disk/part.c: ensure strings in struct disk_partition are valid after successful get_info

Not all ->get_info implementations necessarily populate all the string
members of struct disk_partition.

Currently, only part_get_info_by_type() (and thereby part_get_info)
ensure that the uuid strings are initialized; part_get_info_by_type()
and part_get_info_by_uuid() do not. In fact, the latter could lead to
a false positive match - if the ->get_info backend does not populate
info->uuid, stale contents in info could cause the strncasecmp() to
succeed.

None of the functions currently ensure that the ->name and ->type
strings are initialized.

Instead of forcing all callers of any of these functions to
pre-initialize info, or all implementations of the ->get_info method
to ensure there are valid C strings in all four fields, create a small
helper function and factor all invocations of ->get_info through that.

This also consolidates the -ENOSYS check and standardizes on using
log_debug() for reporting absence, instead of the current mix of
PRINTF and log_debug(). It does mean we have to special-case -ENOSYS
in the error cases inside the loops in the _by_uuid() and _by_name()
functions, but it's still a net win in #LOC.

Acked-by: Quentin Schulz <quentin.schulz@cherry.de>
Signed-off-by: Rasmus Villemoes <ravi@prevas.dk>
Tested-by: Anshul Dalal <anshuld@ti.com>

1 files changed, 16 insertions, 0 deletions

diff --git a/include/part.h b/include/part.h
index 6caaa6526aa..d940f8b5d0e 100644
--- a/include/part.h
+++ b/include/part.h
@@ -509,6 +509,22 @@ struct part_driver {
 	int (*test)(struct blk_desc *desc);
 };
 
+/**
+ * part_driver_get_info() - Call the part_driver's get_info method
+ *
+ * On success, string members of info are guaranteed to be properly
+ * initialized, though they may be empty.
+ *
+ * @drv:	Partition driver
+ * @desc:	Block device descriptor
+ * @part:	Partition number to read
+ * @info:	Returned partition information
+ *
+ * Return: 0 on success, negative errno on failure.
+ */
+int part_driver_get_info(struct part_driver *drv, struct blk_desc *desc, int part,
+			 struct disk_partition *info);
+
 /* Declare a new U-Boot partition 'driver' */
 #define U_BOOT_PART_TYPE(__name)					\
 	ll_entry_declare(struct part_driver, __name, part_driver)