Make editing GPT easier/safer by defaulting offet to beginning of largest

free space and preventing the creation of overlapping partitions.

Prompted & tested by landry@

diff --git a/sbin/fdisk/cmd.c b/sbin/fdisk/cmd.c
index c467056..b283116 100644 (file)
--- a/sbin/fdisk/cmd.c
+++ b/sbin/fdisk/cmd.c
@@ -1,4 +1,4 @@
-/*     $OpenBSD: cmd.c,v 1.98 2017/11/13 21:00:32 krw Exp $    */
+/*     $OpenBSD: cmd.c,v 1.99 2021/01/30 18:16:36 krw Exp $    */
 
 /*
  * Copyright (c) 1997 Tobias Weingartner
@@ -167,7 +167,6 @@ Xgedit(char *args)
        struct gpt_partition *gg;
        char *name;
        u_int16_t *utf;
-       u_int64_t bs, ns;
        int i, pn;
 
        pn = strtonum(args, 0, NGPTPARTITIONS - 1, &errstr);
@@ -187,13 +186,11 @@ Xgedit(char *args)
                goto done;
        }
 
-       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,
-           1, letoh64(gh.gh_lba_end) - bs + 1);
-
-       gg->gp_lba_start = htole64(bs);
-       gg->gp_lba_end = htole64(bs + ns - 1);
+       if (GPT_get_lba_start(pn) == -1 ||
+           GPT_get_lba_end(pn) == -1) {
+               *gg = oldpart;
+               goto done;
+       }
 
        name = ask_string("Partition name", utf16le_to_string(gg->gp_name));
        if (strlen(name) >= GPTPARTNAMESIZE) {

diff --git a/sbin/fdisk/gpt.c b/sbin/fdisk/gpt.c
index 3048e91..105035d 100644 (file)
--- a/sbin/fdisk/gpt.c
+++ b/sbin/fdisk/gpt.c
@@ -1,4 +1,4 @@
-/*     $OpenBSD: gpt.c,v 1.11 2016/03/28 16:55:09 mestre Exp $ */
+/*     $OpenBSD: gpt.c,v 1.12 2021/01/30 18:16:36 krw Exp $    */
 /*
  * Copyright (c) 2015 Markus Muller <mmu@grummel.net>
  * Copyright (c) 2015 Kenneth R Westerback <krw@openbsd.org>
@@ -42,6 +42,9 @@
 struct gpt_header gh;
 struct gpt_partition gp[NGPTPARTITIONS];
 
+struct gpt_partition   **sort_gpt(void);
+int                      lba_start_cmp(const void *e1, const void *e2);
+
 int
 GPT_get_header(off_t where)
 {
@@ -456,3 +459,131 @@ GPT_write(void)
 
