[U-Boot] [PATCH v2 2/7] disk: part: Extend API to get partition info

[Ruslan Trofymenko]

This patch adds part_get_info_by_dev_and_name_or_num() function which
allows us to get partition info from its number or name. Partition of
interest is specified by string like "device_num:partition_number" or
"device_num#partition_name".

The patch was extracted from [1].

[1] https://android-review.googlesource.com/c/platform/external/u-boot/+/729880/2

Signed-off-by: Ruslan Trofymenko <ruslan.trofymenko at linaro.org>
Reviewed-by: Alistair Strachan <astrachan at google.com>
Reviewed-by: Sam Protsenko <semen.protsenko at linaro.org>
---
Changes in v2:
  * Error codes are changed to -EINVAL instead of -1

 disk/part.c    | 68 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 include/part.h | 21 ++++++++++++++++++
 2 files changed, 89 insertions(+)

diff --git a/disk/part.c b/disk/part.c
index f30f9e9..7b739ad 100644
--- a/disk/part.c
+++ b/disk/part.c
@@ -675,6 +675,74 @@ int part_get_info_by_name(struct blk_desc *dev_desc, const char *name,
 	return part_get_info_by_name_type(dev_desc, name, info, PART_TYPE_ALL);
 }
 
+/**
+ * Get partition info from device number and partition name.
+ *
+ * Parse a device number and partition name string in the form of
+ * "device_num#partition_name", for example "0#misc". If the partition
+ * is found, sets dev_desc and part_info accordingly with the information
+ * of the partition with the given partition_name.
+ *
+ * @param[in] dev_iface Device interface
+ * @param[in] dev_part_str Input string argument, like "0#misc"
+ * @param[out] dev_desc Place to store the device description pointer
+ * @param[out] part_info Place to store the partition information
+ * @return 0 on success, or a negative on error
+ */
+static int part_get_info_by_dev_and_name(const char *dev_iface,
+					 const char *dev_part_str,
+					 struct blk_desc **dev_desc,
+					 disk_partition_t *part_info)
+{
+	char *ep;
+	const char *part_str;
+	int dev_num;
+
+	part_str = strchr(dev_part_str, '#');
+	if (!part_str || part_str == dev_part_str)
+		return -EINVAL;
+
+	dev_num = simple_strtoul(dev_part_str, &ep, 16);
+	if (ep != part_str) {
+		/* Not all the first part before the # was parsed. */
+		return -EINVAL;
+	}
+	part_str++;
+
+	*dev_desc = blk_get_dev(dev_iface, dev_num);
+	if (!*dev_desc) {
+		printf("Could not find %s %d\n", dev_iface, dev_num);
+		return -EINVAL;
+	}
+	if (part_get_info_by_name(*dev_desc, part_str, part_info) < 0) {
+		printf("Could not find \"%s\" partition\n", part_str);
+		return -EINVAL;
+	}
+	return 0;
+}
+
+int part_get_info_by_dev_and_name_or_num(const char *dev_iface,
+					 const char *dev_part_str,
+					 struct blk_desc **dev_desc,
+					 disk_partition_t *part_info)
+{
+	/* Split the part_name if passed as "$dev_num#part_name". */
+	if (!part_get_info_by_dev_and_name(dev_iface, dev_part_str,
+					   dev_desc, part_info))
+		return 0;
+	/*
+	 * Couldn't lookup by name, try looking up the partition description
+	 * directly.
+	 */
+	if (blk_get_device_part_str(dev_iface, dev_part_str,
+				    dev_desc, part_info, 1) < 0) {
+		printf("Couldn't find partition %s %s\n",
+		       dev_iface, dev_part_str);
+		return -EINVAL;
+	}
+	return 0;
+}
+
 void part_set_generic_name(const struct blk_desc *dev_desc,
 	int part_num, char *name)
 {
diff --git a/include/part.h b/include/part.h
index 0750aee..9d57b65 100644
--- a/include/part.h
+++ b/include/part.h
@@ -202,6 +202,27 @@ int part_get_info_by_name(struct blk_desc *dev_desc,
 			      const char *name, disk_partition_t *info);
 
 /**
+ * Get partition info from dev number + part name, or dev number + part number.
+ *
+ * Parse a device number and partition description (either name or number)
+ * in the form of device number plus partition name separated by a "#"
+ * (like "device_num#partition_name") or a device number plus a partition number
+ * separated by a ":". For example both "0#misc" and "0:1" can be valid
+ * partition descriptions for a given interface. If the partition is found, sets
+ * dev_desc and part_info accordingly with the information of the partition.
+ *
+ * @param[in] dev_iface	Device interface
+ * @param[in] dev_part_str Input partition description, like "0#misc" or "0:1"
+ * @param[out] dev_desc	Place to store the device description pointer
+ * @param[out] part_info Place to store the partition information
+ * @return 0 on success, or a negative on error
+ */
+int part_get_info_by_dev_and_name_or_num(const char *dev_iface,
+					 const char *dev_part_str,
+					 struct blk_desc **dev_desc,
+					 disk_partition_t *part_info);
+
+/**
  * part_set_generic_name() - create generic partition like hda1 or sdb2
  *
  * Helper function for partition tables, which don't hold partition names
-- 
2.7.4