Port redirect-debugging-output to non-GNU/Linux

[gnu-emacs] / src / sysdep.c

diff --git a/src/sysdep.c b/src/sysdep.c
index 418c50d5e78e907a70f4b00fb8d9de11b40c12bf..67c9bd90df789ccaf6195b86415a4f4341d1b497 100644 (file)
--- a/src/sysdep.c
+++ b/src/sysdep.c
@@ -6,8 +6,8 @@ This file is part of GNU Emacs.
 
 GNU Emacs is free software: you can redistribute it and/or modify
 it under the terms of the GNU General Public License as published by
-the Free Software Foundation, either version 3 of the License, or
-(at your option) any later version.
+the Free Software Foundation, either version 3 of the License, or (at
+your option) any later version.
 
 GNU Emacs is distributed in the hope that it will be useful,
 but WITHOUT ANY WARRANTY; without even the implied warranty of
@@ -130,6 +130,35 @@ static const int baud_convert[] =
     1800, 2400, 4800, 9600, 19200, 38400
   };
 
+/* If FD is not already open, arrange for it to be open with FLAGS.  */
+static void
+force_open (int fd, int flags)
+{
+  if (dup2 (fd, fd) < 0 && errno == EBADF)
+    {
+      int n = open (NULL_DEVICE, flags);
+      if (n < 0 || (fd != n && (dup2 (n, fd) < 0 || emacs_close (n) != 0)))
+       {
+         emacs_perror (NULL_DEVICE);
+         exit (EXIT_FAILURE);
+       }
+    }
+}
+
+/* Make sure stdin, stdout, and stderr are open to something, so that
+   their file descriptors are not hijacked by later system calls.  */
+void
+init_standard_fds (void)
+{
+  /* Open stdin for *writing*, and stdout and stderr for *reading*.
+     That way, any attempt to do normal I/O will result in an error,
+     just as if the files were closed, and the file descriptors will
+     not be reused by later opens.  */
+  force_open (STDIN_FILENO, O_WRONLY);
+  force_open (STDOUT_FILENO, O_RDONLY);
+  force_open (STDERR_FILENO, O_RDONLY);
+}
+
 /* Return the current working directory.  The result should be freed
    with 'free'.  Return NULL on errors.  */
 char *
@@ -1408,6 +1437,12 @@ setup_pty (int fd)
 void
 init_system_name (void)
 {
+  if (!build_details)
+    {
+      /* Set system-name to nil so that the build is deterministic.  */
+      Vsystem_name = Qnil;
+      return;
+    }
   char *hostname_alloc = NULL;
   char *hostname;
 #ifndef HAVE_GETHOSTNAME