libfdisk: do not use va_list in the Ask API

# fdisk /dev/sda
  Welcome to fdisk (util-linux 2.23).

  [...]

  Command (m for help): a
  Segmentation fault (core dumped)

It's too fragile, the va_list implementation is architecture specific
and it seems we need such thing in libfdisk at all.

Reported-by: "Gabor Z. Papp" <gzp@papp.hu>
Signed-off-by: Karel Zak <kzak@redhat.com>

fdisks/fdisk-ask.c

@@ -167,7 +167,6 @@ static int ask_offset(struct fdisk_context *cxt,
 int ask_callback(struct fdisk_context *cxt, struct fdisk_ask *ask,
 		    void *data __attribute__((__unused__)))
 {
-	va_list ap;
 	int rc = 0;
 	char buf[BUFSIZ];
 
@@ -180,23 +179,17 @@ int ask_callback(struct fdisk_context *cxt, struct fdisk_ask *ask,
 	case FDISK_ASKTYPE_OFFSET:
 		return ask_offset(cxt, ask, buf, sizeof(buf));
 	case FDISK_ASKTYPE_INFO:
-		fdisk_ask_print_get_va(ask, ap);
-		vfprintf(stdout, fdisk_ask_print_get_mesg(ask), ap);
+		fputs(fdisk_ask_print_get_mesg(ask), stdout);
 		fputc('\n', stdout);
-		va_end(ap);
 		break;
 	case FDISK_ASKTYPE_WARNX:
-		fdisk_ask_print_get_va(ask, ap);
-		vfprintf(stderr, fdisk_ask_print_get_mesg(ask), ap);
+		fputs(fdisk_ask_print_get_mesg(ask), stderr);
 		fputc('\n', stderr);
-		va_end(ap);
 		break;
 	case FDISK_ASKTYPE_WARN:
-		fdisk_ask_print_get_va(ask, ap);
-		vfprintf(stderr, fdisk_ask_print_get_mesg(ask), ap);
+		fputs(fdisk_ask_print_get_mesg(ask), stderr);
 		errno = fdisk_ask_print_get_errno(ask);
 		fprintf(stderr, ": %m\n");
-		va_end(ap);
 		break;
 	case FDISK_ASKTYPE_YESNO:
 		fputc('\n', stdout);

libfdisk/src/ask.c

@@ -18,11 +18,6 @@ void fdisk_reset_ask(struct fdisk_ask *ask)
 	case FDISK_ASKTYPE_NUMBER:
 		free(ask->data.num.range);
 		break;
-	case FDISK_ASKTYPE_WARNX:
-	case FDISK_ASKTYPE_WARN:
-		if (ask->data.print.has_va)
-			va_end(ask->data.print.va);
-		break;
 	default:
 		break;
 	}
@@ -452,44 +447,32 @@ int fdisk_ask_print_set_mesg(struct fdisk_ask *ask, const char *mesg)
 	return 0;
 }
 
-/* caller has to call va_end(ap) */
-int fdisk_ask_print_get_va(struct fdisk_ask *ask, va_list ap)
-{
-	assert(ask);
-	assert(is_print_ask(ask));
-	va_copy(ap, ask->data.print.va);
-	return 0;
-}
-
-/* note that fdisk_free_ask() calls va_end() to free the private va list. */
-int fdisk_ask_print_set_va(struct fdisk_ask *ask, va_list ap)
-{
-	assert(ask);
-	va_copy(ask->data.print.va, ap);
-	ask->data.print.has_va = 1;
-	return 0;
-}
-
 static int do_vprint(struct fdisk_context *cxt, int errnum, int type,
 		 const char *fmt, va_list va)
 {
 	struct fdisk_ask *ask;
 	int rc;
+	char *mesg;
 
 	assert(cxt);
 
-	ask = fdisk_new_ask();
-	if (!ask)
+	if (vasprintf(&mesg, fmt, va) < 0)
 		return -ENOMEM;
 
+	ask = fdisk_new_ask();
+	if (!ask) {
+		free(mesg);
+		return -ENOMEM;
+	}
+
 	fdisk_ask_set_type(ask, type);
-	fdisk_ask_print_set_mesg(ask, fmt);
-	fdisk_ask_print_set_va(ask, va);
+	fdisk_ask_print_set_mesg(ask, mesg);
 	if (errnum >= 0)
 		fdisk_ask_print_set_errno(ask, errnum);
 	rc = fdisk_do_ask(cxt, ask);
 
 	fdisk_free_ask(ask);
+	free(mesg);
 	return rc;
 }
 

libfdisk/src/fdiskP.h

@@ -231,8 +231,6 @@ struct fdisk_ask {
 		/* FDISK_ASKTYPE_{WARN,WARNX,..} */
 		struct ask_print {
 			const char	*mesg;
-			va_list		va;
-			unsigned int	has_va:1;
 			int		errnum;		/* errno */
 		} print;
 		/* FDISK_ASKTYPE_YESNO */

libfdisk/src/libfdisk.h

@@ -182,8 +182,6 @@ extern int fdisk_ask_print_get_errno(struct fdisk_ask *ask);
 extern int fdisk_ask_print_set_errno(struct fdisk_ask *ask, int errnum);
 extern const char *fdisk_ask_print_get_mesg(struct fdisk_ask *ask);
 extern int fdisk_ask_print_set_mesg(struct fdisk_ask *ask, const char *mesg);
-extern int fdisk_ask_print_get_va(struct fdisk_ask *ask, va_list ap);
-extern int fdisk_ask_print_set_va(struct fdisk_ask *ask, va_list ap);
 
 #ifdef __cplusplus
 }