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-rw-r--r--src/common/tuklib_open_stdxxx.c51
1 files changed, 51 insertions, 0 deletions
diff --git a/src/common/tuklib_open_stdxxx.c b/src/common/tuklib_open_stdxxx.c
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index 00000000..70c8e73d
--- /dev/null
+++ b/src/common/tuklib_open_stdxxx.c
@@ -0,0 +1,51 @@
+///////////////////////////////////////////////////////////////////////////////
+//
+/// \file tuklib_open_stdxxx.c
+/// \brief Make sure that file descriptors 0, 1, and 2 are open
+//
+// Author: Lasse Collin
+//
+// This file has been put into the public domain.
+// You can do whatever you want with this file.
+//
+///////////////////////////////////////////////////////////////////////////////
+
+#include "tuklib_open_stdxxx.h"
+
+#ifndef TUKLIB_DOSLIKE
+# include <stdlib.h>
+# include <errno.h>
+# include <fcntl.h>
+# include <unistd.h>
+#endif
+
+
+extern void
+tuklib_open_stdxxx(int err_status)
+{
+#ifndef TUKLIB_DOSLIKE
+ for (int i = 0; i <= 2; ++i) {
+ // We use fcntl() to check if the file descriptor is open.
+ if (fcntl(i, F_GETFD) == -1 && errno == EBADF) {
+ // With stdin, we could use /dev/full so that
+ // writing to stdin would fail. However, /dev/full
+ // is Linux specific, and if the program tries to
+ // write to stdin, there's already a problem anyway.
+ const int fd = open("/dev/null", O_NOCTTY
+ | (i == 0 ? O_WRONLY : O_RDONLY));
+
+ if (fd != i) {
+ // Something went wrong. Exit with the
+ // exit status we were given. Don't try
+ // to print an error message, since stderr
+ // may very well be non-existent. This
+ // error should be extremely rare.
+ (void)close(fd);
+ exit(err_status);
+ }
+ }
+ }
+#endif
+
+ return;
+}