
+-    return 1;
+-}
+-
+ int main(int argc, char **argv)
+ {
+-    frobnitz(fact(10));
++    frobnitz(fib(10));
+ }
+EOF
+
+	STRATEGY=$1
+
+	test_expect_success "$STRATEGY diff" '
+		test_must_fail git diff --no-index "--$STRATEGY" file1 file2 > output &&
+		test_cmp expect output
+	'
+
+	test_expect_success "$STRATEGY diff output is valid" '
+		mv file2 expect &&
+		git apply < output &&
+		test_cmp expect file2
+	'
+}
+
+test_diff_unique() {
+	cat >uniq1 <<\EOF
+1
+2
+3
+4
+5
+6
+EOF
+
+	cat >uniq2 <<\EOF
+a
+b
+c
+d
+e
+f
+EOF
+
+	cat >expect <<\EOF
+diff --git a/uniq1 b/uniq2
+index b414108..0fdf397 100644
+--- a/uniq1
++++ b/uniq2
+@@ -1,6 +1,6 @@
+-1
+-2
+-3
+-4
+-5
+-6
++a
++b
++c
++d
++e
++f
+EOF
+
+	STRATEGY=$1
+
+	test_expect_success 'completely different files' '
+		test_must_fail git diff --no-index "--$STRATEGY" uniq1 uniq2 > output &&
+		test_cmp expect output
+	'
+}
+