FatFs短名解析拒绝点加DEBUG打印并台架实证+AGENTS.md固化严格8.3命名约束

Lib/FatFs/ff.c

@@ -23,6 +23,21 @@
 #include "ff.h"			/* Declarations of FatFs API */
 #include "diskio.h"		/* Declarations of device I/O functions */
 
+/* 项目定制（2026-09-20，".fschk 无限重格式化"事故复盘）：
+ * FF_USE_LFN=0 时 f_open/f_create/f_unlink/f_mkdir 等一切文件 API
+ * 最终都汇聚到 create_short() 做 8.3 短名解析——这是名字合法性的
+ * 唯一咽喉点。在拒绝瞬间打印名字片段+原因，让"非法文件名"这类
+ * 纯 RAM 判定错误从开机日志直接可见，不再需要拿错误码反查枚举表。
+ * 注意：字符串字面量必须纯 ASCII（ARMCC 对无 BOM 文件按 CP936 解析）。 */
+#if FF_USE_LFN == 0
+#define DBG_TAG "[FATFS]"
+#include "dbg_log.h"
+#define FF_DBG_SFN_REJECT(why, seg, ch) \
+	DBG_ERROR("SFN reject (%s) seg='%.24s' bad_ch=0x%02X" \
+	          " - strict 8.3 only: body<=8 ext<=3 no leading dot", \
+	          (why), (seg), (int)(ch))
+#endif
+
 
 /*--------------------------------------------------------------------------
 
@@ -2993,7 +3008,12 @@ static FRESULT create_name (	/* FR_OK: successful, FR_INVALID_NAME: could not cr
 			if (c != '.' || si >= 3) break;
 			sfn[i++] = c;
 		}
-		if (!IsSeparator(c) && c > ' ') return FR_INVALID_NAME;
+		if (!IsSeparator(c) && c > ' ') {
+#if FF_USE_LFN == 0
+			FF_DBG_SFN_REJECT("heading dot", p, c);
+#endif
+			return FR_INVALID_NAME;
+		}
 		*path = p + si;					/* Return pointer to the next segment */
 		sfn[NSFLAG] = (c <= ' ') ? NS_LAST | NS_DOT : NS_DOT;	/* Set last segment flag if end of the path */
 		return FR_OK;
@@ -3007,7 +3027,12 @@ static FRESULT create_name (	/* FR_OK: successful, FR_INVALID_NAME: could not cr
 			break;
 		}
 		if (c == '.' || i >= ni) {		/* End of body or field overflow? */
-			if (ni == 11 || c != '.') return FR_INVALID_NAME;	/* Field overflow or invalid dot? */
+			if (ni == 11 || c != '.') {
+#if FF_USE_LFN == 0
+				FF_DBG_SFN_REJECT("ext overflow or bad dot", p, c);
+#endif
+				return FR_INVALID_NAME;	/* Field overflow or invalid dot? */
+			}
 			i = 8; ni = 11;				/* Enter file extension field */
 			continue;
 		}
@@ -3022,17 +3047,32 @@ static FRESULT create_name (	/* FR_OK: successful, FR_INVALID_NAME: could not cr
 #endif
 		if (dbc_1st(c)) {				/* Check if it is a DBC 1st byte */
 			d = (BYTE)p[si++];			/* Get 2nd byte */
-			if (!dbc_2nd(d) || i >= ni - 1) return FR_INVALID_NAME;	/* Reject invalid DBC */
+			if (!dbc_2nd(d) || i >= ni - 1) {
+#if FF_USE_LFN == 0
+				FF_DBG_SFN_REJECT("invalid DBC", p, c);
+#endif
+				return FR_INVALID_NAME;	/* Reject invalid DBC */
+			}
 			sfn[i++] = c;
 			sfn[i++] = d;
 		} else {						/* SBC */
-			if (strchr("*+,:;<=>[]|\"\?\x7F", (int)c)) return FR_INVALID_NAME;	/* Reject illegal chrs for SFN */
+			if (strchr("*+,:;<=>[]|\"\?\x7F", (int)c)) {
+#if FF_USE_LFN == 0
+				FF_DBG_SFN_REJECT("illegal char", p, c);
+#endif
+				return FR_INVALID_NAME;	/* Reject illegal chrs for SFN */
+			}
 			if (IsLower(c)) c -= 0x20;	/* To upper */
 			sfn[i++] = c;
 		}
 	}
 	*path = &p[si];						/* Return pointer to the next segment */
-	if (i == 0) return FR_INVALID_NAME;	/* Reject nul string */
+	if (i == 0) {
+#if FF_USE_LFN == 0
+		FF_DBG_SFN_REJECT("empty name", p, c);
+#endif
+		return FR_INVALID_NAME;			/* Reject nul string */
+	}
 
 	if (sfn[0] == DDEM) sfn[0] = RDDEM;	/* If the first character collides with DDEM, replace it with RDDEM */
 	sfn[NSFLAG] = (c <= ' ' || p[si] <= ' ') ? NS_LAST : 0;	/* Set last segment flag if end of the path */