wmaker: allow the screenshot filename template to be set

This patch is adding a new option ScreenshotFilenameTemplate for users
to change the default strftime format "screenshot_%Y-%m-%d_at_%H:%M:%S".
For example, Teams is not allowing the ':' char in the filename of file
to be shared so I always have to rename the file.

src/WindowMaker.h

@@ -505,6 +505,7 @@ extern struct WPreferences {
 	Cursor cursor[WCUR_LAST];
 
     int switch_panel_icon_size;               /* icon size in switch panel */
+    char *screenshot_filename_template;       /* strftime format for screenshot filenames */
 
 } wPreferences;
 

src/defaults.c

@@ -91,6 +91,7 @@ typedef struct {
 /* type converters */
 static WDECallbackConvert getBool;
 static WDECallbackConvert getInt;
+static WDECallbackConvert getString;
 static WDECallbackConvert getCoord;
 static WDECallbackConvert getPathList;
 static WDECallbackConvert getEnum;
@@ -540,6 +541,8 @@ WDefaultEntry optionList[] = {
 		&wPreferences.mouse_wheel_focus, getBool, NULL, NULL, NULL},
 	{"KeychainTimeoutDelay", "500", NULL,
 	    &wPreferences.keychain_timeout_delay, getInt, NULL, NULL, NULL},
+	{"ScreenshotFilenameTemplate", DEF_SCREENSHOT_FILENAME_TEMPLATE, NULL,
+	    &wPreferences.screenshot_filename_template, getString, NULL, NULL, NULL},
 
 	/* style options */
 
@@ -1496,6 +1499,29 @@ static int string2index(WMPropList *key, WMPropList *val, const char *def, WOpti
  * ret - is the address to store a pointer to a temporary buffer. ret
  * 	must not be freed and is used by the set functions
  */
+static int getString(WScreen * scr, WDefaultEntry * entry, WMPropList * value, void *addr, void **ret)
+{
+	const char *val;
+	char **sptr;
+
+	/* Parameter not used, but tell the compiler that it is ok */
+	(void) scr;
+
+	GET_STRING_OR_DEFAULT("String", val);
+
+	if (ret)
+		*ret = (void *)val;
+
+	if (addr) {
+		sptr = (char **)addr;
+		if (*sptr)
+			wfree(*sptr);
+		*sptr = wstrdup(val);
+	}
+
+	return True;
+}
+
 static int getBool(WScreen * scr, WDefaultEntry * entry, WMPropList * value, void *addr, void **ret)
 {
 	static char data;

src/screen.c

@@ -1270,7 +1270,14 @@ void ScreenCapture(WScreen *scr, int mode)
 
 	s = time(NULL);
 	tm_info = localtime(&s);
-	strftime(filename_date_part, sizeof(filename_date_part), "screenshot_%Y-%m-%d_at_%H:%M:%S", tm_info);
+	strftime(filename_date_part, sizeof(filename_date_part), wPreferences.screenshot_filename_template, tm_info);
+
+	if (strchr(filename_date_part, '/') != NULL) {
+		wfree(screenshot_dir);
+		werror(_("Unsafe screenshot filename template, it should not contain a path separator"));
+		return;
+	}
+
 	strcpy(filename, filename_date_part);
 
 	filepath = wstrconcat(screenshot_dir, strcat(filename, filetype));

src/wconfig.h.in

@@ -191,6 +191,9 @@
 #define DEF_APPMENU_X		         10
 #define DEF_APPMENU_Y		         10
 
+/* default strftime format for screenshot filenames */
+#define DEF_SCREENSHOT_FILENAME_TEMPLATE "\"screenshot_%Y-%m-%d_at_%H:%M:%S\""
+
 /* calculate window edge resistance from edge resistance */
 #define WIN_RESISTANCE(x)	(((x)*20)/30)