From 801099e786deeebbd6e4db8468d4a84f481fe964 Mon Sep 17 00:00:00 2001
From: VirtualHotBar <yyds_vhb@163.com>
Date: Tue, 2 Jun 2026 02:22:20 +0800
Subject: [PATCH] =?UTF-8?q?fix:=20#51=20=E8=87=AA=E5=8A=A8=E5=88=86?=
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修复 Rust 端 find_first_available_drive_letter() 函数中位掩码与盘符映射错误：
- 原代码遍历 A-Z 但用 idx=25-i 反转检查位，导致返回的盘符与实际检查的位不匹配
- 修复为正确的遍历方式：从 i=25(Z) 到 i=0(A)，确保盘符与位索引一致

同时在前端添加自动分配盘符后的重复检查：
- 检查获取的可用盘符是否为空
- 检查获取的盘符是否已被其他挂载占用
---
 src-tauri/src/utils.rs | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/src-tauri/src/utils.rs b/src-tauri/src/utils.rs
index 2bf7e49..6c4d6be 100644
--- a/src-tauri/src/utils.rs
+++ b/src-tauri/src/utils.rs
@@ -44,9 +44,10 @@ pub fn find_first_available_drive_letter() -> Result<Option<String>, io::Error>
         }
 
         // 从 Z 到 A 遍历，找第一个未被占用的盘符
-        for (i, c) in ('A'..='Z').enumerate() {
-            let idx = 25 - i; // Z=25, Y=24, ..., A=0
-            if drive_mask & (1 << idx) == 0 {
+        // 注意：位掩码中 bit 0 = A, bit 1 = B, ..., bit 25 = Z
+        for i in (0..26).rev() {
+            let c = (b'A' + i as u8) as char;
+            if drive_mask & (1 << i) == 0 {
                 return Ok(Some(format!("{}:", c)));
             }
         }