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[PATCH 1/2] diffcore-rename: split locate_rename_dst into two functions

From
Jeff King <peff@peff.net>
Date
Feb 27, 2015, 01:39 UTC
Message-ID
<20150227013948.GA3210@peff.net>
In-Reply-To
<20150227013847.GA2983@peff.net>

This function manages the mapping of destination pathnames to filepairs, and it handles both insertion and lookup. This makes the return value a bit confusing, as we return a newly created entry (even though no caller cares), and have no room to indicate to the caller that an entry already existed.

Instead, let's break this up into two distinct functions, both backed by a common binary search. The binary search will use our normal "return the index if we found something, or negative index minus one to show where it would have gone" semantics.

Signed-off-by: Jeff King <peff@peff.net>
---
 diffcore-rename.c | 38 ++++++++++++++++++++++++++------------
 1 file changed, 26 insertions(+), 12 deletions(-)
diff --git a/diffcore-rename.c b/diffcore-rename.c
index 4e132f1..4250cc0 100644
--- a/diffcore-rename.c
+++ b/diffcore-rename.c
@@ -15,8 +15,7 @@ static struct diff_rename_dst {
 } *rename_dst;
 static int rename_dst_nr, rename_dst_alloc;
 
-static struct diff_rename_dst *locate_rename_dst(struct diff_filespec *two,
-						 int insert_ok)
+static int find_rename_dst(struct diff_filespec *two)
 {
 	int first, last;
 
@@ -27,16 +26,33 @@ static struct diff_rename_dst *locate_rename_dst(struct diff_filespec *two,
 		struct diff_rename_dst *dst = &(rename_dst[next]);
 		int cmp = strcmp(two->path, dst->two->path);
 		if (!cmp)
-			return dst;
+			return next;
 		if (cmp < 0) {
 			last = next;
 			continue;
 		}
 		first = next+1;
 	}
-	/* not found */
-	if (!insert_ok)
-		return NULL;
+	return -first - 1;
+}
+
+static struct diff_rename_dst *locate_rename_dst(struct diff_filespec *two)
+{
+	int ofs = find_rename_dst(two);
+	return ofs < 0 ? NULL : &rename_dst[ofs];
+}
+
+/*
+ * Returns 0 on success, -1 if we found a duplicate.
+ */
+static int add_rename_dst(struct diff_filespec *two)
+{
+	int first = find_rename_dst(two);
+
+	if (first >= 0)
+		return -1;
+	first = -first - 1;
+
 	/* insert to make it at "first" */
 	ALLOC_GROW(rename_dst, rename_dst_nr + 1, rename_dst_alloc);
 	rename_dst_nr++;
@@ -46,7 +62,7 @@ static struct diff_rename_dst *locate_rename_dst(struct diff_filespec *two,
 	rename_dst[first].two = alloc_filespec(two->path);
 	fill_filespec(rename_dst[first].two, two->sha1, two->sha1_valid, two->mode);
 	rename_dst[first].pair = NULL;
-	return &(rename_dst[first]);
+	return 0;
 }
 
 /* Table of rename/copy src files */
@@ -451,7 +467,7 @@ void diffcore_rename(struct diff_options *options)
 				 is_empty_blob_sha1(p->two->sha1))
 				continue;
 			else
-				locate_rename_dst(p->two, 1);
+				add_rename_dst(p->two);
 		}
 		else if (!DIFF_OPT_TST(options, RENAME_EMPTY) &&
 			 is_empty_blob_sha1(p->one->sha1))
@@ -582,8 +598,7 @@ void diffcore_rename(struct diff_options *options)
 			 * We would output this create record if it has
 			 * not been turned into a rename/copy already.
 			 */
-			struct diff_rename_dst *dst =
-				locate_rename_dst(p->two, 0);
+			struct diff_rename_dst *dst = locate_rename_dst(p->two);
 			if (dst && dst->pair) {
 				diff_q(&outq, dst->pair);
 				pair_to_free = p;
@@ -613,8 +628,7 @@ void diffcore_rename(struct diff_options *options)
 			 */
 			if (DIFF_PAIR_BROKEN(p)) {
 				/* broken delete */
-				struct diff_rename_dst *dst =
-					locate_rename_dst(p->one, 0);
+				struct diff_rename_dst *dst = locate_rename_dst(p->one);
 				if (dst && dst->pair)
 					/* counterpart is now rename/copy */
 					pair_to_free = p;
-- 
2.3.0.449.g1690e78
Previous: Jeff KingNext: Jeff King
Message 10 of 12 in “[BUG] diffcore-rename with duplicate tree entries can segfault”
  1. Jeff KingFeb 24, 2015
  2. Junio C HamanoFeb 24, 2015
  3. Jeff KingFeb 24, 2015
  4. Junio C HamanoFeb 24, 2015
  5. Jeff KingFeb 24, 2015
  6. Junio C HamanoFeb 25, 2015
  7. Jeff KingFeb 25, 2015
  8. Junio C HamanoFeb 25, 2015
  9. 0/2 diffcore-rename with duplicate tree entries can segfaultJeff King, Feb 27, 2015
  10. 1/2 diffcore-rename: split locate_rename_dst into two functionsJeff King, Feb 27, 2015
  11. 2/2 diffcore-rename: avoid processing duplicate destinationsJeff King, Feb 27, 2015
  12. Junio C HamanoFeb 27, 2015

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