From: Tom Gundersen <teg@jklm.no>
Date: Mon, 22 Dec 2014 13:53:40 +0000 (+0100)
Subject: shared: json - support escaping utf16 surrogate pairs
X-Git-Tag: v219~884
X-Git-Url: http://www.chiark.greenend.org.uk/ucgi/~ianmdlvl/git?p=elogind.git;a=commitdiff_plain;h=9bae67d49b861b1f142f1a1e27753fe08e63ade7

shared: json - support escaping utf16 surrogate pairs

We originally only supported escaping ucs2 encoded characters (as \uxxxx). This
only covers the BMP. Support escaping also utf16 surrogate pairs (on the form
\uxxxx\uyyyy) to cover all of unicode.
---

diff --git a/src/shared/json.c b/src/shared/json.c
index 47f801c85..bb3d26f0e 100644
--- a/src/shared/json.c
+++ b/src/shared/json.c
@@ -53,6 +53,42 @@ static void inc_lines(unsigned *line, const char *s, size_t n) {
         }
 }
 
+static int unhex_ucs2(const char *c, uint16_t *ret) {
+        int aa, bb, cc, dd;
+        uint16_t x;
+
+        assert(c);
+        assert(ret);
+
+        aa = unhexchar(c[0]);
+        if (aa < 0)
+                return -EINVAL;
+
+        bb = unhexchar(c[1]);
+        if (bb < 0)
+                return -EINVAL;
+
+        cc = unhexchar(c[2]);
+        if (cc < 0)
+                return -EINVAL;
+
+        dd = unhexchar(c[3]);
+        if (dd < 0)
+                return -EINVAL;
+
+        x =     ((uint16_t) aa << 12) |
+                ((uint16_t) bb << 8) |
+                ((uint16_t) cc << 4) |
+                ((uint16_t) dd);
+
+        if (x <= 0)
+                return -EINVAL;
+
+        *ret = x;
+
+        return 0;
+}
+
 static int json_parse_string(const char **p, char **ret) {
         _cleanup_free_ char *s = NULL;
         size_t n = 0, allocated = 0;
@@ -119,39 +155,40 @@ static int json_parse_string(const char **p, char **ret) {
                         else if (*c == 't')
                                 ch = '\t';
                         else if (*c == 'u') {
-                                int aa, bb, cc, dd;
                                 uint16_t x;
+                                int r;
 
-                                aa = unhexchar(c[1]);
-                                if (aa < 0)
-                                        return -EINVAL;
+                                r = unhex_ucs2(c + 1, &x);
+                                if (r < 0)
+                                        return r;
 
-                                bb = unhexchar(c[2]);
-                                if (bb < 0)
-                                        return -EINVAL;
+                                c += 5;
 
-                                cc = unhexchar(c[3]);
-                                if (cc < 0)
-                                        return -EINVAL;
+                                if (!GREEDY_REALLOC(s, allocated, n + 4))
+                                        return -ENOMEM;
 
-                                dd = unhexchar(c[4]);
-                                if (dd < 0)
+                                if (!utf16_is_surrogate(x))
+                                        n += utf8_encode_unichar(s + n, x);
+                                else if (utf16_is_trailing_surrogate(x))
                                         return -EINVAL;
+                                else {
+                                        uint16_t y;
 
+                                        if (c[0] != '\\' || c[1] != 'u')
+                                                return -EINVAL;
 
-                                x =     ((uint16_t) aa << 12) |
-                                        ((uint16_t) bb << 8) |
-                                        ((uint16_t) cc << 4) |
-                                        ((uint16_t) dd);
+                                        r = unhex_ucs2(c + 2, &y);
+                                        if (r < 0)
+                                                return r;
 
-                                if (x <= 0)
-                                        return -EINVAL;
+                                        c += 6;
 
-                                if (!GREEDY_REALLOC(s, allocated, n + 4))
-                                        return -ENOMEM;
+                                        if (!utf16_is_trailing_surrogate(y))
+                                                return -EINVAL;
+
+                                        n += utf8_encode_unichar(s + n, utf16_surrogate_pair_to_unichar(x, y));
+                                }
 
-                                n += utf8_encode_unichar(s + n, x);
-                                c += 5;
                                 continue;
                         } else
                                 return -EINVAL;
diff --git a/src/test/test-json.c b/src/test/test-json.c
index e53e8ed50..b09131891 100644
--- a/src/test/test-json.c
+++ b/src/test/test-json.c
@@ -99,6 +99,9 @@ int main(int argc, char *argv[]) {
         test_one("\"\xef\xbf\xbd\"", JSON_STRING, "\xef\xbf\xbd", JSON_END);
         test_one("\"\\ufffd\"", JSON_STRING, "\xef\xbf\xbd", JSON_END);
         test_one("\"\\uf\"", -EINVAL);
+        test_one("\"\\ud800a\"", -EINVAL);
+        test_one("\"\\udc00\\udc00\"", -EINVAL);
+        test_one("\"\\ud801\\udc37\"", JSON_STRING, "\xf0\x90\x90\xb7", JSON_END);
 
         return 0;
 }