From 544d23dea91b2be793c805b9e4bce8cd1d28121f Mon Sep 17 00:00:00 2001
From: Jason Wessel <jason.wessel@windriver.com>
Date: Sat, 7 Dec 2019 09:59:22 -0800
Subject: [PATCH] localedef: Add hardlink resolver from util-linux

The hard link resolver that is built into localedef cannot be run in
parallel.  It will search sibling directories (which are be processed
in parallel) and perform a creation of a .tmp file and remove the
original and move the .tmp file in.  The problem is that if a probe
occurs a hard link can be requested to the file that is being removed.
This will lead to a stray copy or potentially, on a loaded system
cause race condition which pseudo cannot deal with, where it is left
with a hard link request to a file that no longer exists.  In this
situation psuedo will inherit the permissions of what ever the target
inode had to offer.

In short, there are two problems:

1) You will be left with stray copies when using the hard link
resolution that is built in while running in parallel with
localedef.

2) When running under pseudo the possibility exists for uid/gid
leakage when the source file is removed before the hard link can
be completed.

The solution is to call localedef with --no-hard-links and separately
process the hardlinks at a later point.  To do this requires the
inclusion of the hardlink utility found in modern versions of
util-linux.  Most host systems do not have this, so it will be
included with the cross-localedef binary.

[YOCTO #11299]
[YOCTO #12434]

Upstream-Status: Pending

Signed-off-by: Jason Wessel <jason.wessel@windriver.com>
Signed-off-by: Khem Raj <raj.khem@gmail.com>
---
 locale/programs/c.h                        | 407 ++++++++++++++++
 locale/programs/cross-localedef-hardlink.c | 528 +++++++++++++++++++++
 locale/programs/xalloc.h                   | 129 +++++
 3 files changed, 1064 insertions(+)
 create mode 100644 locale/programs/c.h
 create mode 100644 locale/programs/cross-localedef-hardlink.c
 create mode 100644 locale/programs/xalloc.h

diff --git a/locale/programs/c.h b/locale/programs/c.h
new file mode 100644
index 0000000000..d0a402e90e
--- /dev/null
+++ b/locale/programs/c.h
@@ -0,0 +1,407 @@
+/*
+ * Fundamental C definitions.
+ */
+
+#ifndef UTIL_LINUX_C_H
+#define UTIL_LINUX_C_H
+
+#include <limits.h>
+#include <stddef.h>
+#include <stdint.h>
+#include <stdio.h>
+#include <unistd.h>
+#include <stdarg.h>
+#include <stdlib.h>
+#include <string.h>
+#include <errno.h>
+
+#include <assert.h>
+
+#ifdef HAVE_ERR_H
+# include <err.h>
+#endif
+
+#ifdef HAVE_SYS_SYSMACROS_H
+# include <sys/sysmacros.h>     /* for major, minor */
+#endif
+
+#ifndef LOGIN_NAME_MAX
+# define LOGIN_NAME_MAX 256
+#endif
+
+#ifndef NAME_MAX
+# define NAME_MAX PATH_MAX
+#endif
+
+/*
+ * __GNUC_PREREQ is deprecated in favour of __has_attribute() and
+ * __has_feature(). The __has macros are supported by clang and gcc>=5.
+ */
+#ifndef __GNUC_PREREQ
+# if defined __GNUC__ && defined __GNUC_MINOR__
+#  define __GNUC_PREREQ(maj, min) \
+	((__GNUC__ << 16) + __GNUC_MINOR__ >= ((maj) << 16) + (min))
+# else
+#  define __GNUC_PREREQ(maj, min) 0
+# endif
+#endif
+
+#ifdef __GNUC__
+
+/* &a[0] degrades to a pointer: a different type from an array */
+# define __must_be_array(a) \
+	UL_BUILD_BUG_ON_ZERO(__builtin_types_compatible_p(__typeof__(a), __typeof__(&a[0])))
+
+# define ignore_result(x) __extension__ ({ \
+	__typeof__(x) __dummy __attribute__((__unused__)) = (x); (void) __dummy; \
+})
+
+#else /* !__GNUC__ */
+# define __must_be_array(a)	0
+# define __attribute__(_arg_)
+# define ignore_result(x) ((void) (x))
+#endif /* !__GNUC__ */
+
+/*
+ * It evaluates to 1 if the attribute/feature is supported by the current
+ * compilation targed. Fallback for old compilers.
