Merge pull request #62 from delroth/ranlib-utime

ranlib: attempt to use utimens variants when available

cctools/configure

@@ -17044,18 +17044,76 @@ fi
 
 
 
-for ac_func in strmode
+for ac_func in strmode, utimensat
 do :
-  ac_fn_c_check_func "$LINENO" "strmode" "ac_cv_func_strmode"
-if test "x$ac_cv_func_strmode" = xyes; then :
+  as_ac_var=`$as_echo "ac_cv_func_$ac_func" | $as_tr_sh`
+ac_fn_c_check_func "$LINENO" "$ac_func" "$as_ac_var"
+if eval test \"x\$"$as_ac_var"\" = x"yes"; then :
   cat >>confdefs.h <<_ACEOF
-#define HAVE_STRMODE 1
+#define `$as_echo "HAVE_$ac_func" | $as_tr_cpp` 1
 _ACEOF
 
 fi
 done
 
 
+### Check how to access struct stat's tv_nsec field.
+{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for st_mtimespec.tv_nsec in struct stat" >&5
+$as_echo_n "checking for st_mtimespec.tv_nsec in struct stat... " >&6; }
+cat confdefs.h - <<_ACEOF >conftest.$ac_ext
+/* end confdefs.h.  */
+#include <sys/stat.h>
+int
+main ()
+{
+
+    struct stat st;
+    st.st_mtimespec.tv_nsec = 0;
+
+  ;
+  return 0;
+}
+_ACEOF
+if ac_fn_c_try_compile "$LINENO"; then :
+
+$as_echo "#define HAVE_STAT_ST_MTIMESPEC 1" >>confdefs.h
+
+   { $as_echo "$as_me:${as_lineno-$LINENO}: result: yes" >&5
+$as_echo "yes" >&6; }
+else
+  { $as_echo "$as_me:${as_lineno-$LINENO}: result: no" >&5
+$as_echo "no" >&6; }
+fi
+rm -f core conftest.err conftest.$ac_objext conftest.$ac_ext
+
+{ $as_echo "$as_me:${as_lineno-$LINENO}: checking for st_mtim.tv_nsec in struct stat" >&5
+$as_echo_n "checking for st_mtim.tv_nsec in struct stat... " >&6; }
+cat confdefs.h - <<_ACEOF >conftest.$ac_ext
+/* end confdefs.h.  */
+#include <sys/stat.h>
+int
+main ()
+{
+
+    struct stat st;
+    st.st_mtim.tv_nsec = 0;
+
+  ;
+  return 0;
+}
+_ACEOF
+if ac_fn_c_try_compile "$LINENO"; then :
+
+$as_echo "#define HAVE_STAT_ST_MTIM 1" >>confdefs.h
+
+   { $as_echo "$as_me:${as_lineno-$LINENO}: result: yes" >&5
+$as_echo "yes" >&6; }
+else
+  { $as_echo "$as_me:${as_lineno-$LINENO}: result: no" >&5
+$as_echo "no" >&6; }
+fi
+rm -f core conftest.err conftest.$ac_objext conftest.$ac_ext
+
 ### Check for __cxa_demangle in various C++ ABI libs ###
 
 { $as_echo "$as_me:${as_lineno-$LINENO}: checking for __cxa_demangle in -lc++abi" >&5

cctools/configure.ac

@@ -268,7 +268,32 @@ AC_CHECK_LIB([uuid],[uuid_generate_random],[
   AC_CHECK_HEADERS([uuid/uuid.h], [UUID_LIB=-luuid])], [])
 AC_SUBST(UUID_LIB)
 
