hashsum: support --check for algorithms with variable output length (#2583)

* hashsum: support --check for var. length outputs

Add the ability for `hashsum --check` to work with algorithms with
variable output length. Previously, the program would terminate with an
error due to constructing an invalid regular expression.

* fixup! hashsum: support --check for var. length outputs

src/uu/hashsum/src/hashsum.rs

@@ -473,15 +473,26 @@ where
         });
         if options.check {
             // Set up Regexes for line validation and parsing
+            //
+            // First, we compute the number of bytes we expect to be in
+            // the digest string. If the algorithm has a variable number
+            // of output bits, then we use the `+` modifier in the
+            // regular expression, otherwise we use the `{n}` modifier,
+            // where `n` is the number of bytes.
             let bytes = options.digest.output_bits() / 4;
+            let modifier = if bytes > 0 {
+                format!("{{{}}}", bytes)
+            } else {
+                "+".to_string()
+            };
             let gnu_re = safe_unwrap!(Regex::new(&format!(
-                r"^(?P<digest>[a-fA-F0-9]{{{}}}) (?P<binary>[ \*])(?P<fileName>.*)",
-                bytes
+                r"^(?P<digest>[a-fA-F0-9]{}) (?P<binary>[ \*])(?P<fileName>.*)",
+                modifier,
             )));
             let bsd_re = safe_unwrap!(Regex::new(&format!(
-                r"^{algorithm} \((?P<fileName>.*)\) = (?P<digest>[a-fA-F0-9]{{{digest_size}}})",
+                r"^{algorithm} \((?P<fileName>.*)\) = (?P<digest>[a-fA-F0-9]{digest_size})",
                 algorithm = options.algoname,
-                digest_size = bytes
+                digest_size = modifier,
             )));
 
             let buffer = file;

tests/by-util/test_hashsum.rs

@@ -1,3 +1,4 @@
+// spell-checker:ignore checkfile
 macro_rules! get_hash(
     ($str:expr) => (
         $str.split(' ').collect::<Vec<&str>>()[0]
@@ -12,6 +13,7 @@ macro_rules! test_digest {
         static DIGEST_ARG: &'static str = concat!("--", stringify!($t));
         static BITS_ARG: &'static str = concat!("--bits=", stringify!($size));
         static EXPECTED_FILE: &'static str = concat!(stringify!($id), ".expected");
+        static CHECK_FILE: &'static str = concat!(stringify!($id), ".checkfile");
 
         #[test]
         fn test_single_file() {
@@ -26,6 +28,16 @@ macro_rules! test_digest {
             assert_eq!(ts.fixtures.read(EXPECTED_FILE),
                        get_hash!(ts.ucmd().arg(DIGEST_ARG).arg(BITS_ARG).pipe_in_fixture("input.txt").succeeds().no_stderr().stdout_str()));
         }
+
+        #[test]
+        fn test_check() {
+            let ts = TestScenario::new("hashsum");
+            ts.ucmd()
+                .args(&[DIGEST_ARG, BITS_ARG, "--check", CHECK_FILE])
+                .succeeds()
+                .no_stderr()
+                .stdout_is("input.txt: OK\n");
+        }
     }
     )*)
 }

tests/fixtures/hashsum/b2sum.checkfile

@@ -0,0 +1 @@
+7355dd5276c21cfe0c593b5063b96af3f96a454b33216f58314f44c3ade92e9cd6cec4210a0836246780e9baf927cc50b9a3d7073e8f9bd12780fddbcb930c6d  input.txt

tests/fixtures/hashsum/md5.checkfile

@@ -0,0 +1 @@
+e4d7f1b4ed2e42d15898f4b27b019da4  input.txt

tests/fixtures/hashsum/sha1.checkfile

@@ -0,0 +1 @@
+b7e23ec29af22b0b4e41da31e868d57226121c84  input.txt

tests/fixtures/hashsum/sha224.checkfile

@@ -0,0 +1 @@
+6e1a93e32fb44081a401f3db3ef2e6e108b7bbeeb5705afdaf01fb27  input.txt

tests/fixtures/hashsum/sha256.checkfile

@@ -0,0 +1 @@
+09ca7e4eaa6e8ae9c7d261167129184883644d07dfba7cbfbc4c8a2e08360d5b  input.txt

tests/fixtures/hashsum/sha384.checkfile

@@ -0,0 +1 @@
+1fcdb6059ce05172a26bbe2a3ccc88ed5a8cd5fc53edfd9053304d429296a6da23b1cd9e5c9ed3bb34f00418a70cdb7e  input.txt

tests/fixtures/hashsum/sha3_224.checkfile

@@ -0,0 +1 @@
+927b362eaf84a75785bbec3370d1c9711349e93f1104eda060784221  input.txt

tests/fixtures/hashsum/sha3_256.checkfile

@@ -0,0 +1 @@
+bfb3959527d7a3f2f09def2f6915452d55a8f122df9e164d6f31c7fcf6093e14  input.txt

tests/fixtures/hashsum/sha3_384.checkfile

@@ -0,0 +1 @@
+fbd0c5931195aaa9517869972b372f717bb69f7f9f72bfc0884ed0531c36a16fc2db5dd6d82131968b23ffe0e90757e5  input.txt

tests/fixtures/hashsum/sha3_512.checkfile

@@ -0,0 +1 @@
+2ed3a863a12e2f8ff140aa86232ff3603a7f24af62f0e2ca74672494ade175a9a3de42a351b5019d931a1deae0499609038d9b47268779d76198e1d410d20974  input.txt

tests/fixtures/hashsum/sha512.checkfile

@@ -0,0 +1 @@
+8710339dcb6814d0d9d2290ef422285c9322b7163951f9a0ca8f883d3305286f44139aa374848e4174f5aada663027e4548637b6d19894aec4fb6c46a139fbf9  input.txt

tests/fixtures/hashsum/shake128_256.checkfile

@@ -0,0 +1 @@
+83d41db453072caa9953f2f316480fbbcb84a5f3505460a18b3a36a814ae8e9e  input.txt

tests/fixtures/hashsum/shake256_512.checkfile

@@ -0,0 +1 @@
+7c9896ea84a2a1b80b2183a3f2b4e43cd59b7d48471dc213bcedaccb699d6e6f7ad5d304928ab79329f1fc62f6db072d95b51209eb807683f5c9371872a2dd4e  input.txt