Merge pull request #366 from gkreitz/346_default_validator_message_truncation

Truncate long tokens in default_validator's judge message. #346

Author: pehrsoderman

support/default_validator/default_validator.cc

@@ -17,6 +17,8 @@ FILE *diffpos = NULL;
 int judgeans_pos = 0, stdin_pos = 0;
 int judgeans_line = 1, stdin_line = 1;
 
+// At some point we should rewrite this to something more C++. Now that we truncate long tokens, having this
+// require c_str() calls gets even messier with object lifetimes.
 void wrong_answer(const char *err, ...) {
 	va_list pvar;
 	va_start(pvar, err);
@@ -64,6 +66,49 @@ FILE *openfeedback(const char *feedbackdir, const char *feedback, const char *wh
 	return res;
 }
 
+/* Truncate string to avoid huge messages when teams forgot to print spaces.
+ * If string is longer than limit (plus 5, as we don't want to replace just a
+ * few characters with ...), we truncate and append "...". String may be in
+ * arbitrary encoding, but as utf-8 is common, we make a small attempt to avoid
+ * cutting in a utf-8 character. So output can be a few bytes longer than limit.
+ */
+std::string truncate(const std::string &str, size_t limit = 30) {
+	if (str.length() <= limit + 5) {
+		return str;
+	}
+	size_t cut = limit;
+	// Heuristic to avoid cutting in the middle of a UTF-8 character.
+	// A continuation byte in UTF-8 starts with binary 10.
+	// We scan forwards from the limit to include the rest of a character,
+	// but at most 3 extra bytes (for up to a 4-byte character).
+	while (cut < str.length() && cut < limit + 4 && (str[cut] & 0xC0) == 0x80) {
+		cut++;
+	}
+	return str.substr(0, cut) + "...";
+}
+
+/* Truncate a pair of strings (judge and user tokens). This preserves the first
+ * few bytes of the common prefix, then adds ..., and then the first few bytes
+ * starting from where the strings differ.
+ */
+std::pair<std::string, std::string> truncate_pair(const std::string &str1, const std::string &str2) {
+	size_t diff_idx = 0;
+	while (diff_idx < str1.length() && diff_idx < str2.length() && str1[diff_idx] == str2[diff_idx]) {
+		diff_idx++;
+	}
+
+	std::string common_prefix = str1.substr(0, diff_idx);
+	std::string s1 = str1.substr(diff_idx);
+	std::string s2 = str2.substr(diff_idx);
+
+	std::string p_part = truncate(common_prefix, 15);
+
+	return std::make_pair(
+		p_part + truncate(s1, 15),
+		p_part + truncate(s2, 15)
+	);
+}
+
 const char *USAGE = "Usage: %s judge_in judge_ans feedback_file [options] < user_out";
 
 int main(int argc, char **argv) {
@@ -82,7 +127,7 @@ int main(int argc, char **argv) {
 	double float_rel_tol = -1;
 
 	for (int a = 4; a < argc; ++a) {
-		if        (!strcmp(argv[a], "case_sensitive")) {
+		if (!strcmp(argv[a], "case_sensitive")) {
 			case_sensitive = true;
 		} else if (!strcmp(argv[a], "space_change_sensitive")) {
 			space_change_sensitive = true;
@@ -108,7 +153,7 @@ int main(int argc, char **argv) {
 	}
 	use_floats = float_abs_tol >= 0 || float_rel_tol >= 0;
 
