new module scandir

[Bruno Haible]

Another new function in POSIX:2008 is scandir. I cannot judge how useful it
is, but it's easy to port the implementation from glibc anyway.

2009-01-18  Bruno Haible  <address@hidden>

        New module 'scandir'.
        * lib/dirent.in.h (scandir): New declaration.
        * lib/scandir.c: New file, from glibc with modifications.
        * m4/scandir.m4: New file.
        * modules/scandir: New file.
        * m4/dirent_h.m4 (gl_DIRENT_H_DEFAULTS): Initialize GNULIB_SCANDIR,
        HAVE_SCANDIR.
        * modules/dirent (Makefile.am): Substitute GNULIB_SCANDIR,
        HAVE_SCANDIR.
        * doc/posix-functions/scandir.texi: Mention the new module and the
        portability problems.

================================== lib/scandir.c ==============================
/* Copyright (C) 1992-1998, 2000, 2002, 2003, 2009 Free Software Foundation, 
Inc.
   This file is part of the GNU C Library.

   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, 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, write to the Free Software Foundation,
   Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.  */

#include <config.h>

#include <dirent.h>

#include <stdlib.h>
#include <string.h>
#include <errno.h>
#if _LIBC
# include <bits/libc-lock.h>
#endif

#if ! defined __builtin_expect && __GNUC__ < 3
# define __builtin_expect(expr, expected) (expr)
#endif

#undef select

#if _LIBC
# ifndef SCANDIR
#  define SCANDIR scandir
#  define READDIR __readdir
#  define DIRENT_TYPE struct dirent
# endif
#else
# define SCANDIR scandir
# define READDIR readdir
# define DIRENT_TYPE struct dirent
# define __opendir opendir
# define __closedir closedir
# define __set_errno(val) errno = (val)
#endif

#ifndef SCANDIR_CANCEL
# define SCANDIR_CANCEL
struct scandir_cancel_struct
{
  DIR *dp;
  void *v;
  size_t cnt;
};

# if _LIBC
static void
cancel_handler (void *arg)
{
  struct scandir_cancel_struct *cp = arg;
  size_t i;
  void **v = cp->v;

  for (i = 0; i < cp->cnt; ++i)
    free (v[i]);
  free (v);
  (void) __closedir (cp->dp);
}
# endif
#endif


int
SCANDIR (const char *dir,
         DIRENT_TYPE ***namelist,
         int (*select) (const DIRENT_TYPE *),
         int (*cmp) (const DIRENT_TYPE **, const DIRENT_TYPE **))
{
  DIR *dp = __opendir (dir);
  DIRENT_TYPE **v = NULL;
  size_t vsize = 0;
  struct scandir_cancel_struct c;
  DIRENT_TYPE *d;
  int save;

  if (dp == NULL)
    return -1;

  save = errno;
  __set_errno (0);

  c.dp = dp;
  c.v = NULL;
  c.cnt = 0;
#if _LIBC
  __libc_cleanup_push (cancel_handler, &c);
#endif

  while ((d = READDIR (dp)) != NULL)
    {
      int use_it = select == NULL;

      if (! use_it)
        {
          use_it = select (d);
          /* The select function might have changed errno.  It was
             zero before and it need to be again to make the latter
             tests work.  */
          __set_errno (0);
        }

      if (use_it)
        {
          DIRENT_TYPE *vnew;
          size_t dsize;

          /* Ignore errors from select or readdir */
          __set_errno (0);

          if (__builtin_expect (c.cnt == vsize, 0))
            {
              DIRENT_TYPE **new;
              if (vsize == 0)
                vsize = 10;
              else
                vsize *= 2;
              new = (DIRENT_TYPE **) realloc (v, vsize * sizeof (*v));
              if (new == NULL)
                break;
              v = new;
              c.v = (void *) v;
            }

          dsize = &d->d_name[_D_ALLOC_NAMLEN (d)] - (char *) d;
          vnew = (DIRENT_TYPE *) malloc (dsize);
          if (vnew == NULL)
            break;

          v[c.cnt++] = (DIRENT_TYPE *) memcpy (vnew, d, dsize);
        }
    }

  if (__builtin_expect (errno, 0) != 0)
    {
      save = errno;

      while (c.cnt > 0)
        free (v[--c.cnt]);
      free (v);
      c.cnt = -1;
    }
  else
    {
      /* Sort the list if we have a comparison function to sort with.  */
      if (cmp != NULL)
        qsort (v, c.cnt, sizeof (*v), (int (*) (const void *, const void *)) 
cmp);

      *namelist = v;
    }

#if _LIBC
  __libc_cleanup_pop (0);
#endif

  (void) __closedir (dp);
  __set_errno (save);

  return c.cnt;
}
================================== m4/scandir.m4 ==============================
# scandir.m4 serial 1
dnl Copyright (C) 2009 Free Software Foundation, Inc.
dnl This file is free software; the Free Software Foundation
dnl gives unlimited permission to copy and/or distribute it,
dnl with or without modifications, as long as this notice is preserved.

