From 64dc75786d12cc4df005de50add12e36503f579a Mon Sep 17 00:00:00 2001
From: Eric Biggers <ebiggers3@gmail.com>
Date: Fri, 23 Sep 2016 21:56:19 -0700
Subject: [PATCH] Detect nonstandard or missing nanosecond-precision stat
 timestamps

Reported-by: maarten-k <maarten.kooyman@surfsara.nl>
---
 programs/detect.sh | 32 ++++++++++++++++++++++++++++++--
 programs/gzip.c    |  8 ++++----
 2 files changed, 34 insertions(+), 6 deletions(-)

diff --git a/programs/detect.sh b/programs/detect.sh
index 7e310a0..5f811b4 100755
--- a/programs/detect.sh
+++ b/programs/detect.sh
@@ -11,24 +11,52 @@ echo "#define CONFIG_H"
 tmpfile="$(mktemp -t libdeflate_config.XXXXXXXX)"
 trap "rm -f \"$tmpfile\"" EXIT
 
+program_compiles() {
+	echo "$1" > "$tmpfile"
+	$CC $PROG_CFLAGS -x c "$tmpfile" -o /dev/null > /dev/null 2>&1
+}
+
 check_function() {
 	funcname="$1"
 	macro="HAVE_$(echo $funcname | tr a-z A-Z)"
-	echo "int main() { $funcname(); }" > "$tmpfile"
 	echo
 	echo "/* Is the $funcname() function available? */"
-	if $CC $CFLAGS -x c $tmpfile -o /dev/null > /dev/null 2>&1; then
+	if program_compiles "int main() { $funcname(); }"; then
 		echo "#define $macro 1"
 	else
 		echo "/* $macro is not set */"
 	fi
 }
 
+have_stat_field() {
+	program_compiles "#include <sys/types.h>
+			  #include <sys/stat.h>
+			  int main() { struct stat st; st.$1; }"
+}
+
+check_stat_nanosecond_precision() {
+	echo
+	echo "/* Does stat() provide nanosecond-precision timestamps? */"
+	if have_stat_field st_atim; then
+		echo "#define HAVE_STAT_NANOSECOND_PRECISION 1"
+	elif have_stat_field st_atimespec; then
+		# Nonstandard field names used by OS X and older BSDs
+		echo "#define HAVE_STAT_NANOSECOND_PRECISION 1"
+		echo "#define st_atim st_atimespec"
+		echo "#define st_mtim st_mtimespec"
+		echo "#define st_ctim st_ctimespec"
+	else
+		echo "/* HAVE_STAT_NANOSECOND_PRECISION is not set */"
+	fi
+}
+
 check_function clock_gettime
 check_function futimens
 check_function futimes
 check_function posix_fadvise
 check_function posix_madvise
 
+check_stat_nanosecond_precision
+
 echo
 echo "#endif /* CONFIG_H */"
diff --git a/programs/gzip.c b/programs/gzip.c
index 00b2a00..61acaf3 100644
--- a/programs/gzip.c
+++ b/programs/gzip.c
@@ -257,23 +257,23 @@ restore_timestamps(struct file_stream *out, const tchar *newpath,
 		   const struct stat *stbuf)
 {
 	int ret;
-#if defined(HAVE_FUTIMENS)
+#if defined(HAVE_FUTIMENS) && defined(HAVE_STAT_NANOSECOND_PRECISION)
 	struct timespec times[2] = {
 		stbuf->st_atim, stbuf->st_mtim,
 	};
 	ret = futimens(out->fd, times);
-#elif defined(HAVE_FUTIMES)
+#elif defined(HAVE_FUTIMES) && defined(HAVE_STAT_NANOSECOND_PRECISION)
 	struct timeval times[2] = {
 		{ stbuf->st_atim.tv_sec, stbuf->st_atim.tv_nsec / 1000, },
 		{ stbuf->st_mtim.tv_sec, stbuf->st_mtim.tv_nsec / 1000, },
 	};
 	ret = futimes(out->fd, times);
-#else /* HAVE_FUTIMES */
+#else
 	struct tutimbuf times = {
 		stbuf->st_atime, stbuf->st_mtime,
 	};
 	ret = tutime(newpath, &times);
-#endif /* !HAVE_FUTIMES */
+#endif
 	if (ret != 0)
 		msg_errno("%"TS": unable to preserve timestamps", out->name);
 }