From 453d903de916a9f705398152cec9db369b7d7bb8 Mon Sep 17 00:00:00 2001
From: Paul Eggert <eggert@cs.ucla.edu>
Date: Sat, 15 Nov 2025 01:05:05 -0800
Subject: [PATCH] Adjust to Gnulib strftime changes for macOS
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

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.
---
 gnulib.modules   |  1 -
 src/checkpoint.c | 25 +++++++++++++++++++------
 2 files changed, 19 insertions(+), 7 deletions(-)

diff --git a/gnulib.modules b/gnulib.modules
index 2640614d..ede48729 100644
--- 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 903b8ce3..a07a54ea 100644
--- 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;