utf8.[ch] et al: use char32_t and char16_t instead of int, int32_t, int16_t

rework C11 utf8.[ch] to use char32_t instead of uint32_t when referring
to unicode chars, to make things more expressive.

[
 @zonque:
  * rebased to current master
  * use AC_CHECK_DECLS to detect availibility of char{16,32}_t
  * make utf8_encoded_to_unichar() return int
]

9 files changed, 66 insertions, 42 deletions

diff --git a/configure.ac b/configure.ac
index 228d5ee1da..1517b4e197 100644
--- a/configure.ac
+++ b/configure.ac
@@ -297,7 +297,8 @@ AC_SUBST(CAP_LIBS)
 
 AC_CHECK_FUNCS([memfd_create])
 AC_CHECK_FUNCS([__secure_getenv secure_getenv])
-AC_CHECK_DECLS([gettid, pivot_root, name_to_handle_at, setns, getrandom, renameat2, kcmp, keyctl, key_serial_t, LO_FLAGS_PARTSCAN],
+AC_CHECK_DECLS([gettid, pivot_root, name_to_handle_at, setns, getrandom, renameat2,
+                kcmp, keyctl, key_serial_t, char16_t, char32_t, LO_FLAGS_PARTSCAN],
                [], [], [[
 #include <sys/types.h>
 #include <unistd.h>
diff --git a/src/basic/escape.c b/src/basic/escape.c
index 5661f36813..f276c36c56 100644
--- a/src/basic/escape.c
+++ b/src/basic/escape.c
@@ -119,7 +119,7 @@ char *cescape(const char *s) {
         return cescape_length(s, strlen(s));
 }
 
-int cunescape_one(const char *p, size_t length, uint32_t *ret, bool *eight_bit) {
+int cunescape_one(const char *p, size_t length, char32_t *ret, bool *eight_bit) {
         int r = 1;
 
         assert(p);
@@ -230,7 +230,7 @@ int cunescape_one(const char *p, size_t length, uint32_t *ret, bool *eight_bit)
 
                 int a[8];
                 unsigned i;
-                uint32_t c;
+                char32_t c;
 
                 if (length != (size_t) -1 && length < 9)
                         return -EINVAL;
@@ -267,7 +267,7 @@ int cunescape_one(const char *p, size_t length, uint32_t *ret, bool *eight_bit)
         case '7': {
                 /* octal encoding */
                 int a, b, c;
-                uint32_t m;
+                char32_t m;
 
                 if (length != (size_t) -1 && length < 3)
                         return -EINVAL;
@@ -327,8 +327,8 @@ int cunescape_length_with_prefix(const char *s, size_t length, const char *prefi
 
         for (f = s, t = r + pl; f < s + length; f++) {
                 size_t remaining;
-                uint32_t u;
                 bool eight_bit = false;
+                char32_t u;
                 int k;
 
                 remaining = s + length - f;
diff --git a/src/basic/escape.h b/src/basic/escape.h
index d943aa71f5..ac8f5f3910 100644
--- a/src/basic/escape.h
+++ b/src/basic/escape.h
@@ -25,8 +25,10 @@
 #include <stddef.h>
 #include <stdint.h>
 #include <sys/types.h>
+#include <uchar.h>
 
 #include "string-util.h"
+#include "missing.h"
 
 /* What characters are special in the shell? */
 /* must be escaped outside and inside double-quotes */
@@ -45,7 +47,7 @@ size_t cescape_char(char c, char *buf);
 int cunescape(const char *s, UnescapeFlags flags, char **ret);
 int cunescape_length(const char *s, size_t length, UnescapeFlags flags, char **ret);
 int cunescape_length_with_prefix(const char *s, size_t length, const char *prefix, UnescapeFlags flags, char **ret);
-int cunescape_one(const char *p, size_t length, uint32_t *ret, bool *eight_bit);
+int cunescape_one(const char *p, size_t length, char32_t *ret, bool *eight_bit);
 
 char *xescape(const char *s, const char *bad);
 
diff --git a/src/basic/extract-word.c b/src/basic/extract-word.c
index 090d2a7884..6dcd4f9f5b 100644
--- a/src/basic/extract-word.c
+++ b/src/basic/extract-word.c
@@ -107,8 +107,8 @@ int extract_first_word(const char **p, char **ret, const char *separators, Extra
                         }
 
                         if (flags & EXTRACT_CUNESCAPE) {
-                                uint32_t u;
                                 bool eight_bit = false;
+                                char32_t u;
 
                                 r = cunescape_one(*p, (size_t) -1, &u, &eight_bit);
                                 if (r < 0) {
diff --git a/src/basic/json.c b/src/basic/json.c
index 1523e9fb09..3a3d1ad1e1 100644
--- a/src/basic/json.c
+++ b/src/basic/json.c
@@ -322,7 +322,7 @@ static int json_parse_string(const char **p, char **ret) {
                         else if (*c == 't')
                                 ch = '\t';
                         else if (*c == 'u') {
-                                uint16_t x;
+                                char16_t x;
                                 int r;
 
