Simple hack to preserve the EFI System partition when

auto-allocating the space on a disk whose GPT contains
any of the magic Apple partitions.

One step towards saving the firmware files on Apple
M1 machines when installing OpenBSD.

Tested & ok kettenis@

4 files changed, 82 insertions, 14 deletions

diff --git a/sbin/fdisk/fdisk.8 b/sbin/fdisk/fdisk.8
index b3ca9c5ec01..11083f06a55 100644
--- a/sbin/fdisk/fdisk.8
+++ b/sbin/fdisk/fdisk.8
@@ -1,4 +1,4 @@
-.\"	$OpenBSD: fdisk.8,v 1.109 2022/02/03 13:24:04 visa Exp $
+.\"	$OpenBSD: fdisk.8,v 1.110 2022/03/11 22:29:55 krw Exp $
 .\"
 .\"
 .\" Copyright (c) 1997 Tobias Weingartner
@@ -15,7 +15,7 @@
 .\" ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
 .\" OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 .\"
-.Dd $Mdocdate: February 3 2022 $
+.Dd $Mdocdate: March 11 2022 $
 .Dt FDISK 8
 .Os
 .Sh NAME
@@ -69,6 +69,19 @@ all existing partitions except the boot partitions
 .Sq HiFive FSBL
 and
 .Sq HiFive BBL .
+.Pp
+If one of
+.Sq APFS ISC ,
+.Sq APFS ,
+.Sq APFS Recovry
+is detected then any existing
+.Sq EFI system
+will also be preserved.
+If the preserved
+.Sq EFI system
+partition has fewer blocks than the number requested with
+.Fl b
+the modification of the GPT is aborted.
 .It Fl b Ar blocks Ns Op @ Ns Ar offset Ns Op : Ns Ar type
 Configures a special boot partition of the specified number of blocks, offset
 and type.
diff --git a/sbin/fdisk/fdisk.c b/sbin/fdisk/fdisk.c
index 6df24f5a2d6..0a68b197e29 100644
--- a/sbin/fdisk/fdisk.c
+++ b/sbin/fdisk/fdisk.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: fdisk.c,v 1.142 2022/02/04 23:32:17 krw Exp $	*/
+/*	$OpenBSD: fdisk.c,v 1.143 2022/03/11 22:29:55 krw Exp $	*/
 
 /*
  * Copyright (c) 1997 Tobias Weingartner
@@ -167,14 +167,16 @@ main(int argc, char *argv[])
 
 	switch (init) {
 	case INIT_GPT:
-		GPT_init(GHANDGP);
+		if (GPT_init(GHANDGP))
+			errx(1, "-g could not create valid GPT");
 		if (ask_yn("Do you wish to write new GPT?"))
 			Xwrite(NULL, &gmbr);
 		break;
 	case INIT_GPTPARTITIONS:
 		if (GPT_read(ANYGPT))
 			errx(1, "-A requires a valid GPT");
-		GPT_init(GPONLY);
+		if (GPT_init(GPONLY))
+			errx(1, "-A could not create valid GPT");
 		if (ask_yn("Do you wish to write new GPT?"))
 			Xwrite(NULL, &gmbr);
 		break;
diff --git a/sbin/fdisk/gpt.c b/sbin/fdisk/gpt.c
index 1cb681ae6f0..61f2d6fd1ca 100644
--- a/sbin/fdisk/gpt.c
+++ b/sbin/fdisk/gpt.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: gpt.c,v 1.58 2022/02/04 23:32:17 krw Exp $	*/
+/*	$OpenBSD: gpt.c,v 1.59 2022/03/11 22:29:55 krw Exp $	*/
 /*
  * Copyright (c) 2015 Markus Muller <mmu@grummel.net>
  * Copyright (c) 2015 Kenneth R Westerback <krw@openbsd.org>
@@ -49,6 +49,7 @@ struct gpt_partition	**sort_gpt(void);
 int			  lba_start_cmp(const void *e1, const void *e2);
 int			  lba_free(uint64_t *, uint64_t *);
 int			  add_partition(const uint8_t *, const char *, uint64_t);
+int			  find_partition(const uint8_t *);
 int			  get_header(const uint64_t);
 int			  get_partition_table(void);
 int			  init_gh(void);
@@ -414,6 +415,23 @@ GPT_print_part(const int n, const char *units, const int verbosity)
 }
 