+ */
+#ifndef __has_attribute
+  #define __has_attribute(x) 0
+#endif
+
+#ifndef __has_feature
+  #define __has_feature(x) 0
+#endif
+
+/*
+ * Function attributes
+ */
+#ifndef __ul_alloc_size
+# if (__has_attribute(alloc_size) && __has_attribute(warn_unused_result)) || __GNUC_PREREQ (4, 3)
+#  define __ul_alloc_size(s) __attribute__((alloc_size(s), warn_unused_result))
+# else
+#  define __ul_alloc_size(s)
+# endif
+#endif
+
+#ifndef __ul_calloc_size
+# if (__has_attribute(alloc_size) && __has_attribute(warn_unused_result)) || __GNUC_PREREQ (4, 3)
+#  define __ul_calloc_size(n, s) __attribute__((alloc_size(n, s), warn_unused_result))
+# else
+#  define __ul_calloc_size(n, s)
+# endif
+#endif
+
+#if __has_attribute(returns_nonnull) || __GNUC_PREREQ (4, 9)
+# define __ul_returns_nonnull __attribute__((returns_nonnull))
+#else
+# define __ul_returns_nonnull
+#endif
+
+/*
+ * Force a compilation error if condition is true, but also produce a
+ * result (of value 0 and type size_t), so the expression can be used
+ * e.g. in a structure initializer (or wherever else comma expressions
+ * aren't permitted).
+ */
+#define UL_BUILD_BUG_ON_ZERO(e) __extension__ (sizeof(struct { int:-!!(e); }))
+#define BUILD_BUG_ON_NULL(e) ((void *)sizeof(struct { int:-!!(e); }))
+
+#ifndef ARRAY_SIZE
+# define ARRAY_SIZE(arr) (sizeof(arr) / sizeof((arr)[0]) + __must_be_array(arr))
+#endif
+
+#ifndef PATH_MAX
+# define PATH_MAX 4096
+#endif
+
+#ifndef TRUE
+# define TRUE 1
+#endif
+
+#ifndef FALSE
+# define FALSE 0
+#endif
+
+#ifndef min
+# define min(x, y) __extension__ ({		\
+	__typeof__(x) _min1 = (x);		\
+	__typeof__(y) _min2 = (y);		\
+	(void) (&_min1 == &_min2);		\
+	_min1 < _min2 ? _min1 : _min2; })
+#endif
+
+#ifndef max
+# define max(x, y) __extension__ ({		\
+	__typeof__(x) _max1 = (x);		\
+	__typeof__(y) _max2 = (y);		\
+	(void) (&_max1 == &_max2);		\
+	_max1 > _max2 ? _max1 : _max2; })
+#endif
+
+#ifndef cmp_numbers
+# define cmp_numbers(x, y) __extension__ ({	\
+	__typeof__(x) _a = (x);			\
+	__typeof__(y) _b = (y);			\
+	(void) (&_a == &_b);			\
+	_a == _b ? 0 : _a > _b ? 1 : -1; })
+#endif
+
+#ifndef offsetof
+#define offsetof(TYPE, MEMBER) ((size_t) &((TYPE *)0)->MEMBER)
+#endif
+
+/*
+ * container_of - cast a member of a structure out to the containing structure
+ * @ptr:	the pointer to the member.
+ * @type:	the type of the container struct this is embedded in.
+ * @member:	the name of the member within the struct.
+ */
+#ifndef container_of
+#define container_of(ptr, type, member) __extension__ ({	\
+	const __typeof__( ((type *)0)->member ) *__mptr = (ptr); \
+	(type *)( (char *)__mptr - offsetof(type,member) );})
+#endif
+
+#ifndef HAVE_PROGRAM_INVOCATION_SHORT_NAME
+# ifdef HAVE___PROGNAME
+extern char *__progname;
+#  define program_invocation_short_name __progname
+# else
+#  ifdef HAVE_GETEXECNAME
+#   define program_invocation_short_name \
+		prog_inv_sh_nm_from_file(getexecname(), 0)
+#  else
+#   define program_invocation_short_name \
+		prog_inv_sh_nm_from_file(__FILE__, 1)
+#  endif
+static char prog_inv_sh_nm_buf[256];
+static inline char *
+prog_inv_sh_nm_from_file(char *f, char stripext)
+{
+	char *t;
+
+	if ((t = strrchr(f, '/')) != NULL)
+		t++;
+	else
+		t = f;
+
+	strncpy(prog_inv_sh_nm_buf, t, sizeof(prog_inv_sh_nm_buf) - 1);
+	prog_inv_sh_nm_buf[sizeof(prog_inv_sh_nm_buf) - 1] = '\0';
+
+	if (stripext && (t = strrchr(prog_inv_sh_nm_buf, '.')) != NULL)
+		*t = '\0';
+
+	return prog_inv_sh_nm_buf;
+}
+# endif
+#endif
+
+
+#ifndef HAVE_ERR_H
+static inline void
+errmsg(char doexit, int excode, char adderr, const char *fmt, ...)
