sources(curl): use json like output inside of custom record

When using `--write-out` we are not using %{json} because older curl
(7.76) will write {"http_connect":000} which python cannot parse.

So we had a custom `--write-out` with `\1xc` as "record" separators
between the fields. This is a bit old-school and not very extensible
so Achilleas had the idea to still use json but "define" our own
subset via the variables that curl provides. This commit does that.

sources/org.osbuild.curl

@@ -20,6 +20,7 @@ up the download.
 
 import concurrent.futures
 import contextlib
+import json
 import os
 import pathlib
 import platform
@@ -96,6 +97,11 @@ SCHEMA = """
 }]
 """
 
+# We are not just using %{json} here because older curl (7.76) will
+# write {"http_connect":000} which python cannot parse so we write our
+# own json subset
+CURL_WRITE_OUT = r'\{\"url\": \"%{url}\"\, \"filename_effective\": \"%{filename_effective}\", \"exitcode\": %{exitcode}, \"errormsg\": \"%{errormsg}\" \}\n'
+
 
 def curl_has_parallel_downloads():
     """
@@ -131,9 +137,11 @@ def _quote_url(url: str) -> str:
     return quoted.geturl()
 
 
-def gen_curl_download_config(config_path: pathlib.Path, chksum_desc_tuple: List[Tuple[str, Dict]]):
+def gen_curl_download_config(config_path: pathlib.Path, chksum_desc_tuple: List[Tuple[str, Dict]], parallel=False):
     with open(config_path, "w", encoding="utf8") as fp:
         # global options
+        if parallel:
+            fp.write("parallel\n")
         fp.write(textwrap.dedent(f"""\
         user-agent = "osbuild (Linux.{platform.machine()}; https://osbuild.org/)"
         silent
@@ -142,6 +150,11 @@ def gen_curl_download_config(config_path: pathlib.Path, chksum_desc_tuple: List[
         fail
         location
         """))
+        if parallel:
+            fp.write(textwrap.dedent(f"""\
+            write-out = "{CURL_WRITE_OUT}"
+            """))
+
         proxy = os.getenv("OSBUILD_SOURCES_CURL_PROXY")
         if proxy:
             fp.write(f'proxy = "{proxy}"\n')
@@ -171,18 +184,11 @@ def gen_curl_download_config(config_path: pathlib.Path, chksum_desc_tuple: List[
 
 
 def try_parse_curl_line(line):
-    line = line.strip()
-    print(line)
-    if not line.startswith("osbuild-dl\x1c"):
-        print(f"WARNING: unexpected prefix in {line}", file=sys.stderr)
+    try:
+        return json.loads(line.strip())
+    except Exception as e:  # pylint: disable=broad-exception-caught
+        print(f"WARNING: cannot json parse {line} {e}", file=sys.stderr)
         return None
-    _, url, filename, exitcode, errormsg = line.split("\x1c")
-    return {
-        "url": url,
-        "filename_effective": filename,
-        "exitcode": int(exitcode),
-        "errormsg": errormsg,
-    }
 
 
 def validate_and_move_to_targetdir(tmpdir, targetdir, checksum, origin):
@@ -203,17 +209,12 @@ def validate_and_move_to_targetdir(tmpdir, targetdir, checksum, origin):
 
 def fetch_many_new_curl(tmpdir, targetdir, dl_pairs):
     curl_config_path = f"{tmpdir}/curl-config.txt"
-    gen_curl_download_config(curl_config_path, dl_pairs)
+    gen_curl_download_config(curl_config_path, dl_pairs, parallel=True)
     curl_command = [
         "curl",
         "--config", curl_config_path,
         # this adds a bunch of noise but might be nice for debug?
         # "--show-error",
-        "--parallel",
-        # this will write out a "record" for each finished download
-        # Not using %{json} here because older curl (7.76) will write
-        # {"http_connect":000} which python cannot parse
-        "--write-out", "osbuild-dl\x1c%{url}\x1c%{filename_effective}\x1c%{exitcode}\x1cerror: %{errormsg}\n",
     ]
     with contextlib.ExitStack() as cm:
         curl_p = subprocess.Popen(curl_command, encoding="utf-8", cwd=tmpdir, stdout=subprocess.PIPE)

sources/test/test_curl_source.py

@@ -241,9 +241,15 @@ TEST_SOURCE_PAIRS_GEN_DOWNLOAD_CONFIG = [
 ]
 
 
-def test_curl_gen_download_config(tmp_path, sources_module):
+def test_curl_gen_download_config_old_curl(tmp_path, sources_module):
     config_path = tmp_path / "curl-config.txt"
-    sources_module.gen_curl_download_config(config_path, TEST_SOURCE_PAIRS_GEN_DOWNLOAD_CONFIG)
+    sources_module.gen_curl_download_config(config_path, [(
+        # sha256("0")
+        "sha256:5feceb66ffc86f38d952786c6d696c79c2dbc239dd4e91b46729d73a27fb57e9",
+        {
+            "url": "http://example.com/file/0",
+        },
+    )])
 
     assert config_path.exists()
     assert config_path.read_text(encoding="utf8") == textwrap.dedent(f"""\
@@ -258,6 +264,28 @@ def test_curl_gen_download_config(tmp_path, sources_module):
     output = "sha256:5feceb66ffc86f38d952786c6d696c79c2dbc239dd4e91b46729d73a27fb57e9"
     no-insecure
 
+    """)
+
+
+def test_curl_gen_download_config_parallel(tmp_path, sources_module):
+    config_path = tmp_path / "curl-config.txt"
+    sources_module.gen_curl_download_config(config_path, TEST_SOURCE_PAIRS_GEN_DOWNLOAD_CONFIG, parallel=True)
+
+    assert config_path.exists()
+    assert config_path.read_text(encoding="utf8") == textwrap.dedent(f"""\
+    parallel
+    user-agent = "osbuild (Linux.{platform.machine()}; https://osbuild.org/)"
+    silent
+    speed-limit = 1000
+    connect-timeout = 30
+    fail
+    location
+    write-out = "{sources_module.CURL_WRITE_OUT}"
+
+    url = "http://example.com/file/0"
+    output = "sha256:5feceb66ffc86f38d952786c6d696c79c2dbc239dd4e91b46729d73a27fb57e9"
+    no-insecure
+
     url = "http://example.com/file/1"
     output = "sha256:6b86b273ff34fce19d6b804eff5a3f5747ada4eaa22f1d49c01e52ddb7875b4b"
     insecure