* NEWS: New option --atime-preserve=system, which uses O_NOATIME.

[chaz/tar] / src / misc.c

diff --git a/src/misc.c b/src/misc.c
index 2ba52a38ae58fd935de74e9c13662184a2a52c90..78844ffcc8f6ed5adca60b9f6cd9fb9a8bab8c74 100644 (file)
--- a/src/misc.c
+++ b/src/misc.c
@@ -23,6 +23,14 @@
 #include <quotearg.h>
 #include <save-cwd.h>
 #include <unlinkdir.h>
+#include <utimens.h>
+
+#if HAVE_STROPTS_H
+# include <stropts.h>
+#endif
+#if HAVE_SYS_FILIO_H
+# include <sys/filio.h>
+#endif
 
 \f
 /* Handling strings.  */
@@ -206,6 +214,61 @@ unquote_string (char *string)
   return result;
 }
 \f
+/* Handling numbers.  */
+
+/* Output fraction and trailing digits appropriate for a nanoseconds
+   count equal to NS, but don't output unnecessary '.' or trailing
+   zeros.  */
+
+void
+code_ns_fraction (int ns, char *p)
+{
+  if (ns == 0)
+    *p = '\0';
+  else
+    {
+      int i = 9;
+      *p++ = '.';
+
+      while (ns % 10 == 0)
+       {
+         ns /= 10;
+         i--;
+       }
+
+      p[i] = '\0';
+
+      for (;;)
+       {
+         p[--i] = '0' + ns % 10;
+         if (i == 0)
+           break;
+         ns /= 10;
+       }
+    }
+}
+
+char const *
+code_timespec (struct timespec t, char sbuf[TIMESPEC_STRSIZE_BOUND])
+{
+  time_t s = t.tv_sec;
+  int ns = t.tv_nsec;
+  char *np;
+  bool negative = s < 0;
+
+  if (negative && ns != 0)
+    {
+      s++;
+      ns = BILLION - ns;
+    }
+
+  np = umaxtostr (negative ? - (uintmax_t) s : (uintmax_t) s, sbuf + 1);
+  if (negative)
+    *--np = '-';
+  code_ns_fraction (ns, sbuf + UINTMAX_STRSIZE_BOUND);
+  return np;
+}
+\f
 /* File handling.  */
 
 /* Saved names in case backup needs to be undone.  */
@@ -435,6 +498,26 @@ deref_stat (bool deref, char const *name, struct stat *buf)
   return deref ? stat (name, buf) : lstat (name, buf);
 }
 
+/* Set FD's (i.e., FILE's) access time to TIMESPEC[0].  If that's not
+   possible to do by itself, set its access and data modification
+   times to TIMESPEC[0] and TIMESPEC[1], respectively.  */
+int
+set_file_atime (int fd, char const *file, struct timespec const timespec[2])
+{
+#ifdef _FIOSATIME
+  if (0 <= fd)
+    {
+      struct timeval timeval;
+      timeval.tv_sec = timespec[0].tv_sec;
+      timeval.tv_usec = timespec[0].tv_nsec / 1000;
+      if (ioctl (fd, _FIOSATIME, &timeval) == 0)
+       return 0;
+    }
+#endif
+
+  return futimens (fd, file, timespec);
+}
+
 /* A description of a working directory.  */
 struct wd
 {