contrib: Fixup verify-binaries OS platform parsing

Parse platform strings with "-" or '.' correctly such as "linux-gnu" or
"x86_64-linux-gnu.tar.gz" to download the matching files or file. String
partition() is used to tolerate more dashes. Update `VERSION_EXAMPLE`
with a new string parsed correctly now. Fix "-aarch64" interpreted as a
release candidate due to sub-string "rc", causing all downloads to fail.
Now "rc" must immediately follow first "-" to indicate an [-rc] string.
Local variables `version_rc`, `version_os` renamed to `rc`, `platform`.
If "-rcN" is specified, `platform` is reassigned to remove the '-rcN'.

Changes are useful to only download one bitcoin core binary on slow
connections. Making `verify.py pub` more intuitive, robust, and
versatile. Closes #30145

When user types a platform string not found in any filename lets help
and say the platform closest to what they typed in a `f"No files
matched the platform specified. Did you mean: {closest_match}"` log.
Improves UX when unaware how we name our files.
Uses the difflib Python built-in which was already imported elsewhere.

Update test.py to test single file verification
verify-binaries/verify.py can accept an entire filename filter for its
"-platform" parameter now so let us test that it succeeds and downloads
and verifies only one file. `verify.py pub 22.0-x86_64-linux-gnu.tar.gz`
should get and verify only the requested binary. It is placed before the
existing <version> wide verification as it is a faster test and possibly
easier to break.

Update doc with examples now possible after bugfix
Add example to show release candidates now work with "-platform" strings
containing "-" and string provided can be from the middle of filename:
`./contrib/verify-binaries/verify.py --json pub 23.0-rc5-linux-gnu`
Change example 5 to not match example 3.
New examples to show platform can now be provided specifically enough to
download only a single binary down to its file extension:
`./contrib/verify-binaries/verify.py pub 25.2-x86_64-linux`
`./contrib/verify-binaries/verify.py pub 24.1-rc1-darwin`
`./contrib/verify-binaries/verify.py pub 27.0-win64-setup.exe`
This is the most common use if not verifying all files so users see it
as the first example for "only download the binaries for a certain
architecture and/or platform". Downloading one file is intuitively what
most will think this meant and this change delivers on that expectation.

Co-authored-by: stickies-v

contrib/verify-binaries/verify.py

@@ -97,23 +97,17 @@ def bool_from_env(key, default=False) -> bool:
 
 
 VERSION_FORMAT = "<major>.<minor>[.<patch>][-rc[0-9]][-platform]"
-VERSION_EXAMPLE = "22.0-x86_64 or 23.1-rc1-darwin"
+VERSION_EXAMPLE = "22.0 or 23.1-rc1-darwin.dmg or 27.0-x86_64-linux-gnu"
 
 def parse_version_string(version_str):
-    parts = version_str.split('-')
-    version_base = parts[0]
-    version_rc = ""
-    version_os = ""
-    if len(parts) == 2:  # "<version>-rcN" or "version-platform"
-        if "rc" in parts[1]:
-            version_rc = parts[1]
-        else:
-            version_os = parts[1]
-    elif len(parts) == 3:  # "<version>-rcN-platform"
-        version_rc = parts[1]
-        version_os = parts[2]
+    # "<version>[-rcN][-platform]"
+    version_base, _, platform = version_str.partition('-')
+    rc = ""
+    if platform.startswith("rc"): # "<version>-rcN[-platform]"
+        rc, _, platform = platform.partition('-')
+    # else "<version>" or "<version>-platform"
 
-    return version_base, version_rc, version_os
+    return version_base, rc, platform
 
 
 def download_with_wget(remote_file, local_file):
@@ -514,7 +508,9 @@ def verify_published_handler(args: argparse.Namespace) -> ReturnCode:
     # Extract hashes and filenames
     hashes_to_verify = parse_sums_file(SUMS_FILENAME, [os_filter])
     if not hashes_to_verify:
-        log.error("no files matched the platform specified")
+        available_versions = ["-".join(line[1].split("-")[2:]) for line in parse_sums_file(SUMS_FILENAME, [])]
+        closest_match = difflib.get_close_matches(os_filter, available_versions, cutoff=0, n=1)[0]
+        log.error(f"No files matched the platform specified. Did you mean: {closest_match}")
         return ReturnCode.NO_BINARIES_MATCH
 
     # remove binaries that are known not to be hosted by bitcoincore.org