[PATCH v3 1/2] part: Add a function to find ESP partition

[Mayuresh Chitale <mchitale@ventanamicro.com>]

If a disk has an EFI system partition (ESP) then it can be used to
locate the boot files. Add a function to find the ESP.

Signed-off-by: Mayuresh Chitale <mchitale@ventanamicro.com>
Reviewed-by: Heinrich Schuchardt <heinrich.schuchardt@canonical.com>
---
Changes in v3:
- Fix part_get_esp signature and header in part.h

 disk/part.c    | 16 ++++++++++++++++
 include/part.h | 13 +++++++++++++
 2 files changed, 29 insertions(+)

diff --git a/disk/part.c b/disk/part.c
index 36b88205eca..6b1fbc18637 100644
--- a/disk/part.c
+++ b/disk/part.c
@@ -848,3 +848,19 @@ int part_get_bootable(struct blk_desc *desc)
 
 	return 0;
 }
+
+int part_get_esp(struct blk_desc *desc)
+{
+	struct disk_partition info;
+	int p;
+
+	for (p = 1; p <= MAX_SEARCH_PARTITIONS; p++) {
+		int ret;
+
+		ret = part_get_info(desc, p, &info);
+		if (!ret && (info.bootable & PART_EFI_SYSTEM_PARTITION))
+			return p;
+	}
+
+	return 0;
+}
diff --git a/include/part.h b/include/part.h
index db34bc6bb7d..1aa6fe44ffb 100644
--- a/include/part.h
+++ b/include/part.h
@@ -690,6 +690,14 @@ int part_get_type_by_name(const char *name);
  */
 int part_get_bootable(struct blk_desc *desc);
 
+/**
+ * part_get_esp() - Find the EFI system partition
+ *
+ * @desc: Block-device descriptor
+ * Return: the EFI system partition, or 0 if there is none
+ */
+int part_get_esp(struct blk_desc *desc);
+
 #else
 static inline int part_driver_get_count(void)
 { return 0; }
@@ -700,6 +708,11 @@ static inline struct part_driver *part_driver_get_first(void)
 static inline bool part_get_bootable(struct blk_desc *desc)
 { return false; }
 
+static inline int part_get_esp(struct blk_desc *desc)
+{
+	return 0;
+}
+
 #endif /* CONFIG_PARTITIONS */
 
 #endif /* _PART_H */
-- 
2.34.1