Support curl on Cygwin

[GitHub #65]

README.md

@@ -2,7 +2,7 @@
   <img alt="chsrc logo" src="image/chsrc.png"/>
 </div>
 
-全平台命令行换源工具，**目标支持 Linux, Windows, macOS, BSD 等尽可能多的操作系统，龙芯、飞腾、RISC-V 等尽可能多的 CPU**。
+全平台命令行换源工具，**目标支持 Linux, Windows (MSYS2, Cygwin), macOS, BSD 等尽可能多的操作系统环境，龙芯、飞腾、RISC-V 等尽可能多的 CPU**。
 
 我们使用 **C99** 来完成上述目标。我们并不使用 Python 或 JS 等解释语言，因为一个简单的换源工具，不应该强行塞给用户一个庞大的解释器和数十、数百 MB 其他文件。
 

include/chsrc.h

@@ -6,8 +6,8 @@
  *               |  Heng Guo  <[email protected]>
  * Contributors  :  Peng Gao  <[email protected]>
  *               |
- * Created on    : <2023-08-29>
- * Last modified : <2024-09-04>
+ * Created On    : <2023-08-29>
+ * Last Modified : <2024-09-05>
  *
  * chsrc 头文件
  * ------------------------------------------------------------*/
@@ -436,16 +436,47 @@ measure_speed_for_url (void *url)
       ipv6 = "--ipv6";
     }
 
+
+  char *os_devnull = xy_os_devnull;
+  bool on_cygwin = false;
+
+  // https://github.com/RubyMetric/chsrc/issues/65
+  // curl (仅)在 Cygwin 上 -o nul 会把 nul 当做普通文件
+  // 为了践行 chsrc everywhere 的承诺，我们也考虑支持 Cygwin
+  if (0==system ("cygcheck --version>nul"))
+    {
+      on_cygwin = true;
+      os_devnull = "/tmp/chsrc-measure-downloaded";
+    }
+
   // 我们用 —L，因为Ruby China源会跳转到其他地方
   // npmmirror 也会跳转
-  char *curl_cmd = xy_strjoin (7, "curl -qsL ", ipv6,
-                                  " -o " xy_os_devnull,
+  char *curl_cmd = xy_strjoin (8, "curl -qsL ", ipv6,
+                                  " -o ", os_devnull,
                                   " -w \"%{http_code} %{speed_download}\" -m", time_sec,
                                   " -A chsrc/" Chsrc_Banner_Version "  ", url);
 
   // chsrc_info (xy_2strjoin ("测速命令 ", curl_cmd));
 
-  char *curl_buf = xy_run (curl_cmd, 0, NULL);
+  char *curl_buf = NULL;
+
+  if (on_cygwin)
+    {
+      char *curl_script = ".chsrc_measure_tmp.sh";
+      FILE *f = fopen (curl_script, "w");
+        if (f==NULL)
+          exit (Exit_UserCause);
+      fputs (curl_cmd, f);
+      fclose (f);
+      curl_buf = xy_run ( xy_2strjoin ("bash .\\", curl_script), 0, NULL);
+      system (xy_2strjoin ("del ", curl_script));
+      system (xy_strjoin (3, "bash -c \"rm ", os_devnull, "\""));
+    }
+  else
+    {
+      curl_buf = xy_run (curl_cmd, 0, NULL);
+    }
+
   // 如果尾部有换行，删除
   curl_buf = xy_str_strip (curl_buf);