From 0d090476dc92a283ed0eac80a715157323c59948 Mon Sep 17 00:00:00 2001
From: Daniel <845765@qq.com>
Date: Mon, 12 Jan 2026 19:29:01 +0800
Subject: [PATCH] :art:
 https://github.com/siyuan-note/siyuan/pull/16714#issuecomment-3738100178

Signed-off-by: Daniel <845765@qq.com>
---
 kernel/util/file.go | 105 ++++++++++++++++++++++++++++++++++++++------
 1 file changed, 92 insertions(+), 13 deletions(-)

diff --git a/kernel/util/file.go b/kernel/util/file.go
index aebeab4f9..4188ac39f 100644
--- a/kernel/util/file.go
+++ b/kernel/util/file.go
@@ -17,7 +17,6 @@
 package util
 
 import (
-	"bytes"
 	"io"
 	"io/fs"
 	"mime"
@@ -247,23 +246,103 @@ func FilterUploadFileName(name string) string {
 }
 
 func TruncateLenFileName(name string) (ret string) {
-	// 插入资源文件时文件名长度最大限制 189 字节 https://github.com/siyuan-note/siyuan/issues/7099
+	// 插入资源文件时文件名长度最大限制 189 字节
+	const maxTotal = 189
+
 	ext := filepath.Ext(name)
-	var byteCount int
-	truncated := false
-	buf := bytes.Buffer{}
-	for _, r := range name {
-		byteCount += utf8.RuneLen(r)
-		if 189-len(ext) < byteCount {
-			truncated = true
+	base := name[:len(name)-len(ext)]
+
+	id := ast.NewNodeID()
+	// 预留 "-" + id + "-" 的字节数
+	reservedForID := len(id) + 2
+
+	available := maxTotal - len(ext) - reservedForID
+	if available <= 0 {
+		// 空间不足以保留 base，退回到 "-id-" + ext（若仍超限则只返回扩展名）
+		candidate := "-" + id + "-" + ext
+		if len(candidate) <= maxTotal {
+			return candidate
+		}
+		if len(ext) <= maxTotal {
+			return ext
+		}
+		return ext
+	}
+
+	// 若 base 整体在可用字节内，直接返回原名
+	if len(base) <= available {
+		return name
+	}
+
+	runes := []rune(base)
+	n := len(runes)
+	if n == 0 {
+		candidate := "-" + id + "-" + ext
+		if len(candidate) <= maxTotal {
+			return candidate
+		}
+		if len(ext) <= maxTotal {
+			return ext
+		}
+		return ext
+	}
+
+	// 计算每个 rune 的字节长度
+	runeBytes := make([]int, n)
+	for i, r := range runes {
+		runeBytes[i] = utf8.RuneLen(r)
+	}
+
+	// 从后往前尝试最多保留 3 个 rune，找到最大的 tailSize 使得 tailBytes <= available
+	tailSize := 0
+	tailBytes := 0
+	for t := 1; t <= 3 && t <= n; t++ {
+		b := 0
+		for i := n - t; i < n; i++ {
+			b += runeBytes[i]
+		}
+		if b <= available {
+			tailSize = t
+			tailBytes = b
+		} else {
 			break
 		}
-		buf.WriteRune(r)
 	}
-	if truncated {
-		buf.WriteString(ext)
+
+	if tailSize == 0 {
+		// 连一个尾部 rune 都放不下，回退到 "-id-" 或扩展名
+		candidate := "-" + id + "-" + ext
+		if len(candidate) <= maxTotal {
+			return candidate
+		}
+		if len(ext) <= maxTotal {
+			return ext
+		}
+		return ext
 	}
-	ret = buf.String()
+
+	// 可用于前缀的字节
+	availFront := available - tailBytes
+	// 前缀最多不能覆盖到尾部
+	maxFrontCount := n - tailSize
+
+	var frontRunes []rune
+	frontBytes := 0
+	for i := 0; i < maxFrontCount; i++ {
+		if frontBytes+runeBytes[i] > availFront {
+			break
+		}
+		frontBytes += runeBytes[i]
+		frontRunes = append(frontRunes, runes[i])
+	}
+
+	// 若前缀与尾部合并能覆盖全部 runes，则说明无需截断（理论上前面已判断过，但再验证一次）
+	if len(frontRunes) == maxFrontCount {
+		return name
+	}
+
+	tailRunes := runes[n-tailSize:]
+	ret = string(frontRunes) + string(tailRunes) + "-" + id + "-" + ext
 	return
 }