Merge branch 'pw/xdiff-alloc-fail'

Improve failure case behaviour of xdiff library when memory
allocation fails.

* pw/xdiff-alloc-fail:
  xdiff: handle allocation failure when merging
  xdiff: refactor a function
  xdiff: handle allocation failure in patience diff
  xdiff: fix a memory leak

Author: gitster

xdiff/xdiffi.c

@@ -315,16 +315,19 @@ int xdl_do_diff(mmfile_t *mf1, mmfile_t *mf2, xpparam_t const *xpp,
 	long *kvd, *kvdf, *kvdb;
 	xdalgoenv_t xenv;
 	diffdata_t dd1, dd2;
+	int res;
 
-	if (XDF_DIFF_ALG(xpp->flags) == XDF_PATIENCE_DIFF)
-		return xdl_do_patience_diff(mf1, mf2, xpp, xe);
-
-	if (XDF_DIFF_ALG(xpp->flags) == XDF_HISTOGRAM_DIFF)
-		return xdl_do_histogram_diff(mf1, mf2, xpp, xe);
+	if (xdl_prepare_env(mf1, mf2, xpp, xe) < 0)
+		return -1;
 
-	if (xdl_prepare_env(mf1, mf2, xpp, xe) < 0) {
+	if (XDF_DIFF_ALG(xpp->flags) == XDF_PATIENCE_DIFF) {
+		res = xdl_do_patience_diff(mf1, mf2, xpp, xe);
+		goto out;
+	}
 
-		return -1;
+	if (XDF_DIFF_ALG(xpp->flags) == XDF_HISTOGRAM_DIFF) {
+		res = xdl_do_histogram_diff(mf1, mf2, xpp, xe);
+		goto out;
 	}
 
 	/*
@@ -359,17 +362,15 @@ int xdl_do_diff(mmfile_t *mf1, mmfile_t *mf2, xpparam_t const *xpp,
 	dd2.rchg = xe->xdf2.rchg;
 	dd2.rindex = xe->xdf2.rindex;
 
-	if (xdl_recs_cmp(&dd1, 0, dd1.nrec, &dd2, 0, dd2.nrec,
-			 kvdf, kvdb, (xpp->flags & XDF_NEED_MINIMAL) != 0, &xenv) < 0) {
-
-		xdl_free(kvd);
-		xdl_free_env(xe);
-		return -1;
-	}
-
+	res = xdl_recs_cmp(&dd1, 0, dd1.nrec, &dd2, 0, dd2.nrec,
+			   kvdf, kvdb, (xpp->flags & XDF_NEED_MINIMAL) != 0,
+			   &xenv);
 	xdl_free(kvd);
+ out:
+	if (res < 0)
+		xdl_free_env(xe);
 
-	return 0;
+	return res;
 }
 
 

xdiff/xhistogram.c

@@ -372,9 +372,6 @@ static int histogram_diff(xpparam_t const *xpp, xdfenv_t *env,
 int xdl_do_histogram_diff(mmfile_t *file1, mmfile_t *file2,
 	xpparam_t const *xpp, xdfenv_t *env)
 {
-	if (xdl_prepare_env(file1, file2, xpp, env) < 0)
-		return -1;
-
 	return histogram_diff(xpp, env,
 		env->xdf1.dstart + 1, env->xdf1.dend - env->xdf1.dstart + 1,
 		env->xdf2.dstart + 1, env->xdf2.dend - env->xdf2.dstart + 1);

xdiff/xmerge.c

@@ -684,54 +684,56 @@ static int xdl_do_merge(xdfenv_t *xe1, xdchange_t *xscr1,
 int xdl_merge(mmfile_t *orig, mmfile_t *mf1, mmfile_t *mf2,
 		xmparam_t const *xmp, mmbuffer_t *result)
 {
-	xdchange_t *xscr1, *xscr2;
+	xdchange_t *xscr1 = NULL, *xscr2 = NULL;
 	xdfenv_t xe1, xe2;
-	int status;
+	int status = -1;
 	xpparam_t const *xpp = &xmp->xpp;
 
 	result->ptr = NULL;
 	result->size = 0;
 
