Make fake fcntl(F_DUPFD) for WIN32

1 files changed, 40 insertions, 12 deletions

diff --git a/win32/mingw.c b/win32/mingw.c
index 219ef96b8..c9b00bbcd 100644
--- a/win32/mingw.c
+++ b/win32/mingw.c
@@ -693,18 +693,46 @@ int mingw_mkdir(const char *path, int mode UNUSED_PARAM)
         return mkdir(path);
 }
 
-int fcntl(int fd UNUSED_PARAM, int cmd, ...)
-{
-        /*
-         * F_GETFL needs to be dealt at higher level
-         * Usually it does not matter if the call is
-         *   fcntl(fd, F_SETFL, fcntl(fd, F_GETFD) | something)
-         * because F_SETFL is not supported
-         */
-        if (cmd == F_GETFD || cmd == F_SETFD || cmd == F_GETFL)
-                return 0;
-        errno = ENOSYS;
-        return -1;
+int fcntl(int fd, int cmd, ...)
+{
+        va_list arg;
+        int result = -1;
+        char *fds;
+        int target, i, newfd;
+
+        va_start(arg, cmd);
+
+        switch (cmd) {
+        case F_GETFD:
+        case F_SETFD:
+        case F_GETFL:
+                /*
+                 * Our fake F_GETFL won't matter if the return value is used as
+                 *    fcntl(fd, F_SETFL, ret|something);
+                 * because F_SETFL isn't supported either.
+                 */
+                result = 0;
+                break;
+        case F_DUPFD:
+                target = va_arg(arg, int);
+                fds = xzalloc(target);
+                while ((newfd = dup(fd)) < target && newfd >= 0) {
+                        fds[newfd] = 1;
+                }
+                for (i = 0; i < target; ++i) {
+                        if (fds[i]) {
+                                close(i);
+                        }
+                }
+                free(fds);
+                result = newfd;
+        default:
+                errno = ENOSYS;
+                break;
+        }
+
+        va_end(arg);
+        return result;
 }
 
 #undef unlink