checksum: Support the '--check' option

This commit also updates 'checksum' to use the Core::Stream::File API.

Base/usr/share/man/man1/checksum.md

@@ -4,12 +4,18 @@ checksum - helper program for calculating checksums
 
 ## Synopsis
 
-`$ md5sum <file>`
-`$ sha1sum <file>`
-`$ sha256sum <file>`
-`$ sha512sum <file>`
+`$ md5sum [options...] <file...>`
+`$ sha1sum [options...] <file...>`
+`$ sha256sum [options...] <file...>`
+`$ sha512sum [options...] <file...>`
 
 ## Description
 
 This program calculates and print specified checksum of files. It cannot be run directly, only
-as `md5sum`, `sha1sum`, `sha256sum` or `sha512sum`.
+as `md5sum`, `sha1sum`, `sha256sum` or `sha512sum`. A non-zero exit code is returned if the
+input cannot be read. If the '--check' option is used, a non-zero exit code is also returned
+if the checksums cannot be verified.
+
+## Options
+
+* `-c`, `--check`: Verify checksums against `file` or stdin.

Userland/Utilities/checksum.cpp

@@ -6,7 +6,7 @@
 
 #include <AK/LexicalPath.h>
 #include <LibCore/ArgsParser.h>
-#include <LibCore/File.h>
+#include <LibCore/Stream.h>
 #include <LibCore/System.h>
 #include <LibCrypto/Hash/HashManager.h>
 #include <LibMain/Main.h>
@@ -36,9 +36,11 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
     auto hash_name = program_name.substring_view(0, program_name.length() - 3).to_string().to_uppercase();
     auto paths_help_string = String::formatted("File(s) to print {} checksum of", hash_name);
 
+    bool verify_from_paths = false;
     Vector<StringView> paths;
 
     Core::ArgsParser args_parser;
+    args_parser.add_option(verify_from_paths, "Verify checksums from file(s)", "check", 'c');
     args_parser.add_positional_argument(paths, paths_help_string.characters(), "path", Core::ArgsParser::Required::No);
     args_parser.parse(arguments);
 
@@ -48,23 +50,79 @@ ErrorOr<int> serenity_main(Main::Arguments arguments)
     Crypto::Hash::Manager hash;
     hash.initialize(hash_kind);
 
-    auto has_error = false;
+    bool has_error = false;
+    int read_fail_count = 0;
+    int failed_verification_count = 0;
 
     for (auto const& path : paths) {
-        NonnullRefPtr<Core::File> file = Core::File::standard_input();
-        if (path != "-"sv) {
-            auto file_or_error = Core::File::open(path, Core::OpenMode::ReadOnly);
-            if (file_or_error.is_error()) {
-                warnln("{}: {}: {}", program_name, path, file->error_string());
-                has_error = true;
-                continue;
+        auto file_or_error = Core::Stream::File::open_file_or_standard_stream(path, Core::Stream::OpenMode::Read);
+        if (file_or_error.is_error()) {
+            ++read_fail_count;
+            has_error = true;
+            warnln("{}: {}", path, file_or_error.release_error());
+            continue;
+        }
+        auto file = file_or_error.release_value();
+        Array<u8, PAGE_SIZE> buffer;
+        if (!verify_from_paths) {
+            while (!file->is_eof())
+                hash.update(TRY(file->read(buffer)));
+            outln("{:hex-dump}  {}", hash.digest().bytes(), path);
+        } else {
+            StringBuilder checksum_list_contents;
+            Array<u8, 1> checksum_list_buffer;
+            while (!file->is_eof())
+                checksum_list_contents.append(TRY(file->read(checksum_list_buffer)).data()[0]);
+            Vector<StringView> const lines = checksum_list_contents.string_view().split_view("\n"sv);
+
+            for (size_t i = 0; i < lines.size(); ++i) {
+                Vector<StringView> const line = lines[i].split_view("  "sv);
+                if (line.size() != 2) {
+                    ++read_fail_count;
+                    // The real line number is greater than the iterator.
+                    warnln("{}: {}: Failed to parse line {}", program_name, path, i + 1);
+                    continue;
+                }
+
+                // line[0] = checksum
+                // line[1] = filename
+                StringView const filename = line[1];
+                auto file_from_filename_or_error = Core::Stream::File::open_file_or_standard_stream(filename, Core::Stream::OpenMode::Read);
+                if (file_from_filename_or_error.is_error()) {
+                    ++read_fail_count;
+                    warnln("{}: {}", filename, file_from_filename_or_error.release_error());
+                    continue;
+                }
+                auto file_from_filename = file_from_filename_or_error.release_value();
+                hash.reset();
+                while (!file_from_filename->is_eof())
+                    hash.update(TRY(file_from_filename->read(buffer)));
+                if (String::formatted("{:hex-dump}", hash.digest().bytes()) == line[0])
+                    outln("{}: OK", filename);
+                else {
+                    ++failed_verification_count;
+                    warnln("{}: FAILED", filename);
+                }
             }
-            file = file_or_error.release_value();
+        }
+    }
+    // Print the warnings here in order to only print them once.
+    if (verify_from_paths) {
+        if (read_fail_count) {
+            if (read_fail_count == 1)
+                warnln("WARNING: 1 file could not be read");
+            else
+                warnln("WARNING: {} files could not be read", read_fail_count);
+            has_error = true;
         }
 
-        while (!file->eof() && !file->has_error())
-            hash.update(file->read(PAGE_SIZE));
-        outln("{:hex-dump}  {}", hash.digest().bytes(), path);
+        if (failed_verification_count) {
+            if (failed_verification_count == 1)
+                warnln("WARNING: 1 checksum did NOT match");
+            else
+                warnln("WARNING: {} checksums did NOT match", failed_verification_count);
+            has_error = true;
+        }
     }
     return has_error ? 1 : 0;
 }