utf8: intruduce utf8_escape_non_printable

src/shared/utf8.c

@@ -212,6 +212,45 @@ char *utf8_escape_invalid(const char *str) {
         return p;
 }
 
+char *utf8_escape_non_printable(const char *str) {
+        char *p, *s;
+
+        assert(str);
+
+        p = s = malloc(strlen(str) * 4 + 1);
+        if (!p)
+                return NULL;
+
+        while (*str) {
+                int len;
+
+                len = utf8_encoded_valid_unichar(str);
+                if (len > 0) {
+                        if (utf8_is_printable(str, len)) {
+                                s = mempcpy(s, str, len);
+                                str += len;
+                        } else {
+                                if ((*str < ' ') || (*str >= 127)) {
+                                        *(s++) = '\\';
+                                        *(s++) = 'x';
+                                        *(s++) = hexchar((int) *str >> 4);
+                                        *(s++) = hexchar((int) *str);
+                                } else
+                                        *(s++) = *str;
+
+                                str += 1;
+                        }
+                } else {
+                        s = mempcpy(s, UTF8_REPLACEMENT_CHARACTER, strlen(UTF8_REPLACEMENT_CHARACTER));
+                        str += 1;
+                }
+        }
+
+        *s = '\0';
+
+        return p;
+}
+
 char *ascii_is_valid(const char *str) {
         const char *p;
 

src/shared/utf8.h

@@ -30,6 +30,7 @@
 const char *utf8_is_valid(const char *s) _pure_;
 char *ascii_is_valid(const char *s) _pure_;
 char *utf8_escape_invalid(const char *s);
+char *utf8_escape_non_printable(const char *str);
 
 bool utf8_is_printable_newline(const char* str, size_t length, bool newline) _pure_;
 _pure_ static inline bool utf8_is_printable(const char* str, size_t length) {

src/test/test-utf8.c

@@ -66,12 +66,37 @@ static void test_utf8_escaping(void) {
         assert_se(utf8_is_valid(p3));
 }
 
+static void test_utf8_escaping_printable(void) {
+        _cleanup_free_ char *p1, *p2, *p3, *p4, *p5;
+
+        p1 = utf8_escape_non_printable("goo goo goo");
+        puts(p1);
+        assert_se(utf8_is_valid(p1));
+
+        p2 = utf8_escape_non_printable("\341\204\341\204");
+        puts(p2);
+        assert_se(utf8_is_valid(p2));
+
+        p3 = utf8_escape_non_printable("\341\204");
+        puts(p3);
+        assert_se(utf8_is_valid(p3));
+
+        p4 = utf8_escape_non_printable("ąę\n가너도루\n1234\n\341\204\341\204\n\001 \019\20\a");
+        puts(p4);
+        assert_se(utf8_is_valid(p4));
+
+        p5 = utf8_escape_non_printable("\001 \019\20\a");
+        puts(p5);
+        assert_se(utf8_is_valid(p5));
+}
+
 int main(int argc, char *argv[]) {
         test_utf8_is_valid();
         test_utf8_is_printable();
         test_ascii_is_valid();
         test_utf8_encoded_valid_unichar();
         test_utf8_escaping();
+        test_utf8_escaping_printable();
 
         return 0;
 }