o Save the partition number (=index) in the internal map. The index

starts at 1. No index is represented by 0.
o  Change the show command to display the partition number at the expense
   of the partition end columm. We already display the start and size.
o  Enhance the add command to accept the -i option. The -i option allows
   the user to specify which partition number the new partition should
   get.
o  Update the manpage accordingly.

sbin/gpt/add.c

@@ -43,13 +43,15 @@
 
 static uuid_t type;
 static off_t block, size;
+static unsigned int entry;
 
 static void
 usage_add(void)
 {
 
 	fprintf(stderr,
-	    "usage: %s [-b lba] [-s lba] [-t uuid] device\n", getprogname());
+	    "usage: %s [-b lba] [-i index] [-s lba] [-t uuid] device\n",
+	    getprogname());
 	exit(1);
 }
 
@@ -84,10 +86,34 @@ add(int fd)
 		return;
 	}
 
-	/* Create UFS partitions by default. */
-	if (uuid_is_nil(&type, NULL)) {
-		uuid_t ufs = GPT_ENT_TYPE_FREEBSD_UFS;
-		type = ufs;
+	hdr = gpt->map_data;
+	if (entry > hdr->hdr_entries) {
+		warnx("%s: error: index %u out of range (%u max)", device_name,
+		    entry, hdr->hdr_entries);
+		return;
+	}
+
+	if (entry > 0) {
+		i = entry - 1;
+		ent = (void*)((char*)tbl->map_data + i * hdr->hdr_entsz);
+		if (!uuid_is_nil(&ent->ent_type, NULL)) {
+			warnx("%s: error: entry at index %u is not free",
+			    device_name, entry);
+			return;
+		}
+	} else {
+		/* Find empty slot in GPT table. */
+		for (i = 0; i < hdr->hdr_entries; i++) {
+			ent = (void*)((char*)tbl->map_data + i *
+			    hdr->hdr_entsz);
+			if (uuid_is_nil(&ent->ent_type, NULL))
+				break;
+		}
+		if (i == hdr->hdr_entries) {
+			warnx("%s: error: no available table entries",
+			    device_name);
+			return;
+		}
 	}
 
 	map = map_alloc(block, size);
@@ -96,18 +122,6 @@ add(int fd)
 		return;
 	}
 
-	/* Find empty slot in GPT table. */
-	hdr = gpt->map_data;
-	for (i = 0; i < hdr->hdr_entries; i++) {
-		ent = (void*)((char*)tbl->map_data + i * hdr->hdr_entsz);
-		if (uuid_is_nil(&ent->ent_type, NULL))
-			break;
-	}
-	if (i == hdr->hdr_entries) {
-		warnx("%s: error: no available table entries", device_name);
-		return;
-	}
-
 	ent->ent_type = type;
 	ent->ent_lba_start = map->map_start;
 	ent->ent_lba_end = map->map_start + map->map_size - 1LL;
@@ -144,7 +158,7 @@ cmd_add(int argc, char *argv[])
 	uint32_t status;
 
 	/* Get the migrate options */
-	while ((ch = getopt(argc, argv, "b:s:t:")) != -1) {
+	while ((ch = getopt(argc, argv, "b:i:s:t:")) != -1) {
 		switch(ch) {
 		case 'b':
 			if (block > 0)
@@ -153,6 +167,13 @@ cmd_add(int argc, char *argv[])
 			if (*p != 0 || block < 1)
 				usage_add();
 			break;
+		case 'i':
+			if (entry > 0)
+				usage_add();
+			entry = strtol(optarg, &p, 10);
+			if (*p != 0 || entry < 1)
+				usage_add();
+			break;
 		case 's':
 			if (size > 0)
 				usage_add();
@@ -174,10 +195,10 @@ cmd_add(int argc, char *argv[])
 				} else if (strcmp(optarg, "ufs") == 0) {
 					uuid_t ufs = GPT_ENT_TYPE_FREEBSD_UFS;
 					type = ufs;
-				} else if ((strcmp(optarg, "linux") == 0)
-					  || (strcmp(optarg, "windows") == 0)) {
-					uuid_t ext = GPT_ENT_TYPE_MS_BASIC_DATA;
-					type = ext ;
+				} else if (strcmp(optarg, "linux") == 0 ||
+				    strcmp(optarg, "windows") == 0) {
+					uuid_t m = GPT_ENT_TYPE_MS_BASIC_DATA;
+					type = m;
 				} else
 					usage_add();
 			}
@@ -190,6 +211,12 @@ cmd_add(int argc, char *argv[])
 	if (argc == optind)
 		usage_add();
 
