Make changeset printer util able to parse sync logs (#6375)

CHANGELOG.md

@@ -19,7 +19,7 @@
 -----------
 
 ### Internals
-* None.
+* PrintChangeset sync CLI utility can now ingest trace-level log files and decode hex/base64-compressed changeset data within the logs ([#6375](https://github.com/realm/realm-core/pull/6375))
 
 ----------------------------------------------
 

src/realm/sync/tools/print_changeset.cpp

@@ -1,16 +1,18 @@
 #include <cstring>
 #include <cstdlib>
+#include <fstream>
 #include <string>
 #include <iostream>
 
+#include <realm/util/cli_args.hpp>
 #include <realm/util/compression.hpp>
 #include <realm/util/base64.hpp>
 #include <realm/util/load_file.hpp>
 #include <realm/sync/changeset.hpp>
 #include <realm/sync/changeset_parser.hpp>
 
 using namespace realm;
-
+#if REALM_DEBUG
 namespace {
 
 sync::Changeset changeset_binary_to_sync_changeset(const std::string& changeset_binary)
@@ -70,9 +72,17 @@ std::string changeset_compressed_to_binary(const std::string& changeset_compress
     return decompressed;
 }
 
-void print_changeset(const std::string& path, bool hex, bool compressed)
+void parse_and_print_changeset(const std::string& changeset_binary)
+{
+    sync::Changeset changeset = changeset_binary_to_sync_changeset(changeset_binary);
+    changeset.print(std::cout);
+}
+
+void print_changeset_in_file(std::istream& input_file, bool hex, bool compressed)
 {
-    std::string file_contents = util::load_file(path);
+    std::stringstream input_file_ss;
+    input_file_ss << input_file.rdbuf();
+    const auto& file_contents = input_file_ss.str();
     std::string changeset_binary;
     if (hex) {
         changeset_binary = changeset_hex_to_binary(file_contents);
@@ -83,92 +93,112 @@ void print_changeset(const std::string& path, bool hex, bool compressed)
     else {
         changeset_binary = file_contents;
     }
-    sync::Changeset changeset = changeset_binary_to_sync_changeset(changeset_binary);
-#if REALM_DEBUG
-    changeset.print(std::cout);
-#else
-    std::cout << "changeset printing is disabled in Release mode, build in Debug mode to use this tool" << std::endl;
-#endif
+    parse_and_print_changeset(changeset_binary);
 }
 
-} // namespace
-
-int main(int argc, char* argv[])
+void print_changesets_in_log_file(std::istream& input_file)
 {
-    std::string changeset_path;
-    bool hex = false;
-    bool compressed = false;
-
-    // Process command line
-    {
-        const char* prog = argv[0];
-        --argc;
-        ++argv;
-        bool error = false;
-        bool help = false;
-        int argc_2 = 0;
-        int i = 0;
-        char* arg = nullptr;
-        auto get_string_value = [&](std::string& var) {
-            if (i < argc) {
-                var = argv[i++];
-                return true;
-            }
-            return false;
-        };
-        while (i < argc) {
-            arg = argv[i++];
-            if (arg[0] != '-') {
-                argv[argc_2++] = arg;
-                continue;
+    int log_line_num = 1;
+    try {
+        for (std::string line; std::getline(input_file, line); ++log_line_num) {
+            const std::string_view changeset_prefix("Changeset: ");
+            const std::string_view compressed_changeset_prefix("Changeset(comp): ");
+            std::string changeset_contents;
+            if (auto pos = line.find(changeset_prefix); pos != std::string::npos) {
+                changeset_contents = changeset_hex_to_binary(line.substr(pos + changeset_prefix.size()));
             }
-            if (std::strcmp(arg, "-h") == 0 || std::strcmp(arg, "--help") == 0) {
-                help = true;
-                continue;
+            else if (auto pos = line.find(compressed_changeset_prefix); pos != std::string::npos) {
+                changeset_contents =
+                    changeset_compressed_to_binary(line.substr(pos + compressed_changeset_prefix.size()));
             }
-            else if (std::strcmp(arg, "-H") == 0 || std::strcmp(arg, "--hex") == 0) {
-                hex = true;
+            else {
+                std::cout << line << std::endl;
                 continue;
             }
-            else if (std::strcmp(arg, "-C") == 0 || std::strcmp(arg, "--compressed") == 0) {
-                compressed = true;
-                continue;
-            }
-            std::cerr << "ERROR: Unknown option: " << arg << "\n";
-            error = true;
+            parse_and_print_changeset(changeset_contents);
         }
-        argc = argc_2;
+    }
+    catch (const Exception& e) {
+        throw RuntimeError(e.code(), util::format("Exception at line number %1: %2", log_line_num, e.to_status()));
+    }
+    catch (const std::exception& e) {
+        throw RuntimeError(ErrorCodes::RuntimeError,
+                           util::format("Exception at line number %1: %2", log_line_num, e.what()));
+    }
+}
+
+void print_help(std::string_view prog_name)
+{
+    std::cerr << "Synopsis: " << prog_name
+              << " [changeset file]\n"
+                 "\n"
+                 "Where <changeset file> is the file system path of a file containing a\n"
+                 "changeset encoded in hex/base64 compressed format or sync client trace-level log output.\n"
+                 "If no changeset file is given, input shall be read from stdin.\n"
+                 "\n"
+                 "Options:\n"
+                 "  -h, --help             Display command-line synopsis followed by the list of\n"
+                 "                         available options.\n"
+                 "  -H, --hex              Interpret file contents as hex encoded.\n"
+                 "  -C, --compressed       Interpret file contents as Base64 encoded and compressed.\n"
+                 "  -l, -input-is-logfile  Read input from stdin as a trace-level log file\n";
+}
 
