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=a62099cde9b7102dd059de11aaf24c3f5a8e92f3'>root</a>/<a href='/guix/log/gnu?id=a62099cde9b7102dd059de11aaf24c3f5a8e92f3'>gnu</a>/<a href='/guix/log/gnu/installer?id=a62099cde9b7102dd059de11aaf24c3f5a8e92f3'>installer</a>/<a href='/guix/log/gnu/installer/substitutes.scm?id=a62099cde9b7102dd059de11aaf24c3f5a8e92f3'>substitutes.scm</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/gnu/installer/substitutes.scm?id=a62099cde9b7102dd059de11aaf24c3f5a8e92f3&amp;showmsg=1'>Expand</a>)</th><th class='left'>Author</th></tr>
<tr><td><span title='2020-12-11 21:37:07 +0100'>2020-12-11</span></td><td><a href='/guix/commit/gnu/installer/substitutes.scm?id=8361817bf693742757b096468198626f297bb09e'>install: Discover local substitute servers.</a><span class='msg-avail'>...<span class='msg-tooltip'>* gnu/installer/substitutes.scm: New file.
* gnu/installer/newt/substitutes.scm: New file.
* gnu/local.mk (INSTALLER_MODULES): Add them.
* po/guix/POTFILES.in: Add gnu/installer/newt/substitutes.scm.
* gnu/installer/proxy.scm (with-silent-shepherd): Move to ...
* gnu/installer/utils.scm: ... here.
* gnu/installer/record.scm (&lt;installer&gt;)[substitutes-page]: New field.
* gnu/installer/newt.scm (substitutes-page): New procedure,
(newt-installer): register it.
* gnu/installer.scm (installer-steps): Add "substitutes-page" step.
* gnu/system/install.scm (%installation-services): Add avahi-service-type and
enable substitute server discover in guix-service-type.
[&lt;name-service-switch&gt;]: Set it to %mdns-host-lookup-nss.
</span></span></td><td>Mathieu Othacehe</td></tr>