Consolidate scandir{at}{64} implementation

This patch consolidates scandir{at}{64} implementation on just
the default dirent/scandir{at}{64}{_r}.c ones.  It changes the logic
to follow the conventions used on other code consolidation:

  * scandir{at} is only built for _DIRENT_MATCHES_DIRENT64 being 0.

  * scandir{at}{64} is always built and aliased to getdents for ABIs
    that define _DIRENT_MATCHES_DIRENT64 to 1.

Also on Linux the compat symbol for old non-LFS dirent64 definition
requires a platform-specific scandir64.c.

Checked on aarch64-linux-gnu, x86_64-linux-gnu, i686-linux-gnu,
sparcv9-linux-gnu, sparc64-linux-gnu, powerpc-linux-gnu, and
powerpc64le-linux-gnu.

	* dirent/scandir-tail-common.c: New file.
	* dirent/scandir-tail.c: Use scandir-tail-common.c.
	(__scandir_tail): Build iff _DIRENT_MATCHES_DIRENT64 is not defined.
	* dirent/scandir.c: Use scandir-tail-common.c.
	* dirent/scandirat.c: Likewise.
	* dirent/scandir64-tail.c: Use scandir-tail-common.c.
	* dirent/scandir64.c (scandir64): Always build and alias to scandir
	if _DIRENT_MATCHES_DIRENT64 is defined.
	* dirent/scandirat64.c (scandirat64): Likewise.
	* include/dirent.h (__scandir_tail): Only define iff
	_DIRENT_MATCHES_DIRENT64 is not defined.
	(__scandir64_tail): Define regardless.
	(__scandirat, scandirat64): Remove libc_hidden_proto.
	* sysdeps/unix/sysv/linux/arm/scandir64.c: Remove file.
	* sysdeps/unix/sysv/linux/m68k/scandir64.c: Likewise.
	* sysdeps/unix/sysv/linux/powerpc/powerpc32/scandir64.c: Likewise.
	* sysdeps/unix/sysv/linux/s390/s390-32/scandir64.c: Likewise.
	* sysdeps/unix/sysv/linux/i386/scandir64.c: Likewise.
	* sysdeps/unix/sysv/linux/sparc/sparc32/scandir64.c: Likewise.
	* sysdeps/unix/sysv/linux/scandir64.c: New file.

1 files changed, 103 insertions, 0 deletions

diff --git a/dirent/scandir-tail-common.c b/dirent/scandir-tail-common.c
new file mode 100644
index 0000000000..f89cf77b56
--- /dev/null
+++ b/dirent/scandir-tail-common.c
@@ -0,0 +1,103 @@
+/* Common implementation for scandir{at}.
+   Copyright (C) 2018 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
+   <http://www.gnu.org/licenses/>.  */
+
+#include <string.h>
+#include <errno.h>
+
+int
+SCANDIR_TAIL (DIR *dp,
+              DIRENT_TYPE ***namelist,
+              int (*select) (const DIRENT_TYPE *),
+              int (*cmp) (const DIRENT_TYPE **, const DIRENT_TYPE **))
+{
+  if (dp == NULL)
+    return -1;
+
+  int save = errno;
+  __set_errno (0);
+
+  int result;
+  struct scandir_cancel_struct c = { .dp = dp };
+  __libc_cleanup_push (&__scandir_cancel_handler, &c);
+
+  DIRENT_TYPE **v = NULL;
+  size_t vsize = 0;
+  DIRENT_TYPE *d;
+  while ((d = READDIR (dp)) != NULL)
+    {
+      if (select != NULL)
+        {
+          int selected = (*select) (d);
+
+	  /* The SELECT function might have set errno to non-zero on
+	     success.  It was zero before and it needs to be again to
+	     make the later tests work.  */
+	  __set_errno (0);
+
+          if (!selected)
+            continue;
+        }
+
+      if (__glibc_unlikely (c.cnt == vsize))
+        {
+          if (vsize == 0)
+            vsize = 10;
+          else
+            vsize *= 2;
+          DIRENT_TYPE **new = realloc (v, vsize * sizeof *v);
+          if (new == NULL)
+            break;
+          c.v = v = new;
+        }
+
+      size_t dsize = &d->d_name[_D_ALLOC_NAMLEN (d)] - (char *) d;
+      DIRENT_TYPE *vnew = malloc (dsize);
+      if (vnew == NULL)
+        break;
+      v[c.cnt++] = (DIRENT_TYPE *) memcpy (vnew, d, dsize);
+
+      /* Ignore errors from readdir, malloc or realloc.  These functions
+	 might have set errno to non-zero on success.  It was zero before
+	 and it needs to be again to make the latter tests work.  */
+      __set_errno (0);
+    }
+
+  if (__glibc_likely (errno == 0))
+    {
+      __closedir (dp);
+
+      /* Sort the list if we have a comparison function to sort with.  */
+      if (cmp != NULL)
+	qsort (v, c.cnt, sizeof *v, (__compar_fn_t) cmp);
+
+      *namelist = v;
+      result = c.cnt;
+    }
+  else
+    {
+      /* This frees everything and calls closedir.  */
+      __scandir_cancel_handler (&c);
+      result = -1;
+    }
+
+  __libc_cleanup_pop (0);
+
+  if (result >= 0)
+    __set_errno (save);
+  return result;
+}