+{
+	fprintf(stderr, "%s: ", program_invocation_short_name);
+	if (fmt != NULL) {
+		va_list argp;
+		va_start(argp, fmt);
+		vfprintf(stderr, fmt, argp);
+		va_end(argp);
+		if (adderr)
+			fprintf(stderr, ": ");
+	}
+	if (adderr)
+		fprintf(stderr, "%m");
+	fprintf(stderr, "\n");
+	if (doexit)
+		exit(excode);
+}
+
+#ifndef HAVE_ERR
+# define err(E, FMT...) errmsg(1, E, 1, FMT)
+#endif
+
+#ifndef HAVE_ERRX
+# define errx(E, FMT...) errmsg(1, E, 0, FMT)
+#endif
+
+#ifndef HAVE_WARN
+# define warn(FMT...) errmsg(0, 0, 1, FMT)
+#endif
+
+#ifndef HAVE_WARNX
+# define warnx(FMT...) errmsg(0, 0, 0, FMT)
+#endif
+#endif /* !HAVE_ERR_H */
+
+
+/* Don't use inline function to avoid '#include "nls.h"' in c.h
+ */
+#define errtryhelp(eval) __extension__ ({ \
+	fprintf(stderr, _("Try '%s --help' for more information.\n"), \
+			program_invocation_short_name); \
+	exit(eval); \
+})
+
+/* After failed execvp() */
+#define EX_EXEC_FAILED		126	/* Program located, but not usable. */
+#define EX_EXEC_ENOENT		127	/* Could not find program to exec.  */
+#define errexec(name)	err(errno == ENOENT ? EX_EXEC_ENOENT : EX_EXEC_FAILED, \
+			_("failed to execute %s"), name)
+
+
+static inline __attribute__((const)) int is_power_of_2(unsigned long num)
+{
+	return (num != 0 && ((num & (num - 1)) == 0));
+}
+
+#ifndef HAVE_LOFF_T
+typedef int64_t loff_t;
+#endif
+
+#if !defined(HAVE_DIRFD) && (!defined(HAVE_DECL_DIRFD) || HAVE_DECL_DIRFD == 0) && defined(HAVE_DIR_DD_FD)
+#include <sys/types.h>
+#include <dirent.h>
+static inline int dirfd(DIR *d)
+{
+	return d->dd_fd;
+}
+#endif
+
+/*
+ * Fallback defines for old versions of glibc
+ */
+#include <fcntl.h>
+
+#ifdef O_CLOEXEC
+#define UL_CLOEXECSTR	"e"
+#else
+#define UL_CLOEXECSTR	""
+#endif
+
+#ifndef O_CLOEXEC
+#define O_CLOEXEC 0
+#endif
+
+#ifdef __FreeBSD_kernel__
+#ifndef F_DUPFD_CLOEXEC
+#define F_DUPFD_CLOEXEC	17	/* Like F_DUPFD, but FD_CLOEXEC is set */
+#endif
+#endif
+
+
+#ifndef AI_ADDRCONFIG
+#define AI_ADDRCONFIG 0x0020
+#endif
+
+#ifndef IUTF8
+#define IUTF8 0040000
+#endif
+
+/*
+ * MAXHOSTNAMELEN replacement
+ */
+static inline size_t get_hostname_max(void)
+{
+	long len = sysconf(_SC_HOST_NAME_MAX);
+
+	if (0 < len)
+		return len;
+
+#ifdef MAXHOSTNAMELEN
+	return MAXHOSTNAMELEN;
+#elif HOST_NAME_MAX
+	return HOST_NAME_MAX;
+#endif
+	return 64;
+}
+
+
+/*
+ * Constant strings for usage() functions. For more info see
+ * Documentation/{howto-usage-function.txt,boilerplate.c}
+ */
+#define USAGE_HEADER     ("\nUsage:\n")
+#define USAGE_OPTIONS    ("\nOptions:\n")
+#define USAGE_FUNCTIONS  ("\nFunctions:\n")
+#define USAGE_COMMANDS   ("\nCommands:\n")
+#define USAGE_COLUMNS    ("\nAvailable output columns:\n")
+#define USAGE_SEPARATOR    "\n"
+
+#define USAGE_OPTSTR_HELP     ("display this help")
+#define USAGE_OPTSTR_VERSION  ("display version")
+
+#define USAGE_HELP_OPTIONS(marg_dsc) \
+		"%-" #marg_dsc "s%s\n" \
+		"%-" #marg_dsc "s%s\n" \
+		, " -h, --help",    USAGE_OPTSTR_HELP \
+		, " -V, --version", USAGE_OPTSTR_VERSION
+
+#define USAGE_MAN_TAIL(_man)   ("\nFor more details see %s.\n"), _man
+
+#define UTIL_LINUX_VERSION ("%s from %s\n"), program_invocation_short_name, PACKAGE_STRING
+
+#define print_version(eval) __extension__ ({ \
+		printf(UTIL_LINUX_VERSION); \
+		exit(eval); \
+})
+
+/*
+ * scanf modifiers for "strings allocation"
+ */
+#ifdef HAVE_SCANF_MS_MODIFIER
+#define UL_SCNsA	"%ms"
+#elif defined(HAVE_SCANF_AS_MODIFIER)
+#define UL_SCNsA	"%as"
+#endif
+
+/*
+ * seek stuff
+ */
+#ifndef SEEK_DATA
+# define SEEK_DATA	3
+#endif
+#ifndef SEEK_HOLE
+# define SEEK_HOLE	4
+#endif
+
+
+/*
+ * Macros to convert #define'itions to strings, for example
+ * #define XYXXY 42
+ * printf ("%s=%s\n", stringify(XYXXY), stringify_value(XYXXY));
+ */
+#define stringify_value(s) stringify(s)
+#define stringify(s) #s
+
+/*
+ * UL_ASAN_BLACKLIST is a macro to tell AddressSanitizer (a compile-time
+ * instrumentation shipped with Clang and GCC) to not instrument the
+ * annotated function.  Furthermore, it will prevent the compiler from
+ * inlining the function because inlining currently breaks the blacklisting
+ * mechanism of AddressSanitizer.
