[U-Boot] [PATCH v2 3/3] fastboot: Check if partition really exist in getvar_has_slot()

[Sam Protsenko]

From: Igor Opaniuk <igor.opaniuk at toradex.com>

Currently getvar_has_slot() invocation for "boot" and "system"
partitions always returns affirmative response regardless the fact of
existence of these partitions, which leads to impossibility to flash them
on old non-A/B AOSP setups, where _a/_b suffixes aren't used:

$ fastboot flash boot boot.img
Sending 'boot__a' (11301 KB)    OKAY [  0.451s]
Writing 'boot__a'               FAILED (remote: 'cannot find partition')
fastboot: error: Command failed

Although partition layout is:
-> part list mmc 0
Partition Map for MMC device 0  --   Partition Type: EFI

Part	Start LBA	End LBA		Name
	Attributes
	Type GUID
	Partition GUID
  1	0x00000800	0x000107ff	"boot"
	attrs:	0x0000000000000000
	type:	ebd0a0a2-b9e5-4433-87c0-68b6b72699c7
	guid:	ea2e2470-db4a-d646-b828-10167f736d63
  2	0x00010800	0x000127ff	"environment"
	attrs:	0x0000000000000000
	type:	ebd0a0a2-b9e5-4433-87c0-68b6b72699c7
	guid:	10a819d2-6004-3d48-bd87-114e2a796db9
  3	0x00012800	0x0001a7ff	"recovery"
	attrs:	0x0000000000000000
	type:	ebd0a0a2-b9e5-4433-87c0-68b6b72699c7
	guid:	9ea116e4-8a34-0c48-8cf5-2fe9480f56cd
  4	0x0001a800	0x0031a7ff	"system"
	attrs:	0x0000000000000000
......

This patch adds checks of existence for requested partitions
on eMMC/NAND.

Signed-off-by: Igor Opaniuk <igor.opaniuk at toradex.com>
Signed-off-by: Sam Protsenko <semen.protsenko at linaro.org>
---
 drivers/fastboot/fb_getvar.c | 26 ++++++++++++++++++++++----
 1 file changed, 22 insertions(+), 4 deletions(-)

diff --git a/drivers/fastboot/fb_getvar.c b/drivers/fastboot/fb_getvar.c
index b23880089e..563bda0088 100644
--- a/drivers/fastboot/fb_getvar.c
+++ b/drivers/fastboot/fb_getvar.c
@@ -179,11 +179,29 @@ static void getvar_slot_suffixes(char *var_parameter, char *response)
 
 static void getvar_has_slot(char *part_name, char *response)
 {
-	if (part_name && (!strcmp(part_name, "boot") ||
-			  !strcmp(part_name, "system")))
+	char part_name_wslot[PART_NAME_LEN];
+	size_t len;
+	int r;
+
+	if (!part_name)
+		goto no;
+
+	/* Append "_a" prefix to part_name */
+	len = strlcpy(part_name_wslot, part_name, PART_NAME_LEN - 3);
+	if (len > PART_NAME_LEN - 3) {
+		fastboot_fail("too long partition name", response);
+		return;
+	}
+	strcat(part_name_wslot, "_a");
+
+	/* Check if this partition exists */
+	r = getvar_get_part_info(part_name_wslot, response, NULL);
+	if (r >= 0) {
 		fastboot_okay("yes", response);
-	else
-		fastboot_okay("no", response);
+		return;
+	}
+no:
+	fastboot_okay("no", response);
 }
 
 #if CONFIG_IS_ENABLED(FASTBOOT_FLASH_MMC)
-- 
2.20.1