Introduce string_policy().

2 files changed, 27 insertions, 0 deletions

diff --git a/src/core/utf8.c b/src/core/utf8.c
index 1daaf03f..d931ba19 100644
--- a/src/core/utf8.c
+++ b/src/core/utf8.c
@@ -25,6 +25,8 @@
 #include "utf8.h"
 #include "module.h"
 #include "wcwidth.c"
+/* Provide is_utf8(): */
+#include "recode.h"
 
 int string_advance(char const **str, gboolean utf8)
 {
@@ -41,3 +43,14 @@ int string_advance(char const **str, gboolean utf8)
 		return 1;
 	}
 }
+
+int string_policy(const char *str)
+{
+	if (is_utf8()) {
+		if (!str || g_utf8_validate(str, -1, NULL)) {
+			/* No string provided or valid UTF-8 string: treat as UTF-8: */
+			return TREAT_STRING_AS_UTF8;
+		}
+	}
+	return TREAT_STRING_AS_BYTES;
+}
diff --git a/src/core/utf8.h b/src/core/utf8.h
index 50ee0886..fa11b737 100644
--- a/src/core/utf8.h
+++ b/src/core/utf8.h
@@ -19,6 +19,20 @@ int mk_wcwidth(unichar c);
  */
 int string_advance(char const **str, gboolean utf8);
 
+/* TREAT_STRING_AS_BYTES means strings are to be treated using strncpy,
+ * strnlen, etc.
+ * TREAT_STRING_AS_UTF8 means strings are to be treated using g_utf8_*
+ * functions.
+ */
+#define TREAT_STRING_AS_BYTES 0
+#define TREAT_STRING_AS_UTF8  1
+
+/* Return how the str string ought to be treated: TREAT_STRING_AS_UTF8 if the
+ * terminal handles UTF-8 and if the string appears to be a valid UTF-8 string;
+ * TREAT_STRING_AS_BYTES otherwise.
+ */
+int string_policy(const char *str);
+
 #define unichar_isprint(c) (((c) & ~0x80) >= 32)
 #define is_utf8_leading(c) (((c) & 0xc0) != 0x80)