+ */
+#if __has_feature(address_sanitizer) && __has_attribute(no_sanitize_memory) && __has_attribute(no_sanitize_address)
+# define UL_ASAN_BLACKLIST __attribute__((noinline)) __attribute__((no_sanitize_memory)) __attribute__((no_sanitize_address))
+#else
+# define UL_ASAN_BLACKLIST	/* nothing */
+#endif
+
+/*
+ * Note that sysconf(_SC_GETPW_R_SIZE_MAX) returns *initial* suggested size for
+ * pwd buffer and in some cases it is not large enough. See POSIX and
+ * getpwnam_r man page for more details.
+ */
+#define UL_GETPW_BUFSIZ	(16 * 1024)
+
+/*
+ * Darwin or other BSDs may only have MAP_ANON. To get it on Darwin we must
+ * define _DARWIN_C_SOURCE before including sys/mman.h. We do this in config.h.
+ */
+#if !defined MAP_ANONYMOUS && defined MAP_ANON
+# define MAP_ANONYMOUS  (MAP_ANON)
+#endif
+
+#endif /* UTIL_LINUX_C_H */
diff --git a/locale/programs/cross-localedef-hardlink.c b/locale/programs/cross-localedef-hardlink.c
new file mode 100644
index 0000000000..63615896b0
--- /dev/null
+++ b/locale/programs/cross-localedef-hardlink.c
@@ -0,0 +1,528 @@
+/*
+ * hardlink - consolidate duplicate files via hardlinks
+ *
+ * Copyright (C) 2018 Red Hat, Inc. All rights reserved.
+ * Written by Jakub Jelinek <jakub@redhat.com>
+ *
+ * Copyright (C) 2019 Karel Zak <kzak@redhat.com>
+ *
+ * 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 would 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 <sys/types.h>
+#include <stdlib.h>
+#include <getopt.h>
+#include <stdio.h>
+#include <unistd.h>
+#include <sys/stat.h>
+#include <sys/mman.h>
+#include <string.h>
+#include <dirent.h>
+#include <fcntl.h>
+#include <errno.h>
+#ifdef HAVE_PCRE
+# define PCRE2_CODE_UNIT_WIDTH 8
+# include <pcre2.h>
+#endif
+
+#include "c.h"
+#include "xalloc.h"
+#include "nls.h"
+#include "closestream.h"
+
+#define NHASH   (1<<17)  /* Must be a power of 2! */
+#define NBUF    64
+
+struct hardlink_file;
+
+struct hardlink_hash {
+	struct hardlink_hash *next;
+	struct hardlink_file *chain;
+	off_t size;
+	time_t mtime;
+};
+
+struct hardlink_dir {
+	struct hardlink_dir *next;
+	char name[];
+};
+
+struct hardlink_file {
+	struct hardlink_file *next;
+	ino_t ino;
+	dev_t dev;
+	unsigned int cksum;
+	char name[];
+};
+
+struct hardlink_dynstr {
+	char *buf;
+	size_t alloc;
+};
+
+struct hardlink_ctl {
+	struct hardlink_dir *dirs;
+	struct hardlink_hash *hps[NHASH];
+	char iobuf1[BUFSIZ];
+	char iobuf2[BUFSIZ];
+	/* summary counters */
+	unsigned long long ndirs;
+	unsigned long long nobjects;
+	unsigned long long nregfiles;
+	unsigned long long ncomp;
+	unsigned long long nlinks;
+	unsigned long long nsaved;
+	/* current device */
+	dev_t dev;
+	/* flags */
+	unsigned int verbose;
+	unsigned int
+		no_link:1,
+		content_only:1,
+		force:1;
+};
+/* ctl is in global scope due use in atexit() */
+struct hardlink_ctl global_ctl;
+
+__attribute__ ((always_inline))
+static inline unsigned int hash(off_t size, time_t mtime)
+{
+	return (size ^ mtime) & (NHASH - 1);
+}
+
+__attribute__ ((always_inline))
+static inline int stcmp(struct stat *st1, struct stat *st2, int content_scope)
+{
+	if (content_scope)
+		return st1->st_size != st2->st_size;
+
+	return st1->st_mode != st2->st_mode
+		|| st1->st_uid != st2->st_uid
+		|| st1->st_gid != st2->st_gid
+		|| st1->st_size != st2->st_size
+		|| st1->st_mtime != st2->st_mtime;
+}
+
+static void print_summary(void)
+{
+	struct hardlink_ctl const *const ctl = &global_ctl;
+
+	if (!ctl->verbose)
+		return;
+
+	if (ctl->verbose > 1 && ctl->nlinks)
+		fputc('\n', stdout);
+
+	printf(_("Directories:   %9lld\n"), ctl->ndirs);
+	printf(_("Objects:       %9lld\n"), ctl->nobjects);
+	printf(_("Regular files: %9lld\n"), ctl->nregfiles);
+	printf(_("Comparisons:   %9lld\n"), ctl->ncomp);
+	printf(  "%s%9lld\n", (ctl->no_link ?
