util: allow subst to build on systems that do not have utimes()

Make subst more portable so it can deal with such oler systems that do
not have utimes().  Note that it is important that subst build
correctly without an autoconf-generated config.h (since that is what
happens on a cross-compile), as well as using whatever features are
available as determined by autoconf when doing a native build.  We
currently assume the presence of utime(), but not utimes() or
futimes().

Signed-off-by: Theodore Ts'o <tytso@mit.edu>

configure

@@ -13003,7 +13003,7 @@ if test "$ac_res" != no; then :
 fi
 
 fi
-for ac_func in  	__secure_getenv 	backtrace 	blkid_probe_get_topology 	blkid_probe_enable_partitions 	chflags 	fadvise64 	fallocate 	fallocate64 	fchown 	fdatasync 	fstat64 	ftruncate64 	futimes 	getcwd 	getdtablesize 	getmntinfo 	getpwuid_r 	getrlimit 	getrusage 	jrand48 	llseek 	lseek64 	mallinfo 	mbstowcs 	memalign 	mempcpy 	mmap 	msync 	nanosleep 	open64 	pathconf 	posix_fadvise 	posix_fadvise64 	posix_memalign 	prctl 	pread 	pwrite 	pread64 	pwrite64 	secure_getenv 	setmntent 	setresgid 	setresuid 	snprintf 	srandom 	stpcpy 	strcasecmp 	strdup 	strnlen 	strptime 	strtoull 	sync_file_range 	sysconf 	usleep 	utime 	valloc
+for ac_func in  	__secure_getenv 	backtrace 	blkid_probe_get_topology 	blkid_probe_enable_partitions 	chflags 	fadvise64 	fallocate 	fallocate64 	fchown 	fdatasync 	fstat64 	ftruncate64 	futimes 	getcwd 	getdtablesize 	getmntinfo 	getpwuid_r 	getrlimit 	getrusage 	jrand48 	llseek 	lseek64 	mallinfo 	mbstowcs 	memalign 	mempcpy 	mmap 	msync 	nanosleep 	open64 	pathconf 	posix_fadvise 	posix_fadvise64 	posix_memalign 	prctl 	pread 	pwrite 	pread64 	pwrite64 	secure_getenv 	setmntent 	setresgid 	setresuid 	snprintf 	srandom 	stpcpy 	strcasecmp 	strdup 	strnlen 	strptime 	strtoull 	sync_file_range 	sysconf 	usleep 	utime 	utimes 	valloc
 do :
   as_ac_var=`$as_echo "ac_cv_func_$ac_func" | $as_tr_sh`
 ac_fn_c_check_func "$LINENO" "$ac_func" "$as_ac_var"

configure.in

@@ -1087,6 +1087,7 @@ AC_CHECK_FUNCS(m4_flatten([
 	sysconf
 	usleep
 	utime
+	utimes
 	valloc
 ]))
 dnl

lib/config.h.in

@@ -536,6 +536,9 @@
 /* Define to 1 if you have the `utime' function. */
 #undef HAVE_UTIME
 
+/* Define to 1 if you have the `utimes' function. */
+#undef HAVE_UTIMES
+
 /* Define to 1 if you have the <utime.h> header file. */
 #undef HAVE_UTIME_H
 

util/subst.c

@@ -7,6 +7,8 @@
 
 #ifdef HAVE_CONFIG_H
 #include "config.h"
+#else
+#define HAVE_SYS_TIME_H
 #endif
 #include <stdio.h>
 #include <errno.h>
@@ -291,6 +293,23 @@ static int compare_file(FILE *old_f, FILE *new_f)
 	return retval;
 }
 
+void set_utimes(const char *filename, int fd, const struct timeval times[2])
+{
+#ifdef HAVE_FUTIMES
+	if (futimes(fd, times) < 0)
+		perror("futimes");
+#elif HAVE_UTIMES
+	if (utimes(filename, times) < 0)
+		perror("utimes");
+#else
+	struct utimbuf ut;
+
+	ut.actime = times[0].tv_sec;
+	ut.modtime = times[1].tv_sec;
+	if (utime(filename, &ut) < 0)
+		perror("utime");
+#endif
+}
 
 
 int main(int argc, char **argv)
@@ -405,13 +424,7 @@ int main(int argc, char **argv)
 					tv[0] = tv[1];
 				else if (verbose)
 					printf("Using original atime\n");
-#ifdef HAVE_FUTIMES
+				set_utimes(outfn, fileno(old), tv);
-				if (futimes(fileno(old), tv) < 0)
-					perror("futimes");
-#else
-				if (utimes(outfn, tv) < 0)
-					perror("utimes");
-#endif
 			}
 			fclose(out);
 			if (unlink(newfn) < 0)