[core] buffer_append_string_encoded_json()

src/buffer.c

@@ -667,6 +667,85 @@ void buffer_append_string_encoded(buffer * const restrict b, const char * const
 	}
 }
 
+void buffer_append_string_encoded_json(buffer * const restrict b, const char * const restrict s, const size_t len) {
+	const unsigned char * const restrict ds = (unsigned char *)s;
+	size_t dlen = 0;
+
+	/* calculate space needed for string including encodings */
+	for (size_t i = 0; i < len; ++i) {
+		int c = ds[i];
+		if (c == '"' || c == '\\' || c < 0x20 || c == 0x7f) {
+			switch (c) {
+			  case '\b':
+			  case '\t':
+			  case '\n':
+			  case '\f':
+			  case '\r':
+			  case '"':
+			  case '\\':
+				dlen += 2;
+				break;
+			  default:
+				dlen += 6; /* \uCCCC */
+				break;
+			}
+		}
+		else {
+			++dlen;
+		}
+	}
+
+	unsigned char * const d = (unsigned char *)buffer_extend(b, dlen);
+
+	if (__builtin_expect( (dlen == len), 1)) {/*(short-circuit; nothing to encode)*/
+		memcpy(d, ds, len);
+		return;
+	}
+
+	dlen = 0;
+	for (size_t i = 0; i < len; ++i) {
+		int c = ds[i];
+		if (c == '"' || c == '\\' || c < 0x20 || c == 0x7f) {
+			d[dlen++] = '\\';
+			switch (c) {
+			  case '\b':
+				d[dlen++] = 'b';
+				break;
+			  case '\t':
+				d[dlen++] = 't';
+				break;
+			  case '\n':
+				d[dlen++] = 'n';
+				break;
+			  case '\f':
+				d[dlen++] = 'f';
+				break;
+			  case '\r':
+				d[dlen++] = 'r';
+				break;
+			  case '"':
+				d[dlen++] = '"';
+				break;
+			  case '\\':
+				d[dlen++] = '\\';
+				break;
+			  default:
+				d[dlen  ] = 'u';
+				d[dlen+1] = '0';
+				d[dlen+2] = '0';
+				d[dlen+3] = hex_chars_lc[(c >> 4) & 0x0F];
+				d[dlen+4] = hex_chars_lc[c & 0x0F];
+				dlen += 5;
+				break;
+			}
+		}
+		else {
+			d[dlen++] = c;
+		}
+	}
+}
+
+
 void buffer_append_string_c_escaped(buffer * const restrict b, const char * const restrict s, size_t s_len) {
 	unsigned char *ds, *d;
 	size_t d_len, ndx;

src/buffer.h

@@ -186,6 +186,8 @@ typedef enum {
 
 void buffer_append_string_encoded(buffer * restrict b, const char * restrict s, size_t s_len, buffer_encoding_t encoding);
 
+void buffer_append_string_encoded_json(buffer * restrict b, const char * restrict s, size_t len);
+
 /* escape non-printable characters; simple escapes for \t, \r, \n; fallback to \xCC */
 __attribute_nonnull__()
 void buffer_append_string_c_escaped(buffer * restrict b, const char * restrict s, size_t s_len);