+	       _("Would link:    ") :
+	       _("Linked:        ")), ctl->nlinks);
+	printf(  "%s %9lld\n", (ctl->no_link ?
+	       _("Would save:   ") :
+	       _("Saved:        ")), ctl->nsaved);
+}
+
+static void __attribute__((__noreturn__)) usage(void)
+{
+	fputs(USAGE_HEADER, stdout);
+	printf(_(" %s [options] directory...\n"), program_invocation_short_name);
+
+	fputs(USAGE_SEPARATOR, stdout);
+	puts(_("Consolidate duplicate files using hardlinks."));
+
+	fputs(USAGE_OPTIONS, stdout);
+	puts(_(" -c, --content          compare only contents, ignore permission, etc."));
+	puts(_(" -n, --dry-run          don't actually link anything"));
+	puts(_(" -v, --verbose          print summary after hardlinking"));
+	puts(_(" -vv                    print every hardlinked file and summary"));
+	puts(_(" -f, --force            force hardlinking across filesystems"));
+	puts(_(" -x, --exclude <regex>  exclude files matching pattern"));
+
+	fputs(USAGE_SEPARATOR, stdout);
+	printf(USAGE_HELP_OPTIONS(16)); /* char offset to align option descriptions */
+	printf(USAGE_MAN_TAIL("hardlink(1)"));
+	exit(EXIT_SUCCESS);
+}
+
+__attribute__ ((always_inline))
+static inline size_t add2(size_t a, size_t b)
+{
+	size_t sum = a + b;
+
+	if (sum < a)
+		errx(EXIT_FAILURE, _("integer overflow"));
+	return sum;
+}
+
+__attribute__ ((always_inline))
+static inline size_t add3(size_t a, size_t b, size_t c)
+{
+	return add2(add2(a, b), c);
+}
+
+static void growstr(struct hardlink_dynstr *str, size_t newlen)
+{
+	if (newlen < str->alloc)
+		return;
+	str->buf = xrealloc(str->buf, str->alloc = add2(newlen, 1));
+}
+
+static void process_path(struct hardlink_ctl *ctl, const char *name)
+{
+	struct stat st, st2, st3;
+	const size_t namelen = strlen(name);
+
+	ctl->nobjects++;
+	if (lstat(name, &st))
+		return;
+
+	if (st.st_dev != ctl->dev && !ctl->force) {
+		if (ctl->dev)
+			errx(EXIT_FAILURE,
+			     _("%s is on different filesystem than the rest "
+			       "(use -f option to override)."), name);
+		ctl->dev = st.st_dev;
+	}
+	if (S_ISDIR(st.st_mode)) {
+		struct hardlink_dir *dp = xmalloc(add3(sizeof(*dp), namelen, 1));
+		memcpy(dp->name, name, namelen + 1);
+		dp->next = ctl->dirs;
+		ctl->dirs = dp;
+
+	} else if (S_ISREG(st.st_mode)) {
+		int fd, i;
+		struct hardlink_file *fp, *fp2;
+		struct hardlink_hash *hp;
+		const char *n1, *n2;
+		unsigned int buf[NBUF];
+		int cksumsize = sizeof(buf);
+		unsigned int cksum;
+		time_t mtime = ctl->content_only ? 0 : st.st_mtime;
+		unsigned int hsh = hash(st.st_size, mtime);
+		off_t fsize;
+
+		ctl->nregfiles++;
+		if (ctl->verbose > 1)
+			printf("%s\n", name);
+
+		fd = open(name, O_RDONLY);
+		if (fd < 0)
+			return;
+
+		if ((size_t)st.st_size < sizeof(buf)) {
+			cksumsize = st.st_size;
+			memset(((char *)buf) + cksumsize, 0,
+			       (sizeof(buf) - cksumsize) % sizeof(buf[0]));
+		}
+		if (read(fd, buf, cksumsize) != cksumsize) {
+			close(fd);
+			return;
+		}
+		cksumsize = (cksumsize + sizeof(buf[0]) - 1) / sizeof(buf[0]);
+		for (i = 0, cksum = 0; i < cksumsize; i++) {
+			if (cksum + buf[i] < cksum)
+				cksum += buf[i] + 1;
+			else
+				cksum += buf[i];
+		}
+		for (hp = ctl->hps[hsh]; hp; hp = hp->next) {
+			if (hp->size == st.st_size && hp->mtime == mtime)
+				break;
+		}
+		if (!hp) {
+			hp = xmalloc(sizeof(*hp));
