fix：解决变长参数方法（fcntl, ioctl）hook后参数转发实现不正确导致使用异常问题。

Update the implementation of hooked fcntl & ioctl to fix the problem.

src/co/hook.cc

@@ -240,42 +240,59 @@ int pipe2(int pipefd[2], int flags) {
 #define F_DUPFD_CLOEXEC F_DUPFD 
 #endif
 
+/* 
+    For system IO functions which take a variable number of arguments (like fcntl, ioctl),
+      we assume that the variadic parameters part's memory usage <= 8*sizeof(intptr_t) .  
+    So, we can use 'a1'..'a8' to hold the stack memory data of variadic parameters passed from function caller (with va_star/va_arg/va_end).
+    Then, pass these parameters to destination function (raw function) in the prescribed order.
+    If the parameters is more than actually what the caller passed, it is just OK, 
+        because the extra part only takes some stack memory space and will be ignored.
+    If the parameters is LESS than actually what the caller passed, some missed parameters cannot be passed!
+    It will cause error/fatal!
+    Ref: 
+        https://docs.microsoft.com/en-us/cpp/cpp/cdecl?view=msvc-170
+        https://baike.baidu.com/item/__cdecl/9518056
+
+*/
+#define VARG_8_GET(st) intptr_t a1,a2,a3,a4,a5,a6,a7,a8;\
+    {va_list ap; va_start(ap,st);    \
+    a1=va_arg(ap,intptr_t); a2=va_arg(ap,intptr_t); a3=va_arg(ap,intptr_t); a4=va_arg(ap,intptr_t); \
+    a5=va_arg(ap,intptr_t); a6=va_arg(ap,intptr_t); a7=va_arg(ap,intptr_t); a8=va_arg(ap,intptr_t); \
+    va_end(ap);}
+
+#define VARG_8_PARAMS  a1,a2,a3,a4,a5,a6,a7,a8
+
+
 int fcntl(int fd, int cmd, ... /* arg */) {
     init_hook(fcntl);
     if (fd < 0) { errno = EBADF; return -1; }
 
-    va_list args;
-    va_start(args, cmd);
+    VARG_8_GET(cmd);
 
-    int r, v;
     auto& ctx = gHook().get_hook_ctx(fd);
     if (!ctx.is_sock_or_pipe()) {
-        r = CO_RAW_API(fcntl)(fd, cmd, args); 
-        va_end(args);
-        return r;
+        return CO_RAW_API(fcntl)(fd, cmd, VARG_8_PARAMS);
     }
+
+    int r;
 
     if (cmd == F_SETFL) {
-        v = va_arg(args, int);
-        va_end(args);
-        r = CO_RAW_API(fcntl)(fd, cmd, v); 
+        // 'F_SETFL' only need one extra parameter 
+        r = CO_RAW_API(fcntl)(fd, cmd, a1);
         if (r != -1) {
-            ctx.set_non_blocking(v & O_NONBLOCK);
-            HOOKLOG << "hook fcntl F_SETFL, fd: " << fd << ", non_block: " << (v & O_NONBLOCK);
+            ctx.set_non_blocking(a1 & O_NONBLOCK);
+            HOOKLOG << "hook fcntl F_SETFL, fd: " << fd << ", non_block: " << (a1 & O_NONBLOCK);
         }
 
     } else if (cmd == F_DUPFD || cmd == F_DUPFD_CLOEXEC) {
-        v = va_arg(args, int);
-        va_end(args);
-        r = CO_RAW_API(fcntl)(fd, cmd, v); 
+        // 'F_DUPFD'/'F_DUPFD_CLOEXEC' only need one extra parameter 
+        r = CO_RAW_API(fcntl)(fd, cmd, a1);
         if (r != -1) {
             gHook().get_hook_ctx(r) = ctx;
             HOOKLOG << "hook fcntl F_DUPFD, fd: " << fd << ", r: " << r;
         }
-
     } else {
-        r = CO_RAW_API(fcntl)(fd, cmd, args); 
-        va_end(args);
+        r = CO_RAW_API(fcntl)(fd, cmd, VARG_8_PARAMS);
     }
 
     HOOKLOG << "hook fcntl cmd: " << cmd << ", fd: " << fd << ", r: " << r;
@@ -286,18 +303,20 @@ int ioctl(int fd, co::ioctl_param<ioctl_fp_t>::type request, ...) {
     init_hook(ioctl);
     if (fd < 0) { errno = EBADF; return -1; }
 
-    va_list args;
-    va_start(args, request);
-    void* arg = va_arg(args, void*);
-    va_end(args);
+    VARG_8_GET(request);
 
+    int r;
     auto& ctx = gHook().get_hook_ctx(fd);
-    int r = CO_RAW_API(ioctl)(fd, request, arg);
-    if (r != -1) {
-        if (request == FIONBIO && ctx.is_sock_or_pipe()) {
-            ctx.set_non_blocking(*(int*)arg);
-            HOOKLOG << "hook ioctl FIONBIO, fd: " << fd << ", non_block: " << *(int*)arg; 
+
+    if (request == FIONBIO && ctx.is_sock_or_pipe()) {
+        int v=*(int*)a1;
+        r = CO_RAW_API(ioctl)(fd, request, v);
+        if (r != -1) {
+            ctx.set_non_blocking(v);
+            HOOKLOG << "hook ioctl FIONBIO, fd: " << fd << ", non_block: " << v; 
         }
+    }else {
+        r = CO_RAW_API(ioctl)(fd, request, VARG_8_PARAMS);
     }
 
     HOOKLOG << "hook ioctl, fd: " << fd << ", req: " << request << ", r: " << r;