                                 r = unhex_ucs2(c + 1, &x);
@@ -335,11 +335,11 @@ static int json_parse_string(const char **p, char **ret) {
                                         return -ENOMEM;
 
                                 if (!utf16_is_surrogate(x))
-                                        n += utf8_encode_unichar(s + n, x);
+                                        n += utf8_encode_unichar(s + n, (char32_t) x);
                                 else if (utf16_is_trailing_surrogate(x))
                                         return -EINVAL;
                                 else {
-                                        uint16_t y;
+                                        char16_t y;
 
                                         if (c[0] != '\\' || c[1] != 'u')
                                                 return -EINVAL;
diff --git a/src/basic/missing.h b/src/basic/missing.h
index 6ed2133ed1..48ca04a8a1 100644
--- a/src/basic/missing.h
+++ b/src/basic/missing.h
@@ -36,6 +36,7 @@
 #include <stdlib.h>
 #include <sys/resource.h>
 #include <sys/syscall.h>
+#include <uchar.h>
 #include <unistd.h>
 
 #ifdef HAVE_AUDIT
@@ -1159,4 +1160,13 @@ static inline key_serial_t request_key(const char *type, const char *description
 
 #ifndef IF_OPER_UP
 #define IF_OPER_UP 6
+
+#ifndef HAVE_DECL_CHAR32_T
+#define char32_t uint32_t
+#endif
+
+#ifndef HAVE_DECL_CHAR16_T
+#define char16_t uint16_t
+#endif
+
 #endif
diff --git a/src/basic/string-util.c b/src/basic/string-util.c
index 1f95a9abba..cb75b09c74 100644
--- a/src/basic/string-util.c
+++ b/src/basic/string-util.c
@@ -450,6 +450,7 @@ char *ellipsize_mem(const char *s, size_t old_length, size_t new_length, unsigne
         char *e;
         const char *i, *j;
         unsigned k, len, len2;
+        int r;
 
         assert(s);
         assert(percent <= 100);
@@ -469,10 +470,10 @@ char *ellipsize_mem(const char *s, size_t old_length, size_t new_length, unsigne
 
         k = 0;
         for (i = s; k < x && i < s + old_length; i = utf8_next_char(i)) {
-                int c;
+                char32_t c;
 
-                c = utf8_encoded_to_unichar(i);
-                if (c < 0)
+                r = utf8_encoded_to_unichar(i, &c);
+                if (r < 0)
                         return NULL;
                 k += unichar_iswide(c) ? 2 : 1;
         }
@@ -481,11 +482,11 @@ char *ellipsize_mem(const char *s, size_t old_length, size_t new_length, unsigne
                 x ++;
 
         for (j = s + old_length; k < new_length && j > i; ) {
-                int c;
+                char32_t c;
 
                 j = utf8_prev_char(j);
-                c = utf8_encoded_to_unichar(j);
-                if (c < 0)
+                r = utf8_encoded_to_unichar(j, &c);
+                if (r < 0)
                         return NULL;
                 k += unichar_iswide(c) ? 2 : 1;
         }
diff --git a/src/basic/utf8.c b/src/basic/utf8.c
index 124effd6df..3f024f7e58 100644
--- a/src/basic/utf8.c
+++ b/src/basic/utf8.c
@@ -53,7 +53,7 @@
 #include "macro.h"
 #include "utf8.h"
 
-bool unichar_is_valid(uint32_t ch) {
+bool unichar_is_valid(char32_t ch) {
 
         if (ch >= 0x110000) /* End of unicode space */
                 return false;
@@ -67,7 +67,7 @@ bool unichar_is_valid(uint32_t ch) {
         return true;
 }
 
-static bool unichar_is_control(uint32_t ch) {
+static bool unichar_is_control(char32_t ch) {
 
         /*
           0 to ' '-1 is the C0 range.
@@ -103,8 +103,9 @@ static int utf8_encoded_expected_len(const char *str) {
 }
 
 /* decode one unicode char */
-int utf8_encoded_to_unichar(const char *str) {
-        int unichar, len, i;
+int utf8_encoded_to_unichar(const char *str, char32_t *ret_unichar) {
+        char32_t unichar;
+        int len, i;
 
         assert(str);
 
@@ -112,34 +113,37 @@ int utf8_encoded_to_unichar(const char *str) {
 
         switch (len) {
         case 1:
-                return (int)str[0];
+                *ret_unichar = (char32_t)str[0];
+                return 0;
         case 2:
                 unichar = str[0] & 0x1f;
                 break;
         case 3:
-                unichar = (int)str[0] & 0x0f;
+                unichar = (char32_t)str[0] & 0x0f;
                 break;
         case 4:
-                unichar = (int)str[0] & 0x07;
+                unichar = (char32_t)str[0] & 0x07;
                 break;
         case 5:
-                unichar = (int)str[0] & 0x03;
+                unichar = (char32_t)str[0] & 0x03;
                 break;
         case 6:
-                unichar = (int)str[0] & 0x01;
+                unichar = (char32_t)str[0] & 0x01;
                 break;
         default:
                 return -EINVAL;
         }
 
         for (i = 1; i < len; i++) {
-                if (((int)str[i] & 0xc0) != 0x80)
+                if (((char32_t)str[i] & 0xc0) != 0x80)
                         return -EINVAL;
                 unichar <<= 6;
-                unichar |= (int)str[i] & 0x3f;
+                unichar |= (char32_t)str[i] & 0x3f;
         }
 
