From e5f31446166de7212213c62a019945afb8e197ef Mon Sep 17 00:00:00 2001
From: Karel Zak <kzak@redhat.com>
Date: Tue, 14 Jan 2020 11:43:24 +0100
Subject: [PATCH] libfdisk: add fdisk_set_disklabel_id_from_string()

We have fdisk_set_disklabel_id(), but it's old ask-API based function.
It's not comfortable if you want to avoid dialog or template.

Addresses: https://github.com/karelzak/util-linux/issues/916
Signed-off-by: Karel Zak <kzak@redhat.com>
---
 libfdisk/docs/libfdisk-sections.txt |  1 +
 libfdisk/src/dos.c                  | 29 ++++++++++++++++++-----------
 libfdisk/src/fdiskP.h               |  2 +-
 libfdisk/src/gpt.c                  | 18 ++++++++++--------
 libfdisk/src/label.c                | 19 ++++++++++++++++++-
 libfdisk/src/libfdisk.h.in          |  1 +
 libfdisk/src/libfdisk.sym           |  3 +++
 7 files changed, 52 insertions(+), 21 deletions(-)

diff --git a/libfdisk/docs/libfdisk-sections.txt b/libfdisk/docs/libfdisk-sections.txt
index f148da527..6675c1100 100644
--- a/libfdisk/docs/libfdisk-sections.txt
+++ b/libfdisk/docs/libfdisk-sections.txt
@@ -81,6 +81,7 @@ fdisk_list_disklabel
 fdisk_locate_disklabel
 fdisk_reorder_partitions
 fdisk_set_disklabel_id
+fdisk_set_disklabel_id_from_string
 fdisk_set_partition_type
 fdisk_toggle_partition_flag
 fdisk_verify_disklabel
diff --git a/libfdisk/src/dos.c b/libfdisk/src/dos.c
index 53713ec5f..98314dfa6 100644
--- a/libfdisk/src/dos.c
+++ b/libfdisk/src/dos.c
@@ -707,12 +707,12 @@ static int dos_create_disklabel(struct fdisk_context *cxt)
 	return 0;
 }
 
-static int dos_set_disklabel_id(struct fdisk_context *cxt)
+static int dos_set_disklabel_id(struct fdisk_context *cxt, const char *str)
 {
-	char *end = NULL, *str = NULL;
+	char *str0 = str;
 	unsigned int id, old;
 	struct fdisk_dos_label *l;
-	int rc;
+	int rc = 0;
 
 	assert(cxt);
 	assert(cxt->label);
@@ -722,18 +722,25 @@ static int dos_set_disklabel_id(struct fdisk_context *cxt)
 
 	l = self_label(cxt);
 	old = mbr_get_id(cxt->firstsector);
-	rc = fdisk_ask_string(cxt,
+
+	if (!str)
+		rc = fdisk_ask_string(cxt,
 			_("Enter the new disk identifier"), &str);
-	if (rc)
-		return rc;
+	if (!rc) {
+		char *end = NULL;
 
-	errno = 0;
-	id = strtoul(str, &end, 0);
-	if (errno || str == end || (end && *end)) {
-		fdisk_warnx(cxt, _("Incorrect value."));
-		return -EINVAL;
+		errno = 0;
+		id = strtoul(str, &end, 0);
+		if (errno || str == end || (end && *end)) {
+			fdisk_warnx(cxt, _("Incorrect value."));
+			rc = -EINVAL;
+		}
 	}
 
+	if (!str0)
+		free(str);
+	if (rc)
+		return -EINVAL;
 
 	mbr_set_id(cxt->firstsector, id);
 	l->non_pt_changed = 1;
diff --git a/libfdisk/src/fdiskP.h b/libfdisk/src/fdiskP.h
index fefebae2a..0487466e3 100644
--- a/libfdisk/src/fdiskP.h
+++ b/libfdisk/src/fdiskP.h
@@ -220,7 +220,7 @@ struct fdisk_label_operations {
 	/* get details from label */
 	int (*get_item)(struct fdisk_context *cxt, struct fdisk_labelitem *item);
 	/* set disk label ID */
-	int (*set_id)(struct fdisk_context *cxt);
+	int (*set_id)(struct fdisk_context *cxt, const char *str);
 