 int
+find_partition(const uint8_t *beuuid)
+{
+	struct uuid		uuid, gp_type;
+	unsigned int		pn, pncnt;
+
+	uuid_dec_be(beuuid, &uuid);
+	uuid_enc_le(&gp_type, &uuid);
+
+	pncnt = letoh32(gh.gh_part_num);
+	for (pn = 0; pn < pncnt; pn++) {
+		if (uuid_compare(&gp[pn].gp_type, &gp_type, NULL) == 0)
+			return pn;
+	}
+	return -1;
+}
+
+int
 add_partition(const uint8_t *beuuid, const char *name, uint64_t sectors)
 {
 	struct uuid		uuid, gp_type;
@@ -529,6 +547,7 @@ init_gp(const int how)
 	struct gpt_partition	oldgp[NGPTPARTITIONS];
 	const uint8_t		gpt_uuid_efi_system[] = GPT_UUID_EFI_SYSTEM;
 	const uint8_t		gpt_uuid_openbsd[] = GPT_UUID_OPENBSD;
+	uint64_t		prt_ns;
 	int			pn, rslt;
 
 	memcpy(&oldgp, &gp, sizeof(oldgp));
@@ -544,8 +563,18 @@ init_gp(const int how)
 
 	rslt = 0;
 	if (disk.dk_bootprt.prt_ns > 0) {
-		rslt = add_partition(gpt_uuid_efi_system, "EFI System Area",
-		    disk.dk_bootprt.prt_ns);
+		pn = find_partition(gpt_uuid_efi_system);
+		if (pn == -1) {
+			rslt = add_partition(gpt_uuid_efi_system,
+			    "EFI System Area", disk.dk_bootprt.prt_ns);
+		} else {
+			prt_ns = gp[pn].gp_lba_end - gp[pn].gp_lba_start + 1;
+			if (prt_ns < disk.dk_bootprt.prt_ns) {
+				printf("EFI System Area < %llu sectors\n",
+				    disk.dk_bootprt.prt_ns);
+				rslt = -1;
+			}
+		}
 	}
 	if (rslt == 0)
 		rslt = add_partition(gpt_uuid_openbsd, "OpenBSD Area", 0);
diff --git a/sbin/fdisk/part.c b/sbin/fdisk/part.c
index cc10cda98af..32348cc551b 100644
--- a/sbin/fdisk/part.c
+++ b/sbin/fdisk/part.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: part.c,v 1.116 2022/02/04 23:32:17 krw Exp $	*/
+/*	$OpenBSD: part.c,v 1.117 2022/03/11 22:29:55 krw Exp $	*/
 
 /*
  * Copyright (c) 1997 Tobias Weingartner
@@ -29,6 +29,7 @@
 #include "part.h"
 #include "disk.h"
 #include "misc.h"
+#include "gpt.h"
 
 const char		*ascii_id(const int);
 
@@ -183,26 +184,49 @@ const struct gpt_type		gpt_types[] = {
 int
 PRT_protected_guid(const struct uuid *uuid)
 {
-	char			*str = NULL;
+	const uint8_t		 gpt_uuid_efi_system[] = GPT_UUID_EFI_SYSTEM;
+	struct uuid		 uuid_efi_system;
+	char			*efistr = NULL, *str = NULL;
+	char			*typename;
 	int			 rslt = 0;
 	unsigned int		 i;
 	uint32_t		 status;
 
+	uuid_dec_be(gpt_uuid_efi_system, &uuid_efi_system);
+
+	uuid_to_string(&uuid_efi_system, &efistr, &status);
+	if (status != uuid_s_ok) {
+		rslt = -1;
+		goto done;
+	}
 	uuid_to_string(uuid, &str, &status);
 	if (status != uuid_s_ok) {
 		rslt = -1;
 		goto done;
 	}
 
-	for(i = 0; i < nitems(gpt_types); i++) {
-		if (strncmp(str, gpt_types[i].gt_guid, UUID_STR_LEN) == 0) {
-			if (gpt_types[i].gt_protected)
-				rslt = -1;
+	if (strncmp(str, efistr, UUID_STR_LEN) == 0) {
+		/* Look for partitions indicating a need to preserve EFI Sys */
+		for (i = 0; i < NGPTPARTITIONS; i++) {
+			typename = PRT_uuid_to_typename(&gp[i].gp_type);
+			if (strncmp(typename, "APFS ", 5))
+				continue;
+			rslt = -1;
 			break;
 		}
+	} else {
+		for(i = 0; i < nitems(gpt_types); i++) {
+			if (strncmp(str, gpt_types[i].gt_guid, UUID_STR_LEN))
+				continue;
+			if (gpt_types[i].gt_protected) {
+				rslt = -1;
+				break;
+			}
+		}
 	}
 
  done:
+	free(efistr);
 	free(str);
 	return rslt;
 }