libfdisk: add {first,last}-lba header to sfdisk scritps

The current sfdisk does not allow to create partition that
starts before the default libfdisk First LBA (~1MiB). It
means that

 # sfdisk --dump /dev/sda > foo
 # sfdisk /dev/sdb < foo

does not work on systems where 1st partition does not start at offset
2048.

This patch add new headers to scripts to inform libfdisk about different
First/Last LBA ranges. For example:

 label: gpt
 first-lba: 34

allows to override the library default.

Signed-off-by: Karel Zak <kzak@redhat.com>

2 files changed, 94 insertions, 10 deletions

diff --git a/libfdisk/src/gpt.c b/libfdisk/src/gpt.c
index 7a2997ccc..61b0a32e1 100644
--- a/libfdisk/src/gpt.c
+++ b/libfdisk/src/gpt.c
@@ -520,20 +520,82 @@ static struct gpt_header *gpt_copy_header(struct fdisk_context *cxt,
 	return res;
 }
 
-static void count_first_last_lba(struct fdisk_context *cxt,
+static int get_script_u64(struct fdisk_context *cxt, uint64_t *num, const char *name)
+{
+	const char *str;
+	int pwr = 0, rc = 0;
+
+	assert(cxt);
+
+	*num = 0;
+
+	if (!cxt->script)
+		return 1;
+
+	str = fdisk_script_get_header(cxt->script, name);
+	if (!str)
+		return 1;
+
+	rc = parse_size(str, (uintmax_t *) num, &pwr);
+	if (rc < 0)
+		return rc;
+	if (pwr)
+		*num /= cxt->sector_size;
+	return 0;
+}
+
+static int count_first_last_lba(struct fdisk_context *cxt,
 				 uint64_t *first, uint64_t *last)
 {
+	int rc = 0;
+	uint64_t flba, llba;
+
 	uint64_t esz = 0;
 
 	assert(cxt);
+	assert(first);
+	assert(last);
 
+	*first = *last = 0;
+
+	/* UEFI default */
 	esz = sizeof(struct gpt_entry) * GPT_NPARTITIONS / cxt->sector_size;
-	*last = cxt->total_sectors - 2 - esz;
-	*first = esz + 2;
+	llba = cxt->total_sectors - 2 - esz;
+	flba = esz + 2;
+
+	/* script default */
+	if (cxt->script) {
+		rc = get_script_u64(cxt, first, "first-lba");
+		if (rc < 0)
+			return rc;
+
+		DBG(LABEL, ul_debug("FirstLBA: script=%ju, uefi=%ju, topology=%ju.", *first, flba, cxt->first_lba));
+
+		if (rc == 0 && (*first < flba || *first > llba)) {
+			fdisk_warnx(cxt, _("First LBA specified by script is out of range."));
+			return -ERANGE;
+		}
+
+		rc = get_script_u64(cxt, last, "last-lba");
+		if (rc < 0)
+			return rc;
+
+		DBG(LABEL, ul_debug("LastLBA: script=%ju, uefi=%ju, topology=%ju.", *last, llba, cxt->last_lba));
 
-	if (*first < cxt->first_lba && cxt->first_lba < *last)
-		/* Align according to topology */
-		*first = cxt->first_lba;
+		if (rc == 0 && (*last > llba || *last < flba)) {
+			fdisk_warnx(cxt, _("Last LBA specified by script is out of range."));
+			return -ERANGE;
+		}
+	}
+
+	if (!*last)
+		*last = llba;
+
+	/* default by topology */
+	if (!*first)
+		*first = flba < cxt->first_lba &&
+			 cxt->first_lba < *last ? cxt->first_lba : flba;
+	return 0;
 }
 
 /*
@@ -548,7 +610,7 @@ static int gpt_mknew_header(struct fdisk_context *cxt,
 			    struct gpt_header *header, uint64_t lba)
 {
 	uint64_t first, last;
-	int has_id = 0;
+	int has_id = 0, rc;
 
 	if (!cxt || !header)
 		return -ENOSYS;
@@ -571,7 +633,10 @@ static int gpt_mknew_header(struct fdisk_context *cxt,
 	header->npartition_entries     = cpu_to_le32(GPT_NPARTITIONS);
 	header->sizeof_partition_entry = cpu_to_le32(sizeof(struct gpt_entry));
 
-	count_first_last_lba(cxt, &first, &last);
+	rc = count_first_last_lba(cxt, &first, &last);
+	if (rc)
+		return rc;
+
 	header->first_usable_lba = cpu_to_le64(first);
 	header->last_usable_lba  = cpu_to_le64(last);
 
diff --git a/libfdisk/src/script.c b/libfdisk/src/script.c
index 5a89790d7..eb4e31d20 100644
--- a/libfdisk/src/script.c
+++ b/libfdisk/src/script.c
@@ -238,17 +238,22 @@ int fdisk_script_set_header(struct fdisk_script *dp,
 	if (!dp || !name)
 		return -EINVAL;
 
+
 	fi = script_get_header(dp, name);
 	if (!fi && !data)
 		return 0;	/* want to remove header that does not exist, success */
 
 	if (!data) {
+		DBG(SCRIPT, ul_debugobj(dp, "freeing header %s", name));
+
 		/* no data, remove the header */
 		fdisk_script_free_header(dp, fi);
 		return 0;
 	}
 
 	if (!fi) {
+		DBG(SCRIPT, ul_debugobj(dp, "setting new header %s='%s'", name, data));
+
 		/* new header */
 		fi = calloc(1, sizeof(*fi));
 		if (!fi)
@@ -265,6 +270,8 @@ int fdisk_script_set_header(struct fdisk_script *dp,
 		/* update existing */
 		char *x = strdup(data);
 
+		DBG(SCRIPT, ul_debugobj(dp, "update '%s' header '%s' -> '%s'", name, fi->data, data));
+
 		if (!x)
 			return -ENOMEM;
 		free(fi->data);
@@ -366,7 +373,17 @@ int fdisk_script_read_context(struct fdisk_script *dp, struct fdisk_context *cxt
 	if (!rc)
 		rc = fdisk_script_set_header(dp, "unit", "sectors");
 
-	/* TODO: label specific headers (e.g. uuid for GPT) */
+	if (!rc && fdisk_is_label(cxt, GPT)) {
+		char buf[64];
+
+		snprintf(buf, sizeof(buf), "%ju", cxt->first_lba);
+		rc = fdisk_script_set_header(dp, "first-lba", buf);
+
+		if (!rc) {
+			snprintf(buf, sizeof(buf), "%ju", cxt->last_lba);
+			rc = fdisk_script_set_header(dp, "last-lba", buf);
+		}
+	}
 
 	DBG(SCRIPT, ul_debugobj(dp, "read context done [rc=%d]", rc));
 	return rc;
@@ -493,7 +510,9 @@ static int parse_header_line(struct fdisk_script *dp, char *s)
 		if (strcmp(value, "sectors") != 0)
 			goto done;			/* only "sectors" supported */
 	} else if (strcmp(name, "label-id") == 0
-		   || strcmp(name, "device") == 0) {
+		   || strcmp(name, "device") == 0
+		   || strcmp(name, "first-lba") == 0
+		   || strcmp(name, "last-lba") == 0) {
 		;					/* whatever is posssible */
 	} else
 		goto done;				/* unknown header */