glob: Simplify the interface for the GLOB_ALTDIRFUNC callback gl_readdir

Previously, application code had to set up the d_namlen member if
the target supported it, involving conditional compilation.  After
this change, glob will use the length of the string in d_name instead
of d_namlen to determine the file name length.  All glibc targets
provide the d_type and d_ino members, and setting them as needed for
gl_readdir is straightforward.

Changing the behavior with regards to d_ino is left to a future
cleanup.

1 files changed, 42 insertions, 0 deletions

diff --git a/manual/examples/mkdirent.c b/manual/examples/mkdirent.c
new file mode 100644
index 0000000000..f8400f46d7
--- /dev/null
+++ b/manual/examples/mkdirent.c
@@ -0,0 +1,42 @@
+/* Example for creating a struct dirent object for use with glob.
+   Copyright (C) 2016 Free Software Foundation, Inc.
+
+   This program 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 2
+   of the License, or (at your option) any later version.
+
+   This program 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 General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program; if not, if not, see <http://www.gnu.org/licenses/>.
+*/
+
+#include <dirent.h>
+#include <errno.h>
+#include <stddef.h>
+#include <stdlib.h>
+#include <string.h>
+
+struct dirent *
+mkdirent (const char *name)
+{
+  size_t dirent_size = offsetof (struct dirent, d_name) + 1;
+  size_t name_length = strlen (name);
+  size_t total_size = dirent_size + name_length;
+  if (total_size < dirent_size)
+    {
+      errno = ENOMEM;
+      return NULL;
+    }
+  struct dirent *result = malloc (total_size);
+  if (result == NULL)
+    return NULL;
+  result->d_type = DT_UNKNOWN;
+  result->d_ino = 1;            /* Do not skip this entry.  */
+  memcpy (result->d_name, name, name_length + 1);
+  return result;
+}