fix(watchdog): wd_vol_save 不再 O_TRUNC 毁 settings.conf(改读改写单键+去重,与SDK同款语义) — 真机实证整文件被抹/重复行/丢max+step。test_wd_fw 17/17 PASS; 52f2dadd 已热更 /usr/data/meow_watchdog

patch_v2/meow_watchdog/meow_watchdog.c

@@ -367,17 +367,38 @@ static void wd_vol_write(int pct)
     wd_log("DAC vol -> L/R=%d (pct %d)", dac, pct);
 }
 
+/* M2.92+ 修复（真机实证 settings.conf 被毁）：旧版 O_TRUNC 整文件重写只剩 4 行 ——
+ * 抹掉全部其它设置；与其它写者交错还叠出重复 audio.volume 行、丢 volume_max/step。
+ * 改为读改写单键（流式拷贝、命中行全部改写去重、缺失末尾追加、rename 原子替换），
+ * 与 SDK meow_ui_vol_set 同款语义。 */
 static void wd_vol_save(void)
 {
     system("mkdir -p /usr/data/meow 2>/dev/null");
-    int fd = open(MEOW_SETTINGS_FILE, O_WRONLY | O_CREAT | O_TRUNC, 0644);
-    if (fd < 0) { wd_log("vol: open %s fail: %s", MEOW_SETTINGS_FILE, strerror(errno)); return; }
-    char buf[128];
-    int l = snprintf(buf, sizeof buf,
-        "# meow-settings 1\naudio.volume = %d\naudio.volume_max = %d\naudio.volume_step = %d\n",
-        wd_vol, wd_vol_max, wd_vol_step);
-    if (write(fd, buf, l) < 0) wd_log("vol: write fail: %s", strerror(errno));
-    close(fd);
+    const char *path = MEOW_SETTINGS_FILE;
+    char tmp[300];
+    snprintf(tmp, sizeof tmp, "%s.tmp", path);
+    FILE *in = fopen(path, "r");
+    FILE *out = fopen(tmp, "w");
+    if (!out) { if (in) fclose(in); wd_log("vol: save open tmp fail"); return; }
+    int found = 0;
+    char line[256];
+    while (in && fgets(line, sizeof line, in)) {
+        char *eq = strchr(line, '=');
+        char *k = line;
+        while (*k == ' ' || *k == '\t') k++;
+        int n = eq ? (int)(eq - k) : 0;
+        while (n > 0 && (k[n-1] == ' ' || k[n-1] == '\t')) n--;
+        if (eq && n == 12 && strncmp(k, "audio.volume", 12) == 0) {
+            if (!found) fprintf(out, "audio.volume = %d\n", wd_vol);   /* 命中：只写一次（去重） */
+            found = 1;
+        } else {
+            fputs(line, out);
+        }
+    }
+    if (in) fclose(in);
+    if (!found) fprintf(out, "audio.volume = %d\n", wd_vol);
+    fclose(out);
+    if (rename(tmp, path) != 0) { remove(tmp); wd_log("vol: save rename fail"); return; }
     wd_log("vol: saved volume=%d(max=%d,step=%d)", wd_vol, wd_vol_max, wd_vol_step);
 }