 
 	/* new partition */
diff --git a/libfdisk/src/gpt.c b/libfdisk/src/gpt.c
index f50bb4441..9608053a2 100644
--- a/libfdisk/src/gpt.c
+++ b/libfdisk/src/gpt.c
@@ -2502,11 +2502,11 @@ done:
 	return rc;
 }
 
-static int gpt_set_disklabel_id(struct fdisk_context *cxt)
+static int gpt_set_disklabel_id(struct fdisk_context *cxt, const char *str)
 {
 	struct fdisk_gpt_label *gpt;
 	struct gpt_guid uuid;
-	char *str, *old, *new;
+	char *old, *new;
 	int rc;
 
 	assert(cxt);
@@ -2514,12 +2514,14 @@ static int gpt_set_disklabel_id(struct fdisk_context *cxt)
 	assert(fdisk_is_label(cxt, GPT));
 
 	gpt = self_label(cxt);
-	if (fdisk_ask_string(cxt,
-			_("Enter new disk UUID (in 8-4-4-4-12 format)"), &str))
-		return -EINVAL;
-
-	rc = string_to_guid(str, &uuid);
-	free(str);
+	if (!str) {
+		if (fdisk_ask_string(cxt,
+				_("Enter new disk UUID (in 8-4-4-4-12 format)"), &str))
+			return -EINVAL;
+		rc = string_to_guid(str, &uuid);
+		free(str);
+	} else
+		rc = string_to_guid(str, &uuid);
 
 	if (rc) {
 		fdisk_warnx(cxt, _("Failed to parse your UUID."));
diff --git a/libfdisk/src/label.c b/libfdisk/src/label.c
index a18cdeaff..fd4555de2 100644
--- a/libfdisk/src/label.c
+++ b/libfdisk/src/label.c
@@ -481,7 +481,24 @@ int fdisk_set_disklabel_id(struct fdisk_context *cxt)
 		return -ENOSYS;
 
 	DBG(CXT, ul_debugobj(cxt, "setting %s disk ID", cxt->label->name));
-	return cxt->label->op->set_id(cxt);
+	return cxt->label->op->set_id(cxt, NULL);
+}
+
+/**
+ * fdisk_set_disklabel_id_from_string
+ * @cxt: fdisk context
+ *
+ * Returns: 0 on success, otherwise, a corresponding error.
+ */
+int fdisk_set_disklabel_id_from_string(struct fdisk_context *cxt, const char *str)
+{
+	if (!cxt || !cxt->label || !str)
+		return -EINVAL;
+	if (!cxt->label->op->set_id)
+		return -ENOSYS;
+
+	DBG(CXT, ul_debugobj(cxt, "setting %s disk ID from '%s'", cxt->label->name, str));
+	return cxt->label->op->set_id(cxt, str);
 }
 
 /**
diff --git a/libfdisk/src/libfdisk.h.in b/libfdisk/src/libfdisk.h.in
index 0669c0a7c..2ba34dc0a 100644
--- a/libfdisk/src/libfdisk.h.in
+++ b/libfdisk/src/libfdisk.h.in
@@ -399,6 +399,7 @@ extern int fdisk_get_disklabel_item(struct fdisk_context *cxt, int id, struct fd
 
 extern int fdisk_get_disklabel_id(struct fdisk_context *cxt, char **id);
 extern int fdisk_set_disklabel_id(struct fdisk_context *cxt);
+extern int fdisk_set_disklabel_id_from_string(struct fdisk_context *cxt, const char *str);
 
 extern int fdisk_get_partition(struct fdisk_context *cxt, size_t partno, struct fdisk_partition **pa);
 extern int fdisk_set_partition(struct fdisk_context *cxt, size_t partno, struct fdisk_partition *pa);
diff --git a/libfdisk/src/libfdisk.sym b/libfdisk/src/libfdisk.sym
index 96fcadd71..eee2d6bda 100644
--- a/libfdisk/src/libfdisk.sym
+++ b/libfdisk/src/libfdisk.sym
@@ -308,3 +308,6 @@ FDISK_2.35 {
 	fdisk_script_set_table;
 	fdisk_assign_device_by_fd;
 } FDISK_2.33;
+FDISK_2.36 {
+	fdisk_set_disklabel_id_from_string;
+} FDISK_2.35;
-- 
2.18.2