Adjust to Gnulib strftime changes for macOS

Stop using the fprintftime module, as as with recent Gnulib changes
it breaks the build on macOS, and fixing this would drag in threading
libraries and macOS-specific libraries that are overkill for tar.
Instead, just use strftime; that’s good enough here and arguably
better in case someone attacks tar with a huge time format string.
* gnulib.modules: Remove fprintftime.
* src/checkpoint.c: Do not include fprintftime.
(format_checkpoint_string): Always output some useful info (a decimal
seconds count), even if localtime fails. Do not output more than
256 bytes of time info, as that’s likely a DoS attack.  Stick with
plain strftime, as fprintftime’s extra features are overkill here.

diff --git a/gnulib.modules b/gnulib.modules
index 2640614d092df9d4871743e8009a7f9600b04a19..ede48729bd604a81d3fb0dc1a34fd53158da8abe 100644 (file)
--- a/gnulib.modules
+++ b/gnulib.modules
@@ -49,7 +49,6 @@ file-has-acl
 fileblocks
 flexmember
 fnmatch-gnu
-fprintftime
 free-posix
 fseeko
 fstatat

diff --git a/src/checkpoint.c b/src/checkpoint.c
index 903b8ce320db84ddeb42ed1de82f3058e2211358..a07a54eaa2733af215ae9aca6eae00f1555f4854 100644 (file)
--- a/src/checkpoint.c
+++ b/src/checkpoint.c
@@ -21,9 +21,7 @@
 #include "common.h"
 
 #include <wordsplit.h>
-
 #include <flexmember.h>
-#include <fprintftime.h>
 
 #include <sys/ioctl.h>
 #include <termios.h>
@@ -153,6 +151,9 @@ checkpoint_finish_compile (void)
     }
 }
 
+/* Get the number of columns in the FP output stream.
+   FIXME: The rest of the code counts bytes, not columns,
+   so columns don't line up if multi-byte characters are output.  */
 static intmax_t
 getwidth (FILE *fp)
 {
@@ -304,11 +305,23 @@ format_checkpoint_string (FILE *fp, intmax_t len,
            case 't':
              {
                struct timespec ts = current_timespec ();
-               const char *fmt = arg ? arg : "%c";
                struct tm *tm = localtime (&ts.tv_sec);
-               len = add_printf (len,
-                                 (tm ? fprintftime (fp, fmt, tm, 0, ts.tv_nsec)
-                                  : fprintf (fp, "????""-??""-?? ??:??:??")));
+               char const *tmstr = NULL;
+
+               /* Keep BUF relatively small, as any text timestamp
+                  not fitting into BUF is likely a DoS attack.  */
+               char buf[max (SYSINT_BUFSIZE, 256)];
+
+               if (tm)
+                 {
+                   buf[0] = '\0';
+                   char const *fmt = arg ? arg : "%c";
+                   if (strftime (buf, sizeof buf, fmt, tm) != 0 || !buf[0])
+                     tmstr = buf;
+                 }
+               if (!tmstr)
+                 tmstr = timetostr (ts.tv_sec, buf);
+               len = add_printf (len, fprintf (fp, "%s", tmstr));
              }
              break;