Implement SSH key file path env substitution

Supports all platforms, including Windows with %FOO% syntax.

Fixes #3523

src/core/Tools.cpp

@@ -324,6 +324,29 @@ namespace Tools
         return QUuid::fromRfc4122(QByteArray::fromHex(uuid.toLatin1()));
     }
 
+    QString envSubstitute(const QString& filepath, QProcessEnvironment environment)
+    {
+        QString subbed = filepath;
+
+#if defined(Q_OS_WIN)
+        QRegularExpression varRe("\\%([A-Za-z][A-Za-z0-9_]*)\\%");
+#else
+        QRegularExpression varRe("\\$([A-Za-z][A-Za-z0-9_]*)");
+        subbed.replace("~", environment.value("HOME"));
+#endif
+
+        QRegularExpressionMatch match;
+
+        do {
+            match = varRe.match(subbed);
+            if (match.hasMatch()) {
+                subbed.replace(match.capturedStart(), match.capturedLength(), environment.value(match.captured(1)));
+            }
+        } while (match.hasMatch());
+
+        return subbed;
+    }
+
     Buffer::Buffer()
         : raw(nullptr)
         , size(0)

src/core/Tools.h

@@ -22,6 +22,7 @@
 #include "core/Global.h"
 
 #include <QObject>
+#include <QProcessEnvironment>
 #include <QString>
 #include <QUuid>
 
@@ -48,6 +49,8 @@ namespace Tools
                                       bool useWildcards = false,
                                       bool exactMatch = false,
                                       bool caseSensitive = false);
+    QString envSubstitute(const QString& filepath,
+                          QProcessEnvironment environment = QProcessEnvironment::systemEnvironment());
 
     template <typename RandomAccessIterator, typename T>
     RandomAccessIterator binaryFind(RandomAccessIterator begin, RandomAccessIterator end, const T& value)

src/sshagent/KeeAgentSettings.cpp

@@ -17,6 +17,7 @@
  */
 
 #include "KeeAgentSettings.h"
+#include "core/Tools.h"
 
 KeeAgentSettings::KeeAgentSettings()
     : m_lifetimeConstraintDuration(600)
@@ -115,6 +116,11 @@ const QString KeeAgentSettings::fileName() const
     return m_fileName;
 }
 
+const QString KeeAgentSettings::fileNameEnvSubst(QProcessEnvironment environment) const
+{
+    return Tools::envSubstitute(m_fileName, environment);
+}
+
 void KeeAgentSettings::setAllowUseOfSshKey(bool allowUseOfSshKey)
 {
     m_allowUseOfSshKey = allowUseOfSshKey;
@@ -361,7 +367,7 @@ bool KeeAgentSettings::toOpenSSHKey(const Entry* entry, OpenSSHKey& key, bool de
         fileName = m_attachmentName;
         privateKeyData = entry->attachments()->value(fileName);
     } else {
-        QFile localFile(m_fileName);
+        QFile localFile(fileNameEnvSubst());
         QFileInfo localFileInfo(localFile);
         fileName = localFileInfo.fileName();
 

src/sshagent/KeeAgentSettings.h

@@ -54,6 +54,7 @@ class KeeAgentSettings
     const QString attachmentName() const;
     bool saveAttachmentToTempFile() const;
     const QString fileName() const;
+    const QString fileNameEnvSubst(QProcessEnvironment environment = QProcessEnvironment::systemEnvironment()) const;
 
     void setAllowUseOfSshKey(bool allowUseOfSshKey);
     void setAddAtDatabaseOpen(bool addAtDatabaseOpen);

tests/TestTools.cpp

@@ -64,3 +64,24 @@ void TestTools::testIsBase64()
     QVERIFY(not Tools::isBase64(QByteArray("abc_")));
     QVERIFY(not Tools::isBase64(QByteArray("123")));
 }
+
+void TestTools::testEnvSubstitute()
+{
+    QProcessEnvironment environment;
+
+#if defined(Q_OS_WIN)
+    environment.insert("HOMEDRIVE", "C:");
+    environment.insert("HOMEPATH", "\\Users\\User");
+
+    QCOMPARE(Tools::envSubstitute("%HOMEDRIVE%%HOMEPATH%\\.ssh\\id_rsa", environment),
+             QString("C:\\Users\\User\\.ssh\\id_rsa"));
+    QCOMPARE(Tools::envSubstitute("start%EMPTY%%EMPTY%%%HOMEDRIVE%%end", environment), QString("start%C:%end"));
+#else
+    environment.insert("HOME", QString("/home/user"));
+    environment.insert("USER", QString("user"));
+
+    QCOMPARE(Tools::envSubstitute("~/.ssh/id_rsa", environment), QString("/home/user/.ssh/id_rsa"));
+    QCOMPARE(Tools::envSubstitute("$HOME/.ssh/id_rsa", environment), QString("/home/user/.ssh/id_rsa"));
+    QCOMPARE(Tools::envSubstitute("start/$EMPTY$$EMPTY$HOME/end", environment), QString("start/$/home/user/end"));
+#endif
+}

tests/TestTools.h

@@ -27,6 +27,7 @@ private slots:
     void testHumanReadableFileSize();
     void testIsHex();
     void testIsBase64();
+    void testEnvSubstitute();
 };
 
 #endif // KEEPASSX_TESTTOOLS_H