        return (0);
 }
+
+int
+gp_lba_start_cmp(const void *e1, const void *e2)
+{
+       struct gpt_partition *p1 = *(struct gpt_partition **)e1;
+       struct gpt_partition *p2 = *(struct gpt_partition **)e2;
+       u_int64_t o1;
+       u_int64_t o2;
+
+       o1 = letoh64(p1->gp_lba_start);
+       o2 = letoh64(p2->gp_lba_start);
+
+       if (o1 < o2)
+               return -1;
+       else if (o1 > o2)
+               return 1;
+       else
+               return 0;
+}
+
+struct gpt_partition **
+sort_gpt(void)
+{
+       static struct gpt_partition *sgp[NGPTPARTITIONS+2];
+       unsigned int i, j;
+
+       memset(sgp, 0, sizeof(sgp));
+
+       j = 0;
+       for (i = 0; i < letoh32(gh.gh_part_num); i++) {
+               if (letoh64(gp[i].gp_lba_start) >= letoh64(gh.gh_lba_start))
+                       sgp[j++] = &gp[i];
+       }
+
+       if (j > 1) {
+               if (mergesort(sgp, j, sizeof(sgp[0]), gp_lba_start_cmp) == -1) {
+                       printf("unable to sort gpt by lba start\n");
+                       return NULL;
+               }
+       }
+
+       return (sgp);
+}
+
+int
+GPT_get_lba_start(unsigned int pn)
+{
+       struct gpt_partition    **sgp;
+       uint64_t                  bs, bigbs, nextbs, ns;
+       unsigned int              i;
+
+       bs = letoh64(gh.gh_lba_start);
+
+       if (letoh64(gp[pn].gp_lba_start) >= bs) {
+               bs = letoh64(gp[pn].gp_lba_start);
+       } else {
+               sgp = sort_gpt();
+               if (sgp == NULL)
+                       return -1;
+               if (sgp[0] != NULL) {
+                       bigbs = bs;
+                       ns = 0;
+                       for (i = 0; sgp[i] != NULL; i++) {
+                               nextbs = letoh64(sgp[i]->gp_lba_start);
+                               if (bs < nextbs && ns < nextbs - bs) {
+                                       ns = nextbs - bs;
+                                       bigbs = bs;
+                               }
+                               bs = letoh64(sgp[i]->gp_lba_end) + 1;
+                       }
+                       nextbs = letoh64(gh.gh_lba_end) + 1;
+                       if (bs < nextbs && ns < nextbs - bs) {
+                               ns = nextbs - bs;
+                               bigbs = bs;
+                       }
+                       if (ns == 0) {
+                               printf("no space for partition %u\n", pn);
+                               return -1;
+                       }
+                       bs = bigbs;
+               }
+       }
+
+       bs = getuint64("Partition offset", bs, letoh64(gh.gh_lba_start),
+           letoh64(gh.gh_lba_end));
+
+       for (i = 0; i < letoh32(gh.gh_part_num); i++) {
+               if (i == pn)
+                       continue;
+               if (bs >= letoh64(gp[i].gp_lba_start) &&
+                   bs <= letoh64(gp[i].gp_lba_end)) {
+                       printf("partition %u can't start inside partition %u\n",
+                           pn, i);
+                       return -1;
+               }
+       }
+
+       gp[pn].gp_lba_start = htole64(bs);
+
+       return 0;
+}
+
+int
+GPT_get_lba_end(unsigned int pn)
+{
+       struct gpt_partition    **sgp;
+       uint64_t                  bs, nextbs, ns;
+       unsigned int              i;
+
+       sgp = sort_gpt();
+       if (sgp == NULL)
+               return -1;
+
+       bs = letoh64(gp[pn].gp_lba_start);
+       ns = letoh64(gh.gh_lba_end) - bs + 1;
+       for (i = 0; sgp[i] != NULL; i++) {
+               nextbs = letoh64(sgp[i]->gp_lba_start);
+               if (nextbs > bs) {
+                       ns = nextbs - bs;
+                       break;
+               }
+       }
+       ns = getuint64("Partition size", ns, 1, ns);
+
+       gp[pn].gp_lba_end = htole64(bs + ns - 1);
+
+       return 0;
+}

diff --git a/sbin/fdisk/gpt.h b/sbin/fdisk/gpt.h
index ace4b25..d606024 100644 (file)
--- a/sbin/fdisk/gpt.h
+++ b/sbin/fdisk/gpt.h
@@ -1,4 +1,4 @@
-/*     $OpenBSD: gpt.h,v 1.6 2016/01/09 18:10:57 krw Exp $     */
+/*     $OpenBSD: gpt.h,v 1.7 2021/01/30 18:16:36 krw Exp $     */
 /*
  * Copyright (c) 2015 Markus Muller <mmu@grummel.net>
  * Copyright (c) 2015 Kenneth R Westerback <krw@openbsd.org>
@@ -16,15 +16,17 @@
  * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
  */
 
-int GPT_get_hdr(off_t);
-int GPT_get_partition_table(off_t);
-void GPT_get_gpt(int);
-int GPT_init(void);
-int GPT_write(void);
+void           GPT_get_gpt(int);
+int            GPT_get_hdr(off_t);
+int            GPT_get_partition_table(off_t);
+int            GPT_get_lba_start(unsigned int);
+int            GPT_get_lba_end(unsigned int);
 
-void GPT_print(char *, int);
-void GPT_print_part(int, char *, int);
-void GPT_print_parthdr(int);
+int            GPT_init(void);
+int            GPT_write(void);
+void           GPT_print(char *, int);
+void           GPT_print_part(int, char *, int);
+void           GPT_print_parthdr(int);
 
 extern struct gpt_header gh;
 extern struct gpt_partition gp[NGPTPARTITIONS];