input: only change mode of input fd if there is an input fd

src/nvim/if_cscope.c

@@ -778,7 +778,6 @@ err_closing:
     if (execl("/bin/sh", "sh", "-c", cmd, (char *)NULL) == -1)
       PERROR(_("cs_create_connection exec failed"));
 
-    stream_set_blocking(input_global_fd(), true);  // normalize stream (#2598)
     exit(127);
   /* NOTREACHED */
   default:      /* parent. */

src/nvim/misc1.c

@@ -2622,7 +2622,10 @@ void preserve_exit(void)
 
   // Prevent repeated calls into this method.
   if (really_exiting) {
-    stream_set_blocking(input_global_fd(), true);  //normalize stream (#2598)
+    if (input_global_fd() >= 0) {
+      // normalize stream (#2598)
+      stream_set_blocking(input_global_fd(), true);
+    }
     exit(2);
   }
 

src/nvim/os/input.c

@@ -37,7 +37,7 @@ typedef enum {
 static Stream read_stream = {.closed = true};
 static RBuffer *input_buffer = NULL;
 static bool input_eof = false;
-static int global_fd = 0;
+static int global_fd = -1;
 static int events_enabled = 0;
 static bool blocking = false;
 

src/nvim/os_unix.c

@@ -144,7 +144,9 @@ void mch_exit(int r) FUNC_ATTR_NORETURN
   if (!event_teardown() && r == 0) {
     r = 1;  // Exit with error if main_loop did not teardown gracefully.
   }
+  if (input_global_fd() >= 0) {
     stream_set_blocking(input_global_fd(), true);  // normalize stream (#2598)
+  }
 
 #ifdef EXITFREE
   free_all_mem();