-	std::string judge, team;
+	std::string judge, team, judge_trunc, team_trunc;
 	for (int token = 0; true; token++) {
 		// Space!  Can't live with it, can't live without it...
 		while (isspace(judgeans.peek())) {
@@ -140,46 +185,57 @@ int main(int argc, char **argv) {
 		if (!(std::cin >> team)) {
 			if (token == 0) {
 				if (stdin_pos == 0) {
+					judge_trunc = truncate(judge);
 					wrong_answer(
 						"User EOF while judge had more output; user output was empty.\n(Next judge token: %s)",
-						judge.c_str()
+						judge_trunc.c_str()
 					);
 				} else {
+					judge_trunc = truncate(judge);
 					wrong_answer(
 						"User EOF while judge had more output; user output contained only whitespace.\n(Next judge token: %s)",
-						judge.c_str()
+						judge_trunc.c_str()
 					);
 				}
 			} else {
-				wrong_answer("User EOF while judge had more output\n(Next judge token: %s)", judge.c_str());
+				judge_trunc = truncate(judge);
+				wrong_answer("User EOF while judge had more output\n(Next judge token: %s)", judge_trunc.c_str());
 			}
 		}
-     
+
 		double jval, tval;
 		if (use_floats && isfloat(judge.c_str(), jval)) {
 			if (!isfloat(team.c_str(), tval)) {
-				wrong_answer("Expected float, got: %s", team.c_str());
+				team_trunc = truncate(team);
+				wrong_answer("Expected float, got: %s", team_trunc.c_str());
 			}
 			if (!(fabs(jval - tval) <= float_abs_tol) &&
 			   !(fabs(jval - tval) <= float_rel_tol * fabs(jval))) {
+				// We don't want to truncate as a pair here, that just gets more confusing for floats (and something has
+				// gone very wrong if we're dealing with floats so long we need to truncate anyway :)
+				judge_trunc = truncate(judge);
+				team_trunc = truncate(team);
 				wrong_answer("Too large difference.\n Judge: %s\n User: %s\n Difference: %le\n (abs tol %le rel tol %le)", 
-							 judge.c_str(), team.c_str(), jval-tval, float_abs_tol, float_rel_tol);
+				             judge_trunc.c_str(), team_trunc.c_str(), jval-tval, float_abs_tol, float_rel_tol);
 			}
 		} else if (case_sensitive) {
 			if (strcmp(judge.c_str(), team.c_str()) != 0) {
-				wrong_answer("String tokens mismatch\nJudge: \"%s\"\nUser: \"%s\"", judge.c_str(), team.c_str());
+				std::tie(judge_trunc, team_trunc) = truncate_pair(judge, team);
+				wrong_answer("String tokens mismatch\nJudge: \"%s\"\nUser: \"%s\"", judge_trunc.c_str(), team_trunc.c_str());
 			}
 		} else {
 			if (strcasecmp(judge.c_str(), team.c_str()) != 0) {
-				wrong_answer("String tokens mismatch\nJudge: \"%s\"\nUser: \"%s\"", judge.c_str(), team.c_str());
+				std::tie(judge_trunc, team_trunc) = truncate_pair(judge, team);
+				wrong_answer("String tokens mismatch\nJudge: \"%s\"\nUser: \"%s\"", judge_trunc.c_str(), team_trunc.c_str());
 			}
 		}
 		judgeans_pos += judge.length();
 		stdin_pos += team.length();
 	}
 
 	if (std::cin >> team) {
-		wrong_answer("Trailing output:\n%s", team.c_str());
+		team_trunc = truncate(team);
+		wrong_answer("Trailing output:\n%s", team_trunc.c_str());
 	}
 
 	exit(EXIT_AC);

tests/default_validator_tests/test_empty_wa/expected_exit_code.txt

@@ -0,0 +1 @@
+43

tests/default_validator_tests/test_empty_wa/expected_message.txt

@@ -0,0 +1,3 @@
+Wrong answer on line 1 of output (corresponding to line 1 in answer file)
+User EOF while judge had more output; user output was empty.
+(Next judge token: Hello)

tests/default_validator_tests/test_empty_wa/judge.ans

@@ -0,0 +1 @@
+Hello World!

tests/default_validator_tests/test_empty_wa/user.out

@@ -0,0 +1 @@
+float_absolute_tolerance 0.5

tests/default_validator_tests/test_float_rocket_wa/args.txt

@@ -0,0 +1 @@
+43

tests/default_validator_tests/test_float_rocket_wa/expected_exit_code.txt

@@ -0,0 +1,2 @@
+Wrong answer on line 1 of output (corresponding to line 1 in answer file)
+Expected float, got: 1.4🚀🚀🚀🚀🚀🚀🚀...

tests/default_validator_tests/test_float_rocket_wa/expected_message.txt

@@ -0,0 +1 @@
+1

tests/default_validator_tests/test_float_rocket_wa/judge.ans

@@ -0,0 +1 @@
+1.4🚀🚀🚀🚀🚀🚀🚀🚀🚀🚀🚀🚀🚀🚀🚀🚀🚀🚀🚀🚀🚀🚀🚀🚀🚀🚀🚀🚀🚀🚀🚀🚀🚀🚀🚀🚀🚀🚀🚀🚀🚀🚀🚀🚀🚀🚀🚀🚀🚀🚀🚀🚀🚀🚀🚀🚀🚀🚀🚀🚀🚀🚀🚀🚀🚀🚀🚀🚀🚀🚀🚀🚀🚀🚀🚀🚀🚀🚀🚀🚀🚀🚀🚀🚀🚀🚀🚀🚀🚀🚀🚀🚀🚀🚀🚀🚀🚀🚀🚀🚀🚀🚀🚀🚀🚀🚀🚀🚀🚀🚀🚀🚀🚀🚀🚀🚀🚀🚀🚀🚀🚀🚀🚀🚀🚀🚀🚀🚀🚀🚀🚀🚀🚀🚀🚀🚀🚀🚀🚀🚀🚀🚀🚀🚀🚀🚀🚀🚀🚀🚀🚀🚀🚀🚀🚀🚀🚀🚀🚀🚀🚀🚀🚀🚀🚀🚀🚀🚀🚀🚀🚀🚀🚀🚀🚀🚀🚀🚀🚀🚀🚀🚀🚀🚀🚀🚀🚀🚀🚀🚀🚀🚀🚀🚀🚀🚀🚀🚀🚀🚀🚀🚀