-	if (xdl_do_diff(orig, mf1, xpp, &xe1) < 0) {
+	if (xdl_do_diff(orig, mf1, xpp, &xe1) < 0)
 		return -1;
-	}
-	if (xdl_do_diff(orig, mf2, xpp, &xe2) < 0) {
-		xdl_free_env(&xe1);
-		return -1;
-	}
+
+	if (xdl_do_diff(orig, mf2, xpp, &xe2) < 0)
+		goto free_xe1; /* avoid double free of xe2 */
+
 	if (xdl_change_compact(&xe1.xdf1, &xe1.xdf2, xpp->flags) < 0 ||
 	    xdl_change_compact(&xe1.xdf2, &xe1.xdf1, xpp->flags) < 0 ||
-	    xdl_build_script(&xe1, &xscr1) < 0) {
-		xdl_free_env(&xe1);
-		return -1;
-	}
+	    xdl_build_script(&xe1, &xscr1) < 0)
+		goto out;
+
 	if (xdl_change_compact(&xe2.xdf1, &xe2.xdf2, xpp->flags) < 0 ||
 	    xdl_change_compact(&xe2.xdf2, &xe2.xdf1, xpp->flags) < 0 ||
-	    xdl_build_script(&xe2, &xscr2) < 0) {
-		xdl_free_script(xscr1);
-		xdl_free_env(&xe1);
-		xdl_free_env(&xe2);
-		return -1;
-	}
-	status = 0;
+	    xdl_build_script(&xe2, &xscr2) < 0)
+		goto out;
+
 	if (!xscr1) {
 		result->ptr = xdl_malloc(mf2->size);
+		if (!result->ptr)
+			goto out;
+		status = 0;
 		memcpy(result->ptr, mf2->ptr, mf2->size);
 		result->size = mf2->size;
 	} else if (!xscr2) {
 		result->ptr = xdl_malloc(mf1->size);
+		if (!result->ptr)
+			goto out;
+		status = 0;
 		memcpy(result->ptr, mf1->ptr, mf1->size);
 		result->size = mf1->size;
 	} else {
 		status = xdl_do_merge(&xe1, xscr1,
 				      &xe2, xscr2,
 				      xmp, result);
 	}
+ out:
 	xdl_free_script(xscr1);
 	xdl_free_script(xscr2);
 
-	xdl_free_env(&xe1);
 	xdl_free_env(&xe2);
+ free_xe1:
+	xdl_free_env(&xe1);
 
 	return status;
 }

xdiff/xpatience.c

@@ -198,7 +198,7 @@ static int binary_search(struct entry **sequence, int longest,
  * item per sequence length: the sequence with the smallest last
  * element (in terms of line2).
  */
-static struct entry *find_longest_common_sequence(struct hashmap *map)
+static int find_longest_common_sequence(struct hashmap *map, struct entry **res)
 {
 	struct entry **sequence = xdl_malloc(map->nr * sizeof(struct entry *));
 	int longest = 0, i;
@@ -211,6 +211,9 @@ static struct entry *find_longest_common_sequence(struct hashmap *map)
 	 */
 	int anchor_i = -1;
 
+	if (!sequence)
+		return -1;
+
 	for (entry = map->first; entry; entry = entry->next) {
 		if (!entry->line2 || entry->line2 == NON_UNIQUE)
 			continue;
@@ -230,8 +233,9 @@ static struct entry *find_longest_common_sequence(struct hashmap *map)
 
 	/* No common unique lines were found */
 	if (!longest) {
+		*res = NULL;
 		xdl_free(sequence);
-		return NULL;
+		return 0;
 	}
 
 	/* Iterate starting at the last element, adjusting the "next" members */
@@ -241,8 +245,9 @@ static struct entry *find_longest_common_sequence(struct hashmap *map)
 		entry->previous->next = entry;
 		entry = entry->previous;
 	}
+	*res = entry;
 	xdl_free(sequence);
-	return entry;
+	return 0;
 }
 
 static int match(struct hashmap *map, int line1, int line2)
@@ -358,25 +363,23 @@ static int patience_diff(mmfile_t *file1, mmfile_t *file2,
 		return 0;
 	}
 
-	first = find_longest_common_sequence(&map);
+	result = find_longest_common_sequence(&map, &first);
+	if (result)
+		goto out;
 	if (first)
 		result = walk_common_sequence(&map, first,
 			line1, count1, line2, count2);
 	else
 		result = fall_back_to_classic_diff(&map,
 			line1, count1, line2, count2);
-
+ out:
 	xdl_free(map.entries);
 	return result;
 }
 
 int xdl_do_patience_diff(mmfile_t *file1, mmfile_t *file2,
 		xpparam_t const *xpp, xdfenv_t *env)
 {
-	if (xdl_prepare_env(file1, file2, xpp, env) < 0)
-		return -1;
-
-	/* environment is cleaned up in xdl_diff() */
 	return patience_diff(file1, file2, xpp, env,
 			1, env->xdf1.nrec, 1, env->xdf2.nrec);
 }