stat: support high resolution time stamps.

* configure (have_sys_stat): New variable. Set to y when our
test detects <sys/stat.h>. New test added for the presence of
high resolution time stamps in struct stat. If we have these,
we #define HAVE_STAT_NSEC 1 in config.h.

* share/txr/stdlib/path-test.tl (path-newer): Compare
nanosecond parts of the modification time if the seconds are
equal, improving the resolution of the test.

* sysif.c (atime_nsec_s, mtime_nsec_s, ctime_nsec_s): New
symbol variables.
(stat_to_struct): If nanosecond resolution is available, set
the new nanosecond slots from the three tv_nsec fields in
struct stat. Otherwise, set the new slots to zero.
(sysif_init): Initialize the new symbol variables. Add the
three new slots to the stat struct.

* sysif.c (atime_nsec_s, mtime_nsec_s, ctime_nsec_s):
Declared.

* txr.1: Documented new atime-nsec, mtime-nsec and ctime-nsec
slots of stat structure. Added note to path-newer mentioning
high resolution support.

1 files changed, 23 insertions, 0 deletions

diff --git a/configure b/configure
index ba3c6f4d..5d31d359 100755
--- a/configure
+++ b/configure
@@ -127,6 +127,7 @@ debug_support=y
 gen_gc=y
 have_dbl_decimal_dig=
 have_unistd=
+have_sys_stat=
 have_sys_types=
 have_sys_time=
 have_makedev=
@@ -1609,10 +1610,32 @@ int main(void)
 if conftest ; then
   printf "yes\n"
   printf "#define HAVE_SYS_STAT 1\n" >> config.h
+  have_sys_stat=y
 else
   printf "no\n"
 fi
 
+if [ "$have_sys_stat" ] ; then
+  printf "Checking for sub-second resolution time in struct stat ... "
+
+  cat > conftest.c <<!
+
+#include <sys/stat.h>
+
+struct stat s;
+
+int main(void)
+{
+  return s.st_mtim.tv_nsec != 0;
+}
+!
+  if conftest ; then
+    printf "yes\n"
+    printf "#define HAVE_STAT_NSEC 1\n" >> config.h
+  else
+    printf "no\n"
+  fi
+fi
 
 #
 # environ