工程(ci远端化·修复): mac_setup Godot URL模板修正(双stable+漏v前缀致404)+镜像假zip校验(200错误页体当失败, unzip -tq守卫双处)+chunk_dl.py收编(分片并行断点续传下载器,已实证方案仓库化)

tools/ci/chunk_dl.py

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+#!/usr/bin/env python3
+r"""chunk_dl.py — 分片并行下载器（断点续传），2026-11-03 CI 迁移批收编。
+
+背景：GitHub 直连在本项目两台机器均不可用，加速镜像站速度慢且会掐连接/回错误页。
+本件把大文件切成 N 片经镜像并行拉取（单片断了自动续传重试），全部齐后拼合。
+已实证：74MB Godot Linux 包约 15 分钟拉完（2026-11-03 mac_setup 依赖此件拉 Godot macOS 包）。
+
+用法: python3 tools/ci/chunk_dl.py <URL> <输出路径> [分片数=16]
+镜像回落顺序：直连 → gh-proxy.net → gh-proxy.com（HEAD 探测 Content-Length 决定实际用的源）。
+校验：分片按字节范围落盘、按序拼合；zip 结构校验由调用方（mac_setup.sh 的 unzip -tq）承担。
+退出码：0=成功 1=失败。
+"""
+import concurrent.futures as cf
+import os
+import subprocess
+import sys
+
+MIRRORS = ["", "https://gh-proxy.net/", "https://gh-proxy.com/"]
+
+
+def pick_mirror(url: str):
+    """HEAD 探测取 Content-Length；返回（实际可用 URL, 字节数）或 (None, 0)。"""
+    for m in MIRRORS:
+        u = m + url
+        r = subprocess.run(["curl", "-sIL", "-m", "30", u], capture_output=True, text=True)
+        size = 0
+        for line in r.stdout.splitlines():
+            if line.lower().startswith("content-length:"):
+                try:
+                    size = int(line.split(":", 1)[1].strip())
+                except ValueError:
+                    size = 0
+        if size > 0:
+            return u, size
+    return None, 0
+
+
+def fetch(job) -> bool:
+    i, s, e, url, out = job
+    p = "%s.part%02d" % (out, i)
+    want = e - s + 1
+    for _attempt in range(200):
+        have = os.path.getsize(p) if os.path.exists(p) else 0
+        if have >= want:
+            return True
+        r0 = s + have
+        subprocess.run(
+            ["curl", "-sL", "--speed-limit", "1024", "--speed-time", "30",
+             "-m", "600", "-r", "%d-%d" % (r0, e), "-o", p + ".new", url],
+            capture_output=True)
+        if os.path.exists(p + ".new"):
+            with open(p, "ab") as f, open(p + ".new", "rb") as g:
+                f.write(g.read())
+            os.remove(p + ".new")
+    return False
+
+
+def main() -> int:
+    if len(sys.argv) < 3:
+        print("用法: python3 chunk_dl.py <URL> <输出路径> [分片数=16]")
+        return 1
+    url, out = sys.argv[1], sys.argv[2]
+    n = int(sys.argv[3]) if len(sys.argv) > 3 else 16
+    real, size = pick_mirror(url)
+    if not real:
+        print("全部下载源失败")
+        return 1
+    print("size=%d url=%s" % (size, real), flush=True)
+    chunk = (size + n - 1) // n
+    jobs = [(i, i * chunk, min((i + 1) * chunk, size) - 1, real, out)
+            for i in range(n) if i * chunk < size]
+    with cf.ThreadPoolExecutor(n) as ex:
+        for ok in ex.map(fetch, jobs):
+            if not ok:
+                print("分片重试耗尽")
+                return 1
+    with open(out, "wb") as f:
+        for i, _, _, _, _ in jobs:
+            with open("%s.part%02d" % (out, i), "rb") as g:
+                f.write(g.read())
+    for i, _, _, _, _ in jobs:
+        os.remove("%s.part%02d" % (out, i))
+    print("done %d" % os.path.getsize(out))
+    return 0
+
+
+if __name__ == "__main__":
+    sys.exit(main())