-        i = 0;
-        if (!get_string_value(changeset_path)) {
-            error = true;
+} // namespace
+#endif
+
+int main(int argc, const char** argv)
+{
+#if !REALM_DEBUG
+    static_cast<void>(argc);
+    static_cast<void>(argv);
+    util::format(std::cerr, "changeset printing is disabled in Release mode, build in Debug mode to use this tool\n");
+    return EXIT_FAILURE;
+#else
+    util::CliArgumentParser arg_parser;
+    util::CliFlag hex(arg_parser, "hex", 'H');
+    util::CliFlag compressed(arg_parser, "compressed", 'C');
+    util::CliFlag help(arg_parser, "help", 'h');
+    util::CliFlag as_logs(arg_parser, "input-is-logfile", 'l');
+
+    std::fstream changeset_input_file;
+    std::istream* changeset_input = &std::cin;
+    try {
+        auto arg_result = arg_parser.parse(argc, argv);
+        if (arg_result.unmatched_arguments.size() > 1) {
+            throw std::runtime_error(
+                util::format("Expected one input argument, got %1", arg_result.unmatched_arguments.size()));
         }
-        else if (i < argc) {
-            error = true;
+        else if (arg_result.unmatched_arguments.size() == 1) {
+            std::string file_path(arg_result.unmatched_arguments.front());
+            if (file_path.empty() || file_path.front() == '-') {
+                throw std::runtime_error(util::format("Expected path to file, got \"%1\"", file_path));
+            }
+            changeset_input_file.open(file_path);
+            changeset_input = &changeset_input_file;
         }
+    }
+    catch (const std::runtime_error& e) {
+        util::format(std::cerr, "Error parsing arguments: %1\n", e.what());
+        return EXIT_FAILURE;
+    }
 
-        if (help) {
-            std::cerr << "Synopsis: " << prog
-                      << " <changeset file>\n"
-                         "\n"
-                         "Where <changeset file> is the file system path of a file containing a\n"
-                         "changeset, possibly in hex format.\n"
-                         "\n"
-                         "Options:\n"
-                         "  -h, --help           Display command-line synopsis followed by the list of\n"
-                         "                       available options.\n"
-                         "  -H, --hex            Interpret file contents as hex encoded.\n"
-                         "  -C, --compressed     Interpret file contents as Base64 encoded and compressed.\n";
-            return EXIT_SUCCESS;
-        }
+    if (help) {
+        print_help(argv[0]);
+        return EXIT_SUCCESS;
+    }
 
-        if (error) {
-            std::cerr << "ERROR: Bad command line.\n"
-                         "Try `"
-                      << prog << " --help`\n";
-            return EXIT_FAILURE;
+    try {
+        if (as_logs) {
+            print_changesets_in_log_file(*changeset_input);
+        }
+        else {
+            print_changeset_in_file(*changeset_input, static_cast<bool>(hex), static_cast<bool>(compressed));
         }
     }
-
-    print_changeset(changeset_path, hex, compressed);
+    catch (const std::exception& e) {
+        util::format(std::cerr, "Error parsing/printing changesets: %1", e.what());
+        return EXIT_FAILURE;
+    }
+#endif
 }

src/realm/util/cli_args.hpp

@@ -98,6 +98,7 @@ class CliArgument : public CliFlag {
 };
 
 class CliParseException : public std::runtime_error {
+public:
     using std::runtime_error::runtime_error;
 };