Add new closefrom() function

Code taken from sudo, man page from FreeBSD.

COPYING

@@ -174,6 +174,33 @@
 
     --
 
+    Copyright (c) 2009 Advanced Computing Technologies LLC
+    Written by: John H. Baldwin <jhb@FreeBSD.org>
+    All rights reserved.
+
+    Redistribution and use in source and binary forms, with or without
+    modification, are permitted provided that the following conditions
+    are met:
+    1. Redistributions of source code must retain the above copyright
+       notice, this list of conditions and the following disclaimer.
+    2. Redistributions in binary form must reproduce the above copyright
+       notice, this list of conditions and the following disclaimer in the
+       documentation and/or other materials provided with the distribution.
+
+    THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
+    ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+    IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+    ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
+    FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+    DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+    OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+    HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+    LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+    OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+    SUCH DAMAGE.
+
+    --
+
     Copyright © 1998, M. Warner Losh <imp@freebsd.org>
     All rights reserved.
 
@@ -349,7 +376,8 @@
 
     --
 
-    Copyright © 2000-2002, 2007 Todd C. Miller <Todd.Miller@courtesan.com>
+    Copyright © 2000-2002, 2004-2005, 2007, 2010
+        Todd C. Miller <Todd.Miller@courtesan.com>
 
     Permission to use, copy, modify, and distribute this software for any
     purpose with or without fee is hereby granted, provided that the above

configure.ac

@@ -25,6 +25,7 @@ AC_PROG_LN_S
 # Checks for libraries.
 
 # Checks for header files.
+AC_CHECK_HEADERS([sys/ndir.h sys/dir.h dir.h dirent.h])
 
 # Checks for typedefs, structures, and compiler characteristics.
 AC_TYPE_UID_T
@@ -36,6 +37,13 @@ AC_TYPE_PID_T
 AC_TYPE_SIZE_T
 AC_TYPE_SSIZE_T
 
+AC_CHECK_DECL([F_CLOSEM],
+              [AC_DEFINE([HAVE_FCNTL_CLOSEM], [1],
+                         [Define to 1 if you have fcntl(F_CLOSEM)])],
+              [],
+              [#include <limits.h>
+               #include <fcntl.h>])
+
 # Checks for library functions.
 AC_MSG_CHECKING([for __progname])
 AC_LINK_IFELSE(
@@ -46,7 +54,7 @@ AC_LINK_IFELSE(
 	 AC_MSG_RESULT([yes])],
 	[AC_MSG_RESULT([no])])
 
-AC_CHECK_FUNCS([getexecname])
+AC_CHECK_FUNCS([dirfd getexecname sysconf])
 
 AC_CONFIG_FILES([
 	Makefile

include/bsd/unistd.h

@@ -54,6 +54,8 @@ int bsd_getopt(int argc, char * const argv[], const char *shortopts);
 mode_t getmode(const void *set, mode_t mode);
 void *setmode(const char *mode_str);
 
+void closefrom(int lowfd);
+
 void setproctitle(const char *fmt, ...);
 
 int getpeereid(int s, uid_t *euid, gid_t *egid);

man/Makefile.am

@@ -19,6 +19,7 @@ dist_man_MANS = \
 	arc4random_buf.3 \
 	arc4random_stir.3 \
 	arc4random_uniform.3 \
+	closefrom.3 \
 	dehumanize_number.3 \
 	fgetln.3 \
 	flopen.3 \

man/closefrom.3

@@ -0,0 +1,54 @@
+.\" Copyright (c) 2009 Advanced Computing Technologies LLC
+.\" Written by: John H. Baldwin <jhb@FreeBSD.org>
+.\" All rights reserved.
+.\"
+.\" Redistribution and use in source and binary forms, with or without
+.\" modification, are permitted provided that the following conditions
+.\" are met:
+.\" 1. Redistributions of source code must retain the above copyright
+.\"    notice, this list of conditions and the following disclaimer.
+.\" 2. Redistributions in binary form must reproduce the above copyright
+.\"    notice, this list of conditions and the following disclaimer in the
+.\"    documentation and/or other materials provided with the distribution.
+.\"
+.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
+.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+.\" ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
+.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+.\" SUCH DAMAGE.
+.\"
+.\" $FreeBSD$
+.\"
+.Dd June 12, 2009
+.Dt CLOSEFROM 3
+.Os
+.Sh NAME
+.Nm closefrom
+.Nd delete open file descriptors
+.Sh LIBRARY
+.ds str-Lb-libbsd Utility functions from BSD systems (libbsd, \-lbsd)
+.Lb libbsd
+.Sh SYNOPSIS
+.In bsd/unistd.h
+.Ft void
+.Fn closefrom "int lowfd"
+.Sh DESCRIPTION
+The
+.Fn closefrom
+system call deletes all open file descriptors greater than or equal to
+.Fa lowfd
+from the per-process object reference table.
+Any errors encountered while closing file descriptors are ignored.
+.Sh SEE ALSO
+.Xr close 2
+.Sh HISTORY
+The
+.Fn closefrom
+function first appeared in
+.Fx 8.0 .

