From: Arran Cudbard-Bell <a.cudbardb@freeradius.org>
Date: Sat, 6 Mar 2021 21:43:31 +0000 (+0000)
Subject: Have strftime extend the output buffer
X-Git-Url: http://git.ipfire.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=a961a670c49c35a8addb66092a2ff0f188fe6a7d;p=thirdparty%2Ffreeradius-server.git

Have strftime extend the output buffer
---

diff --git a/src/lib/util/time.c b/src/lib/util/time.c
index 52d1d9e4a41..42989cb20e1 100644
--- a/src/lib/util/time.c
+++ b/src/lib/util/time.c
@@ -543,6 +543,11 @@ done:
 
 DIAG_OFF(format-nonliteral)
 /** Copy a time string (local timezone) to an sbuff
+ *
+ * @note This function will attempt to extend the sbuff by double the length of
+ *	 the fmt string.  It is recommended to either pre-extend the sbuff before
+ *	 calling this function, or avoid using format specifiers that expand to
+ *	 character strings longer than 4 bytes.
  *
  * @param[in] out	Where to write the formatted time string.
  * @param[in] time	Internal server time to convert to wallclock
@@ -560,13 +565,18 @@ size_t fr_time_strftime_local(fr_sbuff_t *out, fr_time_t time, char const *fmt)
 
 	localtime_r(&utime, &tm);
 
-	len = strftime(fr_sbuff_current(out), fr_sbuff_remaining(out), fmt, &tm);
+	len = strftime(fr_sbuff_current(out), fr_sbuff_extend_lowat(NULL, out, strlen(fmt) * 2), fmt, &tm);
 	if (len == 0) return 0;
 
 	return fr_sbuff_advance(out, len);
 }
 
 /** Copy a time string (UTC) to an sbuff
+ *
+ * @note This function will attempt to extend the sbuff by double the length of
+ *	 the fmt string.  It is recommended to either pre-extend the sbuff before
+ *	 calling this function, or avoid using format specifiers that expand to
+ *	 character strings longer than 4 bytes.
  *
  * @param[in] out	Where to write the formatted time string.
  * @param[in] time	Internal server time to convert to wallclock
@@ -584,7 +594,7 @@ size_t fr_time_strftime_utc(fr_sbuff_t *out, fr_time_t time, char const *fmt)
 
 	gmtime_r(&utime, &tm);
 
-	len = strftime(fr_sbuff_current(out), fr_sbuff_remaining(out), fmt, &tm);
+	len = strftime(fr_sbuff_current(out), fr_sbuff_extend_lowat(NULL, out, strlen(fmt) * 2), fmt, &tm);
 	if (len == 0) return 0;
 
 	return fr_sbuff_advance(out, len);