[libcalamares] Get target path relative to host /

src/libcalamares/utils/CalamaresUtilsSystem.cpp

@@ -244,7 +244,7 @@ System::runCommand(
 }
 
 QString
-System::createTargetFile( const QString& path, const QByteArray& contents )
+System::targetPath( const QString& path ) const
 {
     QString completePath;
     
@@ -265,6 +265,18 @@ System::createTargetFile( const QString& path, const QByteArray& contents )
         completePath = QStringLiteral( "/" ) + path;
     }
     
+    return completePath;
+}
+
+QString
+System::createTargetFile( const QString& path, const QByteArray& contents ) const
+{
+    QString completePath = targetPath( path );
+    if ( completePath.isEmpty() )
+    {
+        return QString();
+    }
+    
     QFile f( completePath );
     if ( f.exists() )
     {

src/libcalamares/utils/CalamaresUtilsSystem.h

@@ -205,9 +205,27 @@ public:
         return targetEnvOutput( QStringList{ command }, output, workingPath, stdInput, timeoutSec );
     }
 
+    
+    /** @brief Gets a path to a file in the target system, from the host.
+     * 
+     * @param path Path to the file; this is interpreted
+     *      from the root of the target system (whatever that may be,
+     *      but / in the chroot, or / in OEM modes).
+     * 
+     * @return The complete path to the target file, from
+     *      the root of the host system, or empty on failure.
+     * 
+     * For instance, during installation where the target root is
+     * mounted on /tmp/calamares-something, asking for targetPath("/etc/passwd")
+     * will give you /tmp/calamares-something/etc/passwd.
+     * 
+     * No attempt is made to canonicalize anything, since paths might not exist.
+     */ 
+    DLLEXPORT QString targetPath( const QString& path ) const;
+    
     /** @brief Create a (small-ish) file in the target system.
      * 
-     * @param path Path to the file; this is **always** interpreted
+     * @param path Path to the file; this is interpreted
      *      from the root of the target system (whatever that may be,
      *      but / in the chroot, or / in OEM modes).
      * @param contents Actual content of the file.
@@ -215,9 +233,11 @@ public:
      * Will not overwrite files. Returns an empty string if the
      * target file already exists.
      * 
-     * @return The complete canonical path to the target file, or empty on failure.
+     * @return The complete canonical path to the target file from the
+     *      root of the host system, or empty on failure. (Here, it is
+     *      possible to be canonical because the file exists).
      */
-    QString createTargetFile( const QString& path, const QByteArray& contents );
+    DLLEXPORT QString createTargetFile( const QString& path, const QByteArray& contents ) const;
     
     /**
      * @brief getTotalMemoryB returns the total main memory, in bytes.