flash-image: Get size from meta data

This makes sure the progress bar matches the expected image size.

We don't make the lack of meta data fatal yet so we can use this
script on outdated build jobs too for some time.

scripts/librem5-devkit-flash-image

@@ -12,6 +12,7 @@ import subprocess
 import sys
 import tempfile
 import tqdm
+import yaml
 
 try:
     import coloredlogs
@@ -26,6 +27,7 @@ JENKINS = 'https://arm01.puri.sm'
 TYPE = 'devkit'
 DIST = 'buster+ci'
 IMAGE = 'devkit.img'
+META_YAML = 'files/meta.yml'
 IMAGE_JOB_NAME = 'Images/Image Build'
 UBOOT = 'u-boot-devkit-recovery.imx'
 UBOOT_JOB_NAME = 'u-boot_builds/devkit-recovery_uboot_build'
@@ -47,20 +49,34 @@ FB: flash -raw2sparse all {image}
 FB: Done
 '''
 BLOCK_SIZE = 8192
-# TODO store in image metadata
 UNCOMPRESSED_SIZE = 3600000000
 
 
 def download_image(url, target):
     decomp = lzma.LZMADecompressor()
     logging.info("Downloading image from {}".format(url))
+
+    # We expect metadata to be right next to the image
+    meta_yml_url = "{}/{}".format(url.rsplit('/', 1)[0], META_YAML)
+    resp = requests.get(meta_yml_url)
+    # No meta data is no yet fatal
+    try:
+        resp.raise_for_status()
+        meta = yaml.safe_load(resp.text)
+        uncompressed_size = int(meta['image']['size'])
+        logging.debug("Image size is %d", uncompressed_size)
+    except requests.exceptions.HTTPError:
+        logging.warning("No meta data found, size may be incorrect")
+        meta = None
+        uncompressed_size = UNCOMPRESSED_SIZE
+
     resp = requests.get(url, stream=True)
     resp.raise_for_status()
     ts = int(resp.headers.get('content-length', 0))
     download_bar = tqdm.tqdm(total=ts,
                              desc='Download',
                              leave=False)
-    decompress_bar = tqdm.tqdm(total=UNCOMPRESSED_SIZE,
+    decompress_bar = tqdm.tqdm(total=uncompressed_size,
                                desc='Decompr.',
                                leave=False)
     with open(target, 'wb+') as f: