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From: "Johannes Schindelin via GitGitGadget" <gitgitgadget@gmail.com>
To: git@vger.kernel.org
Cc: Thomas Rast <tr@thomasrast.ch>,
	Junio C Hamano <gitster@pobox.com>,
	Johannes Schindelin <johannes.schindelin@gmx.de>
Subject: [PATCH 2/4] line-log: adjust start/end of ranges individually
Date: Sat, 04 Aug 2018 15:18:25 -0700 (PDT)	[thread overview]
Message-ID: <7f92d92154143127734a638e41e064adce46a2e2.1533421100.git.gitgitgadget@gmail.com> (raw)
In-Reply-To: <pull.15.git.gitgitgadget@gmail.com>

From: Johannes Schindelin <johannes.schindelin@gmx.de>

When traversing commits and adjusting the ranges, things can get really
tricky. For example, when the line range of interest encloses several
hunks of a commit, the line range can actually shrink.

Currently, range_set_shift_diff() does not anticipate that scenario and
blindly adjusts start and end by the same offset ("shift" the range).

This can lead to a couple of surprising issues, such as assertions in
range_set_append() (when the end of a given range is not adjusted
properly, it can point after the start of the next range) or even
segmentation faults (when t_end in the loop of dump_diff_hacky_one()
points outside the valid line range).

Let's fix this by adjusting the start and the end offsets individually.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
---
 line-log.c | 10 ++++++++--
 1 file changed, 8 insertions(+), 2 deletions(-)

diff --git a/line-log.c b/line-log.c
index 72a5fed66..d8d09b5ee 100644
--- a/line-log.c
+++ b/line-log.c
@@ -427,7 +427,7 @@ static void range_set_shift_diff(struct range_set *out,
 				 struct diff_ranges *diff)
 {
 	unsigned int i, j = 0;
-	long offset = 0;
+	long offset = 0, start_offset;
 	struct range *src = rs->ranges;
 	struct range *target = diff->target.ranges;
 	struct range *parent = diff->parent.ranges;
@@ -438,7 +438,13 @@ static void range_set_shift_diff(struct range_set *out,
 				- (target[j].end-target[j].start);
 			j++;
 		}
-		range_set_append(out, src[i].start+offset, src[i].end+offset);
+		start_offset = offset;
+		while (j < diff->target.nr && src[i].end > target[j].end) {
+			offset += (parent[j].end-parent[j].start)
+				- (target[j].end-target[j].start);
+			j++;
+		}
+		range_set_append(out, src[i].start+start_offset, src[i].end+offset);
 	}
 }
 
-- 
gitgitgadget


  parent reply	other threads:[~2018-08-04 22:18 UTC|newest]

Thread overview: 20+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-08-04 22:18 [PATCH 0/4] line-log: be more careful when adjusting multiple line ranges Johannes Schindelin via GitGitGadget
2018-08-04 22:18 ` [PATCH 1/4] line-log: demonstrate a bug with nearly-overlapping ranges Johannes Schindelin via GitGitGadget
2018-08-05  1:59   ` Jonathan Nieder
2018-08-06 10:27     ` Johannes Schindelin
2018-08-06 14:47       ` Jonathan Nieder
2018-08-06 15:33         ` Jonathan Nieder
2018-08-04 22:18 ` Johannes Schindelin via GitGitGadget [this message]
2018-08-05 10:14   ` [PATCH 2/4] line-log: adjust start/end of ranges individually Eric Sunshine
2018-08-05 10:57     ` Eric Sunshine
2018-08-06 12:52     ` Johannes Schindelin
2018-08-04 22:18 ` [PATCH 3/4] line-log: optimize ranges by joining them when possible Johannes Schindelin via GitGitGadget
2018-08-05  6:11   ` Junio C Hamano
2018-08-05  8:45   ` Andrei Rybak
2018-08-05 10:31     ` Eric Sunshine
2018-08-04 22:18 ` [PATCH 4/4] line-log: convert an assertion to a full BUG() call Johannes Schindelin via GitGitGadget
2018-08-05 10:42   ` Eric Sunshine
2018-08-06 13:14     ` Johannes Schindelin
2018-08-07  9:09       ` Eric Sunshine
2018-08-07 22:00         ` Eric Sunshine
2018-08-05 10:39 ` [PATCH 0/4] line-log: be more careful when adjusting multiple line ranges Eric Sunshine

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