+			hp->size = st.st_size;
+			hp->mtime = mtime;
+			hp->chain = NULL;
+			hp->next = ctl->hps[hsh];
+			ctl->hps[hsh] = hp;
+		}
+		for (fp = hp->chain; fp; fp = fp->next) {
+			if (fp->cksum == cksum)
+				break;
+		}
+		for (fp2 = fp; fp2 && fp2->cksum == cksum; fp2 = fp2->next) {
+			if (fp2->ino == st.st_ino && fp2->dev == st.st_dev) {
+				close(fd);
+				return;
+			}
+		}
+		for (fp2 = fp; fp2 && fp2->cksum == cksum; fp2 = fp2->next) {
+
+			if (!lstat(fp2->name, &st2) && S_ISREG(st2.st_mode) &&
+			    !stcmp(&st, &st2, ctl->content_only) &&
+			    st2.st_ino != st.st_ino &&
+			    st2.st_dev == st.st_dev) {
+
+				int fd2 = open(fp2->name, O_RDONLY);
+				if (fd2 < 0)
+					continue;
+
+				if (fstat(fd2, &st2) || !S_ISREG(st2.st_mode)
+				    || st2.st_size == 0) {
+					close(fd2);
+					continue;
+				}
+				ctl->ncomp++;
+				lseek(fd, 0, SEEK_SET);
+
+				for (fsize = st.st_size; fsize > 0;
+				     fsize -= (off_t)sizeof(ctl->iobuf1)) {
+					ssize_t xsz;
+					ssize_t rsize = fsize > (ssize_t) sizeof(ctl->iobuf1) ?
+							(ssize_t) sizeof(ctl->iobuf1) : fsize;
+
+					if ((xsz = read(fd, ctl->iobuf1, rsize)) != rsize)
+						warn(_("cannot read %s"), name);
+					else if ((xsz = read(fd2, ctl->iobuf2, rsize)) != rsize)
+						warn(_("cannot read %s"), fp2->name);
+
+					if (xsz != rsize) {
+						close(fd);
+						close(fd2);
+						return;
+					}
+					if (memcmp(ctl->iobuf1, ctl->iobuf2, rsize))
+						break;
+				}
+				close(fd2);
+				if (fsize > 0)
+					continue;
+				if (lstat(name, &st3)) {
+					warn(_("cannot stat %s"), name);
+					close(fd);
+					return;
+				}
+				st3.st_atime = st.st_atime;
+				if (stcmp(&st, &st3, 0)) {
+					warnx(_("file %s changed underneath us"), name);
+					close(fd);
+					return;
+				}
+				n1 = fp2->name;
+				n2 = name;
+
+				if (!ctl->no_link) {
+					const char *suffix =
+					    ".$$$___cleanit___$$$";
+					const size_t suffixlen = strlen(suffix);
+					size_t n2len = strlen(n2);
+					struct hardlink_dynstr nam2 = { NULL, 0 };
+
+					growstr(&nam2, add2(n2len, suffixlen));
+					memcpy(nam2.buf, n2, n2len);
+					memcpy(&nam2.buf[n2len], suffix,
+					       suffixlen + 1);
+					/* First create a temporary link to n1 under a new name */
+					if (link(n1, nam2.buf)) {
+						warn(_("failed to hardlink %s to %s (create temporary link as %s failed)"),
+							n1, n2, nam2.buf);
+						free(nam2.buf);
+						continue;
+					}
+					/* Then rename into place over the existing n2 */
+					if (rename(nam2.buf, n2)) {
+						warn(_("failed to hardlink %s to %s (rename temporary link to %s failed)"),
+							n1, n2, n2);
+						/* Something went wrong, try to remove the now redundant temporary link */
+						if (unlink(nam2.buf))
+							warn(_("failed to remove temporary link %s"), nam2.buf);
+						free(nam2.buf);
+						continue;
+					}
+					free(nam2.buf);
+				}
+				ctl->nlinks++;
+				if (st3.st_nlink > 1) {
+					/* We actually did not save anything this time, since the link second argument
+					   had some other links as well.  */
+					if (ctl->verbose > 1)
+						printf(_(" %s %s to %s\n"),
+							(ctl->no_link ? _("Would link") : _("Linked")),
+							n1, n2);
+				} else {
+					ctl->nsaved += ((st.st_size + 4095) / 4096) * 4096;
+					if (ctl->verbose > 1)
