Garbage Values in MySQL Fields when Alias Length exceeds 250 characters

deps/mariadb-client-library/client_deprecate_eof.patch

@@ -170,7 +170,7 @@ index e475e25..1a04b2f 100644
 + */
 +int
 +unpack_field(const MYSQL *mysql, MA_MEM_ROOT *alloc, my_bool default_value,
-+    MYSQL_ROWS *row, MYSQL_FIELD *field)
++    MYSQL_ROWS *row, MYSQL_FIELD *field, ulong* field_length)
 +{
 +  unsigned int i, field_count = sizeof(rset_field_offsets) / sizeof(size_t) / 2;
 +  char *p = NULL;
@@ -187,7 +187,7 @@ index e475e25..1a04b2f 100644
 +    // Copy data in case of not empty
 +    else
 +    {
-+      uint length = (uint)(row->data[i+1] - row->data[i] - 1);
++      uint length = (uint)((field_length != NULL) ? field_length[i] : (row->data[i+1] - row->data[i] - 1));
 +      *(char **)(((char *)field) + rset_field_offsets[i*2]) =
 +        ma_strdup_root(alloc, (char *)row->data[i]);
 +      *(unsigned int *)(((char *)field) + rset_field_offsets[i*2+1]) =
@@ -314,7 +314,7 @@ index e475e25..1a04b2f 100644
 -    field->def_length= 0;
 -
 -    field->max_length= 0;
-+    if (unpack_field(mysql, alloc, default_value, row, field) != 0)
++    if (unpack_field(mysql, alloc, default_value, row, field, NULL) != 0)
 +      goto error;
    }
    if (field < result + fields)
@@ -440,7 +440,7 @@ index e475e25..1a04b2f 100644
 +    {
 +        if (mthd_my_read_one_row(mysql, m_field_count, m_rows.data, m_len) == -1)
 +          return NULL;
-+        if (unpack_field(mysql, mem_root, 0, &m_rows, m_fields++))
++        if (unpack_field(mysql, mem_root, 0, &m_rows, m_fields++, m_len))
 +          return NULL;
 +    }
 +    // read EOF packet in case of client not supporting 'CLIENT_DEPRECATE_EOF'

test/tap/tests/reg_test_4402-mysql_fields-t.cpp

@@ -0,0 +1,129 @@
+/**
+ * @file reg_test_4402-mysql-fields-t.cpp
+ * @brief This TAP test checks if the length of the column alias and table alias surpasses 250 characters, 
+ *		should not impact MySQL field name length (MySQL_FIELD::name_length) and the MySQL field database length (MySQL_FIELD::db_length)
+ */
+
+#include <stdio.h>
+#include <unistd.h>
+#include <string>
+#include <thread>
+#include "tap.h"
+#include "command_line.h"
+#include "utils.h" 
+
+#define MYSQL_QUERY__(mysql, query) \
+	do { \
+		if (mysql_query(mysql, query)) { \
+			fprintf(stderr, "File %s, line %d, Error: %s\n", \
+					__FILE__, __LINE__, mysql_error(mysql)); \
+			goto cleanup; \
+		} \
+	} while(0)
+
+CommandLine cl;
+
+std::string generate_random_string(size_t length) {
+	std::srand(static_cast<unsigned int>(std::time(nullptr)));
+	static const char characters[] = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ";
+	static const int numCharacters = (sizeof(characters) - 1)/ sizeof(char);
+
+	std::string randomString;
+	randomString.reserve(length);
+
+	for (size_t i = 0; i < length; ++i) {
+		char randomChar = characters[std::rand() % numCharacters];
+		randomString.push_back(randomChar);
+	}
+
+	return randomString;
+}
+
+int main(int argc, char** argv) {
+
+	if (cl.getEnv()) {
+		diag("Failed to get the required environmental variables.");
+		return -1;
+	}
+
+	plan(256*2);
+
+	// Initialize ProxySQL connection
+	MYSQL* proxysql = mysql_init(NULL);
+	if (!proxysql) {
+		fprintf(stderr, "File %s, line %d, Error: %s\n", __FILE__, __LINE__, mysql_error(proxysql));
+		return -1;
+	}
+
+	// Connect to ProxySQL
+	if (!mysql_real_connect(proxysql, cl.host, cl.username, cl.password, NULL, cl.port, NULL, 0)) {
+		fprintf(stderr, "File %s, line %d, Error: %s\n", __FILE__, __LINE__, mysql_error(proxysql));
+		return exit_status();
+	}
+
+	MYSQL_QUERY__(proxysql, "DROP DATABASE IF EXISTS testdb");
+	MYSQL_QUERY__(proxysql, "CREATE DATABASE testdb");
+
+	diag("Creating echo_int function...");
+	MYSQL_QUERY__(proxysql, "CREATE FUNCTION testdb.echo_int(N INT) RETURNS INT DETERMINISTIC RETURN N;");
+
+	diag("Creating dummy_table...");
+	MYSQL_QUERY__(proxysql, "CREATE TABLE testdb.dummy_table(data VARCHAR(10))");
+
+	// wait for replication
+	std::this_thread::sleep_for(std::chrono::seconds(2));
+
+	// alias maximum length is 256.  
+	// https://dev.mysql.com/doc/refman/8.2/en/identifier-length.html
+	// https://mariadb.com/kb/en/identifier-names/#maximum-length
+	for (unsigned int length = 1; length <= 256; length++) {
+
+		// to check column alias issue:
+		{
+			const std::string& query = "SELECT testdb.echo_int(1) AS " + generate_random_string(length);
+			MYSQL_QUERY__(proxysql, query.c_str());
+
+			MYSQL_RES* res = mysql_use_result(proxysql);
+			if (!res) {
+				fprintf(stderr, "File %s, line %d, Error: %s\n", __FILE__, __LINE__, mysql_error(proxysql));
+				return exit_status();
+			}
+
+			MYSQL_FIELD* field = mysql_fetch_fields(res);
+
+			ok(field->name_length == length, "name_length: '%u'. Expected length: '%u'", field->name_length, length);
+
+			if (res) {
+				mysql_free_result(res);
+				res = NULL;
+			}
+		}
+
+		// to check table alias issue:
+		{
+			const std::string& query = "SELECT data FROM testdb.dummy_table AS " + generate_random_string(length);
+			MYSQL_QUERY__(proxysql, query.c_str());
+
+			MYSQL_RES* res = mysql_use_result(proxysql);
+			if (!res) {
+				fprintf(stderr, "File %s, line %d, Error: %s\n", __FILE__, __LINE__, mysql_error(proxysql));
+				return exit_status();
+			}
+
+			MYSQL_FIELD* field = mysql_fetch_fields(res);
+
+			ok(field->db_length == (sizeof("testdb")-1), "db_length: '%u'. Expected length: '%u'", 
+				field->db_length, (unsigned int)(sizeof("testdb")-1));
+
+			if (res) {
+				mysql_free_result(res);
+				res = NULL;
+			}
+		}
+	}
+cleanup:
+	mysql_query(proxysql, "DROP DATABASE IF EXISTS testdb");
+	mysql_close(proxysql);
+
+	return exit_status();
+}