Add comment to gawkapi.h about string termination.

1 files changed, 6 insertions, 0 deletions

diff --git a/gawkapi.h b/gawkapi.h
index f0244604..975f82df 100644
--- a/gawkapi.h
+++ b/gawkapi.h
@@ -278,6 +278,12 @@ enum {
  * The API deals exclusively with regular chars; these strings may
  * be multibyte encoded in the current locale's encoding and character
  * set. Gawk will convert internally to wide characters if necessary.
+ *
+ * Note that the string may not be terminated with a '\0' character.
+ * In particular, this happens for field values $n where n > 0 and n < NF,
+ * since the string points directly into the $0 buffer. All other strings,
+ * including those created by extensions, should be NUL-terminated. In general
+ * though, extension code should not assume that the string is NUL-terminated!
  */
 typedef struct awk_string {
 	char *str;	/* data */