Adopted from NixOS
pkgs/development/libraries/kde-frameworks/kio/samba-search-path.patch

===================================================================
--- kio-5.17.0.orig/src/core/ksambashare.cpp
+++ kio-5.17.0/src/core/ksambashare.cpp
@@ -67,13 +67,18 @@ KSambaSharePrivate::~KSambaSharePrivate(
 
 bool KSambaSharePrivate::isSambaInstalled()
 {
-    if (QFile::exists(QStringLiteral("/usr/sbin/smbd"))
-            || QFile::exists(QStringLiteral("/usr/local/sbin/smbd"))) {
-        return true;
+    const QByteArray pathEnv = qgetenv("PATH");
+    if (!pathEnv.isEmpty()) {
+        QLatin1Char pathSep(':');
+        QStringList paths = QFile::decodeName(pathEnv).split(pathSep, QString::SkipEmptyParts);
+        for (QStringList::iterator it = paths.begin(); it != paths.end(); ++it) {
+            it->append(QStringLiteral("/smbd"));
+            if (QFile::exists(*it)) {
+                return true;
+            }
+        }
     }
 
-    //qDebug() << "Samba is not installed!";
-
     return false;
 }
 
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<div class='path'>path: <a href='/guix/log/?id=c2ab0f895080503d624787177df90403ee9aae58'>root</a>/<a href='/guix/log/tests?id=c2ab0f895080503d624787177df90403ee9aae58'>tests</a>/<a href='/guix/log/tests/guix-register.sh?id=c2ab0f895080503d624787177df90403ee9aae58'>guix-register.sh</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/tests/guix-register.sh?id=c2ab0f895080503d624787177df90403ee9aae58&amp;showmsg=1'>Expand</a>)</th><th class='left'>Author</th></tr>
<tr><td><span title='2016-07-29 11:39:30 +0200'>2016-07-29</span></td><td><a href='/guix/commit/tests/guix-register.sh?id=57c7e46d391bea11cacf44f9743c721c070bd3a8'>tests: Improve synchronization in 'tests/guix-register.sh'.</a><span class='msg-avail'>...<span class='msg-tooltip'>* tests/guix-register.sh: When launching guix-daemon, add retry loop
around 'open-connection'.  This fixes test failures that could occur
under heavy load where the daemon's socket file wouldn't be ready yet
when the client connects.
</span></span></td><td>Ludovic Courtès</td></tr>
<tr><td><span title='2015-06-10 13:47:58 +0200'>2015-06-10</span></td><td><a href='/guix/commit/tests/guix-register.sh?id=369755847b942806efe710b88146311849046017'>guix-register: Perform deduplication even when --prefix is passed.</a><span class='msg-avail'>...<span class='msg-tooltip'>Fixes &lt;http://bugs.gnu.org/19044&gt;.

* nix/guix-register/guix-register.cc (register_validity): Change the (optimize
  &amp;&amp; prefix.empty ()) condition to just (optimize).  Change settings.nixStore
  around the loop.  Prepend PREFIX to the argument passed to 'optimisePath'.
* tests/guix-register.sh: Use 'guix-register -p' with duplicate files, and
  make sure they are deduplicated on the target.  Adjust existing tests.
</span></span></td><td>Ludovic Courtès</td></tr>
<tr><td><span title='2015-06-10 11:11:52 +0200'>2015-06-10</span></td><td><a href='/guix/commit/tests/guix-register.sh?id=4ae1fe14b90dba3b3394852079783ca43272a675'>tests: Make the daemon socket explicit in guix-register test.</a><span class='msg-avail'>...<span class='msg-tooltip'>* tests/guix-register.sh: Define GUIX_DAEMON_SOCKET.  Pass it explicitly to
  'open-connection'.
</span></span></td><td>Ludovic Courtès</td></tr>
<tr><td><span title='2015-02-02 12:46:36 +0100'>2015-02-02</span></td><td><a href='/guix/commit/tests/guix-register.sh?id=bd98ad1fbcc572a292bb98b2c667dcb48bf7cc49'>tests: Skip 'guix-register' when the socket name length is exceeded.</a><span class='msg-avail'>...<span class='msg-tooltip'>* tests/guix-register.sh: Before running 'guix-daemon', check whether
  the socket name length exceeds the system limitation.
</span></span></td><td>Ludovic Courtès</td></tr>