-        return unichar;
+        *ret_unichar = unichar;
+
+        return 0;
 }
 
 bool utf8_is_printable_newline(const char* str, size_t length, bool newline) {
@@ -148,15 +152,16 @@ bool utf8_is_printable_newline(const char* str, size_t length, bool newline) {
         assert(str);
 
         for (p = str; length;) {
-                int encoded_len, val;
+                int encoded_len, r;
+                char32_t val;
 
                 encoded_len = utf8_encoded_valid_unichar(p);
                 if (encoded_len < 0 ||
                     (size_t) encoded_len > length)
                         return false;
 
-                val = utf8_encoded_to_unichar(p);
-                if (val < 0 ||
+                r = utf8_encoded_to_unichar(p, &val);
+                if (r < 0 ||
                     unichar_is_control(val) ||
                     (!newline && val == '\n'))
                         return false;
@@ -276,7 +281,7 @@ char *ascii_is_valid(const char *str) {
  * Returns: The length in bytes that the UTF-8 representation does or would
  *          occupy.
  */
-size_t utf8_encode_unichar(char *out_utf8, uint32_t g) {
+size_t utf8_encode_unichar(char *out_utf8, char32_t g) {
 
         if (g < (1 << 7)) {
                 if (out_utf8)
@@ -320,7 +325,7 @@ char *utf16_to_utf8(const void *s, size_t length) {
         t = r;
 
         while (f < (const uint8_t*) s + length) {
-                uint16_t w1, w2;
+                char16_t w1, w2;
 
                 /* see RFC 2781 section 2.2 */
 
@@ -354,7 +359,7 @@ char *utf16_to_utf8(const void *s, size_t length) {
 }
 
 /* expected size used to encode one unicode char */
-static int utf8_unichar_to_encoded_len(int unichar) {
+static int utf8_unichar_to_encoded_len(char32_t unichar) {
 
         if (unichar < 0x80)
                 return 1;
@@ -372,7 +377,8 @@ static int utf8_unichar_to_encoded_len(int unichar) {
 
 /* validate one encoded unicode char and return its length */
 int utf8_encoded_valid_unichar(const char *str) {
-        int len, unichar, i;
+        int len, i, r;
+        char32_t unichar;
 
         assert(str);
 
@@ -389,7 +395,9 @@ int utf8_encoded_valid_unichar(const char *str) {
                 if ((str[i] & 0x80) != 0x80)
                         return -EINVAL;
 
-        unichar = utf8_encoded_to_unichar(str);
+        r = utf8_encoded_to_unichar(str, &unichar);
+        if (r < 0)
+                return r;
 
         /* check if encoded length matches encoded value */
         if (utf8_unichar_to_encoded_len(unichar) != len)
diff --git a/src/basic/utf8.h b/src/basic/utf8.h
index 16c4b5b55d..3e2e35b967 100644
--- a/src/basic/utf8.h
+++ b/src/basic/utf8.h
@@ -24,12 +24,14 @@
 #include <stdbool.h>
 #include <stddef.h>
 #include <stdint.h>
+#include <uchar.h>
 
 #include "macro.h"
+#include "missing.h"
 
 #define UTF8_REPLACEMENT_CHARACTER "\xef\xbf\xbd"
 
-bool unichar_is_valid(uint32_t c);
+bool unichar_is_valid(char32_t c);
 
 const char *utf8_is_valid(const char *s) _pure_;
 char *ascii_is_valid(const char *s) _pure_;
@@ -40,20 +42,20 @@ bool utf8_is_printable_newline(const char* str, size_t length, bool newline) _pu
 char *utf8_escape_invalid(const char *s);
 char *utf8_escape_non_printable(const char *str);
 
-size_t utf8_encode_unichar(char *out_utf8, uint32_t g);
+size_t utf8_encode_unichar(char *out_utf8, char32_t g);
 char *utf16_to_utf8(const void *s, size_t length);
 
 int utf8_encoded_valid_unichar(const char *str);
-int utf8_encoded_to_unichar(const char *str);
+int utf8_encoded_to_unichar(const char *str, char32_t *ret_unichar);
 
-static inline bool utf16_is_surrogate(uint16_t c) {
+static inline bool utf16_is_surrogate(char16_t c) {
         return (0xd800 <= c && c <= 0xdfff);
 }
 
-static inline bool utf16_is_trailing_surrogate(uint16_t c) {
+static inline bool utf16_is_trailing_surrogate(char16_t c) {
         return (0xdc00 <= c && c <= 0xdfff);
 }
 
-static inline uint32_t utf16_surrogate_pair_to_unichar(uint16_t lead, uint16_t trail) {
+static inline char32_t utf16_surrogate_pair_to_unichar(char16_t lead, char16_t trail) {
                 return ((lead - 0xd800) << 10) + (trail - 0xdc00) + 0x10000;
 }