[U-Boot] [PATCH v2 1/2] tools: Fix return code of fit_image_process_sig()

[Mario Six <mario.six@gdsys.cc>]

When signing images, we repeatedly call fit_add_file_data() with
successively increasing size values to include the keys in the DTB.

Unfortunately, if large keys are used (such as 4096 bit RSA keys), this
process fails sometimes, and mkimage needs to be called repeatedly to
integrate the keys into the DTB.

This is because fit_add_file_data actually returns the wrong error
code, and the loop terminates prematurely, instead of trying again with
a larger size value.

This patch corrects the return value and also removes a error message,
which is misleading, since we actually allow the function to fail. A
(hopefully helpful) comment is also added to explain the lack of error
message.

This is probably related to 1152a05 ("tools: Correct error handling in
fit_image_process_hash()") and the corresponding error reported here:

https://www.mail-archive.com/u-boot at lists.denx.de/msg217417.html

Signed-off-by: Mario Six <mario.six@gdsys.cc>
---

Changes in v2:
 - Added an additional NULL check, as suggested by Simon Glass
 - Re-formatted the comment block

---
 tools/image-host.c | 16 +++++++++++-----
 1 file changed, 11 insertions(+), 5 deletions(-)

diff --git a/tools/image-host.c b/tools/image-host.c
index 3e14fdc..1104695 100644
--- a/tools/image-host.c
+++ b/tools/image-host.c
@@ -238,12 +238,18 @@ static int fit_image_process_sig(const char *keydir, void *keydest,
 	/* Get keyname again, as FDT has changed and invalidated our pointer */
 	info.keyname = fdt_getprop(fit, noffset, "key-name-hint", NULL);

-	/* Write the public key into the supplied FDT file */
-	if (keydest && info.algo->add_verify_data(&info, keydest)) {
-		printf("Failed to add verification data for '%s' signature node in '%s' image node\n",
-		       node_name, image_name);
+	if (keydest)
+		ret = info.algo->add_verify_data(&info, keydest);
+	else
 		return -1;
-	}
+
+	/*
+	 * Write the public key into the supplied FDT file; this might fail
+	 * several times, since we try signing with successively increasing
+	 * size values
+	 */
+	if (keydest && ret)
+		return ret;

 	return 0;
 }
--
2.9.0