Correctly copy preferences

When just assigning one structure to the other we copy the string
pointers. If we then modify those strings in the copy, we happily free
the strings of the original. And then resetting the preferences equally
happily reused those strings, pointing to long since freed memory.

I think what I did now is excessive for the current use case in that it
copies a ton of strings that are unset in the default_prefs. But I figured
this is a rarely used function and I might as well do it correctly.

Also, once we implement multi user support with per user preferences we
will be copying completely populated preferences around (at least that's
my guess).

Fixes #940

Signed-off-by: Dirk Hohndel <dirk@hohndel.org>

export-html.cpp

@@ -18,7 +18,7 @@ int main(int argc, char **argv)
 {
 	QApplication *application = new QApplication(argc, argv);
 	git_libgit2_init();
-	prefs = default_prefs;
+	copy_prefs(&default_prefs, &prefs);
 	init_qt_late();
 
 	QCommandLineParser parser;

main.cpp

@@ -53,7 +53,7 @@ int main(int argc, char **argv)
 	git_libgit2_init();
 #endif
 	setup_system_prefs();
-	prefs = default_prefs;
+	copy_prefs(&default_prefs, &prefs);
 	fill_profile_color();
 	parse_xml_init();
 	taglist_init_global();

qt-ui/preferences.cpp

@@ -4,6 +4,7 @@
 #include "divelocationmodel.h"
 #include "prefs-macros.h"
 #include "qthelper.h"
+#include "subsurfacestartup.h"
 
 #include <QSettings>
 #include <QFileDialog>
@@ -494,7 +495,7 @@ void PreferencesDialog::on_resetSettings_clicked()
 
 	int result = response.exec();
 	if (result == QMessageBox::Ok) {
-		prefs = default_prefs;
+		copy_prefs(&default_prefs, &prefs);
 		setUiFromPrefs();
 		Q_FOREACH (QString key, s.allKeys()) {
 			s.remove(key);

subsurfacestartup.c

@@ -272,6 +272,28 @@ void setup_system_prefs(void)
 	default_prefs.units = IMPERIAL_units;
 }
 
+/* copy a preferences block, including making copies of all included strings */
+void copy_prefs(struct preferences *src, struct preferences *dest)
+{
+	*dest = *src;
+	dest->divelist_font = copy_string(src->divelist_font);
+	dest->default_filename = copy_string(src->default_filename);
+	dest->default_cylinder = copy_string(src->default_cylinder);
+	dest->cloud_base_url = copy_string(src->cloud_base_url);
+	dest->cloud_git_url = copy_string(src->cloud_git_url);
+	dest->userid = copy_string(src->userid);
+	dest->proxy_host = copy_string(src->proxy_host);
+	dest->proxy_user = copy_string(src->proxy_user);
+	dest->proxy_pass = copy_string(src->proxy_pass);
+	dest->cloud_storage_password = copy_string(src->cloud_storage_password);
+	dest->cloud_storage_newpassword = copy_string(src->cloud_storage_newpassword);
+	dest->cloud_storage_email = copy_string(src->cloud_storage_email);
+	dest->cloud_storage_email_encoded = copy_string(src->cloud_storage_email_encoded);
+	dest->facebook.access_token = copy_string(src->facebook.access_token);
+	dest->facebook.user_id = copy_string(src->facebook.user_id);
+	dest->facebook.album_id = copy_string(src->facebook.album_id);
+}
+
 /*
  * Free strduped prefs before exit.
  *

subsurfacestartup.h

@@ -16,6 +16,7 @@ extern bool imported;
 void setup_system_prefs(void);
 void parse_argument(const char *arg);
 void free_prefs(void);
+void copy_prefs(struct preferences *src, struct preferences *dest);
 void print_files(void);
 
 #ifdef __cplusplus

tests/testgitstorage.cpp

@@ -5,6 +5,7 @@
 #include "git2.h"
 #include "prefs-macros.h"
 #include "windowtitleupdate.h"
+#include "subsurfacestartup.h"
 #include <QDir>
 #include <QTextStream>
 #include <QNetworkProxy>
@@ -17,7 +18,7 @@ extern "C" char *get_local_dir(const char *remote, const char *branch);
 void TestGitStorage::testSetup()
 {
 	// first, setup the preferences an proxy information
-	prefs = default_prefs;
+	copy_prefs(&default_prefs, &prefs);
 	QCoreApplication::setOrganizationName("Subsurface");
 	QCoreApplication::setOrganizationDomain("subsurface.hohndel.org");
 	QCoreApplication::setApplicationName("Subsurface");

tests/testplan.cpp

@@ -14,7 +14,7 @@ extern pressure_t first_ceiling_pressure;
 
 void setupPrefs()
 {
-	prefs = default_prefs;
+	copy_prefs(&default_prefs, &prefs);
 	prefs.ascrate50 = feet_to_mm(30) / 60;
 	prefs.ascrate75 = prefs.ascrate50;
 	prefs.ascratestops = prefs.ascrate50;
@@ -24,7 +24,7 @@ void setupPrefs()
 
 void setupPrefsVpmb()
 {
-	prefs = default_prefs;
+	copy_prefs(&default_prefs, &prefs);
 	prefs.ascrate50 = 10000 / 60;
 	prefs.ascrate75 = prefs.ascrate50;
 	prefs.ascratestops = prefs.ascrate50;