+						printf(_(" %s %s to %s, %s %jd\n"),
+							(ctl->no_link ? _("Would link") : _("Linked")),
+							n1, n2,
+							(ctl->no_link ? _("would save") : _("saved")),
+							(intmax_t)st.st_size);
+				}
+				close(fd);
+				return;
+			}
+		}
+		fp2 = xmalloc(add3(sizeof(*fp2), namelen, 1));
+		close(fd);
+		fp2->ino = st.st_ino;
+		fp2->dev = st.st_dev;
+		fp2->cksum = cksum;
+		memcpy(fp2->name, name, namelen + 1);
+
+		if (fp) {
+			fp2->next = fp->next;
+			fp->next = fp2;
+		} else {
+			fp2->next = hp->chain;
+			hp->chain = fp2;
+		}
+		return;
+	}
+}
+
+int main(int argc, char **argv)
+{
+	int ch;
+	int i;
+#ifdef HAVE_PCRE
+	int errornumber;
+	PCRE2_SIZE erroroffset;
+	pcre2_code *re = NULL;
+	PCRE2_SPTR exclude_pattern = NULL;
+	pcre2_match_data *match_data = NULL;
+#endif
+	struct hardlink_dynstr nam1 = { NULL, 0 };
+	struct hardlink_ctl *ctl = &global_ctl;
+
+	static const struct option longopts[] = {
+		{ "content",    no_argument, NULL, 'c' },
+		{ "dry-run",    no_argument, NULL, 'n' },
+		{ "exclude",    required_argument, NULL, 'x' },
+		{ "force",      no_argument, NULL, 'f' },
+		{ "help",       no_argument, NULL, 'h' },
+		{ "verbose",    no_argument, NULL, 'v' },
+		{ "version",    no_argument, NULL, 'V' },
+		{ NULL, 0, NULL, 0 },
+	};
+
+	setlocale(LC_ALL, "");
+	bindtextdomain(PACKAGE, LOCALEDIR);
+	textdomain(PACKAGE);
+	close_stdout_atexit();
+
+	while ((ch = getopt_long(argc, argv, "cnvfx:Vh", longopts, NULL)) != -1) {
+		switch (ch) {
+		case 'n':
+			ctl->no_link = 1;
+			break;
+		case 'v':
+			ctl->verbose++;
+			break;
+		case 'c':
+			ctl->content_only = 1;
+			break;
+		case 'f':
+			ctl->force = 1;
+			break;
+		case 'x':
+#ifdef HAVE_PCRE
+			exclude_pattern = (PCRE2_SPTR) optarg;
+#else
+			errx(EXIT_FAILURE,
+			     _("option --exclude not supported (built without pcre2)"));
+#endif
+			break;
+		case 'V':
+			print_version(EXIT_SUCCESS);
+		case 'h':
+			usage();
+		default:
+			errtryhelp(EXIT_FAILURE);
+		}
+	}
+
+	if (optind == argc) {
+		warnx(_("no directory specified"));
+		errtryhelp(EXIT_FAILURE);
+	}
+
+#ifdef HAVE_PCRE
+	if (exclude_pattern) {
+		re = pcre2_compile(exclude_pattern, /* the pattern */
+				   PCRE2_ZERO_TERMINATED, /* indicates pattern is zero-terminate */
+				   0, /* default options */
+				   &errornumber, &erroroffset, NULL); /* use default compile context */
+		if (!re) {
+			PCRE2_UCHAR buffer[256];
+			pcre2_get_error_message(errornumber, buffer,
+						sizeof(buffer));
+			errx(EXIT_FAILURE, _("pattern error at offset %d: %s"),
+				(int)erroroffset, buffer);
+		}
+		match_data = pcre2_match_data_create_from_pattern(re, NULL);
+	}
+#endif
+	atexit(print_summary);
+
+	for (i = optind; i < argc; i++)
+		process_path(ctl, argv[i]);
+
+	while (ctl->dirs) {
+		DIR *dh;
+		struct dirent *di;
+		struct hardlink_dir *dp = ctl->dirs;
+		size_t nam1baselen = strlen(dp->name);
+
+		ctl->dirs = dp->next;
+		growstr(&nam1, add2(nam1baselen, 1));
+		memcpy(nam1.buf, dp->name, nam1baselen);
+		free(dp);
+		nam1.buf[nam1baselen++] = '/';
+		nam1.buf[nam1baselen] = 0;
+		dh = opendir(nam1.buf);
+
+		if (dh == NULL)
+			continue;
+		ctl->ndirs++;
+
+		while ((di = readdir(dh)) != NULL) {
+			if (!di->d_name[0])
+				continue;
+			if (di->d_name[0] == '.') {
+				if (!di->d_name[1] || !strcmp(di->d_name, ".."))
