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

3 files changed, 32 insertions, 19 deletions

diff --git a/contrib/verify-binaries/README.md b/contrib/verify-binaries/README.md
index 04d683e69b..0f3e16a5bc 100644
--- a/contrib/verify-binaries/README.md
+++ b/contrib/verify-binaries/README.md
@@ -50,6 +50,7 @@ Get JSON output and don't prompt for user input (no auto key import):
 
 ```sh
 ./contrib/verify-binaries/verify.py --json pub 22.0-x86
+./contrib/verify-binaries/verify.py --json pub 23.0-rc5-linux-gnu
 ```
 
 Rely only on local GPG state and manually specified keys, while requiring a
@@ -57,14 +58,15 @@ threshold of at least 10 trusted signatures:
 ```sh
 ./contrib/verify-binaries/verify.py \
     --trusted-keys 74E2DEF5D77260B98BC19438099BAD163C70FBFA,9D3CC86A72F8494342EA5FD10A41BDC3F4FAFF1C \
-    --min-good-sigs 10 pub 22.0-x86
+    --min-good-sigs 10 pub 22.0-linux
 ```
 
-If you only want to download the binaries for a certain platform, add the corresponding suffix, e.g.:
+If you only want to download the binaries for a certain architecture and/or platform, add the corresponding suffix, e.g.:
 
 ```sh
-./contrib/verify-binaries/verify.py pub 24.0.1-darwin
-./contrib/verify-binaries/verify.py pub 23.1-rc1-win64
+./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
 ```
 
 If you do not want to keep the downloaded binaries, specify the cleanup option.
diff --git a/contrib/verify-binaries/test.py b/contrib/verify-binaries/test.py
index 22d718ece3..875606ec22 100755
--- a/contrib/verify-binaries/test.py
+++ b/contrib/verify-binaries/test.py
@@ -12,6 +12,21 @@ def main():
     expect_code(run_verify("", "pub", '0.32.awefa.12f9h'), 11, "Malformed version should fail")
     expect_code(run_verify('--min-good-sigs 20', "pub", "22.0"), 9, "--min-good-sigs 20 should fail")
 
+    print("- testing verification (22.0-x86_64-linux-gnu.tar.gz)", flush=True)
+    _220_x86_64_linux_gnu = run_verify("--json", "pub", "22.0-x86_64-linux-gnu.tar.gz")
+    try:
+        result = json.loads(_220_x86_64_linux_gnu.stdout.decode())
+    except Exception:
+        print("failed on 22.0-x86_64-linux-gnu.tar.gz --json:")
+        print_process_failure(_220_x86_64_linux_gnu)
+        raise
+
+    expect_code(_220_x86_64_linux_gnu, 0, "22.0-x86_64-linux-gnu.tar.gz should succeed")
+    v = result['verified_binaries']
+    assert result['good_trusted_sigs']
+    assert len(v) == 1
+    assert v['bitcoin-22.0-x86_64-linux-gnu.tar.gz'] == '59ebd25dd82a51638b7a6bb914586201e67db67b919b2a1ff08925a7936d1b16'
+
     print("- testing verification (22.0)", flush=True)
     _220 = run_verify("--json", "pub", "22.0")
     try:
diff --git a/contrib/verify-binaries/verify.py b/contrib/verify-binaries/verify.py
index 12e6e10d8a..6c07b36c9d 100755
--- a/contrib/verify-binaries/verify.py
+++ b/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