This patch fixes a crash in the libxml2 bindings for Python 3.x
that 'itstool' stumbles upon when processing UTF-8 data:

  https://issues.guix.gnu.org/issue/37468

Patch by Jan Matejek
from <https://bugzilla.opensuse.org/show_bug.cgi?id=1065270>.

--- libxml2-2.9.5.orig/python/libxml.c
+++ libxml2-2.9.5/python/libxml.c
@@ -1620,6 +1620,7 @@ libxml_xmlErrorFuncHandler(ATTRIBUTE_UNU
     PyObject *message;
     PyObject *result;
     char str[1000];
+    unsigned char *ptr = (unsigned char *)str;
 
 #ifdef DEBUG_ERROR
     printf("libxml_xmlErrorFuncHandler(%p, %s, ...) called\n", ctx, msg);
@@ -1636,12 +1637,20 @@ libxml_xmlErrorFuncHandler(ATTRIBUTE_UNU
 	    str[999] = 0;
         va_end(ap);
 
+#if PY_MAJOR_VERSION >= 3
+        /* Ensure the error string doesn't start at UTF8 continuation. */
+        while (*ptr && (*ptr & 0xc0) == 0x80)
+            ptr++;
+#endif
+
         list = PyTuple_New(2);
         PyTuple_SetItem(list, 0, libxml_xmlPythonErrorFuncCtxt);
         Py_XINCREF(libxml_xmlPythonErrorFuncCtxt);
-        message = libxml_charPtrConstWrap(str);
+        message = libxml_charPtrConstWrap(ptr);
         PyTuple_SetItem(list, 1, message);
         result = PyEval_CallObject(libxml_xmlPythonErrorFuncHandler, list);
+        /* Forget any errors caused in the error handler. */
+        PyErr_Clear();
         Py_XDECREF(list);
         Py_XDECREF(result);
     }
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<div class='path'>path: <a href='/guix/log/?id=88bcee3235d044262621e874ee0c4324b44de5cb'>root</a>/<a href='/guix/log/nix?id=88bcee3235d044262621e874ee0c4324b44de5cb'>nix</a>/<a href='/guix/log/nix/libstore?id=88bcee3235d044262621e874ee0c4324b44de5cb'>libstore</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/nix/libstore?id=88bcee3235d044262621e874ee0c4324b44de5cb&amp;showmsg=1'>Expand</a>)</th><th class='left'>Author</th></tr>
<tr><td><span title='2024-03-12 14:07:28 +0100'>2024-03-12</span></td><td><a href='/guix/commit/nix/libstore?id=ff1251de0bc327ec478fc66a562430fbf35aef42'>daemon: Address shortcoming in previous security fix for CVE-2024-27297.</a><span class='msg-avail'>...</span></td><td>Ludovic Courtès</td></tr>
<tr><td><span title='2024-03-11 22:12:34 +0100'>2024-03-11</span></td><td><a href='/guix/commit/nix/libstore?id=8f4ffb3fae133bb21d7991e97c2f19a7108b1143'>daemon: Protect against FD escape when building fixed-output derivations (CVE...</a><span class='msg-avail'>...</span></td><td>Ludovic Courtès</td></tr>
<tr><td><span title='2024-01-05 17:27:21 +0100'>2024-01-05</span></td><td><a href='/guix/commit/nix/libstore?id=d5724111ea2a8f5312b47fe9aae2bc74278c127e'>daemon: Change default ‘timeout’ and ‘max-silent-time’ values.</a><span class='msg-avail'>...</span></td><td>Ludovic Courtès</td></tr>
<tr><td><span title='2023-12-17 01:00:00 +0100'>2023-12-17</span></td><td><a href='/guix/commit/nix/libstore?id=892ec53b7eedf998afa149b9cdd169f0cab8f41d'>daemon: Fix my own whitespace errors.</a><span class='msg-avail'>...</span></td><td>Tobias Geerinckx-Rice</td></tr>
<tr><td><span title='2023-12-10 01:00:00 +0100'>2023-12-10</span></td><td><a href='/guix/commit/nix/libstore?id=d993ed43b2bae8717437aa27d9d33fd223a6411f'>daemon: Sacrifice builders on OOM.</a><span class='msg-avail'>...</span></td><td>Tobias Geerinckx-Rice</td></tr>
