linux-kernel - [PATCH 1/1 (variant 2)] remap-log: fix map generator

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Date:	Thu,  3 Nov 2011 16:01:52 +0200
From:	Artem Bityutskiy <dedekind1@...il.com>
To:	Al Viro <viro@...IV.linux.org.uk>
Cc:	Artem Bityutskiy <dedekind1@...il.com>,
	"Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>,
	linux-kernel@...r.kernel.org
Subject: [PATCH 1/1 (variant 2)] remap-log: fix map generator

From: Artem Bityutskiy <artem.bityutskiy@...ux.intel.com>

This patch fixes a bug in the 'parse_diff()' function. This function iterates
over every changed file and every hunk in this file and at each iteration it
prints the hunk's map for the _previous_ iteration. This is taken into account
when it switches to the next file - just before starting processing hunks in
this file, it prints the map for the last hunk of the _previous_ file.

However, if we are at the very last file or we have a diff which changes only
one single file, and the last hunk is processed - we do not print the map of
this last hunk and just exit. The result is a buggy map - because the map of
the very last hunk is not printed.

Here is a short example to demonstrate the bug. The diff is:

|||diff --git a/sound/soc/codecs/sn95031.c b/sound/soc/codecs/sn95031.c
|||index 920e7bb..8c43fdd 100644
|||--- a/sound/soc/codecs/sn95031.c
|||+++ b/sound/soc/codecs/sn95031.c
|||@@ -811,0 +812 @@ static int sn95031_pcm_hs_mute(struct snd_soc_dai *dai, int mute)
|||+       int tmp = !mute;
|||@@ -813 +814 @@ static int sn95031_pcm_hs_mute(struct snd_soc_dai *dai, int mute)
|||-                       SN95031_HSLVOLCTRL, BIT(7), (!mute << 7));
|||+                       SN95031_HSLVOLCTRL, BIT(7), tmp << 7);
|||@@ -815 +816,3 @@ static int sn95031_pcm_hs_mute(struct snd_soc_dai *dai, int mute)
|||-                       SN95031_HSRVOLCTRL, BIT(7), (!mute << 7));
|||+                       SN95031_HSRVOLCTRL, BIT(7), tmp << 7);
|||+       snd_soc_update_bits(dai->codec,
|||+                       SN95031_DRIVEREN, BIT(0) | BIT(1), tmp | tmp << 1);

And remap-log generates an incorrect map:

M sound/soc/codecs/sn95031.c sound/soc/codecs/sn95031.c
1 1
812 813
813 0
814 815
815 0

Notice that the last map entry basically says that all lines in the old file
starting from line 815 have been deleted, which is not true - only one line
number 815 has been deleted.

The correct map should look like this:

M sound/soc/codecs/sn95031.c sound/soc/codecs/sn95031.c
1 1
812 813
813 0
814 815
815 0
816 819

To fix the bug this patch prints the map of the last hung just before
'parse_diff()' exits.

Signed-off-by: Artem Bityutskiy <artem.bityutskiy@...ux.intel.com>
---
 tools/remap-log.c |    3 +++
 1 files changed, 3 insertions(+), 0 deletions(-)

diff --git a/tools/remap-log.c b/tools/remap-log.c
index 327b870..ee79ed9 100644
--- a/tools/remap-log.c
+++ b/tools/remap-log.c
@@ -424,6 +424,9 @@ void parse_diff(void)
 			break;
 		}
 	}
+
+	if (!suppress && skipping && from + to != 2)
+		printf("%d %d\n", from, to);
 	return;
 Ediff:
 	die("odd diff");
-- 
1.7.7.1

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