From 317beebef8b0f60eb36255b35cbea71c84f6ac38 Mon Sep 17 00:00:00 2001
From: Wayne Davison <wayne@opencoder.net>
Date: Tue, 30 Jun 2020 12:02:48 -0700
Subject: [PATCH] Avoid crash of transfer logging w/default log format.

---
 NEWS.md             |  3 +++
 loadparm.c          | 19 +++++++++----------
 testsuite/rsync.fns |  6 +++++-
 3 files changed, 17 insertions(+), 11 deletions(-)

diff --git a/NEWS.md b/NEWS.md
index 8d35e252b..1d6dea697 100644
--- a/NEWS.md
+++ b/NEWS.md
@@ -8,6 +8,9 @@ Protocol: 31 (unchanged)
 
 ### BUG FIXES:
 
+ - Avoid a crash when a daemon module enables `transfer logging` without
+   setting a `log format` value.
+
  - Fixed installing rsync-ssl script from an alternate build dir.
 
  - Fixed the updating of configure.sh from an alternate build dir.
diff --git a/loadparm.c b/loadparm.c
index 819888c5d..180cf8295 100644
--- a/loadparm.c
+++ b/loadparm.c
@@ -463,25 +463,25 @@ void reset_daemon_vars(void)
 
 /* Expand %VAR% references.  Any unknown vars or unrecognized
  * syntax leaves the raw chars unchanged. */
-static char *expand_vars(char *str)
+static char *expand_vars(const char *str)
 {
-	char *buf, *t, *f;
+	char *buf, *t;
+	const char *f;
 	int bufsize;
 
 	if (!str || !strchr(str, '%'))
-		return str;
+		return (char *)str; /* TODO change return value to const char* at some point. */
 
 	bufsize = strlen(str) + 2048;
 	buf = new_array(char, bufsize+1); /* +1 for trailing '\0' */
 
 	for (t = buf, f = str; bufsize && *f; ) {
-		if (*f == '%' && *++f != '%') {
-			char *percent = strchr(f, '%');
-			if (percent) {
+		if (*f == '%' && isUpper(f+1)) {
+			char *percent = strchr(f+1, '%');
+			if (percent && percent - f < bufsize) {
 				char *val;
-				*percent = '\0';
-				val = getenv(f);
-				*percent = '%';
+				strlcpy(t, f+1, percent - f);
+				val = getenv(t);
 				if (val) {
 					int len = strlcpy(t, val, bufsize+1);
 					if (len > bufsize)
@@ -492,7 +492,6 @@ static char *expand_vars(char *str)
 					continue;
 				}
 			}
-			f--;
 		}
 		*t++ = *f++;
 		bufsize--;
diff --git a/testsuite/rsync.fns b/testsuite/rsync.fns
index 246aab0ce..58701fd73 100644
--- a/testsuite/rsync.fns
+++ b/testsuite/rsync.fns
@@ -297,8 +297,9 @@ use chroot = no
 munge symlinks = no
 hosts allow = localhost 127.0.0.0/24 192.168.0.0/16 10.0.0.0/8 $hostname
 log file = $logfile
-log format = %i %h [%a] %m (%u) %l %f%L
 transfer logging = yes
+# We don't define log format here so that the test-hidden module will default
+# to the internal static string (since we had a crash trying to tweak it).
 exclude = ? foobar.baz
 max verbosity = 4
 $uid_setting
@@ -306,16 +307,19 @@ $gid_setting
 
 [test-from]
 	path = $fromdir
+	log format = %i %h [%a] %m (%u) %l %f%L
 	read only = yes
 	comment = r/o
 
 [test-to]
 	path = $todir
+	log format = %i %h [%a] %m (%u) %l %f%L
 	read only = no
 	comment = r/w
 
 [test-scratch]
 	path = $scratchdir
+	log format = %i %h [%a] %m (%u) %l %f%L
 	read only = no
 
 [test-hidden]