Copied from Debian.

From 03a820b173ed1fdef6ff14b4468f5dbc02ff59be Mon Sep 17 00:00:00 2001
From: Heiko Lewin <heiko.lewin@worldiety.de>
Date: Tue, 15 Dec 2020 16:48:19 +0100
Subject: [PATCH] Fix mask usage in image-compositor

[trimmed test case, since not used in Debian build]

---
 src/cairo-image-compositor.c                |   8 ++--

--- cairo-1.16.0.orig/src/cairo-image-compositor.c
+++ cairo-1.16.0/src/cairo-image-compositor.c
@@ -2601,14 +2601,14 @@ _inplace_src_spans (void *abstract_rende
 		    unsigned num_spans)
 {
     cairo_image_span_renderer_t *r = abstract_renderer;
-    uint8_t *m;
+    uint8_t *m, *base = (uint8_t*)pixman_image_get_data(r->mask);
     int x0;
 
     if (num_spans == 0)
 	return CAIRO_STATUS_SUCCESS;
 
     x0 = spans[0].x;
-    m = r->_buf;
+    m = base;
     do {
 	int len = spans[1].x - spans[0].x;
 	if (len >= r->u.composite.run_length && spans[0].coverage == 0xff) {
@@ -2646,7 +2646,7 @@ _inplace_src_spans (void *abstract_rende
 				      spans[0].x, y,
 				      spans[1].x - spans[0].x, h);
 
-	    m = r->_buf;
+	    m = base;
 	    x0 = spans[1].x;
 	} else if (spans[0].coverage == 0x0) {
 	    if (spans[0].x != x0) {
@@ -2675,7 +2675,7 @@ _inplace_src_spans (void *abstract_rende
 #endif
 	    }
 
-	    m = r->_buf;
+	    m = base;
 	    x0 = spans[1].x;
 	} else {
 	    *m++ = spans[0].coverage;
ix-manual.es.po?id=2eb061be7981789199990f93058fa070728aad18'>commit</a><a href='/guix/diff/po/doc/guix-manual.es.po?id=2eb061be7981789199990f93058fa070728aad18'>diff</a></td><td class='form'><form class='right' method='get' action='/guix/log/po/doc/guix-manual.es.po'>
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<div class='path'>path: <a href='/guix/log/?id=2eb061be7981789199990f93058fa070728aad18'>root</a>/<a href='/guix/log/po?id=2eb061be7981789199990f93058fa070728aad18'>po</a>/<a href='/guix/log/po/doc?id=2eb061be7981789199990f93058fa070728aad18'>doc</a>/<a href='/guix/log/po/doc/guix-manual.es.po?id=2eb061be7981789199990f93058fa070728aad18'>guix-manual.es.po</a></div><div class='content'><table class='list nowrap'><tr class='nohover'><th class='left'>Age</th><th class='left'>Commit message (<a href='/guix/log/po/doc/guix-manual.es.po?id=2eb061be7981789199990f93058fa070728aad18&amp;showmsg=1'>Expand</a>)</th><th class='left'>Author</th></tr>
<tr><td><span title='2023-10-05 23:14:54 +0200'>2023-10-05</span></td><td><a href='/guix/commit/po/doc/guix-manual.es.po?id=3d4d7fec05a8bdb0764a37515bb7c739b1094ab5'>doc: Fix channel name typo.</a><span class='msg-avail'>...<span class='msg-tooltip'>When the manual has "variant-personal-packages", it actually refers to the
channel "variant-packages", as it is named so elsewhere.

To correct this, I ran the command

    grep -r -l variant-personal-packages | xargs \
    sed -i 's/variang-personal-packages/variant-packages/g'

* doc/guix.texi (Specifying Additional Channels): Fix channel name typo.
* po/doc/guix-manual.de.po: Fix channel name typo.
* po/doc/guix-manual.es.po: Fix channel name typo.
* po/doc/guix-manual.fr.po: Fix channel name typo.
* po/doc/guix-manual.pt_BR.po: Fix channel name typo.
* po/doc/guix-manual.ru.po: Fix channel name typo.
* po/doc/guix-manual.zh_CN.po: Fix channel name typo.