-AC_CHECK_FUNCS([strmode])
+AC_CHECK_FUNCS([strmode, utimensat])
+
+### Check how to access struct stat's tv_nsec field.
+AC_MSG_CHECKING(for st_mtimespec.tv_nsec in struct stat)
+AC_COMPILE_IFELSE(
+  [AC_LANG_PROGRAM(
+    [[#include <sys/stat.h>]],
+    [[
+    struct stat st;
+    st.st_mtimespec.tv_nsec = 0;
+    ]])],
+  [AC_DEFINE(HAVE_STAT_ST_MTIMESPEC, 1, [struct stat has st_mtimespec.tv_nsec])
+   AC_MSG_RESULT([yes])],
+  [AC_MSG_RESULT([no])])
+
+AC_MSG_CHECKING(for st_mtim.tv_nsec in struct stat)
+AC_COMPILE_IFELSE(
+  [AC_LANG_PROGRAM(
+    [[#include <sys/stat.h>]],
+    [[
+    struct stat st;
+    st.st_mtim.tv_nsec = 0;
+    ]])],
+  [AC_DEFINE(HAVE_STAT_ST_MTIM, 1, [struct stat has st_mtim.tv_nsec])
+   AC_MSG_RESULT([yes])],
+  [AC_MSG_RESULT([no])])
 
 ### Check for __cxa_demangle in various C++ ABI libs ###
 

cctools/misc/libtool.c

@@ -59,9 +59,47 @@
 #include <servers/bootstrap.h>
 #endif
 
-/* cctools-port */
+/* cctools-port start */
 int asprintf(char **strp, const char *fmt, ...); 
 
+/*
+ * utimens utility to set file times with sub-second resolution when available.
+ * This is done by using utimensat if available at compile time.
+ *
+ * macOS is special cased: utimensat is only visible at compile time when
+ * building for macOS >= 10.13, but with proper runtime checks we can make
+ * builds targeted at older versions also work with sub-second resolution when
+ * available. This is especially important because APFS introduces sub-second
+ * timestamp resolution.
+ */
+#if defined(__APPLE__) && defined(HAVE_UTIMENSAT)
+#pragma weak utimensat
+#endif
+
+static int utimens(const char *path, const struct timespec times[2])
+{
+#ifdef HAVE_UTIMENSAT
+#ifdef __APPLE__
+    if (utimensat != NULL)
+#endif
+	return utimensat(AT_FDCWD, path, times, 0);
+#endif
+
+    /* Fall back to truncating the timestamp to 1s resolution. */
+#ifndef __OPENSTEP__
+    struct utimbuf timep;
+    timep.actime = times[0].tv_sec;
+    timep.modtime = times[1].tv_sec;
+    return utime(path, &timep);
+#else
+    time_t timep[2];
+    timep[0] = times[0].tv_sec;
+    timep[1] = times[1].tv_sec;
+    return utime(path, timep);
+#endif
+}
+/* cctools-port end */
+
 /*
  * This is used internally to build the table of contents.
  */
@@ -2307,11 +2345,7 @@ struct ofile *ofile)
     struct fat_arch *fat_arch;
     struct fat_arch_64 *fat_arch64;
     int fd;
-#ifndef __OPENSTEP__
-    struct utimbuf timep;
-#else
-    time_t timep[2];
-#endif
+    struct timespec times[2];
     struct stat stat_buf;
     struct ar_hdr toc_ar_hdr;
     enum bool some_tocs, same_toc, different_offsets;
@@ -2881,15 +2915,19 @@ struct ofile *ofile)
 	 * Now set the modtime of the created library back to it's stat time
 	 * when we first closed it.
 	 */
-#ifndef __OPENSTEP__
-	timep.actime = stat_buf.st_mtime;
-	timep.modtime = stat_buf.st_mtime;
-	if(utime(output, &timep) == -1)
+#ifdef HAVE_STAT_ST_MTIMESPEC
+	times[0] = stat_buf.st_mtimespec;
+	times[1] = stat_buf.st_mtimespec;
+#elif HAVE_STAT_ST_MTIM
+	times[0] = stat_buf.st_mtim;
+	times[1] = stat_buf.st_mtim;
 #else
-	timep[0] = stat_buf.st_mtime;
-	timep[1] = stat_buf.st_mtime;
-	if(utime(output, timep) == -1)
+	times[0].tv_sec = stat_buf.st_mtime;
+	times[0].tv_nsec = 0;
+	times[1].tv_sec = stat_buf.st_mtime;
+	times[0].tv_nsec = 0;
 #endif
+	if(utimens(output, times) == -1)
 	{
 	    system_fatal("can't set the modifiy times in output file: %s",
 			 output);