1 files changed, 46 insertions, 0 deletions
diff --git a/posix/shm-directory.c b/posix/shm-directory.c
new file mode 100644
index 0000000000..c06bf96aa7
--- /dev/null
+++ b/posix/shm-directory.c
@@ -0,0 +1,46 @@
+/* Determine directory for shm/sem files.  Generic POSIX version.
+   Copyright (C) 2014-2021 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <https://www.gnu.org/licenses/>.  */
+
+#include <unistd.h>
+
+#if _POSIX_MAPPED_FILES
+
+#include <alloc_buffer.h>
+#include <shm-directory.h>
+#include <string.h>
+
+int
+__shm_get_name (struct shmdir_name *result, const char *name, bool sem_prefix)
+{
+  while (name[0] == '/')
+    ++name;
+  size_t namelen = strlen (name);
+
+  struct alloc_buffer buffer
+    = alloc_buffer_create (result->name, sizeof (result->name));
+  alloc_buffer_copy_bytes (&buffer, SHMDIR, strlen (SHMDIR));
+  if (sem_prefix)
+    alloc_buffer_copy_bytes (&buffer, "sem.", strlen ("sem."));
+  alloc_buffer_copy_bytes (&buffer, name, namelen + 1);
+  if (namelen == 0 || memchr (name, '/', namelen) != NULL
+      || alloc_buffer_has_failed (&buffer))
+    return -1;
+  return 0;
+}
+
+#endif