Signed-off-by: Nikolaos Chatzikonstantinou &lt;nchatz314@gmail.com&gt;
Signed-off-by: Ludovic Courtès &lt;ludo@gnu.org&gt;
</span></span></td><td>Nikolaos Chatzikonstantinou</td></tr>
<tr><td><span title='2023-06-30 14:26:07 +0200'>2023-06-30</span></td><td><a href='/guix/commit/po/doc/guix-manual.es.po?id=8af22b493199a17f46351c2f3d9f6ee759e48564'>nls: Update translations.</a><span class='msg-avail'>...<span class='msg-tooltip'>* po/packages/ja.po: New file.
* po/packages/LINGUAS: Add it.
</span></span></td><td>Florian Pelz</td></tr>
<tr><td><span title='2023-05-31 17:23:21 +0200'>2023-05-31</span></td><td><a href='/guix/commit/po/doc/guix-manual.es.po?id=8e9e6a6482f3ba98d1cdcad344ee488e8751fee7'>nls: Update translations.</a><span class='msg-avail'>...<span class='msg-tooltip'>* doc/guix-cookbook.texi (Top): Mention Slovak.
</span></span></td><td>Florian Pelz</td></tr>
<tr><td><span title='2023-03-07 21:14:57 +0100'>2023-03-07</span></td><td><a href='/guix/commit/po/doc/guix-manual.es.po?id=d333958763b0840c4cd895601b079b68358a6a46'>nls: Update translations.</a></td><td>Julien Lepiller</td></tr>
<tr><td><span title='2023-01-05 08:14:55 +0100'>2023-01-05</span></td><td><a href='/guix/commit/po/doc/guix-manual.es.po?id=dc7eb6f07ae982b4c9d083cfb10f72cb031c0424'>nls: Update translations.</a><span class='msg-avail'>...<span class='msg-tooltip'>* po/guix/ka.po: New file.
* po/guix/LINGUAS: Add it.
* po/packages/uk.po: New file.
* po/packages/LINGUAS: Add it.
</span></span></td><td>Julien Lepiller</td></tr>
<tr><td><span title='2022-12-15 00:15:36 +0100'>2022-12-15</span></td><td><a href='/guix/commit/po/doc/guix-manual.es.po?id=047ae5c3458d03bea4926e6cc1760bcfce1e2ab4'>doc: Use VM image file name consistently.</a><span class='msg-avail'>...<span class='msg-tooltip'>Previously, what "/tmp/qemu-image" refers to could be unclear at first.

* doc/guix.texi (Running Guix in a VM): Use the original image file
name instead of /tmp/qemu-image.
* po/doc/guix-manual.de.po, po/doc/guix-manual.es.po,
po/doc/guix-manual.fr.po, po/doc/guix-manual.pt_BR.po,
po/doc/guix-manual.ru.po, po/doc/guix-manual.zh_CN.po: Adjust
accordingly.
</span></span></td><td>Ludovic Courtès</td></tr>
<tr><td><span title='2022-12-04 23:15:02 +0100'>2022-12-04</span></td><td><a href='/guix/commit/po/doc/guix-manual.es.po?id=29a09fa5e46347ca223b849c47198f82cf6df271'>nls: Update translations.</a><span class='msg-avail'>...<span class='msg-tooltip'>po/packages/vi.po: New file.
po/packages/LINGUAS: Add it.
</span></span></td><td>Julien Lepiller</td></tr>
<tr><td><span title='2022-11-04 10:56:38 +0100'>2022-11-04</span></td><td><a href='/guix/commit/po/doc/guix-manual.es.po?id=a65ce9dd500460af4f97e7398fb35dd817f4c677'>nls: Update translations.</a><span class='msg-avail'>...<span class='msg-tooltip'>* po/guix/lt.po: New file.
* po/guix/LINGUAS: Add lt.
</span></span></td><td>Julien Lepiller</td></tr>
<tr><td><span title='2022-10-06 08:20:20 +0200'>2022-10-06</span></td><td><a href='/guix/commit/po/doc/guix-manual.es.po?id=70fc8f6d619ce9f16a8cc0bbb10a011bd3a9997a'>nls: Update translations.</a></td><td>Julien Lepiller</td></tr>
<tr><td><span title='2022-09-04 16:52:02 +0200'>2022-09-04</span></td><td><a href='/guix/commit/po/doc/guix-manual.es.po?id=77e3042aef6d8e519d016555464e466399318b4f'>nls: Update translations.</a></td><td>Julien Lepiller</td></tr>