X-Git-Url: https://mattmccutchen.net/rsync/rsync.git/blobdiff_plain/8950ac03f8fd0fb645c7d2374195ea884d091f72..740819ef7b3b96451e16b2fa3891d46cfc73ec64:/log.c

diff --git a/log.c b/log.c
index 64e97b91..3b53a9ae 100644
--- a/log.c
+++ b/log.c
@@ -289,7 +289,31 @@ void rprintf(enum logcode code, const char *format, ...)
 	len = vsnprintf(buf, sizeof(buf), format, ap);
 	va_end(ap);
 
-	if (len > sizeof(buf)-1) exit_cleanup(RERR_MESSAGEIO);
+	/* Deal with buffer overruns.  Instead of panicking, just
+	 * truncate the resulting string.  Note that some vsnprintf()s
+	 * return -1 on truncation, e.g., glibc 2.0.6 and earlier. */
+	if (len > sizeof(buf)-1  ||  len < 0) {
+		const char ellipsis[] = "[...]";
+
+		/* Reset length, and zero-terminate the end of our buffer */
+		len = sizeof(buf)-1;
+		buf[len] = '\0';
+
+		/* Copy the ellipsis to the end of the string, but give
+		 * us one extra character:
+		 *
+		 *                  v--- null byte at buf[sizeof(buf)-1]
+		 *        abcdefghij0
+		 *     -> abcd[...]00  <-- now two null bytes at end
+		 *
+		 * If the input format string has a trailing newline,
+		 * we copy it into that extra null; if it doesn't, well,
+		 * all we lose is one byte.  */
+		strncpy(buf+len-sizeof(ellipsis), ellipsis, sizeof(ellipsis));
+		if (format[strlen(format)-1] == '\n') {
+			buf[len-1] = '\n';
+		}
+	}
 
 	rwrite(code, buf, len);
 }