implement confirmation switch

doc/ncdu.pod

@@ -103,6 +103,11 @@ List sizes using base 10 prefixes, that is, powers of 1000 (KB, MB, etc), as
 defined in the International System of Units (SI), instead of the usual base 2
 prefixes, that is, powers of 1024 (KiB, MiB, etc).
 
+=item --confirm-quit
+
+Requires a confirmation before quitting ncdu. Very helpful when you
+accidentally press 'q' during or after a very long scan.
+
 =back
 
 =head2 Scan Options

src/browser.c

@@ -397,7 +397,9 @@ int browse_key(int ch) {
       if(info_show)
         info_show = 0;
       else
-        quit_init();
+        if (confirm_quit)
+          quit_init();
+        else return 1;
       break;
     case 'g':
       if(++graph > 3)

src/browser.h

@@ -28,6 +28,7 @@
 
 #include "global.h"
 
+int  confirm_quit;
 int  browse_key(int);
 void browse_draw(void);
 void browse_init(struct dir *);

src/global.h

@@ -90,6 +90,8 @@ extern int read_only;
 extern long update_delay;
 /* filter directories with CACHEDIR.TAG */
 extern int cachedir_tags;
+/* flag if we should ask for confirmation when quitting */
+extern int confirm_quit;
 
 /* handle input from keyboard and update display */
 int input_handle(int);

src/main.c

@@ -130,6 +130,7 @@ static void argv_parse(int argc, char **argv) {
     { 'X', 1, "-X,--exclude-from" },
     { 'C', 0, "--exclude-caches" },
     { 's', 0, "--si" },
+    { 'Q', 0, "--confirm-quit" },
     {0,0,NULL}
   };
 
@@ -154,6 +155,7 @@ static void argv_parse(int argc, char **argv) {
       printf("  --exclude PATTERN          Exclude files that match PATTERN\n");
       printf("  -X, --exclude-from FILE    Exclude files that match any pattern in FILE\n");
       printf("  --exclude-caches           Exclude directories containing CACHEDIR.TAG\n");
+      printf("  --confirm-quit             Confirm quitting ncdu\n");
       exit(0);
     case 'q': update_delay = 2000; break;
     case 'v':
@@ -167,6 +169,7 @@ static void argv_parse(int argc, char **argv) {
     case '0': dir_ui = 0; break;
     case '1': dir_ui = 1; break;
     case '2': dir_ui = 2; break;
+    case 'Q': confirm_quit = 1; break;
     case  1 : exclude_add(val); break; /* --exclude */
     case 'X':
       if(exclude_addfile(val)) {