common: validate PLIST_DATE values before Time64_T conversion

Avoid undefined behavior when serializing malformed PLIST_DATE values
containing NaN, infinity, or values outside the Time64_T range. Add a
shared helper for checked date conversion and use it across writer paths.

1 files changed, 2 insertions, 0 deletions

diff --git a/src/common.h b/src/common.h
index 7e5aff7..ffaa78c 100644
--- a/src/common.h
+++ b/src/common.h
@@ -22,11 +22,13 @@
 #define COMMON_H
 
 #include <stddef.h>
+#include "time64.h"
 
 #define MAC_EPOCH 978307200
 
 size_t dtostr(char *buf, size_t bufsize, double realval);
 int num_digits_i(int64_t i);
 int num_digits_u(uint64_t i);
+int plist_real_to_time64(double realval, Time64_T *timev);
 
 #endif