Replace memory-size detection.

- drop use of dmidecode to determine exact physical memory size
 - use sysinfo() to find memory size (assumes linux 2.3.48 or later)

src/libcalamares/utils/CalamaresUtilsSystem.cpp

@@ -26,6 +26,15 @@
 #include <QProcess>
 #include <QRegularExpression>
 
+#ifdef Q_OS_LINUX
+#include <sys/sysinfo.h>
+#endif
+
+#ifdef Q_OS_FREEBSD
+#include <sys/types.h>
+#include <sys/sysctl.h>
+#endif
+
 namespace CalamaresUtils
 {
 
@@ -224,47 +233,32 @@ System::targetEnvOutput( const QString& command,
 qint64
 System::getPhysicalMemoryB()
 {
-        QProcess p;
-        p.start( "dmidecode", { "-t", "17" } );
-        p.waitForFinished();
-        QStringList lines = QString::fromLocal8Bit( p.readAllStandardOutput() ).split( '\n' );
-        lines = lines.filter( QRegularExpression( "^\\W*Size:\\W\\d*\\WMB" ) );
-        if ( !lines.isEmpty() )
-            return 0;
-
-        qint64 availableRamMb = 0;
-        foreach( const QString& line, lines )
-        {
-            bool ok = false;
-            availableRamMb += line.simplified()
-                                  .split( ' ' )
-                                  .value( 1 )
-                                  .toInt( &ok );
-            if ( !ok )
-                return 0;
-        }
-        qint64 availableRam = availableRamMb * 1024 * 1024;
-        return availableRam;
+    return 0;
 }
 
 
 qint64
 System::getTotalMemoryB()
 {
-    // A line in meminfo looks like this, with {print $2} we grab the second column.
-    // MemTotal:        8133432 kB
+#ifdef Q_OS_LINUX
+    struct sysinfo i;
+    int r = sysinfo( &i );
 
-    QProcess p;
-    p.start( "awk", { "/MemTotal/ {print $2}", "/proc/meminfo" } );
-    p.waitForFinished();
-    QString memoryLine = p.readAllStandardOutput().simplified();
-
-    bool ok = false;
-    qint64 availableRam = memoryLine.toLongLong( &ok ) * 1024;
-    if ( !ok )
+    if (r)
         return 0;
 
-    return availableRam;
+    return qint64( i.mem_unit ) * i.totalram;
+#elif defined( Q_OS_FREEBSD )
+    unsigned long memsize;
+    size_t s = sizeof(memsize);
+
+    int r = sysctlbyname("vm.kmem_size", &memsize, &s, NULL, 0);
+    if (r)
+        return 0;
+
+    return memsize;
+#endif
+    return 0;  // Unsupported
 }