src/Makefile.am

@@ -41,6 +41,7 @@ libbsd_la_LDFLAGS = \
 libbsd_la_SOURCES = \
 	arc4random.c \
 	bsd_getopt.c \
+	closefrom.c \
 	dehumanize_number.c \
 	err.c \
 	fgetln.c \

src/closefrom.c

@@ -0,0 +1,122 @@
+/*
+ * Copyright (c) 2004-2005, 2007, 2010
+ *	Todd C. Miller <Todd.Miller@courtesan.com>
+ *
+ * Permission to use, copy, modify, and distribute this software for any
+ * purpose with or without fee is hereby granted, provided that the above
+ * copyright notice and this permission notice appear in all copies.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+ * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+ * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+ * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+ * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+ * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+ * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+ */
+
+#include <config.h>
+
+#include <sys/types.h>
+#include <sys/param.h>
+#include <unistd.h>
+#include <stdio.h>
+#ifdef STDC_HEADERS
+# include <stdlib.h>
+# include <stddef.h>
+#else
+# ifdef HAVE_STDLIB_H
+#  include <stdlib.h>
+# endif
+#endif /* STDC_HEADERS */
+#include <fcntl.h>
+#ifdef HAVE_DIRENT_H
+# include <dirent.h>
+# define NAMLEN(dirent) strlen((dirent)->d_name)
+#else
+# define dirent direct
+# define NAMLEN(dirent) (dirent)->d_namlen
+# ifdef HAVE_SYS_NDIR_H
+#  include <sys/ndir.h>
+# endif
+# ifdef HAVE_SYS_DIR_H
+#  include <sys/dir.h>
+# endif
+# ifdef HAVE_NDIR_H
+#  include <ndir.h>
+# endif
+#endif
+
+#ifndef OPEN_MAX
+# define OPEN_MAX 256
+#endif
+
+#ifndef HAVE_FCNTL_CLOSEM
+# ifndef HAVE_DIRFD
+#   define closefrom_fallback	closefrom
+# endif
+#endif
+
+/*
+ * Close all file descriptors greater than or equal to lowfd.
+ * This is the expensive (ballback) method.
+ */
+void
+closefrom_fallback(int lowfd)
+{
+	long fd, maxfd;
+
+	/*
+	 * Fall back on sysconf() or getdtablesize().  We avoid checking
+	 * resource limits since it is possible to open a file descriptor
+	 * and then drop the rlimit such that it is below the open fd.
+	 */
+#ifdef HAVE_SYSCONF
+	maxfd = sysconf(_SC_OPEN_MAX);
+#else
+	maxfd = getdtablesize();
+#endif /* HAVE_SYSCONF */
+	if (maxfd < 0)
+		maxfd = OPEN_MAX;
+
+	for (fd = lowfd; fd < maxfd; fd++)
+		(void)close((int)fd);
+}
+
+/*
+ * Close all file descriptors greater than or equal to lowfd.
+ * We try the fast way first, falling back on the slow method.
+ */
+#ifdef HAVE_FCNTL_CLOSEM
+void
+closefrom(int lowfd)
+{
+	if (fcntl(lowfd, F_CLOSEM, 0) == -1)
+		closefrom_fallback(lowfd);
+}
+#else
+# ifdef HAVE_DIRFD
+void
+closefrom(int lowfd)
+{
+	struct dirent *dent;
+	DIR *dirp;
+	char *endp;
+	long fd;
+
+	/* Use /proc/self/fd directory if it exists. */
+	dirp = opendir("/proc/self/fd");
+	if (dirp != NULL) {
+		while ((dent = readdir(dirp)) != NULL) {
+			fd = strtol(dent->d_name, &endp, 10);
+			if (dent->d_name != endp && *endp == '\0' &&
+			    fd >= 0 && fd < INT_MAX && fd >= lowfd &&
+			    fd != dirfd(dirp))
+				(void)close((int)fd);
+		}
+		(void)closedir(dirp);
+	} else
+		closefrom_fallback(lowfd);
+}
+#endif /* HAVE_DIRFD */
+#endif /* HAVE_FCNTL_CLOSEM */

src/libbsd.map

@@ -89,3 +89,7 @@ LIBBSD_0.3 {
 
     fpurge;
 } LIBBSD_0.2;
+
+LIBBSD_0.4 {
+    closefrom;
+} LIBBSD_0.3;