[gsoc-diff] malloc()/free() once

gistfile1.diff

diff --git a/xdiff/xhistogram.c b/xdiff/xhistogram.c
index ea7b82d..2e63235 100644
--- a/xdiff/xhistogram.c
+++ b/xdiff/xhistogram.c
@@ -237,12 +237,10 @@ static int fall_back_to_classic_diff(struct histindex *index,
 				  line1, count1, line2, count2);
 }
 
-static int histogram_diff(xpparam_t const *xpp, xdfenv_t *env,
+static int histogram_diff(struct histindex *index,
 	int line1, int count1, int line2, int count2)
 {
-	struct histindex index;
 	struct region lcs;
-	int sz;
 	int result = -1;
 
 	if (count1 <= 0 && count2 <= 0)
@@ -253,85 +251,57 @@ static int histogram_diff(xpparam_t const *xpp, xdfenv_t *env,
 
 	if (!count1) {
 		while(count2--)
-			env->xdf2.rchg[line2++ - 1] = 1;
+			index->env->xdf2.rchg[line2++ - 1] = 1;
 		return 0;
 	} else if (!count2) {
 		while(count1--)
-			env->xdf1.rchg[line1++ - 1] = 1;
+			index->env->xdf1.rchg[line1++ - 1] = 1;
 		return 0;
 	}
 
-	memset(&index, 0, sizeof(index));
+	index->recs_count = 0;
+	index->cnt = 0;
+	index->has_common = 0;
 
-	index.env = env;
-	index.xpp = xpp;
+	memset(index->table, 0, index->table_size * sizeof(int));
+	memset(index->recs, 0, index->recs_size * sizeof(long));
+	memset(index->next, 0, index->size * sizeof(int));
+	memset(index->rec_idxs, 0, index->size * sizeof(int));
 
-	index.table = NULL;
-	index.recs = NULL;
-	index.next = NULL;
-	index.rec_idxs = NULL;
-
-	index.table_bits = xdl_hashbits(count1);
-	sz = index.table_size = 1 << index.table_bits;
-	sz *= sizeof(int);
-	if (!(index.table = xdl_malloc(sz)))
-		goto cleanup;
-	memset(index.table, 0, sz);
-
-	sz = index.recs_size = XDL_MAX(4, count1 >> 3);
-	sz *= sizeof(long);
-	if (!(index.recs = xdl_malloc(sz)))
-		goto cleanup;
-	memset(index.recs, 0, sz);
-
-	sz = index.size = count1;
-	sz *= sizeof(int);
-	if (!(index.next = xdl_malloc(sz)))
-		goto cleanup;
-	memset(index.next, 0, sz);
-
-	if (!(index.rec_idxs = xdl_malloc(sz)))
-		goto cleanup;
-	memset(index.rec_idxs, 0, sz);
-
-	index.ptr_shift = line1;
-	index.max_chain_length = 64;
+	index->ptr_shift = line1;
+	index->max_chain_length = 64;
 
 	memset(&lcs, 0, sizeof(lcs));
-	if (find_lcs(&index, &lcs, line1, count1, line2, count2))
-		result = fall_back_to_classic_diff(&index, line1, count1, line2, count2);
+	if (find_lcs(index, &lcs, line1, count1, line2, count2))
+		result = fall_back_to_classic_diff(index, line1, count1, line2, count2);
 	else {
 		result = 0;
 		if (lcs.begin1 == 0 && lcs.begin2 == 0) {
 			int ptr;
 			for (ptr = 0; ptr < count1; ptr++)
-				env->xdf1.rchg[line1 + ptr - 1] = 1;
+				index->env->xdf1.rchg[line1 + ptr - 1] = 1;
 			for (ptr = 0; ptr < count2; ptr++)
-				env->xdf2.rchg[line2 + ptr - 1] = 1;
+				index->env->xdf2.rchg[line2 + ptr - 1] = 1;
 		} else {
-			result = histogram_diff(xpp, env,
+			result = histogram_diff(index,
 				line1, lcs.begin1 - line1,
 				line2, lcs.begin2 - line2);
-			result = histogram_diff(xpp, env,
+			result = histogram_diff(index,
 				lcs.end1 + 1, LINE_END(1) - lcs.end1,
 				lcs.end2 + 1, LINE_END(2) - lcs.end2);
 			result *= -1;
 		}
 	}
 
-cleanup:
-	xdl_free(index.table);
-	xdl_free(index.recs);
-	xdl_free(index.next);
-	xdl_free(index.rec_idxs);
-
 	return result;
 }
 
 int xdl_do_histogram_diff(mmfile_t *file1, mmfile_t *file2,
 	xpparam_t const *xpp, xdfenv_t *env)
 {
+	struct histindex index;
 	int line1, line2, count1, count2;
+	int result = -1;
 
 	if (xdl_prepare_env(file1, file2, xpp, env) < 0)
 		return -1;
@@ -342,5 +312,37 @@ int xdl_do_histogram_diff(mmfile_t *file1, mmfile_t *file2,
 
 	reduce_common_start_end(xpp, env, &line1, &count1, &line2, &count2);
 
-	return histogram_diff(xpp, env, line1, count1, line2, count2);
+	index.env = env;
+	index.xpp = xpp;
+
+	index.table = NULL;
+	index.recs = NULL;
+	index.next = NULL;
+	index.rec_idxs = NULL;
+
+	index.table_bits = xdl_hashbits(count1);
+	index.table_size = 1 << index.table_bits;
+	if (!(index.table = xdl_malloc(index.table_size * sizeof(int))))
+		goto cleanup;
+
+	index.recs_size = XDL_MAX(4, count1 >> 3);
+	if (!(index.recs = xdl_malloc(index.recs_size * sizeof(long))))
+		goto cleanup;
+
+	index.size = count1;
+	if (!(index.next = xdl_malloc(index.size * sizeof(int))))
+		goto cleanup;
+
+	if (!(index.rec_idxs = xdl_malloc(index.size * sizeof(int))))
+		goto cleanup;
+
+	result = histogram_diff(&index, line1, count1, line2, count2);
+
+cleanup:
+	xdl_free(index.table);
+	xdl_free(index.recs);
+	xdl_free(index.next);
+	xdl_free(index.rec_idxs);
+
+	return result;
 }