+	/* Create UFS partitions by default. */
+	if (uuid_is_nil(&type, NULL)) {
+		uuid_t ufs = GPT_ENT_TYPE_FREEBSD_UFS;
+		type = ufs;
+	}
+
 	while (optind < argc) {
 		fd = gpt_open(argv[optind++]);
 		if (fd == -1) {

sbin/gpt/gpt.8

@@ -24,7 +24,7 @@
 .\"
 .\" $FreeBSD$
 .\"
-.Dd July 1, 2004
+.Dd August 6, 2004
 .Os
 .Dt GPT 8
 .Sh NAME
@@ -43,7 +43,7 @@ utility provides the necessary functionality to manipulate GUID partition
 tables (GPTs), but see
 .Sx BUGS
 below for how and where functionality is missing.
-The general usage model of the
+The basic usage model of the
 .Nm
 tool follows that of the
 .Xr cvs 1
@@ -94,6 +94,7 @@ There is no formalized definition of the different levels yet.
 .Nm
 .Ic add
 .Op Fl b Ar number
+.Op Fl i Ar index
 .Op Fl s Ar count
 .Op Fl t Ar type
 .Ar device ...
@@ -113,6 +114,12 @@ The minimum sector number is 1, but has to fall inside an unused region of
 disk space that is covered by the GPT.
 .Pp
 The
+.Fl i Ar index
+option allows the user to specify which (free) entry in the GPT table is to
+be used for the new partition.
+By default the first free entry is selected.
+.Pp
+The
 .Fl s Ar count
 option allows the user to specify the size of the partition in sectors.
 The minimum size is 1.
@@ -122,11 +129,11 @@ The
 option allows the user to specify the partition type.
 The type is given as an UUID, but
 .Nm
-has created
+accepts
 .Cm efi , swap , ufs , linux
 and
 .Cm windows
-as aliases for some most commonly used partition types.
+as aliases for the most commonly used partition types.
 .\" ==== create ====
 .It Xo
 .Nm
@@ -221,7 +228,7 @@ However, it is believed that the currently present functionality is reliable
 and stable enough that this tool can be used without bullet-proof footware if
 one thinks one does not make mistakes.
 .Pp
-It is expected that the generic usage model does not change, but it is
+It is expected that the basic usage model does not change, but it is
 possible that future versions will not be compatible in the strictest sense
 of the word.
 For example, the

sbin/gpt/gpt.c

@@ -237,6 +237,7 @@ gpt_mbr(int fd, off_t lba)
 			m = map_add(start, size, MAP_TYPE_MBR_PART, p);
 			if (m == NULL)
 				return (-1);
+			m->map_index = i + 1;
 		} else {
 			if (gpt_mbr(fd, start) == -1)
 				return (-1);
@@ -321,6 +322,7 @@ gpt_gpt(int fd, off_t lba)
 		m = map_add(ent->ent_lba_start, size, MAP_TYPE_GPT_PART, ent);
 		if (m == NULL)
 			return (-1);
+		m->map_index = i + 1;
 	}
 	return (0);
 

sbin/gpt/map.c

@@ -49,6 +49,7 @@ mkmap(off_t start, off_t size, int type)
 	m->map_size = size;
 	m->map_next = m->map_prev = NULL;
 	m->map_type = type;
+	m->map_index = 0;
 	m->map_data = NULL;
 	return (m);
 }

sbin/gpt/map.h

@@ -44,6 +44,7 @@ typedef struct map {
 #define	MAP_TYPE_SEC_GPT_TBL	6
 #define	MAP_TYPE_GPT_PART	7
 #define	MAP_TYPE_PMBR		8
+	int	map_index;
 	void 	*map_data;
 } map_t;
 

sbin/gpt/show.c

@@ -90,25 +90,28 @@ friendly(uuid_t *t)
 static void
 show(int fd __unused)
 {
-	off_t start, end;
+	off_t start;
 	map_t *m, *p;
 	struct mbr *mbr;
 	struct gpt_ent *ent;
 	unsigned int i;
 
 	printf("  %*s", lbawidth, "start");
-	printf("  %*s", lbawidth, "end");
 	printf("  %*s", lbawidth, "size");
-	printf("  %s\n", "contents");
+	printf("  index  contents\n");
 
 	m = map_first();
 	while (m != NULL) {
-		end = m->map_start + m->map_size - 1;
 		printf("  %*llu", lbawidth, (long long)m->map_start);
-		printf("  %*llu", lbawidth, (long long)end);
 		printf("  %*llu", lbawidth, (long long)m->map_size);
-
-		putchar(' '); putchar(' ');
+		putchar(' ');
+		putchar(' ');
+		if (m->map_index > 0)
+			printf("%5d", m->map_index);
+		else
+			printf("     ");
+		putchar(' ');
+		putchar(' ');
 		switch (m->map_type) {
 		case MAP_TYPE_MBR:
 			if (m->map_start != 0)