Bring GPT partition editing into line with MBR partition editing

by presenting the existing offset and size as the defaults. Enhance
getuint64() to take a minimum value as ask_num() does. Use this to
ensure that GPT partitions are constrained to the valid area of the
disk. Leave MBR partition constraints alone for the moment.

Original problem(s) noted by tim@

3 files changed, 14 insertions, 13 deletions

diff --git a/sbin/fdisk/cmd.c b/sbin/fdisk/cmd.c
index 103432b9f87..5481966566b 100644
--- a/sbin/fdisk/cmd.c
+++ b/sbin/fdisk/cmd.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: cmd.c,v 1.89 2015/11/21 02:12:09 krw Exp $	*/
+/*	$OpenBSD: cmd.c,v 1.90 2015/11/21 16:45:41 krw Exp $	*/
 
 /*
  * Copyright (c) 1997 Tobias Weingartner
@@ -187,10 +187,10 @@ Xgedit(char *args)
 		goto done;
 	}
 
-	bs = getuint64("Partition offset", letoh64(gh.gh_lba_start),
-	    letoh64(gh.gh_lba_end));
-	ns = getuint64("Partition size", letoh64(gh.gh_lba_end) - bs + 1,
-	    letoh64(gh.gh_lba_end) - bs + 1);
+	bs = getuint64("Partition offset", letoh64(gg->gp_lba_start),
+	    letoh64(gh.gh_lba_start), letoh64(gh.gh_lba_end));
+	ns = getuint64("Partition size", letoh64(gg->gp_lba_end) - bs + 1,
+	    0, letoh64(gh.gh_lba_end) - bs + 1);
 
 	gg->gp_lba_start = htole64(bs);
 	gg->gp_lba_end = htole64(bs + ns - 1);
@@ -267,9 +267,8 @@ Xedit(char *args, struct mbr *mbr)
 		/* Fix up CHS values for LBA */
 		PRT_fix_CHS(pp);
 	} else {
-		pp->bs = getuint64("Partition offset", pp->bs,
-		    disk.size);
-		pp->ns = getuint64("Partition size",   pp->ns,
+		pp->bs = getuint64("Partition offset", pp->bs, 0, disk.size);
+		pp->ns = getuint64("Partition size",   pp->ns, 0,
 		    disk.size - pp->bs);
 
 		/* Fix up CHS values */
diff --git a/sbin/fdisk/misc.c b/sbin/fdisk/misc.c
index 754128e47c6..0203b17a0d7 100644
--- a/sbin/fdisk/misc.c
+++ b/sbin/fdisk/misc.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: misc.c,v 1.58 2015/11/19 16:14:08 krw Exp $	*/
+/*	$OpenBSD: misc.c,v 1.59 2015/11/21 16:45:41 krw Exp $	*/
 
 /*
  * Copyright (c) 1997 Tobias Weingartner
@@ -203,7 +203,7 @@ ask_yn(const char *str)
  * adapted from sbin/disklabel/editor.c
  */
 u_int64_t
-getuint64(char *prompt, u_int64_t oval, u_int64_t maxval)
+getuint64(char *prompt, u_int64_t oval, u_int64_t minval, u_int64_t maxval)
 {
 	const int secsize = unit_types[SECTORS].conversion;
 	char buf[BUFSIZ], *endptr, *p, operator = '\0';
@@ -215,6 +215,8 @@ getuint64(char *prompt, u_int64_t oval, u_int64_t maxval)
 
 	if (oval > maxval)
 		oval = maxval;
+	if (oval < minval)
+		oval = minval;
 
 	secpercyl = disk.sectors * disk.heads;
 
@@ -304,7 +306,7 @@ getuint64(char *prompt, u_int64_t oval, u_int64_t maxval)
 			d2 = d;
 		}
 
-		if (saveerr == ERANGE || d > maxval || d < 0 || d < d2) {
+		if (saveerr == ERANGE || d > maxval || d < minval || d < d2) {
 			printf("%s is out of range: %c%s%c\n", prompt, operator,
 			    p, unit);
 		} else if (*endptr != '\0') {
diff --git a/sbin/fdisk/misc.h b/sbin/fdisk/misc.h
index 3724cdee928..e80ae59edda 100644
--- a/sbin/fdisk/misc.h
+++ b/sbin/fdisk/misc.h
@@ -1,4 +1,4 @@
-/*	$OpenBSD: misc.h,v 1.32 2015/11/12 15:07:41 krw Exp $	*/
+/*	$OpenBSD: misc.h,v 1.33 2015/11/21 16:45:41 krw Exp $	*/
 
 /*
  * Copyright (c) 1997 Tobias Weingartner
@@ -35,7 +35,7 @@ int ask_num(const char *, int, int, int);
 int ask_pid(int, struct uuid *);
 char *ask_string(const char *, const char *);
 int ask_yn(const char *);
-u_int64_t getuint64(char *, u_int64_t, u_int64_t);
+u_int64_t getuint64(char *, u_int64_t, u_int64_t, u_int64_t);
 u_int32_t crc32(const u_char *, const u_int32_t);
 char *utf16le_to_string(u_int16_t *);
 u_int16_t *string_to_utf16le(char *);