AC_DEFUN([gl_FUNC_SCANDIR],
[
  AC_REQUIRE([gl_DIRENT_H_DEFAULTS])

  dnl Persuade glibc and Solaris <dirent.h> to declare scandir().
  AC_REQUIRE([AC_USE_SYSTEM_EXTENSIONS])

  AC_CHECK_FUNCS([scandir])
  if test $ac_cv_func_scandir = no; then
    HAVE_SCANDIR=0
    AC_LIBOBJ([scandir])
    gl_PREREQ_SCANDIR
  fi
])

# Prerequisites of lib/scandir.c.
AC_DEFUN([gl_PREREQ_SCANDIR], [:])
================================= modules/scandir =============================
Description:
scandir() function: collect entries of a directory

Files:
lib/scandir.c
m4/scandir.m4

Depends-on:
dirent
extensions

configure.ac:
gl_FUNC_SCANDIR
gl_DIRENT_MODULE_INDICATOR([scandir])

Makefile.am:

Include:
<dirent.h>

License:
LGPL

Maintainer:
all, glibc

===============================================================================
--- lib/dirent.in.h.orig        2009-01-18 12:22:31.000000000 +0100
+++ lib/dirent.in.h     2009-01-18 11:39:52.000000000 +0100
@@ -1,5 +1,5 @@
 /* A GNU-like <dirent.h>.
-   Copyright (C) 2006-2008 Free Software Foundation, Inc.
+   Copyright (C) 2006-2009 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
@@ -42,7 +42,7 @@
 extern int closedir (DIR *);
 #endif
 
-/* Declare GNU extensions.  */
+/* Declare other POSIX functions.  */
 
 #if @GNULIB_DIRFD@
 # if address@hidden@ && !defined dirfd
@@ -58,6 +58,24 @@
      dirfd (d))
 #endif
 
+#if @GNULIB_SCANDIR@
+/* Scan the directory DIR, calling FILTER on each directory entry.
+   Entries for which FILTER returns nonzero are individually malloc'd,
+   sorted using qsort with CMP, and collected in a malloc'd array in
+   *NAMELIST.  Returns the number of entries selected, or -1 on error.  */
+# if address@hidden@
+extern int scandir (const char *dir, struct dirent ***namelist,
+                   int (*filter) (const struct dirent *),
+                   int (*cmp) (const struct dirent **, const struct dirent 
**));
+# endif
+#elif defined GNULIB_POSIXCHECK
+# undef scandir
+# define scandir(d,n,f,c) \
+    (GL_LINK_WARNING ("scandir is unportable - " \
+                      "use gnulib module scandir for portability"), \
+     scandir (d, n, f, c))
+#endif
+
 #ifdef __cplusplus
 }
 #endif
--- m4/dirent_h.m4.orig 2009-01-18 12:22:31.000000000 +0100
+++ m4/dirent_h.m4      2009-01-18 11:40:30.000000000 +0100
@@ -1,5 +1,5 @@
-# dirent_h.m4 serial 2
-dnl Copyright (C) 2008 Free Software Foundation, Inc.
+# dirent_h.m4 serial 3
+dnl Copyright (C) 2008-2009 Free Software Foundation, Inc.
 dnl This file is free software; the Free Software Foundation
 dnl gives unlimited permission to copy and/or distribute it,
 dnl with or without modifications, as long as this notice is preserved.
@@ -33,7 +33,9 @@
 [
   AC_REQUIRE([gl_UNISTD_H_DEFAULTS]) dnl for REPLACE_FCHDIR
   GNULIB_DIRFD=0;    AC_SUBST([GNULIB_DIRFD])
+  GNULIB_SCANDIR=0;  AC_SUBST([GNULIB_SCANDIR])
   dnl Assume proper GNU behavior unless another module says otherwise.
   HAVE_DECL_DIRFD=1; AC_SUBST([HAVE_DECL_DIRFD])
+  HAVE_SCANDIR=1;    AC_SUBST([HAVE_SCANDIR])
   DIRENT_H='';       AC_SUBST([DIRENT_H])
 ])
--- modules/dirent.orig 2009-01-18 12:22:31.000000000 +0100
+++ modules/dirent      2009-01-18 11:41:01.000000000 +0100
@@ -25,7 +25,9 @@
              -e 's|@''PRAGMA_SYSTEM_HEADER''@|@PRAGMA_SYSTEM_HEADER@|g' \
              -e 's|@''NEXT_DIRENT_H''@|$(NEXT_DIRENT_H)|g' \
              -e 's|@''GNULIB_DIRFD''@|$(GNULIB_DIRFD)|g' \
+             -e 's|@''GNULIB_SCANDIR''@|$(GNULIB_SCANDIR)|g' \
              -e 's|@''HAVE_DECL_DIRFD''@|$(HAVE_DECL_DIRFD)|g' \
+             -e 's|@''HAVE_SCANDIR''@|$(HAVE_SCANDIR)|g' \
              -e 's|@''REPLACE_FCHDIR''@|$(REPLACE_FCHDIR)|g' \
              -e '/definition of GL_LINK_WARNING/r $(LINK_WARNING_H)' \
              < $(srcdir)/dirent.in.h; \
--- doc/posix-functions/scandir.texi.orig       2009-01-18 12:22:31.000000000 
+0100
+++ doc/posix-functions/scandir.texi    2009-01-18 12:11:04.000000000 +0100
@@ -4,15 +4,21 @@
 
 POSIX specification: 
@url{http://www.opengroup.org/onlinepubs/9699919799/functions/scandir.html}
 
-Gnulib module: ---
+Gnulib module: scandir
 
 Portability problems fixed by Gnulib:
 @itemize
address@hidden
+This function is missing on some platforms:
+Solaris 9, mingw, BeOS.
 @end itemize
 
 Portability problems not fixed by Gnulib:
 @itemize
 @item
-This function is missing on some platforms:
-Solaris 9, mingw, BeOS.
+The fourth parameter of this function is declared as @code{int (*) (const void 
*, const void *)} on some platforms:
+glibc 2.3.6, MacOS X 10.3, FreeBSD 6.0, NetBSD 3.0, OpenBSD 3.8, Interix 3.5.
address@hidden
+The fourth parameter of this function is declared as @code{int (*) (void *, 
void *)} on some platforms:
+AIX 5.1.
 @end itemize