+					continue;
+			}
+#ifdef HAVE_PCRE
+			if (re && pcre2_match(re, /* compiled regex */
+					      (PCRE2_SPTR) di->d_name, strlen(di->d_name), 0, /* start at offset 0 */
+					      0, /* default options */
+					      match_data, /* block for storing the result */
+					      NULL) /* use default match context */
+			    >=0) {
+				if (ctl->verbose) {
+					nam1.buf[nam1baselen] = 0;
+					printf(_("Skipping %s%s\n"), nam1.buf, di->d_name);
+				}
+				continue;
+			}
+#endif
+			{
+				size_t subdirlen;
+				growstr(&nam1,
+					add2(nam1baselen, subdirlen =
+					     strlen(di->d_name)));
+				memcpy(&nam1.buf[nam1baselen], di->d_name,
+				       add2(subdirlen, 1));
+			}
+			process_path(ctl, nam1.buf);
+		}
+		closedir(dh);
+	}
+
+	return 0;
+}
diff --git a/locale/programs/xalloc.h b/locale/programs/xalloc.h
new file mode 100644
index 0000000000..0129a85e2e
--- /dev/null
+++ b/locale/programs/xalloc.h
@@ -0,0 +1,129 @@
+/*
+ * Copyright (C) 2010 Davidlohr Bueso <dave@gnu.org>
+ *
+ * This file may be redistributed under the terms of the
+ * GNU Lesser General Public License.
+ *
+ * General memory allocation wrappers for malloc, realloc, calloc and strdup
+ */
+
+#ifndef UTIL_LINUX_XALLOC_H
+#define UTIL_LINUX_XALLOC_H
+
+#include <stdlib.h>
+#include <string.h>
+
+#include "c.h"
+
+#ifndef XALLOC_EXIT_CODE
+# define XALLOC_EXIT_CODE EXIT_FAILURE
+#endif
+
+static inline void __attribute__((__noreturn__))
+__err_oom(const char *file, unsigned int line)
+{
+	err(XALLOC_EXIT_CODE, "%s: %u: cannot allocate memory", file, line);
+}
+
+#define err_oom()	__err_oom(__FILE__, __LINE__)
+
+static inline __ul_alloc_size(1) __ul_returns_nonnull
+void *xmalloc(const size_t size)
+{
+        void *ret = malloc(size);
+
+        if (!ret && size)
+                err(XALLOC_EXIT_CODE, "cannot allocate %zu bytes", size);
+        return ret;
+}
+
+static inline __ul_alloc_size(2) __ul_returns_nonnull
+void *xrealloc(void *ptr, const size_t size)
+{
+        void *ret = realloc(ptr, size);
+
+        if (!ret && size)
+                err(XALLOC_EXIT_CODE, "cannot allocate %zu bytes", size);
+        return ret;
+}
+
+static inline __ul_calloc_size(1, 2) __ul_returns_nonnull
+void *xcalloc(const size_t nelems, const size_t size)
+{
+        void *ret = calloc(nelems, size);
+
+        if (!ret && size && nelems)
+                err(XALLOC_EXIT_CODE, "cannot allocate %zu bytes", size);
+        return ret;
+}
+
+static inline char __attribute__((warn_unused_result)) __ul_returns_nonnull
+*xstrdup(const char *str)
+{
+        char *ret;
+
+        if (!str)
+                return NULL;
+
+        ret = strdup(str);
+
+        if (!ret)
+                err(XALLOC_EXIT_CODE, "cannot duplicate string");
+        return ret;
+}
+
+static inline char * __attribute__((warn_unused_result)) __ul_returns_nonnull
+xstrndup(const char *str, size_t size)
+{
+        char *ret;
+
+        if (!str)
+                return NULL;
+
+        ret = strndup(str, size);
+
+        if (!ret)
+                err(XALLOC_EXIT_CODE, "cannot duplicate string");
+        return ret;
+}
+
+
+static inline int __attribute__ ((__format__(printf, 2, 3)))
+    xasprintf(char **strp, const char *fmt, ...)
+{
+	int ret;
+	va_list args;
+	va_start(args, fmt);
+	ret = vasprintf(&(*strp), fmt, args);
+	va_end(args);
+	if (ret < 0)
+		err(XALLOC_EXIT_CODE, "cannot allocate string");
+	return ret;
+}
+
+static inline int  __attribute__ ((__format__(printf, 2, 0)))
+xvasprintf(char **strp, const char *fmt, va_list ap)
+{
+	int ret = vasprintf(&(*strp), fmt, ap);
+	if (ret < 0)
+		err(XALLOC_EXIT_CODE, "cannot allocate string");
+	return ret;
+}
+
+
+static inline char * __attribute__((warn_unused_result)) xgethostname(void)
+{
+	char *name;
+	size_t sz = get_hostname_max() + 1;
+
+	name = xmalloc(sizeof(char) * sz);
+
+	if (gethostname(name, sz) != 0) {
+		free(name);
+		return NULL;
+	}
+	name[sz - 1] = '\0';
+	return name;
+}
+
+#endif
