chore: acquire-core migration monorepo (legacy C + Spring Boot target skeleton)

TxCore/ECPG legacy 매입·정산 C 슬라이스(빌드검증) + Spring Boot 멀티모듈 골격(mvn test green) + MIGRATION.md 전환룰 + CI(boot 빌드).

legacy/app/common/util_msg.c

@@ -0,0 +1,109 @@
+/*
+ * util_msg.c - 고정길이 전문 pack/unpack 유틸리티 (plain C)
+ */
+#include "acq_util.h"
+
+#include <string.h>
+#include <ctype.h>
+
+void msg_field_copy(char *out, const char *field, int len)
+{
+    int end;
+
+    if (!out || !field || len < 0)
+        return;
+
+    /* 우측 공백 제거하여 널 종료 문자열 생성 */
+    end = len;
+    while (end > 0 && (field[end - 1] == ' ' || field[end - 1] == '\0'))
+        end--;
+
+    memcpy(out, field, end);
+    out[end] = '\0';
+}
+
+void msg_field_set(char *field, const char *src, int len)
+{
+    int slen, i;
+
+    if (!field || len < 0)
+        return;
+
+    slen = src ? (int)strlen(src) : 0;
+    if (slen > len)
+        slen = len;
+
+    memcpy(field, src, slen);
+    for (i = slen; i < len; i++)   /* 우측 공백 패딩 */
+        field[i] = ' ';
+}
+
+void msg_field_set_num(char *field, const char *src, int len)
+{
+    int slen, pad, i;
+
+    if (!field || len < 0)
+        return;
+
+    slen = src ? (int)strlen(src) : 0;
+    if (slen > len)
+        slen = len;
+
+    pad = len - slen;
+    for (i = 0; i < pad; i++)      /* 좌측 zero 패딩 */
+        field[i] = '0';
+    if (src)
+        memcpy(field + pad, src, slen);
+}
+
+int msg_unpack(acq_msg_t *msg, const char *raw, int rawlen)
+{
+    if (!msg || !raw)
+        return -1;
+    if (rawlen < MSG_ACQ_LEN)
+        return -1;
+
+    /* 위치기반 레이아웃이 곧 구조체 메모리 배열과 동일 */
+    memcpy(msg, raw, MSG_ACQ_LEN);
+    return 0;
+}
+
+int msg_pack(const acq_msg_t *msg, char *raw, int rawlen)
+{
+    if (!msg || !raw)
+        return -1;
+    if (rawlen < MSG_ACQ_LEN)
+        return -1;
+
+    memcpy(raw, msg, MSG_ACQ_LEN);
+    return 0;
+}
+
+static int field_blank(const char *field, int len)
+{
+    int i;
+    for (i = 0; i < len; i++) {
+        if (field[i] != ' ' && field[i] != '\0')
+            return 0;
+    }
+    return 1;
+}
+
+int msg_validate(const acq_msg_t *msg)
+{
+    if (!msg)
+        return -1;
+
+    if (field_blank(msg->msg_type, FLD_MSG_TYPE_LEN))
+        return -1;
+    if (field_blank(msg->merch_id, FLD_MERCH_ID_LEN))
+        return -1;
+    if (field_blank(msg->card_no, FLD_CARD_NO_LEN))
+        return -1;
+    if (field_blank(msg->amount, FLD_AMOUNT_LEN))
+        return -1;
+    if (field_blank(msg->txn_date, FLD_TXN_DATE_LEN))
+        return -1;
+
+    return 0;
+}