<tr><td><span title='2023-12-11 23:18:53 +0100'>2023-12-11</span></td><td><a href='/guix/commit/nix/libstore?id=1e47148f46e31eb99ce8ec7bc12232cf50d0ebec'>daemon: Implement ‘substitute-urls’ RPC.</a><span class='msg-avail'>...</span></td><td>Ludovic Courtès</td></tr>
<tr><td><span title='2023-12-04 22:26:36 +0100'>2023-12-04</span></td><td><a href='/guix/commit/nix/libstore?id=d83d4488da5c3bb65867bffa2b8587a7c7b056cc'>daemon: Simplify “empty status” substitute error message.</a><span class='msg-avail'>...</span></td><td>Ludovic Courtès</td></tr>
<tr><td><span title='2023-09-26 17:36:58 +0200'>2023-09-26</span></td><td><a href='/guix/commit/nix/libstore?id=95f21231352b66f92c466cb30f2258291e854f2f'>daemon: Add “git-download” built-in builder.</a><span class='msg-avail'>...</span></td><td>Ludovic Courtès</td></tr>
<tr><td><span title='2023-09-09 18:47:35 +0200'>2023-09-09</span></td><td><a href='/guix/commit/nix/libstore?id=cd469932758bf2bec1ff9c82aeb373e18730d0c4'>daemon: Fix build with GCC 13.</a><span class='msg-avail'>...</span></td><td>Sören Tempel</td></tr>
<tr><td><span title='2022-12-18 01:16:47 +0100'>2022-12-18</span></td><td><a href='/guix/commit/nix/libstore?id=2d4d26769d6a3be1b21302b0bb2bd099fd55ccf8'>daemon: Make "opening file" error messages distinguishable.</a><span class='msg-avail'>...</span></td><td>Ludovic Courtès</td></tr>
<tr><td><span title='2022-10-17 09:37:27 +0200'>2022-10-17</span></td><td><a href='/guix/commit/nix/libstore?id=eec920ba93ecb086366576e31b785962fbaf81c2'>Revert "nix: Guard against removing temporary roots of living processes."</a><span class='msg-avail'>...</span></td><td>Ludovic Courtès</td></tr>
<tr><td><span title='2022-10-07 16:54:20 -0400'>2022-10-07</span></td><td><a href='/guix/commit/nix/libstore?id=bb0beaecdee1a2315a1269b1746d238c8ab0e699'>nix: Guard against removing temporary roots of living processes.</a><span class='msg-avail'>...</span></td><td>Ludovic Courtès</td></tr>
<tr><td><span title='2022-09-11 16:43:30 +0200'>2022-09-11</span></td><td><a href='/guix/commit/nix/libstore?id=4b32f87e9adf91d5d94287562d8844727d47a07b'>daemon: Remove unused function findOutput.</a><span class='msg-avail'>...</span></td><td>Maxime Devos</td></tr>
<tr><td><span title='2022-09-11 16:43:30 +0200'>2022-09-11</span></td><td><a href='/guix/commit/nix/libstore?id=93032586df6b925e1ed9102dc3a77aa626aa60d3'>daemon: Remove unused function exportPaths.</a><span class='msg-avail'>...</span></td><td>Maxime Devos</td></tr>
<tr><td><span title='2022-09-11 16:43:30 +0200'>2022-09-11</span></td><td><a href='/guix/commit/nix/libstore?id=1c5f5d6d8cb3bd42ed436e31366a328598165734'>daemon: Remove unused function openStore.</a><span class='msg-avail'>...</span></td><td>Maxime Devos</td></tr>
<tr><td><span title='2022-06-05 02:00:00 +0200'>2022-06-05</span></td><td><a href='/guix/commit/nix/libstore?id=0ace58b99c7292dd962bcd244f274f8033a7fce4'>daemon: Quote consistently within a string.</a><span class='msg-avail'>...</span></td><td>Tobias Geerinckx-Rice</td></tr>
<tr><td><span title='2022-05-29 02:00:00 +0200'>2022-05-29</span></td><td><a href='/guix/commit/nix/libstore?id=82b06436b4b563a85e70f3fcc610959482f08e91'>daemon: Clarify ‘--check’ error when outputs are missing.</a><span class='msg-avail'>...</span></td><td>Tobias Geerinckx-Rice</td></tr>