autoupdater: extremely slow image download on HiveAP

[kpanic23]

I'm currently using autoupdater to update the firmware on an Aerohive HiveAP 330. Which takes ages.
So I've used that time to find out about what's holding it up.
The HiveAP 330 uses a 9600bps console output, so any output takes a long time.

The while loop in recv_image_cb outputs the progress in every iteration:

packages/admin/autoupdater/src/autoupdater.c

Lines 252 to 277 in 3d08b0f

	/** Receives data from uclient and writes it to file */
	static void recv_image_cb(struct uclient *cl) {
	struct recv_image_ctx *ctx = uclient_get_custom(cl);
	char buf[1024];
	int len;
	while (true) {
	len = uclient_read_account(cl, buf, sizeof(buf));
	if (len <= 0)
	return;
	printf(
	"\rDownloading image: % 5zi / %zi KiB",
	uclient_data(cl)->downloaded / 1024,
	uclient_data(cl)->length / 1024
	);
	fflush(stdout);
	if (write(ctx->fd, buf, len) < len) {
	fputs("autoupdater: error: downloading firmware image failed: ", stderr);
	perror(NULL);
	return;
	}
	ecdsa_sha256_update(&ctx->hash_ctx, buf, len);
	}
	}

Maybe it would be beneficial if the downloading progress would only get shown, like, every 128th iteration or so?

On a sidenote, it also looks to me like the SHA256 checksum is calculated for every iteration as well? Is this necessary? Wouldn't it be sufficient to calculate it once the download is completed?

packages/admin/autoupdater/src/autoupdater.c

Line 275 in 3d08b0f

ecdsa_sha256_update(&ctx->hash_ctx, buf, len);

Okay, it finally finished downloading, took about 20 minutes for the 44MB image...

EDIT:
using # autoupdater >/dev/null it took merely a couple seconds to download the image. So it definitely is related to terminal output.

[neocturne]

The SHA256 checksum is calculated continuously while the image is downloaded, updating the hash state with every block of new data - there is no duplicate work happening.

Limiting the progress output sounds like a good idea.

[neocturne]

@kpanic23 I have implemented your suggestion in #274.

[rotanid]

@kpanic23 can you test the implementation over at #274 ?