Better formatting for pax extended header times

As specified, don't include the subsecond part if zero and drop trailing
zeros in the subsecond part.  ok millert@

diff --git a/bin/pax/tar.c b/bin/pax/tar.c
index 949e9ce..cd64ec7 100644 (file)
--- a/bin/pax/tar.c
+++ b/bin/pax/tar.c
@@ -1,4 +1,4 @@
-/*     $OpenBSD: tar.c,v 1.78 2023/12/27 08:29:41 jca Exp $    */
+/*     $OpenBSD: tar.c,v 1.79 2024/01/20 17:34:50 jca Exp $    */
 /*     $NetBSD: tar.c,v 1.5 1995/03/21 09:07:49 cgd Exp $      */
 
 /*-
@@ -984,13 +984,28 @@ xheader_add_ts(struct xheader *xhdr, const char *keyword,
 {
        struct xheader_record *rec;
        int reclen, tmplen;
+       char frac[sizeof(".111222333")] = "";
        char *s;
 
+       /* Only write subsecond part if non-zero */
+       if (value->tv_nsec != 0) {
+               int n;
+
+               n = snprintf(frac, sizeof(frac), ".%09ld",
+                   (long)value->tv_nsec);
+               if (n <= 0)
+                       return -1;
+
+               /* Zap trailing zeros */
+               for (n--; n > 1 && frac[n] == '0'; n--)
+                       frac[n] = '\0';
+       }
+
        tmplen = MINXHDRSZ;
        do {
                reclen = tmplen;
-               tmplen = snprintf(NULL, 0, "%d %s=%lld.%09ld\n", reclen,
-                   keyword, (long long)value->tv_sec, (long)value->tv_nsec);
+               tmplen = snprintf(NULL, 0, "%d %s=%lld%s\n", reclen,
+                   keyword, (long long)value->tv_sec, frac);
        } while (tmplen >= 0 && tmplen != reclen);
        if (tmplen < 0)
                return -1;
@@ -999,8 +1014,8 @@ xheader_add_ts(struct xheader *xhdr, const char *keyword,
        if (rec == NULL)
                return -1;
        rec->reclen = reclen;
-       if (asprintf(&s, "%d %s=%lld.%09ld\n", reclen, keyword,
-           (long long)value->tv_sec, (long)value->tv_nsec) < 0) {
+       if (asprintf(&s, "%d %s=%lld%s\n", reclen, keyword,
+           (long long)value->tv_sec, frac) < 0) {
                free(rec);
                return -1;
        }