Merge branch 'rs/avoid-overflow-in-midpoint-computation'

Code clean-up to avoid signed integer overlaps during binary search.

* rs/avoid-overflow-in-midpoint-computation:
  cleanup: fix possible overflow errors in binary search, part 2

Author: gitster

builtin/ls-files.c

@@ -373,7 +373,7 @@ static void prune_index(struct index_state *istate,
 	first = pos;
 	last = istate->cache_nr;
 	while (last > first) {
-		int next = (last + first) >> 1;
+		int next = first + ((last - first) >> 1);
 		const struct cache_entry *ce = istate->cache[next];
 		if (!strncmp(ce->name, prefix, prefixlen)) {
 			first = next+1;

diffcore-rename.c

@@ -23,7 +23,7 @@ static int find_rename_dst(struct diff_filespec *two)
 	first = 0;
 	last = rename_dst_nr;
 	while (last > first) {
-		int next = (last + first) >> 1;
+		int next = first + ((last - first) >> 1);
 		struct diff_rename_dst *dst = &(rename_dst[next]);
 		int cmp = strcmp(two->path, dst->two->path);
 		if (!cmp)
@@ -83,7 +83,7 @@ static struct diff_rename_src *register_rename_src(struct diff_filepair *p)
 	first = 0;
 	last = rename_src_nr;
 	while (last > first) {
-		int next = (last + first) >> 1;
+		int next = first + ((last - first) >> 1);
 		struct diff_rename_src *src = &(rename_src[next]);
 		int cmp = strcmp(one->path, src->p->one->path);
 		if (!cmp)

dir.c

@@ -701,7 +701,7 @@ static struct untracked_cache_dir *lookup_untracked(struct untracked_cache *uc,
 	first = 0;
 	last = dir->dirs_nr;
 	while (last > first) {
-		int cmp, next = (last + first) >> 1;
+		int cmp, next = first + ((last - first) >> 1);
 		d = dir->dirs[next];
 		cmp = strncmp(name, d->name, len);
 		if (!cmp && strlen(d->name) > len)

name-hash.c

@@ -345,8 +345,9 @@ static int handle_range_dir(
 	else {
 		int begin = k_start;
 		int end = k_end;
+		assert(begin >= 0);
 		while (begin < end) {
-			int mid = (begin + end) >> 1;
+			int mid = begin + ((end - begin) >> 1);
 			int cmp = strncmp(istate->cache[mid]->name, prefix->buf, prefix->len);
 			if (cmp == 0) /* mid has same prefix; look in second part */
 				begin = mid + 1;

read-cache.c

@@ -549,7 +549,7 @@ static int index_name_stage_pos(const struct index_state *istate, const char *na
 	first = 0;
 	last = istate->cache_nr;
 	while (last > first) {
-		int next = (last + first) >> 1;
+		int next = first + ((last - first) >> 1);
 		struct cache_entry *ce = istate->cache[next];
 		int cmp = cache_name_stage_compare(name, namelen, stage, ce->name, ce_namelen(ce), ce_stage(ce));
 		if (!cmp)

sh-i18n--envsubst.c

@@ -249,7 +249,7 @@ sorted_string_list_member (const string_list_ty *slp, const char *s)
 	{
 	  /* Here we know that if s is in the list, it is at an index j
 	     with j1 <= j < j2.  */
-	  size_t j = (j1 + j2) >> 1;
+	  size_t j = j1 + ((j2 - j1) >> 1);
 	  int result = strcmp (slp->item[j], s);
 
 	  if (result > 0)