From: Tony Cook <tony@develop-help.com>
Date: Mon, 7 Jan 2019 11:31:33 +0000 (+1100)
Subject: map() would corrupt a channel if there was a gap in the arrayref of channels.
X-Git-Tag: v1.009~9
X-Git-Url: http://git.imager.perl.org/imager.git/commitdiff_plain/35ec3a876754c726ff47cb1fde9a0cf472d9c519

map() would corrupt a channel if there was a gap in the arrayref of channels.
---

diff --git a/Changes b/Changes
index c06e676c..3c58eb57 100644
--- a/Changes
+++ b/Changes
@@ -5,6 +5,9 @@ General changes:
  - to_paletted() and make_palette() now fail (with an error in
    errstr()) if invalid quantization parameters are supplied.
 
+ - map() would corrupt a channel if there was a gap in the arrayref of
+   channels.  Detected by Coverity.  CID 185300.
+
 Coverity finally finished a build[1], fix a few problems:
 
 High severity:
diff --git a/map.c b/map.c
index aedd0dff..9ddc62f8 100644
--- a/map.c
+++ b/map.c
@@ -63,7 +63,8 @@ i_map(i_img *im, unsigned char (*maps)[256], unsigned int mask) {
     i_glin(im, 0, im->xsize, y, vals);
     for (x = 0; x < im->xsize; ++x) {
       for(ch = minset; ch<=maxset; ch++) {
-	if (!maps[ch]) continue;
+	if (!(mask & (1 << ch)))
+	  continue;
 	vals[x].channel[ch] = maps[ch][vals[x].channel[ch]];
       }
     }
diff --git a/t/300-transform/060-map.t b/t/300-transform/060-map.t
index d8d8a18f..67a8744e 100644
--- a/t/300-transform/060-map.t
+++ b/t/300-transform/060-map.t
@@ -73,4 +73,14 @@ SKIP: {
   ok($out, "map done");
 }
 
+{ # CID 185300
+  # the check for whether a map() channel was used was incorrect
+  my @map1 = ( 0 .. 255 );
+  my $im = test_image;
+  my $cmp = test_image->copy;
+  ok($im->map(maps => [ \@map1, undef, \@map1 ]),
+     "map with gap in maps");
+  is_image($im, $cmp, "should be no changes");
+}
+
 done_testing();